i PATE PATS (PDATE CHLOROFORM J.S. DEPARTMENT OF HEALTH & HUMAN SERVICES ublic Health Service Agency for Toxic Substances and Disease Registry FN Federal Recycling Program Lr Printed on Recycled Paper "PUBLIC HEALTH LIBRARY TOXICOLOGICAL PROFILE FOR CHLOROFORM Prepared by: Syracuse Research Corporation Under Subcontract to: Clement International Corporation Under Contract No. 205-88-0608 Prepared for: U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service Agency for Toxic Substances and Disease Registry April 1993 DISCLAIMER The use of company or product name(s) is for identification only and does not imply endorsement by the Agency for Toxic Substances and Disease Registry. ii UPDATE STATEMENT A Toxicological Profile for chloroform was released on January 1989. This edition supersedes any . previously released draft or final profile. a, £ L Toxicological profiles are revised and republished as necessary, but no less than once every three years. For information regarding the update status of previously released profiles, contact ATSDR at: Agency for Toxic Substances and Disease Registry Division of Toxicology/Toxicology Information Branch 1600 Clifton Road NE, E-29 Atlanta, Georgia 30333 FOREWORD The Superfund Amendments and Reauthorization Act (SARA) of 1986 (Public Law 99-499) extended and amended the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA or Superfund). This public law directed the Agency for Toxic Substances and Disease Registry (ATSDR) to prepare toxicological profiles for hazardous substances which are most commonly found at facilities on the CERCLA National Priorities List and which pose the most significant potential threat to human health, as determined by ATSDR and the Environmental Protection Agency (EPA). The lists of the 250 most significant hazardous substances were published in the Federal Register on April 17, 1987, on October 20, 1988, on October 26, 1989, on October 17, 1990, and on October 17, 1991. A revised list of 275 substances was published on October 28. 1992. Section 104(i)(3) of CERCLA, as amended, directs the Administrator of ATSDR to prepare a toxicological profile for each substance on the lists. Each profile must include the following: (A) The examination, summary, and interpretation of available toxicological information and epidemiological evaluations on a hazardous substance in order to ascertain the levels of significant human exposure for the substance and the associated acute, subacute, and chronic health effects. (B) A determination of whether adequate information on the health effects of each substance is available or in the process of development to determine levels of exposure which present a significant risk to human health of acute. subacute, and chronic health effects. (C) Where appropriate, identification of toxicological testing needed to identify the types or levels of exposure that may present significant risk of adverse health effects in humans. This toxicological profile is prepared in accordance with guidelines developed by ATSDR and EPA. The original guidelines were published in the Federal Register on April 17, 1987. Each profile will be revised and republished as necessary. The ATSDR toxicological profile is intended to characterize succinctly the toxicological and adverse health effects information for the hazardous substance being described. Each profile identifies and reviews the key literature (that has been peer-reviewed) that describes a hazardous substance’s toxicological properties. Other pertinent literature is also presented but described in less detail than the key studies. The profile is not intended to be an exhaustive document; however, more comprehensive sources of specialty information are referenced. Each toxicological profile begins with a public health statement, which describes in nontechnical language a substance’s relevant toxicological properties. Following the public health statement is information concerning levels of significant human exposure and, where known, significant health effects. The adequacy of information to determine a substance’s health effects is described in a health effects summary. Data needs that are of significance to protection of public health will be identified by ATSDR and EPA. The focus of the profiles is on health and toxicological information; therefore, we have included this information in the beginning of the document. vi Foreword The principal audiences for the toxicological profiles are health professionals at the federal. state. and local levels, interested private sector organizations and groups. and members of the public. This profile reflects our assessment of all relevant toxicological testing and information that has been peer reviewed. [It has been reviewed by scientists from ATSDR, the Centers for Disease Control and Prevention (CDC). and other federal agencies. It has also been reviewed by a panel of nongovermnment peer reviewers and is being made available for public review. Final responsibility for the contents and views expressed in this toxicological profile resides with ATSDR. William L. Roper, M.D., Administrator Agency for Toxic Substances and Disease Registry vii CONTRIBUTORS CHEMICAL MANAGER(S)/AUTHORS(S): Selene Chou, Ph.D. ATSDR, Division of Toxicology, Atlanta, GA Marc Odin, M.S. Syracuse Research Corporation, Syracuse, NY Hana Pohl, M.D., Ph.D. Syracuse Research Corporation, Syracuse, NY THE PROFILE HAS UNDERGONE THE FOLLOWING ATSDR INTERNAL REVIEWS: 1. 2. Green Border Review. Green Border review assures the consistency with ATSDR policy. Health Effects Review. The Health Effects Review Committee examines the health effects chapter of each profile for consistency and accuracy in interpreting health effects and classifying endpoints. Minimal Risk Level Review. The Minimal Risk Level Workgroup considers issues relevant to substance-specific minimal risk levels (MRLs), reviews the health effects database of each profile, and makes recommendations for derivation of MRLs. Quality Assurance Review. The Quality Assurance Branch assures that consistency across profiles is maintained, identifies any significant problems in format or content, and establishes that Guidance has been followed. CONTENTS FOREWORD . ©. oie ee ee ee eee ee v CONTRIBUTORS © ott te ee ee ee ee ee eee eee vii LISTOF FIGURES .....vi itu inenasnssamsmenssnsssnovansssssssansmsnsnss xiii LIST OF TABLES ©. i titi ttt eee ee ee eee ee eee eee Xv 1. PUBLIC HEALTH STATEMENT . . . eee eee ees 1 1.1 WHAT IS CHLOROFORM? . . . eee eee 1 1.2 WHAT HAPPENS TO CHLOROFORM WHEN IT ENTERS THE ENVIRONMENT? 2 1.3 HOW MIGHT I BE EXPOSED TO CHLOROFORM? ...................... 2 1.4 HOW CAN CHLOROFORM ENTER AND LEAVE MY BODY? .............. 3 1.5 HOW CAN CHLOROFORM AFFECT MY HEALTH? ...................... 3 1.6 IS THERE A MEDICAL TEST TO DETERMINE WHETHER I HAVE BEEN EXPOSED TO CHLOROFORM? . . . «eee ieee 4 1.7 WHAT RECOMMENDATIONS HAS THE FEDERAL GOVERNMENT MADE TO PROTECT HUMAN HEALTH? . . . . «oe 4 1.8 WHERE CAN I GET MORE INFORMATION? .......... 5 2. HEALTH EFFECTS . . oii titties steer eieeee es 7 2.1 INTRODUCTION oot tt eee eee tees es 7 2.2 DISCUSSION OF HEALTH EFFECTS BY ROUTE OF EXPOSURE ............ 7 2.2.1 Inhalation EXpOSUIE . . ...... ct tiiiinii 8 2211 Death ....v. visi nrrsvemsmrssnensrsnsnensnsasasnmnios 8 22.1.2 Systemic Effects . . . ........ ii 8 2.2.1.3 Immunological Effects ........... iii 18 2.2.1.4 Neurological Effects . ........... iia 18 2.2.1.5 Developmental Effects ........... iii 18 22.1.6 Reproductive Effects ............. iii 19 22.1.7 Genotoxic Effects . . ..... i 19 221.8 CANCEI . . oo tia 19 222 OMIEXPOSUIE . cvs rnsstrrnsnssnesmsassvsnassmsmentsesvessn 20 2221 Death oe 20 2222 Systemic Effects . ............ iii 21 2.2.2.3 Immunological Effects ........... ine 41 2.2.2.4 Neurological Effects . ............. iii 41 2.22.5 Developmental Effects ............... i 42 222.6 Reproductive Effects ............. iii 42 2227 GenotoxiC BIfeCtS . .: vc. csc evsntvrunnenesvnsnnsrsnsnsns 43 ZIT8 CONCET «vv vv mv ms ms 5 5a MP MIRE FERS ar vw ai tm mw ws ws a dW 43 223 Dermal EXpOSUIE . . . o.oo tii 44 223.1 Death o.oo 44 2232 Systemic Effects . . .......... iii i Ad 2.2.3.3 Immunological Effects .............. iii 46 2.2.3.4 Neurological Effects . . ........... i 46 2.2.3.5 Developmental Effects ............... cn 46 223.6 Reproductive Effects ................. iii 46 223.7 CentoXiCBHECIS «coro rvininsnss sss ui os adsd mann mene 46 2238 CalOOF « vv vu wm sm ss ws 54 8s 5s oF A FR bw str mans vn pn wn 46 23 TOXICOKINETICS «cio vin ve 58 50 68 #5 64 5.8 505 sn ww maw vw sm nmsosmsmanssme 46 231 ADSOIPUON ..... 46 23.1.1 Inhalation Exposure .................. iii 46 2312 Oral BSpoSUIE , uc crn vr aman on sombs ams some menimemensssa 46 2313 Dermal BXPOSUIC «x: 5: u sasusnrusornmmnimonmsmrnemsms uss 47 232 DISHIDUUHON « 4 46 «15 cs sea vmruvmsnsnmennmsmmnrrmsnennssnssss 47 23.2.1 Inhalation EXposure ............... iii 47 2322 Oral BIpostlIC , oc wim vs ment noms 4855 69nd 4d hid bd mrmemsa 48 2323 Dermal Exposure ........... cuit rvunnsennsonenrnneen 48 233 Metabolism ...............c0tiiiii iii i re 48 234 EXCIetOn ..... 51 2.3.4.1 Inhalation Exposure . ............... i. 51 2342 Oral ESPOSUIE « + «vv so 50 4 88 55 54 1 65 5 58 5 65 sms meomensmonn 51 2343 Dermal EXPOSUIE oo x vv ss x5 55 510 58 56 54 58 55 8 ms weomemeo ome 51 24 RELEVANCE TO PUBLIC HBALTH ..ciuivsvvivnunmenensasmennnsnnas 51 2.5 BIOMARKERS OF EXPOSURE AND EFFECT ...............uuuuuuuo... 62 2.5.1 Biomarkers Used to Identify or Quantify Exposure to Chloroform . .......... 63 2.5.2 Biomarkers Used to Characterize Effects Caused by Chloroform ............ 64 2.6 INTERACTIONS WITH OTHER CHEMICALS ..................0ou...... 64 2.7 POPULATIONS THAT ARE UNUSUALLY SUSCEPTIBLE .................. 64 2.8. METHODS FOR REDUCING TOXIC EFFECTS . ........ 0... 65 2.8.1 Reducing Peak Absorption Following Exposure ....................... 65 282 Reducing Body Burden .................. 65 2.83 Interfering with the Mechanism of Action for Toxic Effects . .............. 66 29 ADEQUACY OF THE DATABASE . . ......... i, 67 29.1 Existing Information on Health Effects of Chloroform .................. 67 29.2 Identification of Data Needs . . ..................... uuu... 67 293 On-goNZ SIUAIEE . ..uio:nivinvnsminsnionrmnmmmensasnamenensnse 73 CHEMICAL AND PHYSICAL INFORMATION ............. cui... 75 3.1 CHEMICAL IDENTITY ..... ee 75 3.2 PHYSICAL AND CHEMICAL PROPERTIES ................couuiunnn... 75 PRODUCTION, IMPORT, USE, AND DISPOSAL . ..............uuuuiinunn.. 79 dl PRODUCTION 5 tc 6.6 5.6 sot ns ss mw sv vn sv sms 5s me we massa noms esis sesso 79 42 IMPORT/EXPORT . . . 79 43 USE 79 44 DISPOSAL vu iviurvsstasnsnsinsssvavmmnmonsnemsurmonsmontnmss 81 POTENTIAL FOR HUMAN EXPOSURE . .............. nnn... 83 5.1 OVERVIEW . Lo 83 52 RELEASES TO THE ENVIRONMENT ................0¢0iuiinnunnnn... 83 S21 Al wun vs ws sib Ee EEE Edm arr EE ERAN Es 83 SAI WRBE out t msn urusvnnemsmsmsmenmomen tnmun nssnesssssssss 85 S523 S00 Lo. 88 53 ENVIRONMENTAL FATE . .... ott 88 53.1 Transport and Partitioning . . ..................... 88 5.3.2 Transformation and Degradation . .........................0...... 89 89 xi 5.32.2 WaAET ov ie i ee ee ee ee ee eee eee eee 89 5.323 SOI © vt ee ee eee eee 90 54 LEVELS MONITORED OR ESTIMATED IN THE ENVIRONMENT ............ 90 BAT Al vim cusmsmsmensmenmmemanmmssnid iHsBIR BIB IME L £220 wre win 90 5.4.2 WALET oo ot ee ee ee ee ee eee ee eee 91 S43 SOM ov ee ee eee 92 5.4.4 Other Environmental Media . . . ... . «iii 92 5.5 GENERAL POPULATION AND OCCUPATIONAL EXPOSURE ............... 93 5.6 POPULATIONS WITH POTENTIALLY HIGH EXPOSURES ................. 94 5.7 ADEQUACY OF THE DATABASE . . . . . ieee 94 5.7.1 Identification of Data Needs . . . . . . . «ci ii ii iii ieee 95 572 On-going Studies . ......... ci 96 6. ANALYTICAL METHODS . . ot titi tt tt ee ee teeta eee 97 6.1 BIOLOGICAL MATERIALS . . . ttt tees eee eee 97 6.2 ENVIRONMENTAL SAMPLES . . . . eee eee eee es 97 63 ADEQUACY OF THE DATABASE . . . . . ieee 104 6.3.1 Identification of Data Needs . . . . . . . cot titi iii 104 632 On-going Studies ............. iii 105 7. REGULATIONS AND ADVISORIES . . . . eee 107 8. REFERENCES . oi ttt t titi tte te ee ee eects eee ees 111 0. GLOSSARY © ot eee 139 APPENDICES A. USER'S GUIDE . «tiie tte et et tetas eee eee A-1 B. ACRONYMS, ABBREVIATIONS, AND SYMBOLS ........................ B-1 C. PEER REVIEW ites ieee esis eee C-1 2-1 2-2 2-3 2-4 5-1 xiii LIST OF FIGURES Levels of Significant Exposure to Chloroform - Inhalation ....................... 14 Levels of Significant Exposure to Chloroform - Oral ............... coven. 32 Metabolic Pathways of Chloroform Biotransformation . . ..............covvnn 49 Existing Information on Health Effects of Chloroform ..................coon.n 68 Frequency of NPL Sites With Chloroform Contamination ..................o..... 84 2-1 2-3 2-4 2-5 3-1 3-2 4-1 5-1 6-2 7-1 LIST OF TABLES Levels of Significant Exposure to Chloroform - Inhalation ....................... 9 Levels of Significant Exposure to Chloroform - Oral ........................... 22 Levels of Significant Exposure to Chloroform - Dermal ......................... 45 Genotoxicity of Chloroform In Vitro . ........... oii 59 Genotoxicity of Chloroform In Vivo ........... oii 61 Chemical Identity of Chloroform ............... 76 Physical and Chemical Properties of Chloroform . .......................... 77 Facilities That Manufacture or Process Chloroform ............................ 80 Releases to the Environment From Facilities That Manuacture or Process 0 110) 40) 0) u ++ YEE I I I 86 Analytical Methods for Determining Chloroform in Biological Materials .............. 98 Analytical Methods for Determining Chloroform in Environmental Samples ........... 100 Regulations and Guidelines Applicable to Chloroform .......................... 108 1. PUBLIC HEALTH STATEMENT This Statement was prepared to give you information about chloroform and to emphasize the human health effects that may result from exposure to it. The Environmental Protection Agency (EPA) has identified 1,300 sites on its National Priorities List (NPL). Chloroform has been found in at least 646 of these sites including 6 in Puerto Rico. However, we do not know how many of the 1,300 NPL sites have been evaluated for chloroform. As EPA evaluates more sites, the number of sites at which chloroform is found may change. This information is important for you to know because chloroform may cause harmful health effects and because these sites are potential or actual sources of human exposure to chloroform. When a chemical is released from a large area, such as an industrial plant, or from a container, such as a drum or bottle, it enters the environment as a chemical emission. This emission, which is also called a release, does not always lead to exposure. You can be exposed to a chemical only when you come into contact with the chemical. You may be exposed to it in the environment by breathing, eating, or drinking substances containing the chemical or from skin contact with it. If you are exposed to a hazardous chemical such as chloroform, several factors will determine whether harmful health effects will occur and what the type and severity of those health effects will be. These factors include the dose (how much), the duration (how long), the route or pathway by which you are exposed (breathing, eating, drinking, or skin contact), the other chemicals to which you are exposed, and your individual characteristics such as age, sex, nutritional status, family traits, life style, and state of health. 1.1 WHAT IS CHLOROFORM? Chloroform, also known as trichloromethane, is a colorless liquid with a pleasant, nonirritating odor. It has a slight, sweet taste. Most of the chloroform found in the environment comes from industry. Chloroform will only burn when it reaches very high temperatures. Nearly all of the chloroform made in the United States is used to make other chemicals, but some has been sold or traded to other countries. We also import chloroform. Chloroform enters the environment from chemical companies, paper mills, waste water from sewage treatment plants, and drinking water that contains chlorine. In addition to its industrial production and use, small amounts of chloroform are formed as an unwanted product during the process of adding chlorine to water. Chlorine is added to most drinking water and many waste waters to destroy bacteria. There are many ways for chloroform to enter the environment, so small amounts of it are likely to be found almost everywhere. You will find more information about what chloroform is, how it is used, and where it comes from in Chapters 3 and 4. 2 1. PUBLIC HEALTH STATEMENT 1.2 WHAT HAPPENS TO CHLOROFORM WHEN IT ENTERS THE ENVIRONMENT? Chloroform can enter the air directly from factories that make or use it, and by evaporating from water and soil that contain it. It can enter water and soil when waste water that contains chlorine is released into water or soil. It may enter water and soil from spills, and by leaks from storage and waste sites. It evaporates very quickly, which means that most of the chloroform that enters the environment will eventually end up in the air. It dissolves easily in water but does not stick to soil very well. This means that it can travel down through soil to groundwater where it can enter well water. Chloroform appears to last for a long time in the air and in groundwater. Most chloroform in the environment breaks down in the air, but the process is slow. The breakdown products in air include phosgene, which is more toxic than chloroform, and hydrogen chloride. Some chloroform may break down in soil. Chloroform does not appear to build up in plants and animals, so large amounts of chloroform are not expected to be found in foods. You will find more information about where chloroform comes from, how it behaves, and how long it remains in the environment in Chapter 5. 1.3 HOW MIGHT | BE EXPOSED TO CHLOROFORM? You are probably exposed to small amounts of chloroform by drinking water and beverages made using drinking water, such as soft drinks, by eating food, by breathing air, and by skin contact with water that contains chloroform. You are most likely to be exposed to chloroform by drinking water and breathing indoor or outdoor air containing it. The estimated amount of chloroform normally expected to be present in air ranges from 0.02 to 0.05 parts per billion parts of air (ppb) and from 2 to 44 ppb in treated drinking water. An estimated concentration of 0.1 ppb is present in surface water, 0.1 ppb in untreated groundwater, and 0.1 ppb in soil. Nevertheless, as much as 610 ppb has been found in air at a municipal landfill and up to 88 ppb has been found in treated municipal drinking water; 1,900 ppb has been found in drinking water derived from well water near a hazardous waste site; 394 ppb has been found in surface water; 1,900 ppb has been found in groundwater taken near a hazardous waste site; and greater than 0.13 ppb has been found in soil at hazardous waste sites. Chloroform has been found in air from all areas of the United States and in nearly all of the drinking water supplies. We do not know how many areas have surface water, groundwater, or soil that contains chloroform. The average amount of chloroform that you might be exposed to on a typical day by breathing air in various places ranges from 2 to 5 micrograms/day (pg/day) in rural areas, 6 to 200 pg/day in cities, and 80 to 2,200 pg/day in areas near major sources of the chemical. The estimated amount of chloroform you probably are exposed to in drinking water ranges from 4 to 88 pg/day. We cannot estimate the amounts that you may be exposed to by eating food and by coming into contact with water that has chloroform in it. Workers who can be exposed to higher than normal amounts of chloroform include workers at or near chemical plants and factories that make or use chloroform, such as drinking water treatment 3 1. PUBLIC HEALTH STATEMENT plants, waste water treatment plants, and other places from which large amounts of chloroform enter the environment, such as waste burning equipment and paper and pulp mills. The National Institute for Occupational Safety and Health (NIOSH) estimated that 95,778 individuals in the United States have had the potential for occupational exposure to chloroform. You will find more information about how you can be exposed to chloroform in Chapter 5. 1.4 HOW CAN CHLOROFORM ENTER AND LEAVE MY BODY? Chloroform can enter your body if you breathe air, eat food, or drink water that contains chloroform. Chloroform easily enters your body through the skin. Therefore, chloroform may also enter your body if you take a bath or shower in water containing chloroform. In addition, you can breathe in chloroform if the shower water is hot enough for chloroform to evaporate. Studies in humans and animals show that after you breathe air or eat food that has chloroform in it, the chloroform can quickly enter your bloodstream from your lungs and intestines. Inside the body, chloroform is carried by the blood to many other organs. Chloroform usually collects in body fat. Some of the chloroform that enters your body leaves unchanged in the air that you breathe out, and some chloroform in the body is broken down into other chemicals. These chemicals are known as breakdown products and some of them can attach to other chemicals inside the cells of your body and cause harmful effects. Some of the breakdown products also leave the body in the air you breathe out. Only a small amount of the breakdown products leaves the body in the urine and the stool. You can find more information about the behavior of chloroform in the body in Chapter 2. 1.5 HOW CAN CHLOROFORM AFFECT MY HEALTH? In humans, chloroform affects the central nervous system, liver, and kidneys after breathing air or drinking liquids that contain large amounts of the chemical. Chloroform was used as an anesthetic during surgery for many years before its harmful effects on the liver and kidneys were recognized. Breathing about 900 parts of chloroform in a million parts of air (900 ppm) for a short time causes tiredness, dizziness, and headache. Breathing 8,000-10,000 ppm chloroform for a short time causes unconsciousness and death. If over a long time you breathe air, eat food, or drink water that has small amounts of chloroform in it, the chloroform may damage your liver and kidneys. Chloroform can cause sores when it comes in contact with your skin. We do not know whether chloroform causes adverse reproductive effects or birth defects in humans. Abortions occurred in rats and mice that breathed smaller amounts of chloroform during pregnancy and in rats that ate chloroform during pregnancy. Furthermore, abnormal sperm were found in mice that breathed small amounts of chloroform for a few days. Offspring of 4 1. PUBLIC HEALTH STATEMENT rats and mice that breathed chloroform during pregnancy had birth defects. Results of studies in humans who drank chlorinated water, which has chloroform in it, showed a possible link between the chloroform in chlorinated water and the occurrence of cancer of the colon and urinary bladder. Cancer of the liver and kidney developed in rats and mice that ate food or drank water for a long time that had small amounts of chloroform in it. We do not know whether liver and kidney cancer would develop in humans after long-term exposure to chloroform in drinking water. The Department of Health and Human Services has determined that chloroform may reasonably be anticipated to be a carcinogen. The International Agency for Research on Cancer has determined that chloroform is possibly carcinogenic to humans. The EPA has determined that chloroform is a probable human carcinogen. You can find a more complete discussion about how chloroform affects your health in Chapter 2. 1.6 IS THERE A MEDICAL TEST TO DETERMINE WHETHER | HAVE BEEN EXPOSED TO CHLOROFORM? Although we can measure the amount of chloroform in the air that you breathe out, in the blood, urine, and body tissues, we have no reliable test to determine how much chloroform you have been exposed to or whether you will experience any health effects. The measurement of chloroform in body fluids and tissues may help to determine if you have come into contact with large amounts of chloroform, but only soon after it happens, because chloroform leaves the body quickly. Since chloroform is a breakdown product of other chemicals (chlorinated hydrocarbons), the presence of chloroform in your body might also indicate that you have come into contact with those other chemicals. Therefore, small amounts of chloroform in the body may indicate exposure to these other chemicals and not low chloroform levels in the environment. From the information obtained by testing your blood to determine the amount of liver enzymes, we can tell whether the liver has been damaged, but we cannot tell whether the liver damage was caused by chloroform. 1.7 WHAT RECOMMENDATIONS HAS THE FEDERAL GOVERNMENT MADE TO PROTECT HUMAN HEALTH? EPA sets rules for the amount of chloroform allowed in water. The EPA limit for total trihalomethanes, which include chloroform, in drinking water is 100 pg/L (1 pg/L = 1 ppb in water). Furthermore, EPA requires that spills of 10 pounds or more of chloroform be reported. The Occupational Safety and Health Administration (OSHA) sets the levels of chloroform allowed in workplace air in the United States. A permissible occupational exposure limit is 2 ppm time-weighted average in air during an 8-hour workday, 40-hour workweek. 1. PUBLIC HEALTH STATEMENT 1.8 WHERE CAN | GET MORE INFORMATION? If you have any more questions or concerns, please contact your community or state health or environmental quality department or: Agency for Toxic Substances and Disease Registry Division of Toxicology 1600 Clifton Road NE, E-29 Atlanta, Georgia 30333 This agency can also provide you with information on the location of the nearest occupational and environmental health clinic. These clinics specialize in the recognition, evaluation, and treatment of illnesses resulting from exposure to hazardous substances. 2. HEALTH EFFECTS 2.1 INTRODUCTION The primary purpose of this chapter is to provide public health officials, physicians, toxicologists, and other interested individuals and groups with an overall perspective of the toxicology of chloroform and a depiction of significant exposure levels associated with various adverse health effects. It contains descriptions and evaluations of studies and presents levels of significant exposure for chloroform based on toxicological studies and epidemiological investigations. 2.2 DISCUSSION OF HEALTH EFFECTS BY ROUTE OF EXPOSURE To help public health professionals address the needs of persons living or working near hazardous waste sites, the information in this section is organized first by route of exposure--inhalation, oral, and dermal--and then by health effect--death, systemic, immunological, neurological, developmental, reproductive, genotoxic, and carcinogenic effects. These data are discussed in terms of three exposure periods--acute (14 days or less), intermediate (15-364 days), and chronic (365 days or more). Levels of significant exposure for each route and duration are presented in tables and illustrated in figures. The points in the figures showing no-observed-adverse-effect levels (NOAELSs) or lowest-observed-adverse-effect levels (LOAELSs) reflect the actual doses (levels of exposure) used in the studies. LOAELs have been classified into "less serious” or "serious" effects. These distinctions are intended to help the users of the document identify the levels of exposure at which adverse health effects start to appear. They should also help to determine whether or not the effects vary with dose and/or duration, and place into perspective the possible significance of these effects to human health. The significance of the exposure levels shown in the tables and figures may differ depending on the user’s perspective. For example, physicians concerned with the interpretation of clinical findings in exposed persons may be interested in levels of exposure associated with "serious" effects. Public health officials and project managers concerned with appropriate actions to take at hazardous waste sites may want information on levels of exposure associated with more subtle effects in humans or animals (LOAEL) or exposure levels below which no adverse effects (NOAEL) have been observed. Estimates of levels posing minimal risk to humans (Minimal Risk Levels, MRLs) may be of interest to health professionals and citizens alike. Levels of exposure associated with the carcinogenic effects of chloroform are indicated in Figures 2-1 and 2-2. Because cancer effects could occur at lower exposure levels, the figures also show a range for the upper bound of estimated excess risks, ranging from a risk of 1 in 10,000 to 1 in 10,000,000 (10 to 107), as developed by EPA. Estimates of exposure levels posing minimal risk to humans (MRLs) have been made, where data were believed reliable, for the most sensitive noncancer effect for each exposure duration. MRLs include adjustments to reflect human variability and extrapolation of data from laboratory animals to humans. Although methods have been established to derive these levels (Barnes and Dourson 1988; EPA 1989a), uncertainties are associated with these techniques. Furthermore, ATSDR acknowledges additional uncertainties inherent in the application of the procedures to derive less than lifetime MRLs. As an example, acute inhalation MRLs may not be protective for health effects that are delayed in development or are acquired following repeated acute insults, such as hypersensitivity reactions, asthma, or chronic bronchitis. As these kinds of health effects data become available and methods to assess levels of significant human exposure improve, these MRLs will be revised. 8 2. HEALTH EFFECTS 2.2.1 Inhalation Exposure Most of the data regarding inhalation exposure to chloroform in humans were obtained from clinical reports describing health effects in patients under anesthesia. In some instances, however, the results may have been confounded by administration of other drugs or by artificial respiration of patients. Furthermore, most of the studies did not provide any information regarding actual exposure levels for observed effects. Despite these facts, chloroform-induced effects in humans are supported by those observed in animals under experimental conditions. The human studies cited in the profile provide the reader with qualitative information on chloroform toxicity in humans. 2.2.1.1 Death Information on the exposure levels of chloroform leading to death in humans was obtained from clinical reports of patients exposed to chloroform via anesthesia. Older clinical reports suggested that concentrations of =40,000 ppm, if continued for several minutes, may be an overdose (Featherstone 1947). When a cohort of 1,502 patients exposed under anesthesia to 10,000-22,500 ppm chloroform was evaluated, no indication of increased mortality was found (Whitaker and Jones 1965). In most patients, the anesthesia did not last longer than 30 minutes. Several studies reported deaths in women after childbirth when chloroform anesthesia had been used (Royston 1924; Townsend 1939). No levels of actual exposure were provided. Death was caused by acute hepatotoxicity. Prolonged labor with starvation, dehydration, and exhaustion contributed to the chloroform-induced hepatotoxicity. Levels of acute exposure resulting in animal deaths are generally lower than those reported for patients under anesthesia; however, the exposure durations are generally longer in the animal studies. An inhalation LCs of 9,770 ppm for a 4-hour exposure was reported for female rats (Lundberg et al. 1986). However, exposure to 8,000 ppm for 4 hours was lethal to albino rats (Smyth et al. 1962). Male mice appear to be more sensitive than female mice. Following exposure to 1,024 ppm for 1-3 hours, 15 of 18 male mice died within 11 days; however, most of the female mice similarly exposed survived for several months (Deringer et al. 1953). Male mice that died had kidney and liver damage, while females did not. An exposure as low as 692 ppm for 1-3 hours resulted in the death of three of six male mice within 8 days. When exposed to 4,500 ppm chloroform for 9 hours, 10 of 20 female mice died (Gehring 1968). Increased mortality was observed in male rats exposed to 85 ppm chloroform for 6 months (Torkelson et al. 1976). The deaths were attributed to pneumonia. Rats of either sex exposed to 50 ppm survived. Exposure to 85 ppm for 6 months did not increase mortality in rabbits and guinea pigs. Similarly, no deaths were reported in dogs exposed to 25 ppm chloroform for the same time period. The LCs, and all reliable LOAEL values for death in each species and duration category are recorded in Table 2-1 and plotted in Figure 2-1. 2.2.1.2 Systemic Effects No studies were located regarding musculoskeletal or dermal/ocular effects in humans or animals after inhalation exposure to chloroform. The effects of inhalation exposure on the respiratory, cardiovascular, gastrointestinal, hematological, hepatic, and renal system are discussed below. The highest NOAEL values and all reliable LOAEL values for each systemic effect in each species and duration category are recorded in Table 2-1 and plotted in Figure 2-1. TABLE 2-1. Levels of Significant Exposure to Chloroform - Inhalation LOAEL (effect) Exposure Key to duration/ NOAEL Less serious Serious figure Species frequency System (ppm) (ppm) (ppm) Reference ACUTE EXPOSURE Death 1 Rat 1d 8,000 (5/6 died) Smyth et al. 4 hr/d 1962 2 Rat 1d 9,770 (LCgq for Lundberg et al. 4 hr/d females) 1986 3 Mouse 1d 4,500 (10/20 females Gehring 1968 9 hr/d died) 4 Mouse 1d 692 (3/6 males died) Deringer et al. » 1-3 hr/d 1953 x m Systemi ystemic q 9 Human 1d Cardio 8,000 (arrhythmia) Smith et al. m 113 min/d Gastro 8,000 (vomiting) 1973 A Hemato 8,000 (increased m prothrombin time) oe Hepatic 8,000 (increased on sul fobromophthalein retention) 6 Human 1d Resp 10,000 (changes in whitaker and 0.5-2 hr/d respiratory rate) Jones 1965 Cardio 10,000 (cardiac arrhythmia, bradycardia) Gastro 10,000 (vomiting) 7 Rat 1d Hepatic 76 153 (SDH-enzyme levels 4,885 (centrilobular Lundberg et al. 4 hr/d increased) necrosis) 1986 8 Rat 0d Other 30 (decreased weight Baeder and Gd 7-16 gain of dams) Hofmann 1988 7 hr/d 9 Mouse 1d Hepatic 246 (fatty changes in Culliford and 2 hr/d both sexes) Hewitt 1957 Renal 246 (tubular necrosis in males) TABLE 2-1 (Continued) Exposure LOAEL (effect) Key to duration/ NOAEL Less serious Serious figure? Species frequency System (ppm) (ppm) (ppm) Reference 10 Mouse 1d Hepatic 100 (increased fat Kylin et al. 4 hr/d infiltration) 1963 1 Mouse 1d Hepatic 692 942 (liver necrosis in Deringer et al. 1-3 hr/d males that died) 1953 Renal 692 (tubular necrosis in males that died) 12 Mouse 8 d Hepatic 100 (increased SGPT Murray et al. Gd 8-15 activity) 1979 7 hr/d Other 100 (decreased weight gain of dams) ~o 13 Mouse 1d Hepatic 4,500 (increased SGPT Gehring 1968 T 9 hr/d activity) A 2 Neurological 3 14 Human 1d 1,500 (light anesthesia) Goodman and y Gilman 1980 .) 5 15 Human 1d 920 (dizziness, Lehmann and » 3 min/d vertigo) Hasegawa 1910 16 Human 1d 8,000 (narcosis) Smith et al. 113 min/d 1973 17 Human 1d 10,000 (narcosis) Whitaker and 0.5-2 hr/d Jones 1965 18 Mouse 1d 2,500 3,100 (slight 4,000 (anesthesia) Lehmann and Flury 0.5-2 hr/d narcosis) 1943 19 Cat 1d 7,200 (disturbed 21,500 (deep anesthesia) Lehmann and Flury 5-15 min/d equilibrium) 1943 Developmental 20 Rat 10 d 30° (delayed 100 (acaudate fetuses Schwetz et al. Gd 6-15 ossification) with imperforate 1974 7 hr/d anus; missing ribs) 300 (fetal resorptions) ok TABLE 2-1 (Continued) LOAEL (effect) Exposure Key to duration/ NOAEL Less serious Serious figure? Species frequency System (ppm) (ppm) (ppm) Reference 21 Rat 10d 30 (slight growth Baeder and Gd 7-16 retardation) Hofmann 1988 7 hr/d 22 Mouse 8d 100 (cleft palate, Murray et al. Gd 8-15 decreased 1979 7 hr/d ossification) Reproductive 23 Rat 10 d 100 300 (73% decreased Schwetz et al. Gd 6-15 conception rate) 1974 7 hr/d > 24 Rat 10d 100 300 (empty Baeder and T Gd 7-16 implantations in Hofmann 1988 xo 8/20 dams) — 7 hr/d z m 25 Mouse 8d 100 (30-48% decreased Murray et al. a Gd 8-15 ability to 1979 m 7 hr/d maintain pregnancy) S » 26 Mouse 5d 400 (increased % Land et al. 1979, 4 hr/d abnormal sperm) 1981 INTERMEDIATE EXPOSURE Death 27 Rat 6 mo 85 (increased Torkelson et al. 5 d/wk mortality in 1976 7 hr/d 6/10 males) Systemic 28 Human 1-6 mo Hepatic 14 (toxic hepatitis) Phoon et al. (occup) Gastro 14 (vomiting) 1983 29 Human 10-24 mo Gastro 22 (nausea) Challen et al. (occup) 1958 LE TABLE 2-1 (Continued) LOAEL (effect) Exposure Key to duration/ NOAEL Less serious Serious figure® Species frequency System (ppm) (ppm) (ppm) Reference 30 Rat 6 mo Resp 50 85 (interstitial Torkelson et al. 5 d/wk pneumonia in 1976 7 hr/d males) Hemato 85 Hepatic 25 (degenerative changes in males) Renal 25 (cloudy swelling in males) Other 50 (decreased body weight in males) 31 Rabbit 6 mo Resp 25 50 (interstitial Torkelson et al. 5 d/wk pneumonia) 1976 7 hr/d Hemato 85 Hepatic 25 (centrilobular necrosis) Renal 25 (interstitial nephritis) 32 Gn pig 6 mo Resp 85 Torkelson et al. 5d/wk Hemato 85 1976 7 hr/d Hepatic 25 (granular degeneration) Renal 25 (nephritis) 33 Dog 6 mo Resp 25 Torkelson et al. 5d/wk Hemato 25 1976 7 hr/d Hepatic 25 Renal 25 (cloudy swelling of tubular epithelium in females) Neurological 34 Human 10-24 mo 22 (exhaustion) Challen et al. (occup) 1958 S103443 H11VaH ¢ cl TABLE 2-1 (Continued) Exposure LOAEL (effect) Key to duration/ NOAEL Less serious Serious figure? Species frequency System (ppm) (ppm) (ppm) Reference CHRONIC EXPOSURE Systemic 35 Human 1-4 yr Hepatic 2 (hepatitis) Bomski et al. (occup) 1967 36 Human 3-10 yr Gastro 77 (nausea) Challen et al. (occup) 1958 Neurological 37 Human 3-10 yr 77 (exhaustion, Challen et al. (occup) irritability, 1958 depression, lack of concentration) ®The number corresponds to entries in Figure 2-1. sed to derive an acute inhalation minimal risk level (MRL) of 0.009 ppm; dose adjusted for intermittent exposure and divided by an uncertainty factor of 1000 (10 for using a LOAEL, 10 for extrapolation from animals to humans, and 10 for human variability). Cardio = cardiovascular; d = day(s); Gastro = gastrointestinal; Gd = gestational day; Gn pig = guinea pig; Hemato = hematological; hr = hour(s); LCgq = Lethal concentration, 50% kill; LOAEL = lowest-observed-adverse-effect level; min = minute(s); mo = month(s); NOAEL = no-observed-adverse-effect level; occup = occupational; Resp = respiratory; SDH = sorbitol dehydrogenase; SGPT = serum glutamic pyruvic transaminase; wk = week(s); yr = year(s) S103443 H11VaH 2 €l FIGURE 2-1. Levels of Significant Exposure to Chloroform - Inhalation ACUTE (< 14 Days) Systemic @ @ & FS FF P $ ° £ £ FS & $ & & & - F fF F & ® & & S$ 8 ppm —— RE 100,000 [~ @® a 10,000 |= 0: mA 4A 4s Aas as ® Orme As 47 @sm 13m ‘ Grom @rem A Orem 1,000 "4 Otim @1im ®n Al 26m Qom or @on ® ® @n @ 100 F Qrom Grom ~ 12m @2n @ @xn Oz Qo Oo Qu Qa Qa = 1 10 : ee I 1 1 1 1 0.1 pb I I 1 0.01 Key CL r Rat @ LOAEL for serious effects (animals) NNT aver L m Mouse @ LOAEL for less serous effects (animals) I effects other than cancer 0.001 c Cat QO NOAEL (animals) 1 A LOAEL for less serious effects (humans) ~~ ~~ A LOAEL for serious effects (humans) Bl LCs501D50 The number next to each point corresponds to entries in Table 2-1. S§103443 H1TV3H 2 14 (bpm) 1,000 100 10 0.01 0.001 0.0001 0.00001 0.000001 0.0000001 FIGURE 2-1 (Continued) INTERMEDIATE CHRONIC (15-365 Days) (= 365 Days) Systemic Systemic & & A é & & & & el & F LS ~ @2r On 3 Pm O32 Osx O3th poe Aer Osx Oath AnA Ox O33 B3zgp 26 Bor Bath Bass Paz PaocrDParn Ax n § » Ass 9 x m m ~ m 0 — i » 10+ Key r Rat & h Rabbit Qo m Mouse (@) d Dog A g Guinea pig A LOAEL for serious effects (animals) LOAEL for less serious effects (animals) NOAEL (animals) LOAEL for less serious effects (humans) LOAEL for serious effects (humans) The number next to each point corresponds to entries in Table 2-2. * Doses represent the lowest dose tested per study that produced a tumorigenic response and do not imply the existence of a threshold for the cancer end point. 10°5 Estimated Upper- Bound Human Cancer Risk 108 Levels 107 132030-1 St 16 2. HEALTH EFFECTS Respiratory Effects. Changes in respiratory rate were observed in patients exposed to chloroform via anesthesia (exposure 10,000-22,500 ppm) (Whitaker and Jones 1965). Increased respiratory rates were observed in 44% of 1,502 patients; however, respiratory rates were depressed during deep and prolonged anesthesia. These changes in respiration reflect the effect of chloroform on the respiratory center in the central nervous system; they do not reflect a direct effect on the lungs. No other studies were located regarding respiratory effects in humans after inhalation exposure to chloroform. In some animal species, the lung may be a target organ when inhalation exposure to chloroform is of intermediate duration. Interstitial pneumonitis was observed in male rats exposed to 85 ppm and in rabbits exposed to 50 ppm chloroform for 6 months (Torkelson et al. 1976). The NOAEL was 50 ppm for rats and 25 ppm for rabbits. No respiratory changes were reported in guinea pigs and dogs exposed to 85 and 25 ppm chloroform, respectively. Cardiovascular Effects. Epidemiology studies indicate that chloroform causes cardiac effects in patients under anesthesia. In a cohort of 1,502 patients (exposure 10,000-22,500 ppm), dose-related bradycardia developed in 8% of the cases, and cardiac arrhythmia developed in 1.3% of the cases (Whitaker and Jones 1965). Hypotension was observed in 27% of the patients and was related to the duration of the anesthesia and to pretreatment with thiopentone. Chloroform anesthesia (exposure 8,000-10,000 ppm) caused arrhythmia (nodal rhythm, first degree atrio-ventricular block, or complete heart block) in 50% of the cases from the cohort of 58 patients and hypotension in 12% (Smith et al. 1973). No studies were located regarding cardiovascular effects in animals after inhalation exposure to chloroform. Gastrointestinal Effects. Nausea and vomiting were frequently observed side effects in humans exposed to chloroform via anesthesia (exposure 8,000-22,500 ppm) (Royston 1924; Smith et al. 1973; Townsend 1939; Whitaker and Jones 1965). Nausea and vomiting were observed in workers exposed to 14-400 ppm chloroform for 1-6 months (Phoon et al. 1983). Similarly, gastrointestinal symptoms (nausea, dry mouth, and fullness of the stomach) were reported in workers exposed to 22-71 and 77-237 ppm chloroform for 10-24 months and 3-10 years, respectively (Challen et al. 1958). No studies were located regarding gastrointestinal effects in animals after inhalation exposure to chloroform. Hematological Effects. The hematological system does not appear to be a target of inhalation exposure to chloroform. Except for increased prothrombin time in some individuals after anesthesia exposure to 8,000 ppm, no hematological effects were observed in humans after inhalation exposure to chloroform (Smith et al. 1973). This effect reflects the hepatotoxicity of chloroform because prothrombin is formed in the liver. No hematological effects were observed in rats, rabbits, and guinea pigs exposed to 85 ppm chloroform and in dogs exposed to 25 ppm chloroform for intermediate durations (Torkelson et al. 1976). Hepatic Effects. Chloroform-induced hepatotoxicity is one of the major toxic effects observed in humans and animals after inhalation exposure. Increased sulfobromophthalein retention was observed in some patients exposed to chloroform via anesthesia (exposure 8,000-10,000 ppm), indicating impaired liver function (Smith et al. 1973). Serum transaminase, cholesterol, total bilirubin, and alkaline phosphatase levels were not affected. Several earlier studies report acute hepatic necrosis in women exposed to chloroform via anesthesia (exact exposure not provided) during childbirth (Lunt 1953; Royston 1924; Townsend 1939). The effects observed in the women included jaundice, liver enlargement and tenderness, delirium, coma, and death. Centrilobular necrosis was found at autopsy in those who died. Workers exposed to 14-400 ppm chloroform for 1-6 months developed toxic 17 2. HEALTH EFFECTS hepatitis and other effects including jaundice, nausea, and vomiting, without fever (Phoon et al. 1983). The workers were originally diagnosed with viral hepatitis; however, in light of epidemiology data, the diagnosis was changed to toxic hepatitis. No clinical evidence of liver injury was observed in workers exposed to as much as 71 and 237 ppm chloroform for intermediate and chronic durations, respectively (Challen et al. 1958). In contrast, toxic hepatitis (with hepatomegaly, enhanced serum glutamic pyruvic transaminase (SGPT) and serum glutamic oxaloacetic transaminase (SGOT) activities, and hypergammaglobulinemia) was observed in workers exposed to 2-205 ppm chloroform (Bomski et al. 1967). Coexposure to trace amounts of other solvents was also detected, however. Chloroform-induced hepatotoxicity in various animal species has been reported in several studies. No changes in SGPT activity were observed in rats exposed to 300 ppm chloroform during gestation days 6-15 (Schwetz et al. 1974). In contrast, serum sorbitol dehydrogenase (SDH) activity was increased in rats exposed to 153 ppm for 4 hours (Lundberg et al. 1986), and SGPT levels were increased in mice exposed to 100 ppm for 8 days (Murray et al. 1979) and 4,500 ppm for 9 hours (Gehring 1968). These increased enzyme levels in serum indicate hepatocellular necrosis. Fatty changes were observed microscopically in mice after acute exposure to chloroform concentrations 100 ppm (Culliford and Hewitt 1957; Kylin et al. 1963). Liver necrosis was observed in rats exposed to 4,885 ppm chloroform for 4 hours (Lundberg et al. 1986) and in mice that died after acute exposure to 692-1,106 ppm chloroform, but not in those that survived and were terminated after a 12-month recovery period (Deringer et al. 1953), indicating that the liver damage was reversible. Centrilobular granular degeneration was observed in rats, rabbits, and guinea pigs exposed to 25 ppm chloroform for 6 months, but not in dogs exposed to 25 ppm for the same time period (Torkelson et al. 1976); however, these pathological findings were not observed in the 50 ppm exposure group of rabbits and guinea pigs, or in the 85 ppm exposure group of guinea pigs. Although the liver effects in rabbits and guinea pigs were not dose-related, the small number of surviving animals in the higher exposure group may have influenced the results of the study. Renal Effects. The only information regarding kidney effects in humans after inhalation exposure to chloroform was obtained from case reports of death among women exposed to chloroform via anesthesia during childbirth (Royston 1924). The fatty degeneration of kidneys observed at autopsy indicated chloroform-induced damage. In animals, the kidney is a target organ of inhalation exposure to chloroform. Tubular necrosis was observed in male mice after acute exposure to chloroform concentrations >246 ppm (Culliford and Hewitt 1957; Deringer et al. 1953). Tubular calcifications were observed in mice that survived the exposure and were terminated after a 12-month recovery period. The greater susceptibility of male mice to chloroform-induced kidney damage, compared to female mice, is related to male hormone levels (Deringer et al. 1953). In a study of intermediate duration, increased kidney weight (both sexes) and cloudy swelling (males) were observed in rats and dogs exposed to chloroform concentrations 225 ppm chloroform (Torkelson et al. 1976). Results were not consistent in rabbits and guinea pigs under the same exposure conditions. Cloudy swelling and tubular and interstitial nephritis were observed in groups of rats exposed to 25 ppm chloroform, but not in groups exposed to 50 ppm. The results in rabbits and guinea pigs, however, may reflect the low survival rate at the higher exposure level. Other Systemic Effects. No studies were located regarding other systemic effects in humans after inhalation exposure to chloroform. Decreased body weight gain was observed in rats exposed to 30 ppm chloroform during gestation (Baeder and Hofmann 1988; Newell and Dilley 1978). Similarly, decreased body weight was observed in mice exposed to 100 ppm chloroform during gestation (Murray et al. 1979). Decreased body weight also occurred in male rats exposed to 50 ppm for 6 months (Torkelson et al. 1976). Decreased body weight gain may be related to an anorexic effect of inhalation exposure to chloroform. 18 2. HEALTH EFFECTS 2.2.1.3 Immunological Effects No studies were located regarding immunological effects in humans after inhalation exposure to chloroform. Information on the immunotoxicity of chloroform is limited to one study on effects of chloroform on host resistance in mice. A single exposure to 10.6 ppm chloroform did not increase the mortality rate after streptococcal challenge and did not alter the ability of alveolar macrophages to destroy bacteria (Aranyi et al. 1986). After repeated chloroform exposure, the mortality rate increased, but the bactericidal activity of macrophages was not suppressed. 2.2.1.4 Neurological Effects The central nervous system is a major target for chloroform toxicity in humans and in animals. Chloroform was once widely used as an anesthetic during surgery in humans but has been replaced with less toxic agents. Levels of 8,000-30,000 ppm were used to induce anesthesia (Featherstone 1947; Smith et al. 1973; Whitaker and Jones 1965). Concentrations of =40,000 ppm, if continued for several minutes, could result in death (Featherstone 1947). To induce anesthesia, increasing concentrations of chloroform gradually to 25,000 or 30,000 ppm during the first 2 or 3 minutes with maintenance at much lower levels was recommended. Concentrations <1,500 ppm are insufficient to induce anesthesia; 1,500-2,000 ppm causes light anesthesia (Goodman and Gilman 1980). Dizziness and vertigo occur after exposure to 920 ppm for 3 minutes; headache and slight intoxication occur at higher concentrations (Lehmann and Hasegawa 1910). Exhaustion was reported in 10 women exposed to >22 ppm chloroform during intermediate-duration occupational exposure (Challen et al. 1958). Chronic exposure to chloroform concentrations 277 ppm caused exhaustion, lack of concentration, depression, or irritability in 9 of 10 occupationally exposed women. A case report of an individual addicted to chloroform inhalation for =12 years reported psychotic episodes, hallucinations and delusions, and convulsions (Heilbrunn et al. 1945). Withdrawal symptoms, consisting of pronounced ataxia and dysarthria, occurred following an abrupt discontinuation of chloroform use. Moderate, unspecified, degenerative changes were observed in the ganglion cells in the putamen and the cerebellum at autopsy. Death resulted from an unrelated disease. Central nervous system toxicity in animals includes disturbed equilibrium in cats exposed to 7,200 ppm chloroform for 5 minutes, deep narcosis in cats exposed to 21,500 ppm for 15 minutes, deep narcosis in mice exposed to 4,000 ppm for 30 minutes, slight narcosis in mice exposed to 3,100 ppm for 1 hour, and no obvious effects in mice exposed to 2,500 ppm for 2 hours (Lehmann and Flury 1943; Sax 1979). Memory retrieval was affected in mice exposed to chloroform via anesthesia (concentration not specified) (Valzelli et al. 1988). The amnestic effect was not long-lasting. The highest NOAEL value and all reliable LOAEL values for neurological effects in each species and duration category are recorded in Table 2-1 and plotted in Figure 2-1. 2.2.1.5 Developmental Effects No studies were located regarding developmental effects in humans after inhalation exposure to chloroform. Chloroform-induced fetotoxicity and teratogenicity were observed in experimental animals. The offspring of rats exposed during gestation had decreased fetal crown-rump length, delayed ossification (at 30 ppm), acaudate fetuses with imperforate anus and missing ribs (at 100 ppm) (Schwetz et al. 1974), and decreased fetal body weight and increased fetal resorptions (at 300 ppm). The LOAEL of 30 ppm was used to derive an MRL of 0.009 ppm for acute inhalation exposure to chloroform, as described in the footnote to Table 2-1. Slight growth retardation of 19 2. HEALTH EFFECTS live fetuses at 30 ppm was observed in rats exposed during gestation; no major teratogenic effects were observed (Baeder and Hofmann 1988). The offspring of mice exposed to 100 ppm chloroform during gestation had increased incidences of cleft palate, decreased ossification, and decreased fetal crown-rump length (Murray et al. 1979). The observed malformations occurred in the fetuses that were exposed during organogenesis (days 8-15). Increased resorptions were observed in dams exposed during gestation days 1-7. All reliable LOAEL values for developmental effects in each species in the acute duration category are recorded in Table 2-1 and plotted in Figure 2-1. 2.2.1.6 Reproductive Effects No studies were located regarding reproductive effects in humans after inhalation exposure to chloroform. Several studies indicate that inhalation exposure to chloroform may cause reproductive effects in animals. Rats exposed to chloroform during gestation had decreased conception rates after exposure to 300 ppm, but not after exposure to 100 ppm (Baeder and Hofmann 1988; Schwetz et al. 1974). Similarly, a decreased ability to maintain pregnancy was observed in mice exposed to 100 ppm chloroform (Murray et al. 1979). In addition to the reproductive effects described above, a significant increase in the percentage of abnormal sperm was observed in mice exposed to 400 ppm chloroform for 5 days (Land et al. 1979, 1981). The highest NOAEL value and all reliable LOAEL values for reproductive effects in each species in the acute duration category are recorded in Table 2-1 and plotted in Figure 2-1. 2.2.1.7 Genotoxic Effects No studies were located regarding genotoxic effects in humans after inhalation exposure to chloroform. Inhalation exposure to 400 ppm chloroform for S days increased the percentage of abnormal sperm in mice (Land et al. 1979, 1981). Other genotoxicity studies are discussed in Section 2.4. 2.2.1.8 Cancer No studies were located regarding cancer in humans or animals after inhalation exposure to chloroform. Studies in animals indicate that oral exposure to chloroform causes cancer (see Section 2.2.2.8). Because chloroform is carcinogenic in animals exposed orally and because chloroform has identical toxicological end points following oral or inhalation exposure, EPA (1985a) derived a q;* for inhalation exposure to chloroform based on mouse liver tumor data from a chronic gavage study (NCI 1976). EPA considered the NCI (1976) study to be appropriate to use in the inhalation risk estimate because there are no inhalation cancer bioassays and no pharmacokinetic data to contraindicate the use of gavage data (IRIS 1992). The geometric mean of the estimates for male and female mice in the NCI (1976) study, 8x102 (mg/kg/day)! was recommended as the inhalation q,* for chloroform. EPA (1985a) combined the estimates for both data sets because the data for males includes observations at a lower dose, which appear to be consistent with the female data. Expressed in terms of air concentration, the q,* is equal to 2.3x10” (ug/m3)! or 1.1x10* (ppb). 20 2. HEALTH EFFECTS The air concentrations associated with individual, lifetime upper-bound risks of 10% to 107 are 4.3x107 to 43x10 mg/m’ (8.8x107 to 8.8x107 ppm), assuming that a 70 kg human breathes 20 m’ air/day. The 104 to 107 levels are indicated in Figure 2-1. 2.2.2 Oral Exposure 2.2.2.1 Death Information regarding mortality in humans after oral exposure to chloroform is limited. A man died of severe hepatic injury 9 days after drinking =6 ounces of chloroform (3,755 mg/kg) (Piersol et al. 1933). He was admitted to a hospital, in a deep coma, within 15 minutes of ingestion. In contrast, a patient who ingested 4 ounces (=2,500 mg/kg) recovered from toxic hepatitis (Schroeder 1965). The recovery may have been due to better therapeutic handling of the case. A fatal dose may be as low as 10 mL (14.8 g) or 212 mg/kg (Schroeder 1965). Oral LDs, values in animals vary somewhat. Acute LDs values of 2,000 mg/kg chloroform (Torkelson et al. 1976) and 2,180 mg/kg chloroform (Smyth et al. 1962) were reported for rats. LDs( values in male rats varied with age: 446 mg/kg for 14-day-olds, 1,337 mg/kg for young adults, and 1,188 mg/kg for old adults (Kimura et al. 1971). LDs, values were different for male rats (908 mg/kg) and female rats (1,117 mg/kg) (Chu et al. 1982b). Similarly, the LDs, for male mice was lower (1,120 mg/kg) than for female mice (1,400 mg/kg) (Bowman et al. 1978). In general, young adult males had lower survival rates. In another study, an acute oral LDs, value of 1,100 mg/kg/day was reported for male and female mice (Jones et al. 1958). Decreased survival rates were also observed in male mice exposed to 250 mg/kg chloroform for 14 days, but not in mice exposed to 100 mg/kg (Gulati et al. 1988). Female mice, however, survived 500 mg/kg chloroform treatment. Pregnant animals may be more susceptible to chloroform lethality. Increased mortality was observed in rats exposed to 516 mg/kg/day and rabbits exposed to 100 mg/kg/day chloroform during gestation (Thompson et al. 1974). There was a high rate of mortality in rats exposed to 83 mg/kg/day chloroform in drinking water for 90 days and during a 90-day observation period. Histopathological examination revealed atrophy of the liver and extensive squamous debris in the esophagus and gastric cardia. These changes suggested to the authors that the rats had died of starvation. Mortality was not increased in the 34 mg/kg/day group (Chu et al. 1982a). The vehicle and mode of administration may influence the lethality of chloroform in mice. In 90-day studies in mice, no effect on mortality was observed in groups treated by gavage with 250 mg/kg/day chloroform in oil (Munson et al. 1982) or with 290 mg/kg/day in drinking water (Jorgenson and Rushbrook 1980). The maximum tolerated dose of chloroform in drinking water was calculated as 306 mg/kg/day for mice (Klaunig et al. 1986). Survival was affected in mice exposed by gavage to 400 mg/kg/day chloroform in oil for 60 days, but not in those exposed to 100 mg/kg (Balster and Borzelleca 1982). Exposure to 150 mg/kg/day chloroform in toothpaste by gavage for 6 weeks caused death in 8 of 10 male mice (Roe et al. 1979). In contrast, no death occurred in mice exposed to 149 mg/kg/day chloroform in oil for 30 days; there was an increased incidence of death in males exposed to 297 mg/kg/day (Eschenbrenner and Miller 1945a). No deaths occurred in dogs exposed to 120 mg/kg/day chloroform in toothpaste capsules for 12-18 weeks (Heywood et al. 1979). Chronic exposure to chloroform increased mortality in all male rats exposed to concentrations =15 mg/kg/day chloroform in toothpaste. The principal cause of death was a concurrent respiratory disease (Palmer et al. 1979). No increase in mortality was observed in rats exposed to 60 mg/kg/day chloroform in toothpaste, when the experiment was repeated. Similarly, mortality was not affected in rats exposed to 160 mg/kg/day chloroform in drinking water (Jorgenson et al. 1985). Decreased survival was observed in rats exposed by gavage to concentrations 90 mg/kg/day chloroform in oil for 78 weeks and in mice exposed to 477 mg/kg/day, but not 21 2. HEALTH EFFECTS in mice exposed to 277 mg/kg/day during the same time period (NCI 1976). In addition, no increase in compound-related mortality was observed in mice exposed by gavage to 60 mg/kg/day chloroform in toothpaste (Roe et al. 1979), or in mice exposed to =260 mg/kg/day chloroform (Jorgenson et al. 1985; Klaunig et al. 1986) in drinking water for chronic durations. Similarly, mortality was not affected in dogs exposed to 30 mg/kg/day chloroform in toothpaste capsules for 7.5 years (Heywood et al. 1979). The LDg, and all reliable LOAEL values for death in each species and duration category are recorded in Table 2-2 and plotted in Figure 2-2. 2.2.2.2 Systemic Effects The systemic effects of oral exposure to chloroform are discussed below. The highest NOAEL values and all reliable LOAEL values for each effect in each species and duration category are recorded in Table 2-2 and plotted in Figure 2-2. Respiratory Effects. Information regarding respiratory effects in humans after oral exposure to chloroform is limited. Upper respiratory tract obstruction due to muscular relaxation was observed in a patient who accidentally ingested =2,500 mg/kg chloroform (Schroeder 1965). Congested lungs and scattered patches of pneumonic consolidation were found at autopsy in a man who committed suicide by drinking =6 ounces (3,755 mg/kg) of chloroform (Piersol et al. 1933). The respiratory system does not appear to be a target of chloroform-induced toxicity in animals after oral exposure. No treatment-related histopathological changes were found in the lungs of rats exposed to 160 mg/kg/day or mice exposed to 290 mg/kg/day chloroform in drinking water in a 90-day study (Jorgenson and Rushbrook 1980). in mice exposed by gavage to 41 mg/kg/day chloroform in oil for 105 days (Gulati et al. 1988), or in mice exposed to 257 mg/kg/day in drinking water for 1 year (Klaunig et al. 1986). Following chronic exposure, no histopathological changes were observed in rats exposed by gavage to 200 mg/kg/day chloroform in oil (NCI 1976). Respiratory disease (not otherwise specified) was observed in all chloroform exposed groups of rats (215 mg/kg/day); however, no histopathological changes were observed in a 60 mg/kg/day exposure group during another experiment by the same investigators (Palmer et al. 1979). No histopathological changes were observed in the lungs of mice exposed by gavage to 477 mg/kg/day chloroform in oil for 78 weeks (NCI 1976) or to 60 mg/kg/day in toothpaste for 80 weeks (Roe et al. 1979). Cardiovascular Effects. Information regarding cardiovascular effects after oral exposure to chloroform is limited to case report studies. On admission to the hospital, the blood pressure was 140/90 mmHg and pulse was 70 beats/minute in a patient who accidentally ingested =2,500 mg/kg chloroform (Schroeder 1965). Electrocardiography showed occasional extrasystoles and a slight S-T segment depression. The patient recovered with no persistent cardiovascular change. In another individual, blood pressure was 100/40 mmHg and pulse was 108 beats/minute after ingestion of an unknown quantity of chloroform (Storms 1973). Coexposure with alcohol was involved in this case. The cardiovascular system was not a target for chloroform toxicity in animal studies. No histopathological changes were observed in rats and mice chronically exposed by gavage to 200 and 477 mg/kg/day chloroform, respectively (NCI 1976). Similarly, no cardiovascular changes were observed in dogs exposed to 30 mg/kg/day chloroform in toothpaste for 7.5 years (Heywood et al. 1979). TABLE 2-2. Levels of Significant Exposure to Chloroform - Oral Key to figure? Species Route Exposure duration/ NOAEL frequency System (mg/kg/day) LOAEL (effect) Less serious Serious (mg/kg/day) Reference ACUTE EXPOSURE Death 1 2 10 Human Rat Rat Rat Rat Rat Rabbit Mouse Mouse Mouse (G) (G) (G) (GO) (GO) (Go) (GO) (GO) (GO) 1d 1d 1x/d 1d 1x/d 1d 1x/d 10 d Gd 6-15 1x/d 1d 1x/d 13d Gd 6-18 1x/d 1d 1x/d 1d 1x/d 14 d 1x/d 212 2,000 2,180 516 908 1,117 100 1,120 1,400 1,100 250 (fatal dose) (fatal dose) (LDgp) (LDgq for young adults) (LDgq for old adults) (LDgq for 14-day olds) (4/6 died) (LDgy males) (LDgo females) (3/5 died) (LDgq for males) (LDgq for females) (LDgg) (5/8 males died) Schroeder 1965 Torkelson et al. 1976 Smyth et al. 1962 Kimura et al. 1971 Thompson et al. 1974 S103443 H1TV3H 2 Chu et al. 1982b Thompson et al. 1974 Bowman et al. 1978 Jones et al. 1958 Gulati et al. 1988 22 TABLE 2-2 (Continued) Exposure LOAEL (effect) Key to duration/ NOAEL Less serious Serious figure® Species Route frequency System (mg/kg/day) (mg/kg/day) (mg/kg/day) Reference Systemic 1 Human 1d Resp 2,500 (respiratory tract Schroeder 1965 1x/d obstruction) Cardio 2,500 (arrhythmia) Gastro 2,500 (vomiting) Musc/skel 2,500 (muscle relaxation) Hepatic 2,500 (toxic hepatitis) Renal 2,500 (oliguria) 12 Rat (GO) 0d Gastro 516 (gastric erosions) Thompson et al. Gd 6-15 Hepatic 516 (hepatitis) 1974 1x/d Renal 516 (acute toxic nephrosis) Other 79 126 (decreased body weight gain) 13 Rat (Go) 1d Hemato 546 (reduced Chu et al. 1982b 1x/d hemoglobin and hematocrit) Renal 546 (increased kidney weight - females) 14 Rat (Go) 10d Derm/oc 50 126 (alopecia) Thompson et al. Gd 6-15 Other 20 50 (decreased body 1974 1x/d weight gain) 15 Rat (Go) 10d Hemato 100 (decreased Ruddick et al. Gd 6-15 hemoglobin, 1983 1x/d hematocrit, and erythrocyte count) Hepatic 100 (increased liver weight) Renal 200 400 (increased kidney weight) Other 100 (32% decreased body weight gain) 16 Rabbit (GO) 13d Gastro 20 (diarrhea) Thompson et al. Gd 6-18 Other 35 50 (decreased body 1974 1x/d weight gain) S103443 HLV3H 2 £2 TABLE 2-2 (Continued) LOAEL (effect) S103443 H1V3H 2 Exposure Key to duration/ NOAEL Less serious Serious figure Species Route frequency System (mg/kg/day) (mg/kg/day) (mg/kg/day) Reference 17 Mouse (G) 1d Hepatic 59.2 199 (increased SGPT) Moore et al. 1x/d Renal 59.2 199 (increased 1982 thymidine uptake, necrosis) 18 Mouse (Go) 1d Hepatic 35 (midzonal fatty 350 (centrilobular Jones et al. 1x/d changes) necrosis) 1958 19 Mouse (GO) 14d Hemato 250 Munson et al. 1x/d Hepatic 125 250 (increased SGPT 1982 and SGOT levels) Other 125 250 (16% decreased body weight gain in males) 20 Mouse (Go) 1d Hepatic 65.6 273 (increased Moore et al. 1x/d thymidine uptake, 1982 B increased SGOT) Renal 17.3 65.6 (necrosis) 21 Mouse (GO) 14d Derm/oc 50 100 (rough coat) Gulati et al. 1x/d Other 100 250 (weight loss in 1988 males) Immunological 22 Rat (G0) 1d 765 1,071 (reduced Chu et al. 1982b 1x/d lymphocytes - females) 23 Mouse (GO) 14d 50 (suppressed Munson et al. 1x/d humoral immunity) 1982 Neurological 24 Human 1d 2,500 (deep coma) Schroeder 1965 1x/d 25 Mouse (GO) 14d 31.1 Balster and 1x/d Borzelleca 1982 26 Mouse (G0) 10d 10 30 (taste aversion) Landauer et al. 1982 ve TABLE 2-2 (Continued) LOAEL (effect) Exposure Key to duration/ NOAEL Less serious Serious figure® Species Route frequency System (mg/kg/day) (mg/kg/day) (mg/kg/day) Reference 27 Mouse (Go) 14d 100 250 (hunched posture, Gulati et al. 1x/d inactivity in 1988 males) 28 Mouse (0) 1d 350 (calculated EDgq Jones et al. 1x/d for narcosis) 1958 29 Mouse (Go) 1d 484 (calculated EDgg Balster and 1x/d for motor Borzelleca 1982 performance) Developmental 30 Rat (Go) 10d 200 400 (decreased fetal Ruddick et al. Gd 6-15 weight) 1983 1x/d 31 Rat (Go) 10d 300 316 (increased Thompson et al. Gd 6-15 resorptions, 1974 1x/d decreased fetal weight) 32 Rat (Go) 10d 50 126 (decreased fetal Thompson et al. Gd 6-15 weight) 1974 1x/d 33 Rabbit (GO) 13d 50 Thompson et al. Gd 6-18 1974 1x/d 34 Rabbit (G0) 13d 63 100 (increased Thompson et al. Gd 6-18 resorptions) 1974 1x/d Reproductive 35 Rat (Go) 10d 300 316 (increased Thompson et al. Gd 6-15 resorptions) 1974 1x/d 36 Rabbit (G0) 13d 25 63 (abortion) Thompson et al. Gd 6-18 100 (no viable 1974 1x/d concepti) S103443 H11V3H 2 Se TABLE 2-2 (Continued) LOAEL (effect) Exposure Key to duration/ NOAEL Less serious Serious figure Species Route frequency System (mg/kg/day) (mg/kg/day) (mg/kg/day) Reference INTERMEDIATE EXPOSURE Death 37 Rat (C)) 90 d 83 (high mortality Chu et al. 1982a during exposure and during recovery period) 38 Mouse (G) 6 wk 150 (8/10 males died) Roe et al. 1979 6 d/wk Systemic 39 Rat (W) 28 d Hemato 4 31 (decreased Chu et al. 1982b neutrophils) Hepatic 31 Renal 31 40 Rat (W) 90 d Hemato 114 Chu et al. 1982a Other 34 83 (25% decreased body weight gain) 41 Rat (W) 90 d Resp 160 Jorgenson and Gastro 160 Rushbrook 1980 Hemato 160 Hepatic 160 Renal 160 Other 81 160 (decreased body weight) 42 Rat (G) 13 wk Hemato 150 410 (increased Palmer et al. 7 d/wk cellular 1979 1x/d proliferation) Hepatic 30 150 (increased relative liver weight) 410 (fatty changes, necrosis) Renal 30 150 (increased relative kidney weight) S103443 H1TV3H 2 92 TABLE 2-2 (Continued) LOAEL (effect) Exposure Key to duration/ NOAEL Less serious Serious figure® Species Route frequency System (mg/kg/day) (mg/kg/day) (mg/kg/day) Reference 43 Mouse (GO) 91-94 d Hepatic 60 (fatty changes) 270 (cirrhosis) Bull et al. 1986 1x/d Other 130 270 (15% decreased body weight in males) 44 Mouse (Go) 105d Resp 41 Gulati et al. 1x/d Hepatic 41 (hepatocellular 1988 degeneration in F, females) Renal 41 45 Mouse (W) 52 wk Resp 257 Klaunig et al. 7 d/wk Hepatic 86 (focal necrosis) 1986 ~ Renal 86 (tubular necrosis) ’ Other 86 (15% decreased body I weight gain) 3 > 46 Mouse (GO) 30d Hepatic 297 595 (cirrhosis) Eschenbrenner z 1x/d and Miller 1945a m A 47 Mouse (GO) 90d Hepatic 50 (hydropic Munson et al. a 1x/d hepatocytes) 1982 —~ Renal 50 (chronic » inflammation) Other 250 48 Mouse ) 90 d Resp 290 Jorgenson and Gastro 290 Rushbrook 1980 Hemato 290 Hepatic 32 64 (reversible fatty changes) Renal 290 Other 290 49 Dog (C) 6 wk Hepatic 15¢ 30 (SGPT activity) Heywood et al. 6 d/wk 1979 1x/d L2 TABLE 2-2 (Continued) LOAEL (effect) Exposure Key to duration/ NOAEL Less serious Serious figure® Species Route frequency System (mg/kg/day) (mg/kg/day) (mg/kg/day) Reference Immunological . 50 Mouse (Go) 90d 50 (depressed humoral Munson et al. 1x/d immunity) 1982 250 (cell-mediated immunity affected in females) Neurological 51 Mouse (G0) 90d 31.1 Balster and 1x/d Borzelleca 1982 52 Mouse (Go) 60d 100 (operant behavior Balster and 1x/d affected) Borzelleca 1982 Developmental 53 Mouse (GO) 6-10 wk 31.1 Burkhalter and 1x/d Balster 1979 54 Mouse (Go) 105d 41 (increased Gulati et al. 1x/d epididymal 1988 weights, degeneration of epididymal epithelium in Fy) Reproductive 55 Rat w) 90 d 160 Jorgenson and Rushbrook 1980 56 Rat (G) 13 wk 150 410 (gonadal atrophy Palmer et al. 7 d/wk in both sexes) 1979 1x/d 57 Mouse (Go) 105d 41 Gulati et al. 1x/d 1988 Cancer 58 Mouse (6c; 30d 595 (CEL: hepatoma) Eschenbrenner 1x/d and Miller 1945a S103443 H1TV3H 2 82 TABLE 2-2 (Continued) LOAEL (effect) Exposure Key to duration/ NOAEL Less serious Serious figure® Species Route frequency System (mg/kg/day) (mg/kg/day) (mg/kg/day) Reference CHRONIC EXPOSURE Death 59 Rat (GO) 78 wk 90 (decreased NCI 1976 5 d/wk survival) 1x/d 60 Mouse (GO) 78 wk 477 (decreased NCI 1976 5 d/wk survival) 1x/d Systemic 61 Rat (wv) 180 wk Hepatic 200 (adenofibrosis) Tumasonis et al. 7 d/wk Other 200 (50% decreased 1985, 1987 body weight gain in males) 62 Rat (GO) 78 wk Resp 200 NCI 1976 5S d/wk Cardio 200 1x/d Gastro 200 Hemato 200 Musc/skel 200 Hepatic 100 200 (necrosis in females) Renal 200 Other 90 (15% decreased weight gain) 63 Rat vd) 106 wk Renal 160 Jorgenson et al. 7 d/wk Other 38 81 (30X decreased 1985 body weight) 64 Mouse (GO) 78 wk Resp 477 NCI 1976 5 d/wk Cardio 477 1x/d Gastro 477 Hemato 477 Musc/skel 477 Hepatic 138 (nodular hyperplasia of the liver) Renal 477 Other 477 S103443 H1TV3H 2 62 TABLE 2-2 (Continued) LOAEL (effect) Exposure Key to duration/ NOAEL Less serious Serious figure® Species Route frequency System (mg/kg/day) (mg/kg/day) (mg/kg/day) Reference 65 Mouse (G) 80 wk Resp 60 Roe et al. 1979 6 d/wk Hepatic 60 Renal 60 Other 60 66 Mouse (CD) 104 wk Other 130 263 (decreased body Jorgenson et al. 7 d/wk weight) 1985 67 Dog (C) 7.5 yr Cardio 30 Heywood et al. 6 d/wk Hemato 30 d 1979 Hepatic 15° (increased SGPT activity) Renal 15 30 (fatty changes) Other 30 Neurological 68 Rat (GO) 78 wk 200 NCI 1976 5 d/wk 1x/d 69 Mouse (G) 80 wk 60 Roe et al. 1979 6 d/wk 70 Mouse (GO) 78 wk 144 NCI 1976 S d/wk 1x/d Reproductive Ia! Rat (GO) 78 wk 200 NCI 1976 5 d/wk 1x/d n° Mouse (GO) 78 wk 477 NCI 1976 5 d/wk 1x/d 3 Dog (C) 7.5 yr 30 Heywood et al. 6 d/wk 1979 S103443 H1TV3H ¢ oe TABLE 2-2 (Continued) Exposure LOAEL (effect) Key to duration/ NOAEL Less serious Serious figure™ Species Route frequency System (mg/kg/day) (mg/kg/day) (mg/kg/day) Reference Cancer 74 Rat (CD) 180 wk 200 (CEL: hepatic Tumasonis et al. 7 d/wk neoplastic 1985, 1987 nodules in females, lymphosarcoma in males) 75 Rat (GO) 78 wk 90 (CEL: renal NCI 1976 5 d/wk tubular cell 1x/d adenoma and carcinoma) ~ 76 Rat W) 104 wk 160 (CEL: renal Jorgenson et al. x 7 d/wk tubular cell 1985 9 adenoma and 5 carcinoma) x m 7 Mouse (GO) 78 wk 138 (CEL: NCI 1976 3 5 d/wk hepatocel lular a 1x/d carcinoma) #3 78 Mouse (G) 80 wk 60 (CEL: kidney Roe et al. 1979 6 d/wk tumors) ®The number corresponds to entries in Table 2-2. bused to derive an acute oral minimal risk level (MRL) of 0.2 mg/kg/day; dose divided by an uncertainty factor of 100 (10 for extrapolation from animals to humans and 10 for human variability). “Used to derive an intermediate oral MRL of 0.1 mg/kg/day; dose adjusted for intermittent exposure and divided by an uncertainty factor of 100 (10 for extrapolation from animals to humans, 10 for human variability). dysed to derive a chronic oral MRL of 0.01 mg/kg/day; dose adjusted for intermittent exposure and divided by an uncertainty factor of 1000 (10 for extrapolation from animals to humans, 10 for the use of a LOAEL, and 10 for human variability). (C) = capsule; Cardio = cardiovascular; CEL = cancer effect level; d = day(s); Derm/oc = dermal/ocular; EDgy = effective dose for a given effect in 50% of animals; F, = first filial generation; (G) = gavage; Gastro = gastrointestinal; Gd = gestational day; (GO) = gavage in oil; Hemato = hematological; LDgy = lethal dose, 50% kill; LOAEL = lowest-observed- adverse-effect level; Musc/skel = musculoskeletal; NOAEL = no-observed-adverse-effect level; Resp = respiratory; SGOT = serum glutamic-oxaloacetic transaminase; SGPT = serum glutamic-pyruvic transaminase; (W) = drinking water; wk = week(s); x = time(s); yr = years Ie FIGURE 2-2. Levels of Significant Exposure to Chloroform - Oral ACUTE (< 14 Days) Systemic ¥ & » &F & £0 & Ff x a ’ 3 & & & »¥ § & & > & & & & &£ dq Ef o & 3 & < (mg/kg/day) m—, (ie — 10,000 p= a War A111 A AN Al AN An Msm Mom | FH War [pe 1000 pen We Wy os @ @ 1a @tem @1x @1> Px At @ om O1om PD 1om ®20m Qs Qin ®17m Ox 100 p= on @ 15 P15 Se O2om Otrm P20m 18m en O2om I 10 p= | 1 Key r Rat @ LOAEL for serious effects (animals) ! 1 1 | m Mouse ( LOAEL for less serious effects (animals) : Minimal risk level for I h Rabbit O NOAEL (animals) " effects other than cancer 1 A LOAEL for less serious effects (humans) ~~ \s ’ A LOAEL for serious effects (humans) / 0.1 Lo Hl LD501C50 The number next to each point corresponds to entries in Table 2-2. S103443 H1TV3H ¢ ce (mg/kg/day) 10,000 1,000 100 10 0.1 FIGURE 2-2 (Continued) ACUTE (< 14 Days) Systemic 3 » @ & & & & - ° & & & © ° Ff S&F * & & Aa On ® 2 @1om P21m ®2m 28m ge O3ir @31r Oss @35 ®2im ®@w Otom Oaim Sw Dis ° Qazm 32 @2h gw m r 14r Ben Psm Qa O2im O14 or Otten Om Boom OF Oa Qa3en QO2sm Key r Rat m Mouse h Rabbit @ LOAEL for serious effects (animals) ( LOAEL for less serious effects (animals) (QO NOAEL (animals) A LOAEL for serious effects (humans) The number next to each point corresponds to entries in Table 2-2. S103443 H1IV3H 2 (mg/kg/day) 10,000 1,000 100 0.1 1 FIGURE 2-2 (Continued) INTERMEDIATE (15-364 Days) Systemic N 5° 3 AQ ® & 3° & & § id OS & ¥ & S S § & ® ¢ © Ff 3 po Ou 6m Osm O4om Qusm Quam Qe @43m Qe @3sm Qu Qurr Or Qu Quatr Pex or @>37 Qesm Quam Quam 44m gon @aor @ 48m Ox Qa Quad Oso 1 i 1 | 1 | I 1 1 \o/ Key L . ’ r Ret S LOAEL for serious effects (animals) Y Nmaskioverior m se LOAEL for less serious effects (animals) 1 effects other than cancer d Dog QO NOAEL (animals) I The number next to each point corresponds to entries in Table 2-2. NU S103443 H1TV3H 2 1 FIGURE 2-2 (Continued) INTERMEDIATE (15-364 Days) Systemic # & 7 & & & & / oe (mg/kg/day) 10,000 p= 1,000 poe. sem @ ss Quem @m 547m O 48m @som Qutr Pax Om [« 30 Oss Ose 100 |= (45m oe asm Quor Quarr @sem 7m (som 54m 57m Omm Or Qa Our Osim dan o 10 j= , Key r Rat @ LOAEL for serous effects (animals) m Mouse LOAEL for less serious effects (animals) d Dog QO NOAEL (animals) od @ CEL - Cancer Effect Level (animals) The number next to each point corresponds to entries in Table 2-2. * Doses represent the lowest dose tested per study that produced a tumorigenic response and do not imply the existence of a threshold for the cancer end point. S103443 H1TV3H 2 SE FIGURE 2-2 (Continued) CHRONIC (2365 Days) Systemic & \ & a rd S &P &° 0 & & « > 5 © & © S & S &L & & > Q € < © FL 3 (mg/kg/day) 10,000 = 1000 | @som QO sam QO eam QO sam QO eam QO eam Qex Osx Qs Qs Qs 100 = 59r . Q 65m QO sd Qed 10 LL 1 | Key 01 Lo a 3 r Rat @ LOAEL for serious effects (animals) m Mouse QO NOAEL (animals) d Dog The number next to each point corresponds to entries in Table 2-2. S103443 HLTV3H ¢ 9€ (mg/kg/day) 10,000 1,000 100 0.1 0.01 0.001 0.0001 0.00001 FIGURE 2-2 (Continued) CHRONIC (> 365 Days) Systemic © dS S a > > A S &$ Q Q & S$ & ® <® & & & & Oem Qé4am O7om Oram 6m Pein @sir Por Osa Osx Beer Qsir Oessr Orr & 77m ® 74 @ 76 Qssm Os Qssm Qesm dl di QOe6om @ 78m 7 n & ! Qed Qed Des O74 < Q 67d Qed o 1 r — ! x m | mn - ! m | oO -— i wn I | | jo \o/ 10-4 10-5 < Estimated Upper- Bound Human Cancer Risk Key 10-6 — Levels r Rat @ LOAEL for serious effects (animals) : NE GRR LG m Mouse ( LOAEL for less serious effects (animals) I ! or d Dog ! effects other than cancer O NOAEL (animals) | 107 4@ CEL - Cancer Effect Level (animals) The number next to each point corresponds to entries in Table 2-2. * Doses represent the lowest dose tested per study that produced a tumorigenic response and do not imply the existence of a threshold for the cancer end point LE 38 2. HEALTH EFFECTS Gastrointestinal Effects. Retrosternal soreness, pain on swallowing. and gastric distress with vomiting were reported in cases of intentional and accidental ingestion of chloroform (Piersol et al. 1933; Schroeder 1965). Atautopsy, congestion with patchy necrosis of the mucosa was observed in the stomach and duodenum of a man who died after drinking =3.755 mg/kg chloroform (Piersol et al. 1933). The colonic mucosa was edematous, and the rectosigmoid junction was hemorrhagic. The effects of chronic oral exposure to chloroform, as a by-product of the chlorination of drinking water, were evaluated in three epidemiology studies (Alavanja et al. 1978; Cantor et al. 1978; Young et al. 1981). The association between the incidence of gastrointestinal cancer in humans and the chlorination of drinking water is discussed in Section 2.2.2.8. Gastrointestinal irritation has been observed in some animals after oral exposure to chloroform. Gastric erosions were observed in rats gavaged with 516 mg/kg chloroform in oil during gestation (Thompson et al 1974). Rabbits exposed by gavage to 20 mg/kg/day chloroform in oil during gestation had diarrhea; no histological results were provided. In a 90-day drinking water study, no histopathological changes were observed in rats and mice exposed to 160 and 290 mg/kg/day chloroform, respectively (Jorgenson and Rushbrook 1980). Vomiting was observed in dogs exposed to 30 mg/kg/day chloroform in toothpaste capsules for 12-18 weeks (Heywood et al. 1979). In a chronic exposure study, no histopathological changes in gastrointestinal tissue were observed in rats and mice exposed by gavage to 200 and 477 mg/kg/day chloroform, respectively (NCI 1976). Hematological Effects. The only information regarding hematological effects in humans after chronic oral exposure to chloroform was reported in a case study. Decreased erythrocytes and hemoglobin were observed in a subject who ingested =21 mg/kg/day chloroform in a cough medicine for 10 years (Wallace 1950). Hematological effects have been observed in some animals after oral exposure to chloroform. Hemoglobin and hematocrit decreased in rats after a single oral dose of 546 mg/kg chloroform in oil (Chu et al. 1982b) and in rats exposed to 100 mg/kg/day chloroform during gestation (Ruddick et al. 1983). No hematological changes were observed in mice exposed to 250 mg/kg/day for 14 days, however (Munson et al. 1982). In an intermediate-duration study, decreased neutrophils were observed in rats exposed to 31 mg/kg/day in drinking water (Chu et al. 1982b); however, no hematological changes were observed in rats and mice exposed to 160 and 290 mg/kg/day chloroform, respectively, for 90 days in drinking water (Jorgenson and Rushbrook 1980). Increased cellular proliferation in the bone marrow was observed in rats exposed by gavage for 13 weeks to 410 mg/kg chloroform in toothpaste (Palmer et al. 1979). No hematological changes were observed, however, in rats similarly exposed to 165 and 60 mg/kg/day chloroform by gavage for 52 and 80 weeks, respectively. Moreover, no histopathological changes in hematopoietic tissues were observed in rats and mice after chronic exposure to 200 and 477 mg/kg/day chloroform in oil, respectively (NCI 1976). No hematological effects were observed in dogs exposed to 30 mg/kg/day chloroform for 7.5 years (Heywood et al. 1979). Musculoskeletal Effects. Muscular relaxation of the jaw caused upper respiratory obstruction in a man who accidentally ingested 2,500 mg/kg chloroform (Schroeder 1965), reflecting the neurological effects of chloroform exposure. No histopathological changes were observed in the musculoskeletal system of rats and mice after chronic gavage exposure to 200 and 477 mg/kg/day chloroform in oil, respectively (NCI 1976). Hepatic Effects. The liver is a primary target of chloroform toxicity in humans. Hepatic injury occurred in patients within 1-3 days following chloroform ingestion (Piersol et al. 1933; Schroeder 1965; Storms 1973). Jaundice and liver enlargement and tenderness developed in all patients. The clinical observations were supported by blood biochemistry results with increased SGOT, SGPT, and LDH activities and increased bilirubin levels. 39 2. HEALTH EFFECTS At autopsy, fatty degeneration and extensive centrilobular necrosis were observed in one fatal case (Piersol et al. 1933). Increased sulfobromophthalein retention indicated impaired liver function in an individual who ingested 21 mg/kg/day chloroform in a cough medicine for 10 years (Wallace 1950). The changes reversed to normal after exposure was discontinued. Biochemical tests indicate that liver function in humans was not affected by the use of mouthwash providing 2.46 mg/kg/day chloroform for <5 years (De Salva et al. 1975). The liver is also a target for chloroform toxicity in animals. In acute studies, hepatitis was observed in pregnant rats exposed by gavage to 516 mg/kg/day chloroform in oil (Thompson et al. 1974), while increased liver weight without any histopathological changes was observed in pregnant rats similarly exposed to 100 mg/kg/day chloroform (Ruddick et al. 1983). Increased serum levels of transaminases, indicative of liver necrosis, were observed in mice treated with a single gavage dose of 199 mg/kg chloroform in toothpaste, 273 mg/kg in oil (Moore et al. 1982), or 250 mg/kg/day in oil for 14 days (Munson et al. 1982). Centrilobular necrosis of the liver with massive fatty changes was also observed in mice after a single dose of 350 mg/kg chloroform in oil (Jones et al. 1958). At a dose of 35 mg/kg, minimal lesions consisting of midzonal fatty changes were observed in mice. Liver effects in animals have been reported in numerous oral studies of intermediate duration. Fatty changes, necrosis, increased liver weight, and hyperplasia have been observed in rats exposed to 2150 mg/kg/day chloroform in drinking water for 90 days (Palmer et al. 1979). An increased incidence of sporadic, mild, reversible, liver changes occurred in mice exposed to chloroform in the drinking water at doses of 0.3-114 mg/kg/day for 90 days, but the incidences were not significantly higher than the incidences in controls (Chu et al 1982a). The effect- and no-effect-levels in the study are clearly defined. Fatty and hydropic changes, necrosis, and cirrhosis were observed in mice treated by gavage with 250 mg/kg/day chloroform in oil for 90 days (Bull et al. 1986; Munson et al. 1982) or 86 mg/kg/day in drinking water for 1 year (Klaunig et al. 1986). In contrast, centrilobular fatty changes observed in mice at 64 mg/kg/day chloroform in drinking water for 90 days appeared to be reversible (Jorgenson and Rushbrook 1980), and no liver effects were found in mice treated with >50 mg/kg/day chloroform in aqueous vehicles (Bull et al. 1986). In addition, hepatocellular degeneration was induced in F, females in a two-generation study in which mice were treated by gavage with 41 mg/kg/day chloroform in oil (Gulati et al. 1988). Significantly increased (p<0.05) SGPT activity occurred in dogs beginning at 6 weeks of exposure to chloroform in toothpaste at a dose of 30 mg/kg/day in a 7.5-year study (Heywood et al. 1979). SGPT activity was not increased at 15 mg/kg/day until week 130. Therefore, 15 mg/kg/day was the NOAEL for intermediate-duration exposure. This NOAEL was used to derive an intermediate-duration oral MRL of 0.1 mg/kg/day, as described in footnote "c” in Table 2-2. In chronic exposure studies, liver effects have been observed in rats, mice, and dogs after oral exposure to chloroform. Necrosis was observed in female rats treated by gavage with 200 mg/kg/day chloroform in oil for 78 weeks (NCI 1976). Nodular hyperplasia occurred in all groups of male and female mice similarly treated at 138 mg/kg/day. Fibrosis of the liver was observed in both sexes of rats exposed to 200 mg/kg/day chloroform in the drinking water for <180 weeks (Tumasonis et al. 1985, 1987). Increased SGPT was observed in dogs given chloroform in toothpaste capsules for 7.5 years (Heywood et al. 1979). The lowest oral dose administered to animals in chronic studies was 15 mg/kg/day, which increased SGPT in dogs. This LOAEL was used to derive a chronic oral MRL of 0.01 mg/kg/day, as described in footnote "d" of Table 2-2. Renal Effects. In addition to the liver, the kidney is also a major target of chloroform-induced toxicity in humans. Oliguria was observed 1 day after the ingestion of =3,755 or 2,500 mg/kg chloroform (Piersol et al. 1933; Schroeder 1965). Increased blood urea nitrogen and creatinine levels also indicated renal injury. Albuminuria and casts were detected in the urine. Histopathological examination at autopsy revealed epithelial swelling and hyaline and fatty degeneration in the convoluted tubules of kidneys in one fatal case of oral 40 2. HEALTH EFFECTS exposure to chloroform (Piersol et al. 1933). Numerous hyaline and granular casts and the presence of albumin were observed in the urine of one subject who ingested 21 mg/kg/day chloroform in cough medicine for 10 years (Wallace 1950). The urinalysis results reversed to normal after discontinuation of chloroform exposure. No indications of renal effects were observed in humans who ingested estimated doses of 0.34-2.46 mg/kg/day chloroform in mouthwash for 5 years (De Salva et al. 1975). The renal toxicity of chloroform in animals has been reported in many studies of acute duration. Acute, toxic nephrosis was observed in rats exposed to 516 mg/kg/day chloroform during gestation (Thompson et al. 1974). Increased kidney weight was observed in female rats after a single gavage dose of 546 mg/kg chloroform (Chu et al. 1982b). Similarly, rats exposed to 400 mg/kg/day by gavage during gestation had increased kidney weight (Ruddick et al. 1983). No increase in kidney weight was found in the rats treated with 200 mg/kg/day during gestation. Renal necrosis in convoluted tubules was observed in mice after a single dose of 199 mg/kg chloroform in toothpaste or 65.6 mg/kg chloroform in oil (Moore et al. 1982). The NOAEL was 17.3 mg/kg chloroform in oil, and was used to derive an acute oral MRL of 0.2 mg/kg/day, as described in footnote "b" of Table 2-2. In intermediate-duration studies, mice appeared to be more sensitive than rats to the nephrotoxic effects of chloroform. Rats exposed to 31 mg/kg/day for 28 days (Chu et al. 1982b) or to 160 mg/kg/day chloroform for 90 days (Jorgenson and Rushbrook 1980) in drinking water had no kidney effects. Increased relative kidney weight was observed in rats exposed by gavage to 150 mg/kg/day for 13 weeks, but not in rats exposed to 30 mg/kg/day (Palmer et al. 1979). Chronic inflammatory changes were observed in the kidneys of mice exposed to 50 mg/kg/day chloroform by gavage (Munson et al. 1982); however, no changes were observed in mice exposed to 41 mg/kg/day by gavage (Gulati et al. 1988) or in mice exposed to 290 mg/kg/day chloroform in drinking water (Jorgenson and Rushbrook 1980). Nonetheless, exposure to 86 mg/kg/day in drinking water for 1 year caused tubular necrosis in mice (Klaunig et al. 1986). In chronic oral studies, no definite renal effects were observed in rats exposed to <200 mg/kg/day or mice exposed to <477 mg/kg/day (Jorgenson et al. 1985; NCI 1976; Roe et al. 1979). In dogs, however, fat deposition in renal glomeruli was observed at a dose of 30 mg/kg/day chloroform for 7.5 years, but not at 15 mg/kg/day (Heywood et al. 1979). Dermal/Ocular Effects. No studies were located regarding dermal/ocular effects in humans after oral exposure to chloroform. Alopecia was observed in pregnant rats exposed to 126 mg/kg/day chloroform in oil (Thompson et al. 1974). Rough coats were observed in mice exposed to 100 mg/kg/day chloroform in oil for 14 days (Gulati et al. 1988). Other Systemic Effects. No studies were located regarding other effects in humans after oral exposure to chloroform. Several studies were located regarding body weight changes in animals after oral exposure to chloroform. A dose-related decrease in body weight gain was observed in rats exposed to 100 mg/kg/day and in rabbits exposed to 50 mg/kg/day chloroform by gavage in oil during gestation (Ruddick et al. 1983; Thompson et al. 1974). In addition, decreased body weight was observed in male mice after acute exposure to 250 mg/kg/day chloroform by gavage in oil (Gulati et al. 1988; Munson et al. 1982). Dose-related decreases in body weight or body weight gain were observed in rats exposed to 283 mg/kg/day in water (Chu et al. 1982a; Jorgenson and Rushbrook 1980) or in oil (NCI 1976) and in mice (Roe et al. 1979) 41 2. HEALTH EFFECTS in studies of intermediate duration. Similar effects were found in rats exposed to 260 mg/kg/day regardless of the vehicle (Jorgenson et al. 1985; NCI 1976; Palmer et al. 1979; Tumasonis et al. 1985) and mice exposed to 263 mg/kg/day in water (Jorgenson et al. 1985) in studies of chronic exposure. In contrast, no effect on body weight was observed in mice treated with 477 mg/kg/day by gavage in oil (NCI 1976) or dogs treated with 30 mg/kg/day (Heywood et al. 1979) chloroform in studies of chronic duration. Food and/or water consumption were decreased in chloroform exposed animals in some studies (Chu et al. 1982a; Jorgenson et al. 1985), but others reported fluctuating food intake unrelated to chloroform exposure (Palmer et al. 1979) or no significantly depressed food consumption at the lowest LOAEL level for body weight effects (Thompson et al. 1974). 2.2.2.3 Immunological Effects No studies were located regarding immunological effects in humans after oral exposure to chloroform. Information regarding immunological effects in animals after oral exposure to chloroform is limited to three studies. Reduced lymphocyte counts were observed in female rats after a single gavage dose of 1,071 mg/kg chloroform (Chu et al. 1982b); no effects were observed in the 765 mg/kg group. Humoral immunity, defined as antibody-forming cells (AFC)/spleen x 100,000, was depressed in both sexes of mice after oral dosing with 50 mg/kg/day chloroform for 14 days (Munson et al. 1982). In contrast, hemagglutination titer was not significantly influenced, and no changes in cell-mediated immunity were recorded. Similar results were obtained in a 90-day experiment. Depressed humoral immunity was observed in mice exposed to 50 mg/kg/day chloroform. Cell-mediated immunity (delayed type hypersensitivity) was affected in the high-dose (250 mg/kg/day) group of females. The chloroform-induced changes were more severe in the 14-day study than in the 90-day study. The highest NOAEL value and all reliable LOAEL values for immunological effects in each species and duration category are recorded in Table 2-2 and plotted in Figure 2-2. 2.2.2.4 Neurological Effects The data regarding neurological effects in humans after oral exposure to chloroform were obtained from clinical case reports. Deep coma occurred immediately after exposure to 2,500 or 3,755 mg/kg in all cases of intentional or accidental ingestion of chloroform (Piersol et al. 1933; Schroeder 1965; Storms 1973). All reflexes were abolished, and pupil size varied. All patients survived the first coma and became fully conscious; however, one patient died in coma several days later due to extensive liver necrosis (Piersol et al. 1933). Mild cerebellar damage (instability of gait, intentional tremor) was observed in one patient, but reversed to normal in 2 weeks (Storms 1973). The central nervous system in animals is a target of chloroform toxicity after oral exposure to chloroform. High, single doses of chloroform caused ataxia, incoordination, and anesthesia in mice (Balster and Borzelleca 1982; Bowman et al. 1978). The calculated EDg, for motor performance was 484 mg/kg chloroform (Balster and Borzelleca 1982). The effects disappeared within 90 minutes postexposure. A minimal narcotic dose for 50% of the treated mice was calculated to be 350 mg/kg (Jones et al. 1958). Hunched posture and inactivity were observed in male mice exposed by gavage for 14 days to 250 mg/kg chloroform in oil (Gulati et al. 1988). No effects were observed after exposure to 100 mg/kg day. Hemorrhaging in the brain was observed at gross pathology of mice that died under chloroform anesthesia following doses 2500 mg/kg/day (Bowman et al. 1978). Lower concentrations of chloroform induced taste aversion to a saccharin solution in mice exposed by gavage for 10 days to 30 mg/kg/day in oil, but not in mice exposed to 10 mg/kg/day (Landauer et al. 1982). No signs of behavioral toxicity were observed in mice exposed to 31.1 mg/kg/day chloroform for 14 days, 10 or 13 weeks, 42 2. HEALTH EFFECTS or in mice exposed to 100 mg/kg for 30 days (Balster and Borzelleca 1982). Operant behavior in mice was affected after exposure to 100 mg/kg/day for 60 days (Balster and Borzelleca 1982). The most severe effects were observed early in the experiment; partial tolerance was observed later. No histopathological changes were observed in the brains of rats after chronic exposure to 200 mg/kg/day, in the brains of mice after chronic exposure to 477 mg/kg/day (NCI 1976), or in the brains of mice after chronic exposure to 60 mg/kg/day (Roe et al. 1979). The highest NOAEL values and all reliable LOAEL values for neurological effects in each species and duration category are recorded in Table 2-2 and plotted in Figure 2-2. 2.2.2.5 Developmental Effects No studies were located regarding developmental effects in humans after oral exposure to chloroform. No teratological effects or skeletal anomalies in rats or rabbits after oral exposure to chloroform were reported in developmental studies (Ruddick et al. 1983; Thompson et al. 1974). Decreased fetal weight was observed in the offspring of rats exposed by gavage to 400 mg/kg/day chloroform during gestation, but not in those exposed to 200 mg/kg/day (Ruddick et al. 1983). In a preliminary dose-finding study, decreased fetal weight and increased resorptions were observed in rats exposed to 316 mg/kg/day chloroform during gestation (Thompson et al. 1974). In the principal study, reduced birth weight of the offspring was reported in the 126 mg/kg/day group; no effects were observed in the 50 mg/kg/day exposure group. Similarly, increased resorptions were observed in rabbits exposed to 100 mg/kg/day during gestation. No behavioral effects were observed in the offspring of the F;, generation mice treated for 6-10 weeks with 31.1 mg/kg chloroform (Burkhalter and Balster 1979). In a two-generation reproductive study, increased epididymal weights and degeneration of epididymal ductal epithelium were observed in mice in the F, generation (Gulati et al. 1988). The production and viability of sperm was not affected, however. The highest NOAEL values and all reliable LOAEL values for developmental effects in each species and duration category are recorded in Table 2-2 and plotted in Figure 2-2. 2.2.2.6 Reproductive Effects No studies were located regarding reproductive effects in humans after oral exposure to chloroform. In animals, increased resorptions were observed in rats exposed to 316 mg/kg/day chloroform during gestation, but not in those exposed to 300 mg/kg/day (Thompson et al. 1974). Furthermore, abortions (not otherwise specified) were observed in rabbits exposed to 63 mg/kg/day chloroform during gestation (Thompson et al. 1974). No histopathological changes were observed in the testes of rats exposed to 160 mg/kg/day chloroform in drinking water for intermediate durations (Jorgenson and Rushbrook 1980). Gonadal atrophy was observed in both sexes of rats treated by gavage with 410 mg/kg/day chloroform in toothpaste (but not with 150 mg/kg/day) (Palmer et al. 1979). In a two-generation reproductive study, chloroform exposure did not affect the fertility in either generation (Gulati et al. 1988). No histopathological changes were observed in the reproductive organs of male and female rats and mice chronically exposed to 200 and 477 mg/kg/day chloroform via gavage (NCI 1976). Similarly, no changes were observed in dogs chronically exposed to 30 mg/kg chloroform (Heywood et al. 1979). 43 2. HEALTH EFFECTS The highest NOAEL values and all reliable LOAEL values for reproductive effects in each species and duration category are recorded in Table 2-2 and plotted in Figure 2-2. 2.2.2.7 Genotoxic Effects No studies were located regarding genotoxic effects in humans after oral exposure to chloroform. Unscheduled DNA (deoxyribonucleic acid) synthesis in hepatocytes was not increased in rats exposed to chloroform at gavage doses 2400 mg/kg in oil (Mirsalis et al. 1982). Exposure to 200 mg/kg/day chloroform in oil by gavage for 4 days increased sister chromatid exchange frequency in bone marrow cells of mice (Morimoto and Koizumi 1983). Other genotoxicity studies are discussed in Section 2.4. 2.2.2.8 Cancer Epidemiology studies suggest an association between cancer in humans and consumption of chlorinated drinking water, but the results are not conclusive (Alavanja et al. 1978; Cantor et al. 1978; Young et al. 1981). Such an association implicates chloroform because chloroform is a known animal carcinogen (see below) and the predominant trihalomethane in chlorinated drinking water (see Chapter 5). Although attempts were made to control for various demographic variables in all of these studies (e.g., social class, ethnic group, marital status, occupation, urban vs. rural, etc.), many confounding effects remained unaccounted for, most notably that numerous chemicals other than chloroform are likely to have been present in the drinking water. Furthermore, the studies differed regarding the type of cancer associated with consumption of chlorinated water. Bladder cancer was reported to have the strongest association with chlorinated water in one study (Cantor et al. 1978), but only colon cancer had an elevated odds ratio (3.6) in another study (Young et al. 1981). Overall, the human data are insufficient to support any conclusion regarding the carcinogenic potential of chloroform in humans. Chloroform is carcinogenic in animals after oral exposure. An increased incidence of hepatomas was observed in mice exposed by gavage for 30 days to 595 mg/kg/day chloroform in oil, but not in mice exposed to 297 mg/kg/day (Eschenbrenner and Miller 1945a). An 8-week exposure to 1,800 mg/kg/day chloroform in oil by gavage did not induce lung tumors in mice (Stoner et al. 1986). In addition, no increase in tumors was found in mice exposed to 257 mg/kg/day chloroform in drinking water for 52 weeks (Klaunig et al. 1986). Chloroform was found to be carcinogenic in several chronic animal studies of oral exposure. The incidence of hepatic neoplastic nodules was increased in female Wistar rats chronically exposed to 200 mg/kg/day chloroform in drinking water, and lymphosarcoma was increased in males (Tumasonis et al. 1987). An increased incidence of tubular cell adenoma and carcinoma was observed in the kidneys of Osborne-Mendel rats chronically exposed to 160 mg/kg/day chloroform in drinking water, but not in those exposed to 81 mg/kg/day (Jorgenson et al. 1985). Similarly, renal tumors (tubular cell adenoma and carcinoma) were observed in male Osborne-Mendel rats after a 78-week exposure to 90 mg/kg/day chloroform by gavage (NCI 1976). In contrast, no increase in the incidence of tumors was observed in Sprague-Dawley rats exposed by gavage to 60 and 165 mg/kg/day chloroform in toothpaste for 80 and 52 weeks, respectively (Palmer et al. 1979). Hepatocellular carcinoma was observed in all groups of B6C3F, mice exposed to gavage doses 2138 mg/kg/day chloroform in oil for 78 weeks (NCI 1976). An increased incidence of kidney tumors was observed in ICI mice chronically exposed to 60 mg/kg/day chloroform by gavage, but not in those exposed to 17 mg/kg/day (Roe et al. 1979). Under the same experimental conditions, chloroform exposure had no effect on the frequency of tumors in C57BI, CBA, and CF/1 mice. Moreover, no increase in tumor incidence was observed in B6C3F| mice exposed to 263 mg/kg/day chloroform 44 2. HEALTH EFFECTS in drinking water for 2 years (Jorgenson et al. 1985). Cancer was not observed in dogs exposed to 30 mg/kg/day chloroform in toothpaste capsules for 7.5 years (Heywood et al. 1979). The CELs (cancer effect levels) are recorded in Table 2-2 and plotted in Figure 2-2. EPA (IRIS 1992) selected the study by Jorgenson et al. (1985) as the basis for the q for oral exposure to chloroform because administration via drinking water better approximates oral exposure in humans than does administration in corn oil by gavage as used in the NCI (1976) study. Based on the incidence of renal tumors in male Osborne-Mendel rats, the qa was calculated to be 6.1x1073 (mg/kg/day). The oral doses associated with individual lifetime upper-bound risks of 10% to 1077 are 1.6x10% to 1.6x107 mg/kg/day, respectively, and are plotted in Figure 2-2. 2.2.3 Dermal Exposure 2.2.3.1 Death No studies were located regarding death in humans after dermal exposure to chloroform. No deaths resulted from dermal exposure of rabbits to 3,980 mg/kg chloroform for 24 hours (Torkelson et al. 1976). 2.2.3.2 Systemic Effects No studies were located regarding respiratory, cardiovascular, gastrointestinal, hematological, or musculoskeletal effects in humans or animals after dermal exposure to chloroform. Hepatic Effects. No studies were located regarding hepatic effects in humans after dermal exposure to chloroform. No hepatic effects were observed in rabbits when 3,980 mg/kg chloroform was applied to the belly for 24 hours (Torkelson et al. 1976). The NOAEL for hepatic effects is recorded in Table 2-3. Renal Effects. No studies were located regarding renal effects in humans after dermal exposure to chloroform. Degenerative, tubular changes were observed in the kidneys of rabbits when 1,000 mg/kg chloroform was applied to the belly for 24 hours (Table 2-3) (Torkelson et al. 1976). Dermal/Ocular Effects. Completely destroyed stratum corneum was observed in the skin of two young volunteers exposed to chloroform for 15 minutes on 6 consecutive days (Malten et al. 1968). Milder changes were observed in two older individuals. Chloroform was applied in a glass cylinder (exact exposure was not specified). Application of 0.01 mL chloroform for 24 hours to the skin of rabbits caused only slight irritation (Smyth et al. 1962). Skin necrosis was observed in rabbits dermally exposed to 1,000 mg/kg chloroform for 24 hours (Torkelson et al. 1976). These LOAEL values are recorded in Table 2-3. Other Systemic Effects. No studies were located regarding other effects in humans after dermal exposure to chloroform. Dermal exposure to 1,000 mg/kg chloroform for 24 hours caused weight loss in rabbits (Table 2-3) (Torkelson et al. 1976). TABLE 2-3. Levels of Significant Exposure to Chloroform - Dermal E pore LOAEL (effect) Species frequency System NOAEL Less serious Serious Reference ACUTE EXPOSURE Systemic Rabbi t 24 hr Derm/oc 0.01 mL (slight skin Smyth et al. irritation) 1962 Rabbit 24 hr Hepatic 3,980 mg/kg Torkelson et al. 1976 Renal 1,000 mg/kg (degenerative tubular changes) Derm/oc 1000 mg/kg (necrosis) Other 1,000 mg/kg (weight loss) Derm/oc = dermal/ocular; hr = hour(s); LOAEL = lowest-observed-adverse-effect level; NOAEL = no-observed-adverse-effect level S103443 H1TV3H 2 SY 46 2. HEALTH EFFECTS No studies were located regarding the following health effects in humans or animals after dermal exposure to chloroform: 2.2.3.3 Immunological Effects 2.2.3.4 Neurological Effects 2.2.3.5 Developmental Effects 2.2.3.6 Reproductive Effects 2.2.3.7 Genotoxic Effects Genotoxicity studies are discussed in Section 2.4. 2.2.3.8 Cancer No studies were located regarding cancer in humans or animals after dermal exposure to chloroform. 2.3 TOXICOKINETICS 2.3.1 Absorption 2.3.1.1 Inhalation Exposure Chloroform absorption depends on the concentration in inhaled air, the duration of exposure, the blood/air partition coefficient, the solubility in various tissues, and the state of physical activity which influences the ventilation rate and cardiac output. Pulmonary absorption of chloroform is also influenced by total body weight and total fat content, with uptake and storage in adipose tissue increasing with excess body weight and obesity. In inhalation exposures, the arterial blood concentration of chloroform is directly proportional to the concentration in inspired air. At anesthetic concentrations (8,000-10,000 ppm), steady-state arterial blood concentrations of chloroform were 0.07-0.165 mg/mL (Smith et al. 1973). The equilibrium between blood concentration and inhaled air concentration was reached in 80-100 minutes in humans exposed to chloroform via anesthesia (Lehmann and Hasegawa 1910). Total body equilibrium with inspired chloroform concentration required at least 2 hours in normal humans at resting ventilation and cardiac output (Lehmann and Hasegawa 1910; Smith et al. 1973). No studies were located regarding absorption in animals after inhalation exposure to chloroform. Evidence that chloroform is absorbed after inhalation exposure is provided in toxicity studies (see Section 2.2.1), but the rate and extent cannot be determined from the toxicity data. 2.3.1.2 Oral Exposure Absorption of an oral dose of 13C.labeled chloroform (0.5 g in a gelatin capsule) was rapid in volunteers, reaching peak blood levels in 1 hour (Fry et al. 1972). Almost 100% of the dose was absorbed from the gastrointestinal tract. Experiments in mice, rats, and monkeys indicate that oral doses (60 mg/kg) of 14C. labeled chloroform in olive oil were almost completely absorbed as indicated by a 93-98% recovery of radioactivity in expired air, urine, 47 2. HEALTH EFFECTS and carcass (Brown et al. 1974a; Taylor et al. 1974). Absorption in mice and monkeys was rapid; the peak blood levels were reached 1 hour after oral administration of 60 mg/kg chloroform in olive oil. Intestinal absorption of chloroform in either water or corn oil administered intragastrically to rats was rapid with both vehicles, but the rate and extent of absorption varied greatly (Withey et al. 1983). The peak concentration of chloroform in blood was 39.3 pg/mL when administered in water and 5.9 pg/mL when administered in com oil. The greater degree of absorption following administration in water can be explained by the faster partitioning of a lipophilic compound such as chloroform with mucosal lipids from an aqueous vehicle. Peak blood concentrations were reached somewhat more rapidly with the water vehicle (5.6 minutes versus 6.0 minutes for com oil). The uptake from a corn oil solution was more complex (pulsed) than from aqueous solution. A possible explanation for this behavior is that the chloroform in com oil was broken up into immiscible globules, some of which did not come into contact with the gastric mucosa. Another possible explanation was that intragastric motility may have separated the doses into aliquots that were differentially absorbed from the gastrointestinal tract. 2.3.1.3 Dermal Exposure No experimental studies were located regarding dermal absorption of chloroform in humans. According to dermal absorption studies with solvents other than chloroform, the absorption of such solvents in guinea pigs is more rapid than metabolism or pulmonary excretion (Jakobson et al. 1982). A dermal absorption rate of 329 pmol/minute/cm? was calculated for the shaved abdominal skin of mice (Tsuruta 1975). The dermal absorption rate for shaved abdominal skin of mice was calculated to be 329 pmol/minute/cm?. This is equivalent to a human absorption rate of 19.7 mg/minute, assuming that a pair of hands is immersed in liquid chloroform (Tsuruta 1975). The calculation was based on the assumptions that the rate of chloroform Jeneiration is uniform for all kinds of skin and that the total surface area of a pair of human hands is 800 cm”. 2.3.2 Distribution 2.3.2.1 Inhalation Exposure Chloroform is lipid soluble and readily passes through cell membranes, causing narcosis at high concentrations. Blood chloroform concentrations during anesthesia (presumed concentrations 8,000-10,000 ppm) were 0.07-0.165 mg/mL in 10 patients (Smith et al. 1973). An arterial chloroform concentration of 0.24 mg/mL during anesthesia corresponded to the following partition coefficients: blood/gas = 8, blood/vessel rich compartment = 1.9, blood/muscle compartment = 1.9, blood/fat compartment = 31, blood/vessel poor compartment = 1, and blood/liver = 2 (Feingold and Holaday 1977). Recently, partition coefficients were calculated based on results in mice and rats, and in human tissues in vitro for humans: blood/air = 7.4, liver/air = 17.0, kidney/air = 11, and fat/air = 280 (Corley et al. 1990). The chloroform levels in seven patients who died after excessive administration during anesthesia were: brain 372-480 mg/kg, lungs 355-485 mg/kg, and liver 190-275 mg/kg (Gettler and Blume 1931). The chloroform levels in patients under anesthesia who died from other causes were: brain 120-182 mg/kg, lungs 92-145 mg/kg, and liver 65-88 mg/kg tissue wet weight. After whole-body autoradiography to study the distribution of 14C.labeled chloroform in mice, most of the radioactivity was found in fat immediately after exposure, while the concentration of radioactivity in the liver increased during the postanesthetic period (Cohen and Hood 1969). Partition coefficients (tissue/air) for mice and 48 2. HEALTH EFFECTS rats were 21.3 and 20.8 for blood; 19.1 and 21.1 for liver; 11.0 and 11.0 for kidney; and 242 and 203 for fat, respectively (Corley et al. 1990). Arterial levels of chloroform in Mongrel dogs reached 0.35-0.40 mg/mL by the time animals were in deep anesthesia (Chenoweth et al. 1962). Chloroform concentrations in the inhaled stream were not measured, however. After 2.5 hours of deep anesthesia, there were 392 mg/kg chloroform in brain tissue, 1,305 mg/kg in adrenals, 2,820 mg/kg in omental fat, and 290 mg/kg in the liver. Radioactivity from !C-labeled chloroform was detected in the placenta and fetuses of mice immediately after inhalation exposure (Danielsson et al. 1986). In early gestation, accumulation of radioactivity was observed in the embryonic neural tissues, while the respiratory epithelium was more involved in chloroform metabolism in the late fetal period. Due to its lipophilic character, chloroform accumulates to a greater extent in tissues of high lipid content. As shown by the results presented above, the relative concentrations of chloroform in different tissues decreased as follows: adipose tissue > brain > liver > kidney > blood. 2.3.2.2 Oral Exposure No studies were located regarding distribution in humans after oral exposure to chloroform. High concentrations of radioactivity were observed in body fat and livers of rats, mice, and squirrel monkeys given oral doses of 60 mg/kg 14C.1abeled chloroform (Brown et al. 1974a). The maximum levels of radioactivity in the blood appeared within 1 hour and were 3 pg equivalents chloroform/mL for mice and 10 pg equivalents chloroform/mL for monkeys, which represented =0.35% and 1%, respectively, of the total radioactivity. In monkeys, bile concentrations peaked within 6 hours. The distribution of radioactively labeled chloroform was studied in three strains of mice (Taylor et al. 1974). No strain-related differences were observed; however, higher levels of radioactivity were found in the renal cortex of males and in the liver of females. The renal binding of radioactive metabolites may have been altered by variations in the testosterone levels as a result of hormonal pretreatment in females or castration in males. Sex-linked differences in chloroform distribution were not observed in rats or monkeys (Brown et al. 1974a). Chloroform accumulates in the adipose tissue of rats after oral exposure of intermediate duration (Pfaffenberger et al. 1980). 2.3.2.3 Dermal Exposure No studies were located regarding distribution in humans or animals after dermal exposure to chloroform. 2.3.3 Metabolism The metabolism of chloroform is well understood. Approximately 50% of an oral dose of 0.5 g chloroform was metabolized to carbon dioxide in humans (Fry et al. 1972). Metabolism was dose-dependent, decreasing with higher exposure. A first pass effect was observed after oral exposure (Chiou 1975). Approximately 38% of the dose was converted in the liver, and <17% was exhaled unchanged from the lungs before reaching the systemic circulation. On the basis of pharmacokinetic results obtained in rats and mice exposed to chloroform by inhalation, and of enzymatic studies in human tissues in vitro, in vivo metabolic rate constants (VimaxC = 15.7 mg/hour/kg, K = 0.448 mg/L) were defined for humans (Corley et al. 1990). The metabolic activation of chloroform to its toxic intermediate, phosgene, was slower in humans than in rodents. Metabolic pathways of chloroform biotransformation are shown in Figure 2-3. Metabolism studies indicated that chloroform was, in part, exhaled from the lungs or was converted by oxidative dehydrochlorination of its 49 2. HEALTH EFFECTS FIGURE 2-3. Metabolic Pathways of Chloroform Biotransformation MAJOR AEROBIC PATHWAY P450.0, - i ———————- H CCl, HOCCl,) NADPH. 2 MICROSOME ACCEPTOR =HO! PROTEIN o.cc! H20 co 2 BE ———— {ip PHOSOENE 2 HCl o co, 7 CONDENSATION H,C-CH-C-OH I 1 § NH QLUTATH ONE \/ CONJUGATES? fi Oo 2-OXOTHIA2ZOLIDINE - 4-CARBOXYLIC ACID INOR ANAEROBIC PATHWAY ANAEROBIC NADPH REDUCED MICROSOMES *H20 Pa s0-Fe2'co af CO ¢2HC! 50 2. HEALTH EFFECTS carbon-hydrogen bond to form phosgene (Pohl et al. 1981; Stevens and Anders 1981). This reaction was mediated by cytochrome P-450 and was observed in the liver and kidneys (Branchflower et al. 1984; Smith et al. 1984). Phosgene may react with two molecules of glutathione (GSH) to form diglutathionyl dithiocarbonate, which is further metabolized in the kidneys, or it may react with other cellular elements and induce cytotoxicity (Pohl and Gillette 1984). In vitro studies indicate that phosgene and other reactive chloroform metabolites bind to lipids and proteins of the endoplasmatic reticulum proximate to the cytochrome P-450 (Sipes et al. 1977; Wolf et al. 1977). The metabolism of chloroform to reactive metabolites occurs not only in microsomes but also in nuclear preparations (Gomez and Castro 1980). Covalent binding of chloroform to lipids can occur under anaerobic and aerobic conditions, while binding to the protein occurs only under aerobic conditions (Testai et al. 1987). It was further demonstrated that chloroform can induce lipid peroxidation and inactivation of cytochrome P-450 in rat liver microsomes under anaerobic conditions (De Groot and Noll 1989). This mechanism may also contribute to chloroform-induced hepatotoxicity in rats, although phosgene and other active metabolites are primarily responsible. Covalent binding of chloroform metabolites to microsomal protein in vitro was intensified by microsomal enzyme inducers and prevented by glutathione (Brown et al. 1974b). It was proposed that the reaction of chloroform metabolites with glutathione may act as a detoxifying mechanism. When glutathione is depleted, however, the metabolites react with microsomal protein, and may cause necrosis. This is supported by observations that chloroform doses that caused liver glutathione depletion produced liver necrosis (Docks and Krishna 1976). Furthermore, chloroform has been found to be more hepatotoxic in fasted animals, possibly due to decreased glutathione content in the liver (Brown et al. 1974b; Docks and Krishna 1976). This may explain the clinical finding of severe acute hepatotoxicity in women exposed to chloroform via anesthesia during prolonged parturition. Evidence that chloroform is metabolized at its carbon-hydrogen bond is provided by experiments using the deuterated derivative of chloroform (Branchflower et al. 1984; McCarty et al. 1979; Pohl et al. 1980a). Deuterated chloroform was one-half to one-third as cytotoxic as chloroform, and its conversion to phosgene was much slower. The results confirmed that the toxicity of chloroform is primarily due to its metabolites. A recent in vitro study of mice hepatic microsomes indicated that a reductive pathway may play also an important role in chloroform hepatotoxicity (Testai et al. 1990). It was demonstrated that radical chloroform metabolites bind to macromolecules (proteins, lipids) and the process can be inhibited by reduced glutathione. The final product of the aerobic metabolic pathway of chloroform is carbon dioxide (Brown et al. 1974a; Fry et al. 1972), which is mostly eliminated through the lungs, but some is incorporated into endogenous metabolites and excreted as bicarbonate, urea, methionine, and other amino acids (Brown et al. 1974a). Inorganic chloride ion is an end product of chloroform metabolism found in the urine (Van Dyke et al. 1964). Carbon monoxide was a minor product of the anaerobic metabolism of chloroform in vitro (Ahmed et al. 1977) and in_vivo in rats (Anders et al. 1978). A sex-related difference in chloroform metabolism was observed in mice (Taylor et al. 1974). Chloroform accumulated and metabolized in the renal cortex of males to a greater extent than in females; the results may have been influenced by testosterone levels. This effect was not observed in any other species. Interspecies differences in the rate of chloroform conversion were observed in mice, rats, and squirrel monkeys. The conversion of chloroform to carbon dioxide was highest in mice (85%) and lowest in squirrel monkeys (28%) (Brown et al. 1974a). Similarly, chloroform metabolism was calculated to be slower in humans than in rodents and was, therefore, estimated that the exposure to equivalent concentrations of chloroform would lead to a much lower delivered dose in humans (Corley et al. 1990). 51 2. HEALTH EFFECTS 2.3.4 Excretion 2.3.4.1 Inhalation Exposure Chloroform was detected in the exhaled air of volunteers exposed to a normal environment, to heavy automobile traffic, or to 2 hours in a dry cleaning establishment (Gordon et al. 1988). Higher chloroform levels in the breath corresponded to higher exposure levels. The calculated biological half-time for chloroform was 7.9 hours. Excretion of radioactivity in mice and rats was monitored for 48 hours following exposure to 14C. labeled chloroform (Corley et al. 1990). In general, 92-99% of the total radioactivity was recovered in mice, and 58-98% was recovered in rats; percent recovery decreased with increasing exposure. With increasing concentration, mice exhaled 80-85% of the total radioactivity recovered as 14C_labeled carbon dioxide, 0.48% as 14C-labeled chloroform. and 8-11% and 0.6-1.4% as urinary and fecal metabolites, respectively. Rats exhaled 48-85% as “C-labeled carbon dioxide, 2-42% as “C-labeled chloroform. and 8-11% and 0.1-0.6% in the urine and feces, respectively. A 4-fold increase in exposure concentration was followed by a 50- and 20-fold increase in the amount of exhaled, unmetabolized chloroform in mice and rats, respectively. 2.3.4.2 Oral Exposure Following a single, oral exposure, most of the 0.5 g radioactively labeled chloroform administered to volunteers was exhaled during the first 8 hours after exposure (Fry et al. 1972). A slower rate of pulmonary excretion was observed during the first 8 hours in volunteers who had more adipose tissue than the other volunteers. Up to 68.3% of the dose was excreted unchanged, and up to 50.6% was excreted as carbon dioxide. A positive correlation was made between pulmonary excretion and blood concentration. Less than 1% of the radioactivity was detected in the urine. Approximately 80% of a single dose of 60 mg/kg 14C.l1abeled chloroform was converted within 24 hours to 14C.labeled carbon dioxide in mice (Brown et al. 1974a; Taylor et al. 1974), while only =66% of the dose was converted to “C-labeled carbon dioxide in rats (Brown et al. 1974a). Eight hours after administration of 100-150 mg/kg of 14C.labeled chloroform, 49.6% and 6.5% of radioactivity was converted to carbon dioxide, 26.1% and 64.8% was expired as unmetabolized parent compound, and 4.9% and 3.6% was detected in the urine in mice and rats, respectively (Mink et al. 1986). These results indicate that mice metabolize high doses of chloroform to a greater degree than rats do. Only 18% of a chloroform dose was metabolized to “C-labeled carbon dioxide in monkeys, and =79% was detected as unchanged parent compound or toluene soluble metabolites (Brown et al. 1974a). Within 48 hours after exposure, =2%, 8%, and 3% of the administered radioactivity was detected in the urine and feces of monkeys, rats, and mice, respectively. 2.3.4.3 Dermal Exposure No studies were located regarding excretion in humans or animals after dermal exposure to chloroform. 2.4 RELEVANCE TO PUBLIC HEALTH Data are available regarding health effects in humans and animals after inhalation, oral, and dermal exposure to chloroform; however, data regarding dermal exposure are quite limited. Chloroform was used as an anesthetic, pain reliever, and antispasmodic for more than a century before its toxic effects were fully recognized. High levels of chloroform in the air are found specifically in highly industrialized areas. Exposure of the general 52 2. HEALTH EFFECTS population to chloroform can also occur via drinking water, as a result of chlorination. Occupational exposure is another source of inhalation and/or dermal exposure for humans. Most of the presented information regarding chloroform toxicity following inhalation exposure in humans was obtained from clinical reports of patients undergoing anesthesia. In some instances, the results in these studies may have been confounded by an intake of other drugs or by artificial respiration during anesthesia. The target organs of chloroform toxicity in humans and animals are the central nervous system, liver, and kidneys. There is a great deal of similarity between chloroform-induced effects following inhalation and oral exposure. No studies were located regarding developmental and reproductive effects in humans after exposure to chloroform. Nevertheless, animal studies indicate that chloroform can cross the placenta and cause fetotoxic and teratogenic effects. Chloroform exposure has also caused increased resorptions in animals. Epidemiology studies suggest a possible risk of colon and bladder cancer in humans that is associated with chloroform in drinking water. In animals, chloroform was carcinogenic after oral exposure. Death. Chloroform levels of =40,000 ppm cause death in patients under chloroform anesthesia (Featherstone 1947; Whitaker and Jones 1965). Death is usually due to respiratory failure or disturbances in cardiac rhythm. Accidental or intentional ingestion of large doses of chloroform may lead to death (Piersol et al. 1933). Death in humans after oral exposure to chloroform is usually caused by respiratory obstruction by the tongue due to jaw relaxation, central respiratory paralysis, acute cardiac failure, or severe hepatic injury (Piersol et al. 1933; Schroeder 1965). The levels of chloroform exposure that cause death in animals are usually lower than those administered to patients to induce anesthesia; however, the duration of exposure in animals is generally longer. Following acute exposure to high concentrations of chloroform, all male mice died; however, most females survived the exposure for several months (Deringer et al. 1953). Survival was associated with testosterone levels, as suggested by the higher mortality rate in adult males. This conclusion is supported by similar observations of higher survival rates in female rats, compared to male rats, after intermediate-duration exposure to chloroform (Torkelson et al. 1976). In regard to LCjq, values in rats, survival rates were highest among females and lowest among young adult males. The correlation between mortality rates and male hormone levels is evident. Increased mortality was also observed in rats and mice after oral exposure of intermediate and chronic duration (Balster and Borzelleca 1982; Chu et al. 1982a; Jorgenson et al. 1985; Klaunig et al. 1986; NCI 1976: Palmer et al. 1979; Roe et al. 1979). Deaths were caused by starvation, toxic liver and kidney effects, and tumors. Chloroform concentrations in air and drinking water in the general environment or near hazardous waste sites are not likely to be high enough to cause death in humans after acute exposure. Whether chronic exposure to low levels of chloroform in the environment, drinking water, or hazardous wastes could shorten the life span of humans is not known. Systemic Effects Respiratory Effects. The respiratory failure observed in patients under chloroform anesthesia was probably due to a direct effect of chloroform on the respiratory center of the central nervous system. A decline of the systolic pressure in the cerebral vessels may also contribute to respiratory failure, as demonstrated in animals: when respiration had stopped under chloroform anesthesia, the animals (species not specified) breathed again if positioned head down (Featherstone 1947). Upper respiratory tract obstruction can occur in patients after inhalation exposure to chloroform via anesthesia (Featherstone 1947) and after chloroform ingestion (Schroeder 1965). Few autopsy reports were located in the literature. Hemorrhage into the lungs, without any signs of 53 2. HEALTH EFFECTS consolidation, was reported in a case study involving death after inhalation exposure (Royston 1924); however, congested lungs with pneumonic consolidation were observed in a man who died after drinking chloroform (Piersol et al. 1933). Interstitial pneumonitis was observed in male rats and rabbits after inhalation exposure to 85 or 50 ppm chloroform, respectively, for 6 months (Torkelson et al. 1976). In most oral studies, no exposure-related histopathological changes were observed in the lungs of exposed animals (Gulati et al. 1988; Jorgenson and Rushbrook 1980; NCI 1976; Palmer et al. 1979; Roe et al. 1979). Respiratory effects are more likely to occur after inhalation exposure to high concentrations of chloroform. It has been demonstrated that chloroform has a destructive influence on the pulmonary surfactant (Enhorning et al. 1986). This effect is probably due to the solubility of phospholipids in the surfactant monolayer and can cause collapse of the respiratory bronchiole due to the sudden increase in inhalation tension. Immediate death after chloroform inhalation may be due principally to this effect in the lungs (Fagan et al 1977). It is unlikely that exposure levels of chloroform in the general environment or at hazardous waste sites would be high enough to cause these severe respiratory effects. Cardiovascular Effects. Chloroform induces cardiac arrhythmia in patients exposed to chloroform via anesthesia (Smith et al. 1973; Whitaker and Jones 1965). Similarly, heart effects were observed upon electrocardiography of an individual who accidentally ingested chloroform (Schroeder 1965). Hypotension was observed in 12-27% of patients exposed to chloroform via anesthesia (Smith et al. 1973; Whitaker and Jones 1965) and also was observed in a patient who ingested chloroform (Storms 1973). No studies were located regarding cardiovascular effects in animals after inhalation exposure to chloroform. No histopathological changes were observed in the heart of rats, mice, (NCI 1976) or dogs (Heywood et al. 1979) chronically exposed to chloroform; however, cardiovascular function was not assessed in these studies. It has been demonstrated in an in vitro study on heart-lung preparations of guinea pigs that chloroform may cause a permanent contractile failure of the heart (Doring 1975). The effect is due to structural damage of the transverse tubular system and is accompanied by increased storage of adenosine triphosphate (ATP) and phosphocreatine. The in vitro induction of changes showed that contractile failure is a direct effect on the cardiovascular system rather than an indirect cardiovascular effect on the central nervous system. This mechanism may operate in humans exposed to high vapor concentrations such as those used in anesthesia or in humans exposed to high oral doses from accidental or intentional ingestion. It is unlikely, however, that concentrations of chloroform in the environment would be high enough to cause overt cardiovascular effects. Gastrointestinal Effects. Nausea and vomiting were not only frequently observed side effects in patients exposed to chloroform via anesthesia (Royston 1924; Smith et al. 1973; Townsend 1939; Whitaker and Jones 1965), but also occurred in humans exposed to lower chloroform concentrations (22-237 ppm) in occupational settings (Challen et al. 1958; Phoon et al. 1983). Vomiting, gastric distress, and pain were observed in individuals who intentionally or accidentally ingested high doses of chloroform (Piersol et al. 1933; Schroeder 1965). No studies were located regarding gastrointestinal effects in animals after inhalation exposure to chloroform. Vomiting in dogs (Heywood et al. 1979) and gastric erosions in rats (Thompson et al. 1974) were observed in oral studies of intermediate duration. These results indicate that severe gastrointestinal irritation in humans and animals are due to direct damage of the gastrointestinal mucosa caused by ingesting high concentrations of chloroform (Piersol et al. 1933; Schroeder et al. 1965; Thompson et al. 1974). Following anesthesia, vomiting and nausea may be due to possible gastric irritation which is provoked by swallowing chloroform gas during induction of narcosis or, more frequently, may be due to the hepatic and renal toxicity of chloroform 54 2. HEALTH EFFECTS (Featherstone 1947). Nausea and vomiting experienced by occupationally exposed individuals is also probably secondary to liver toxicity. Since toxic hepatitis may occur at occupational levels as low as 2 ppm (Bomski et al. 1967), it is possible that levels of chloroform in the air at hazardous waste sites may be high enough to cause some liver effects with secondary gastrointestinal effects, if exposure is prolonged. Hematological Effects. Information regarding hematological effects in humans exposed to chloroform is limited. Increased prothrombin time was observed in some patients, following exposure to chloroform via anesthesia (Smith et al. 1973). This effect, however, reflects chloroform hepatotoxicity, because prothrombin is formed in the liver. Decreased erythrocytes and hemoglobin were observed in a patient who was chronically exposed to chloroform in a cough medicine (Wallace 1950). No hematological effects were observed in rats, rabbits, guinea pigs. or dogs after inhalation exposure to chloroform for intermediate durations (Torkelson et al. 1976). Studies report conflicting results regarding hematological effects in animals after oral exposure to chloroform. No conclusion about hematological effects in humans after exposure to chloroform can be made on the basis of one case study in humans. From the experimental data in animals. it is evident that all hematological effects observed in rats were due to oral exposure of acute, intermediate, or chronic duration. It is possible that the hematological effects observed in rats are transient. Human exposure to chloroform in the environment, drinking walter, or at hazardous waste sites is likely to cause few or no hematological effects. Hepatic Effects. The liver is a primary target organ of chloroform toxicity in humans and animals after inhalation and oral exposure. Impaired liver function was indicated by increased sulfobromophthalein retention in some patients exposed to chloroform via anesthesia (Smith et al. 1973). Acute toxic hepatitis developed after childbirth in several women exposed to chloroform via anesthesia (Lunt 1953; Royston 1924; Townsend 1939). Upon autopsy, centrilobular necrosis was observed in the women who died; however, the hepatotoxicity was associated with exhaustion from prolonged delivery, starvation, and dehydration, indicating improper handling of the delivery procedure by an obstetrician. During occupational exposure to concentrations ranging from 14-400 ppm, chloroform hepatotoxicity was signified by jaundice (Phoon et al. 1983), hepatomegaly, enhanced SGPT and SGOT activities. and by hypergammaglobulinemia were observed following exposure to concentrations ranging from 2 10 205 ppm (Bomski et al. 1967). In contrast, no clinical evidence of liver toxicity was found in another study among chloroform workers exposed to <237 ppm (Challen et al. 1958). Case reports of intentional and accidental ingestion of high doses (22,500 mg/kg) of chloroform indicate severe liver injury (Piersol et al. 1933: Schroeder 1965. Storms 1973). The diagnosis was supported by clinical and biochemical results: fatty degeneration and extensive centrilobular necrosis were observed in one patient who died (Piersol et al. 1933). Liver damage was induced by chronic use of a cough medicine containing chloroform (Wallace 1950), but not in individuals chronically exposed to chloroform in mouthwash (De Salva et al. 1975). Reports regarding chloroform hepatotoxicity in animals are numerous. Liver damage was indicated by biochemical changes in rats (Lundberg et al. 1986) and mice (Gehring 1968; Murray et al. 1986) after acute inhalation exposure. Fatty changes (Culliford and Hewitt 1957; Kylin et al. 1963) and liver necrosis (Deringer et al. 1953) were observed histologically in mice after acute inhalation exposure. Histological findings indicative of liver toxicity were also observed in rabbits and guinea pigs following inhalation exposure of intermediate duration, but the findings were not dose-related (Torkelson et al. 1976). Liver effects have been observed in every species (rats, mice, and dogs) tested by the oral route, method of administration (gavage or via drinking water), or duration (acute, intermediate, or chronic). Observed effects include increased liver weight, increased serum levels of transaminases indicative of liver necrosis, and histological evidence of fatty changes, hydropic changes, necrosis, hyperplasia, cirrhosis, and toxic hepatitis. Two acute oral studies define a LOAEL and a 55 2. HEALTH EFFECTS NOAEL for liver effects in mice. Fatty infiltration was observed in mice given a single gavage dose of 35 mg/kg/day chloroform in oil (Jones et al. 1958). No toxic effects on the livers of mice occurred after a single dose of 17.3 or 59.2 mg/kg chloroform in oil, but increased SGPT occurred at 199 mg/kg (Moore et al. 1982). The 17.3 mg/kg dose was also a NOAEL for kidney effects, but tubular necrosis occurred at 65.6 mg/kg/day. The NOAEL of 17.3 mg/kg for kidney effects was used to derive an acute oral MRL of 0.2 mg/kg. In a 7.5-year study in which dogs were administered chloroform in toothpaste, SGPT activity was significantly increased at 30 mg/kg/day beginning at 6 weeks (Heywood et al. 1979). SGPT activity was not increased at 15 mg/kg/day until 130 weeks. Therefore, 15 mg/kg/day was a NOAEL for intermediate-duration exposure and a LOAEL for chronic-duration exposure. The 15 mg/kg/day dose was used to derive MRL values of 0.1 and 0.01 mg/kg/day for intermediate- and chronic-duration oral exposure, respectively. Data regarding chloroform-induced hepatotoxicity were also supported by results obtained after acute intraperitoneal exposure in rats (Ebel et al. 1987; Lundberg et al. 1986), mice (Klaassen and Plaa 1966), dogs (Klaasen and Plaa 1967), and gerbils (Ebel et al. 1987). However, no hepatic effects were observed in rabbits when chloroform was applied to their skin for 24 hours (Torkelson et al. 1976). As discussed in Section 2.3.3, the mechanism of chloroform-induced liver toxicity may involve metabolism to the reactive intermediate, phosgene, which binds to lipids and proteins of the endoplasmic reticulum, lipid peroxidation, or depletion of glutathione by reactive intermediates. Because liver toxicity has been observed in humans exposed to chloroform levels as low as 2 ppm in the workplace and in several animal species after inhalation and oral exposure. it is possible that liver effects could occur in humans exposed to environmental levels, to levels in drinking water, or to levels found at hazardous waste sites. Renal Effects. Clinical reports indicate that the renal damage observed in women exposed to chloroform via anesthesia during prolonged parturition most likely occurs when chloroform anesthesia is associated with anoxia. Case studies of individuals who intentionally or accidentally ingested high doses of chloroform report biochemical changes indicative of kidney damage, as well as fatty degeneration at autopsy (Piersol et al. 1933; Schroeder 1965). Albuminuria and casts were also reported in a case of chronic use of a cough medicine containing chloroform (Wallace 1950); however, no renal effects were observed in individuals chronically exposed to chloroform in a mouthwash (De Salva et al. 1975). Kidney effects in animals after inhalation exposure to chloroform include tubular necrosis, tubular calcification, increased kidney weight, cloudy swelling, and interstitial nephritis. Animal studies regarding renal toxicity after oral exposure are numerous. Effects include acute toxic nephrosis, tubular necrosis, chronic inflammation, and fatty degeneration. A NOAEL of 17.3 mg/kg for renal effects was used to derive an acute oral MRL of 0.2 mg/kg for chloroform. Mice seem to be more sensitive to chloroform-induced renal toxicity than other experimental animals. Certain strains of male mice are susceptible to chloroform-induced nephrotoxicity, while female mice are resistent (Culliford and Hewitt 1957; Eschenbrenner and Miller 1945b). Castrated mice were no longer susceptible to the effect, and testosterone treatment increased the severity of kidney damage in females, suggesting the role of hormones in chloroform-induced nephrotoxicity. It has been demonstrated that sensitivity to kidney damage is related to the capacity of the kidney to metabolize chloroform to phosgene (Pohl et al. 1984). The activation of chloroform to its reactive metabolites appeared to be cytochrome P-450 dependent: the covalent binding to microsomal protein required nicotinamide adenine dinucleotide phosphate (NADPH) and oxygen, and could be inhibited by carbon monoxide (Hook and Smith 1985; Smith and Hook 1983, 1984; Smith et al. 1984). Furthermore, administration of chloroform to male mice caused a depletion of renal glutathione, indicating that 56 2. HEALTH EFFECTS glutathione can react with reactive intermediates, thereby reducing the extent of the reaction with tissue macromolecules and kidney damage. It is likely that kidney effects may occur in humans after inhalation or oral exposure to high levels of chloroform; however, it is not known whether such effects would occur at the levels of chloroform found in the environment, in drinking water, or at hazardous waste sites. Other Systemic Effects. No studies were located regarding other systemic effects in humans after inhalation or oral exposure to chloroform. Decreased body weight has been observed frequently in animals after inhalation or oral exposure to chloroform. The degree of decreased weight gain was often dose-related and was caused by chloroform toxicity. Decreased weight gain generally occurred at exposure levels similar to or lower than those that induced liver and kidney effects in animals. The possibility of effects on body weight in humans exposed to chloroform cannot be dismissed. Immunological Effects. No studies were located regarding immunological effects in humans after inhalation, oral, or dermal exposure to chloroform. Information about immunological effects in animals is limited. After repeated inhalation exposure to chloroform, mortality was increased in mice challenged with streptococcus infection, suggesting increased susceptibility (Aranyi et al. 1986). However, the bacterial activity of alveolar macrophages was not suppressed in this study. After acute oral exposure, reduced lymphocytes counts were observed in rats (Chu et al. 1982b). Furthermore, humoral immunity was depressed in mice exposed to 50 mg/kg/day chloroform for acute or intermediate durations (Munson et al. 1982). In contrast, cell-mediated immunity was influenced only at high chloroform concentrations administered orally for intermediate durations; however, the chloroform-induced immunological changes appeared to be more severe following acute exposure. In vitro treatment of serum with chloroform resulted in a loss of complement activity (Stefanovic et al. 1987). Immunological effects may result from the ability of chloroform to dissociate antigen-antibody complexes, since it can cause dissociation of certain enzyme-inhibitor complexes (Berger et al. 1983). Everyday, humans are exposed to very low levels of chloroform in the environment, mainly via inhalation and oral exposure (Hajimiragha et al. 1986; Peoples et al. 1979; Wallace et al. 1987a, 1989). There is a risk of chloroform exposure at or near hazardous waste sites. Although no evidence that chloroform can cause immunological effects in humans was located in the literature, the possibility remains that these effects may result from exposure to chloroform. Neurological Effects. Neurological effects in humans after acute inhalation exposure to chloroform are well documented because chloroform has been used as an anesthetic for surgery. Inhaled chloroform acts as a depressant on the central nervous system. Chronic inhalation exposure to chloroform resulted in exhaustion, lack of concentration, depression, and irritability in occupationally exposed people (Challen et al. 1958). In a case study, chloroform inhalation for 12 years resulted in psychotic episodes, hallucinations, and convulsions (Heilbrunn et al. 1945). Central nervous system toxicity was observed in humans after oral exposure to chloroform, which suggests that the effects of inhalation and oral exposure are similar. In case reports of patients who intentionally or accidentally ingested several ounces of chloroform, deep coma with abolished reflexes occurred within a few minutes (Piersol et al. 1933; Schroeder 1965; Storms 1973). Inhalation exposure to high chloroform concentrations induced narcosis (Lehmann and Flury 1943; Sax 1979) and reversible impairment of memory retrieval in animals. High, single, oral doses of chloroform caused ataxia, 57 2. HEALTH EFFECTS incoordination, anesthesia, and brain hemorrhage in mice (Balster and Borzelleca 1982; Bowman et al. 1978). Behavioral effects were observed at lower oral doses. The clinical effects of chloroform toxicity on the central nervous system are well documented. The molecular mechanism of action is not, however, well understood. It has been postulated that anesthetics induce their action at a cell-membranal level due to lipid solubility. The lipid-disordering effect of chloroform and other anesthetics on membrane lipids was increased by gangliosides (Harris and Groh 1985), which may explain why the outer leaflet of the lipid bilayer of neuronal membranes, which has a large ganglioside content, is unusually sensitive to anesthetic agents. Anesthetics may affect calcium-dependent potassium conductance in the central nervous system (Caldwell and Harris 1985). The blockage of potassium conductance by chloroform and other anesthetics resulted in depolarization of squid axon (Haydon et al. 1988). The potential for neurological and behavioral effects in humans exposed to chloroform at levels found in the environment, in drinking water, or at hazardous waste sites is not known. Developmental Effects. No studies were located regarding developmental effects in humans after inhalation, oral, or dermal exposure to chloroform. Inhalation exposure to chloroform during gestation induced fetotoxicity and teratogenicity in rats (Schwetz et al. 1974) and mice (Murray et al. 1979). Decreased fetal crown-rump length, decreased ossifications, imperforate anus (rats), and cleft palate (mice) were observed in the offspring of exposed dams. In contrast, fetotoxicity (decreased fetal weight), but not teratogenicity, was observed in rats after oral exposure to chloroform (Ruddick et al. 1983; Thompson et al. 1974). Increased resorptions were observed in rats and rabbits (Thompson et al. 1974). In a two-generation oral study, degeneration of the epididymal ductal epithelium was observed in mice of the F; generation (Gulati et al. 1988). Due to its chemical nature, chloroform can cross the placenta easily, as demonstrated by its detection in the placenta and fetuses of mice a short time after inhalation exposure (Danielsson et al. 1986). Chloroform may accumulate in the amniotic fluid and fetal tissues. Various developmental effects may result from exposure, depending on the period of in_utero exposure. An acute inhalation MRL of 0.009 ppm was derived for chloroform based on the LOAEL of 30 ppm for developmental effects (delayed ossification) in rats in the study by Schwetz et al. (1974). Although no studies reported developmental effects in humans, chloroform may have the potential to cause developmental effects in humans. Whether such effects could occur from exposure to levels in the environment, in drinking water, or at hazardous waste sites is not known. Reproductive Effects. No studies were located regarding reproductive effects in humans after inhalation, oral, or dermal exposure to chloroform. Studies indicate that exposure to chloroform causes reproductive effects in animals. Dose-related increases of embryonal resorptions were observed in rats and mice after inhalation or oral exposure to chloroform during gestation. A significant increase in the incidence of abnormal sperm was observed in mice after acute inhalation exposure (Land et al. 1979, 1981) but not after intraperitoneal exposure (Topham 1980). Gonadal atrophy was observed in male and female rats treated by gavage (Palmer et al. 1979). Fertility was not affected in either generation of mice exposed orally to chloroform in a two-generation study (Gulati et al. 1988). Oral exposure to chloroform did not induce histopathological changes in the reproductive organs of rats exposed for intermediate durations (Jorgenson and Rushbrook 1980) or in rats and mice (NCI 1976) and dogs (Heywood et al. 1979) exposed for chronic durations. It is not known whether chloroform exposure induces reproductive effects in humans. 58 2. HEALTH EFFECTS Genotoxic Effects. In vitro and in vivo studies of the genotoxic effects of chloroform are summarized in Tables 2-4 and 2-5. In in vitro experiments, chloroform did not cause reverse mutations in Salmonella typhimurium (Gocke et al. 1981; San Augustin and Lim-Sylianco 1978; Simmon et al. 1977; Uehleke et al. 1977; Van Abbe et al. 1982; Varma et al. 1988) or in Escherichia coli (Kirkland et al. 1981) with or without metabolic activation. Inconclusive results were obtained in Saccharomyces cerevisiae and Schistozosaccharomyces pombe (Callen et al. 1980; De Serres et al. 1981). Chloroform, however, induced aneuploidia in Aspergillus nidulans (Crebelli et al. 1988). Chloroform caused forward mutations in L5178Y mouse lymphoma cells after metabolic activation (Mitchell et al. 1988), but did not cause mutations at 8-azaguanine locus in Chinese hamster lung fibroblasts (Sturrock 1977) or sister chromatid exchange in Chinese hamster ovary cells (White et al. 1979). In human lymphocytes, chloroform did not induce unscheduled DNA synthesis (Perocco and Prodi 1981) and did not increase the frequency of sister chromatid exchange and chromosome aberrations (Kirkland et al. 1981). In contrast, increases in sister chromatid exchange were reported after metabolic activation in another study (Morimoto and Koizumi 1983). Information regarding genotoxic effects after in vivo exposure to chloroform is limited. Acute inhalation exposure to chloroform caused an increase in the percentage of abnormal sperm in mice (Land et al. 1979, 1981). Mice exposed to chloroform by gavage had an increase in sister chromatid exchange frequency in bone marrow cells (Morimoto and Koizumi 1983). In contrast, oral exposure to chloroform did not increase unscheduled DNA synthesis in rat hepatocytes (Mirsalis et al. 1982). Chloroform exposure caused mitotic arrest in grasshopper embryos (Liang et al. 1983) and a nonsignificant increase in the recessive lethals in Drosophila melanogaster (Gocke et al 1981). In general, most of the assays for chloroform genotoxicity are negative. Therefore, it seems that chloroform is a weak mutagen and that its potential to interact with DNA is low. Cancer. No studies were available regarding cancer in humans or animals after inhalation exposure to chloroform. Epidemiology studies suggest an association between chronic exposure to chlorinated drinking water sources and increased incidences of colon cancer (Young et al. 1981), and bladder cancer (Cantor et al. 1978). The carcinogenic potential of chloroform has been tested in animal studies. A dose-related increase in the incidence of hepatomas was observed in mice exposed to chloroform for intermediate durations (Eschenbrenner and Miller 1945a). Chronic exposure induced an increased incidence of renal adenoma and carcinoma in rats exposed to chloroform in drinking water (Jorgenson et al. 1985) and in rats treated by gavage with chloroform in oil (NCI 1976). Hepatic neoplastic nodules were observed in female rats, and lymphosarcoma was observed in male rats exposed to chloroform in drinking water (Tumasonis et al. 1987). In addition, hepatocellular carcinoma was observed in B6C3F,; mice given chloroform in oil by gavage (NCI 1976), and kidney tumors were observed in ICI mice exposed by gavage to chloroform in toothpaste (Roe et al. 1979). The data concerning mouse liver tumors are conflicting. In contrast to the increased incidence of liver tumors observed in B6C3F; mice exposed by gavage to chloroform in oil (NCI 1976), no increased incidence of liver tumors was observed in female B6C3F; mice exposed to chloroform in drinking water (Jorgenson et al. 1985). This result is consistent with the absence of liver tumor effects in four other strains of mice exposed by gavage to chloroform in toothpaste (Roe et al. 1979). In a pharmacokinetic study, chloroform was absorbed more slowly and to a lesser extent from com oil than from water (Withey et al. 1983), suggesting that pharmacokinetic effects are not responsible for the differences in liver tumor responses. Nevertheless, data from historical controls indicate that com oil alone is not responsible for the increased incidence of liver tumors (Jorgenson et al. 1985). The com oil vehicle effect on mouse liver tumors may be due to an interaction between the vehicle and chloroform (Bull et al. 1986; Jorgenson et al. 1985). The discrepancy also may be due to the difference in dosing method (bolus gavage doses versus gradual dosing in drinking water). TABLE 2-4. Genotoxicity of Chloroform In Vitro Species (test system) End point Reference Prokaryotic organism: Salmonella typhimurium TA98 S. typhimurium TA100 S. typhimurium TA1535 S. typhimurium TA1535 S. typhimurium TA1538 S. typhimurium TA98 S. typhimurium TA100 S. typhimurium TA1535 S. typhimurium TA1537 S. typhimurium TA98 S. typhimurium TA100 S. typhimurium TA1535 S. typhimurium TA1537 S. typhimurium TA1538 S. typhimurium TA98 S. typhimurium TA100 S. typhimurium TA1535 S. typhimurium TA1537 S. typhimurium TA98 S. typhimurium TA1535 S. typhimurium TA1537 Reverse mutation Reverse mutation Reverse mutation Reverse mutation Reverse mutation Reverse mutation Reverse mutation Reverse mutation Reverse mutation Reverse mutation Reverse mutation Reverse mutation Reverse mutation Reverse mutation Reverse mutation Reverse mutation Reverse mutation Reverse mutation Reverse mutation Reverse mutation Reverse mutation Results With Without activation activation - (+) + (+) - +) - +) Not tested - Not tested - Not tested - Gocke et al. 1981 Gocke et al. 1981 Gocke et al. 1981 Uchleke et al. 1977 Uehleke et al. 1977 Simmon et al. 1977 Simmon et al. 1977 Simmon et al. 1977 Simmon et al. 1977 Van Abbe et al. 1982 Van Abbe et al. 1982 Van Abbe et al. 1982 Van Abbe et al. 1982 Van Abbe et al. 1982 Varma et al. 1988 Varma et al. 1988 Varma et al. 1988 Varma et al. 1988 San Augustin and Lim-Sylianco 1978 San Augustin and Lim-Sylianco 1978 San Augustin and Lim-Sylianco 1978 S103443 H1TV3H °¢ 6S TABLE 2-4 (Continued) Results With Without Species (test system) End point activation activation Reference Escherichia coli Reverse mutation - - Kirkland ct al. 1981 Aspergillus nidulans Ancuploidia + Not tested Crebelli et al. 1988 Saccharomyces cerevisiae Reverse mutation - (+) De Serres et al. 1981 Schizosaccharomyces pombe Recombinations - (+) Callen et al. 1980 Eukaryotic organisms: Mammalian cells: L5178Y mouse lymphoma cells Forward mutation + - Mitchell et al. 1988 Chinese hamster lung fibroblasts Mutationa at 8-azaquonine - Sturrock 1977 Chinese hamster ovary cells Sister chromatid exchange - White et al. 1979 Human lymphocytes Unscheduled DNA synthesis - - Perocco and Prodi 1981 Human lymphocytes Sister chromatid exchange - + Morimoto and Koizumi 1983 Human lymphocytes Sister chromatid exchange - - Kirkland et al. 1981 Human lymphocytes Chromosome aberrations - Kirkland et al. 1981 - = negative result; + = positive result; (+) = weakly positive; DNA = Deoxyribonucleic acid S103443 H1TV3H ¢ 09 TABLE 2-5. Genotoxicity of Chloroform In Vivo Species (test system) End point Results Reference Mammalian cells: Rat hepatocytes Unscheduled DNA synthesis ~~ - Mouse bone marrow Sister chromatid exchange - Mouse Sperm abnormalities + Grasshopper embryo Mitotic arrest + Drosophila_melanogaster Recessive lethals - Host-mediated assays: Salmonella typhimurium TA1535 (mouse host-mediated assay) Reverse mutation - S. typhimurium TA1537 (mouse host-mediated assay) Reverse mutation + (males only) Mirsalis et al. 1982 Morimoto and Koizumi 1983 Land et al. 1981 Liang et al. 1983 Gocke et al. 1981 San Augustin and Lim-Sylianco 1978 San Augustin and Lim-Sylianco 1978 - = negative result; + = positive result; DNA = Deoxyribonucleic acid S103443 H1TVv3H ¢ 19 62 2. HEALTH EFFECTS In a study of the mechanism of chloroform carcinogenicity, single oral doses of 60 and 240 mg/kg chloroform that induced increased tumor incidences in male B6C3F, mice also caused severe necrosis at liver and kidney sites prior to tumor development (Reitz et al. 1980, 1982). A chloroform dose of 15 mg/kg that did not cause an increased tumor incidence also did not cause necrosis and regeneration. These results suggest that the increased proliferation of liver and kidney cells during regeneration after necrosis may be involved in the development of tumors. In vivo studies of DNA alkylation and repair do not indicate any genotoxic effects of chloroform, further supporting the case made for an epigenetic mechanism of carcinogenicity. In the liver bioassay for GGTase positive foci, chloroform had neither an initiating effect nor a promoting effect when administered in drinking water (Herren-Freund and Pereira 1987), but had a promoting effect of these loci initiated by diethylnitrosamine if given in a com oil vehicle (Deml and Oesterle 1985) in rats. Moreover, chloroform enhanced the growth of experimentally inoculated tumors in mice (Capel et al. 1979). In contrast, chloroform had an inhibiting effect on the growth of tumors induced by known carcinogens (1.2-dimethylhydrazine and ethylnitrosurea) (Daniel et al. 1989; Herren-Freund and Pereira 1987). In epidemiology studies, chloroform is not identified as the sole or primary cause of excess cancer rates, but it is one of many organic contaminants found in chlorinated drinking water, many of which are considered to have carcinogenic potential. These studies are often flawed by a lack of measured chloroform concentrations in drinking water; lack of data concerning concentrations of other organics; limited information conceming personal drinking water consumption; long latency periods: and effects of migration, making it difficult to quantify exposure. Although human data suggest a possible increased risk of cancer from exposure to chloroform in chlorinated drinking water. the data are too weak to draw a conclusion about the carcinogenic potential of chloroform in humans. Based on the positive carcinogenic response in animals, some authors tried to estimate the risk of liver cancer associated with human exposure to chloroform (Reitz et al. 1990). Chloroform has been classificd as a probable human carcinogen by EPA (IRIS 1992). as a possible human carcinogen by IARC (1987), and as a substance that may reasonably be anticipated to be carcinogenic in humans (NTP 1989). 2.5 BIOMARKERS OF EXPOSURE AND EFFECT Biomarkers are broadly defined as indicators signaling events in biologic systems or samples. They have been classificd as markers of exposure, markers of effect, and markers of susceptibility (NAS/NRC 1989). A biomarker of exposure is a xenobiotic substance or its metabolite(s) or the product of an interaction between a xenobiotic agent and some target molecule(s) or cell(s) that is measured within a compartment of an organism (NAS/NRC 1989). The preferred biomarkers of exposure are generally the substance itself or substance-specific metabolites in readily obtainable body fluid(s) or excreta. However, several factors can confound the use and interpretation of biomarkers of exposure. The body burden of a substance may be the result of exposures from more than one source. The substance being measured may be a metabolite of another xenobiotic substance (e.g., high urinary levels of phenol can result from exposure to several different aromatic compounds). Depending on the properties of the substance (e.g., biologic half-life) and environmental conditions (e.g. duration and route of exposure), the substance and all of its metabolites may have left the body by the time biologic samples can be taken. It may be difficult to identify individuals exposed to hazardous substances that are commonly found in body tissues and fluids (e.g.. essential mineral nutrients such as copper, zinc, and selenium). Biomarkers of exposure to chloroform are discussed in Section 2.5.1. Biomarkers of effect are defined as any measurable biochemical, physiologic. or other alteration within an organism that, depending on magnitude, can be recognized as an established or potential health impairment or disease (NAS/NRC 1989). This definition encompasses biochemical or cellular signals of tissue dysfunction (e.g., 63 2. HEALTH EFFECTS increased liver enzyme activity or pathologic changes in female genital epithelial cells), as well as physiologic signs of dysfunction such as increased blood pressure or decreased lung capacity. Note that these markers are often not substance specific. They also may not be directly adverse, but can indicate potential health impairment (e.g.. DNA adducts). Biomarkers of effects caused by chloroform are discussed in Section 2.5.2. A biomarker of susceptibility is an indicator of an inherent or acquired limitation of an organism's ability to respond to the challenge of exposure to a specific xenobiotic substance. It can be an intrinsic genetic or other characteristic or a preexisting disease that results in an increase in absorbed dose, biologically effective dose, or target tissue response. If biomarkers of susceptibility exist, they are discussed in Section 2.7, "Populations That Are Unusually Susceptible.” 2.5.1 Biomarkers Used to Identify or Quantify Exposure to Chloroform Methods for measuring chloroform in biological fluids, tissues, and exhaled breath are available; however, there is relatively little quantitative information relating monitored chloroform levels in tissues or fluids to exposure levels, possibly due to the volatility and rapid elimination of chloroform from tissues. In addition, the presence of chloroform or its metabolites in biological fluids and tissues may result from the metabolism of other chlorinated hydrocarbons; thus, elevated tissue levels of chloroform or its metabolites may reflect exposure to other compounds. The relationship between chloroform concentration in inspired air and resulting blood chloroform levels is the most well-defined measure of exposure due to the extensive use of chloroform as a surgical anesthetic. A mean arterial blood concentration of 9.8 mg/dL (range 7-16.6 mg/dL) was observed among 10 patients receiving chloroform anesthesia at an inspired air concentration of 8.000-10,000 ppm (Smith et al. 1973). Monitoring of blood levels in workers experiencing toxic jaundice due to chloroform exposure revealed that when workroom air concentrations were estimated to be >400 ppm, the blood samples of 13 workers with jaundice were 0.10-0.3 pg/100 mL blood (Phoon et al. 1983). In another group of 18 workers with toxic hepatitis. blood samples revealed chloroform in some but not all workers, and workroom air contained 14.4-50.4 ppm on various days. These data suggest an association between increased blood concentrations and increased exposure concentrations, but the blood levels varied too greatly to establish a direct quantitative relationship. Environmental exposure to chloroform in humans probably represents a combination of inhalation exposure (from the air polluted with volatile halogenated hydrocarbons) and oral exposure (from chlorinated water sources). The chloroform levels detected in human blood varied according to geographical areas. Chloroform was detected in 66.7% of the blood samples taken from 39 individuals in West Germany (Hajimiragha et al. 1986). The blood levels ranged from 0.1 to 1.7 pg/L with a median level of 0.2 pg/L. The chloroform concentration in the air was 14x10 ppm. and trihalomethanes in tap water were <1 pg/L. Chloroform levels ranged from 13 to 49 pg/L in serum samples taken from 10 individuals in Florida (Peoples et al. 1979). The level of environmental exposure was not reported. The mean blood chloroform concentration was 1.5 pg/L in blood samples taken from 250 individuals in Louisiana; exposure levels were not reported (Antoine et al. 1986). Chloroform was found in breath samples from large cohorts of people from New Jersey, North Carolina, and North Dakota (Wallace et al. 1987a). The levels of chloroform in breathing zone (personal) air were consistently higher than outdoor concentrations and correlated with chloroform concentrations in the exhaled breath samples. Some activities (visiting the dry cleaners or showering) were associated with increased chloroform breath levels (Wallace et al. 1989). Chloroform was detected in 7/42 samples of human milk collected in four geographical areas in the United States (Pellizzari et al. 1982). 64 2. HEALTH EFFECTS Tissue levels of chloroform obtained at autopsy reflected environmental exposure levels in other studies. The levels ranged from 20 to 49 pg/L in adipose tissue samples taken from 10 individuals in Florida (Peoples et al. 1979). In 30 autopsy cases in Germany, the adipose tissue contained a mean of 23.4 pg/kg wet tissue; 24.8 ng/kg perinephric fat; 10.8 pg/kg liver tissue; 9.9 pg/kg lung tissue; and 10.0 pg/kg muscle tissue (Alles et al. 1988). The maximum chloroform content increased with age and was not dependent on the volume of fat in the tissues. No correlation has been made between the exact environmental levels of chloroform and the amount of chloroform in the exhaled breath or in the blood. Furthermore, chloroform also can be detected in the breath after exposure to carbon tetrachloride and other chlorinated hydrocarbons (Butler 1961). Therefore, chloroform levels cannot be used as reliable biomarkers of exposure to this chemical. 2.5.2 Biomarkers Used to Characterize Effects Caused by Chloroform The primary targets of chloroform toxicity are the central nervous system, liver, and kidney. The signs and symptoms of central nervous system effects (e.g., dizziness, tiredness, headache) are easily recognized. Monitoring liver and kidney effects induced by exposure to low levels of chloroform requires the testing of organ functions. Liver effects are commonly detected by monitoring for elevated levels of liver enzymes in the serum or testing for sulfobromophthalein retention. Urinalysis and measurement of blood urea nitrogen are used to detect abnormalities in kidney function. Because many toxic chemicals can cause adverse liver and kidney effects, these tests are not specific for chloroform. No specific biomarkers used to characterize effects caused by chloroform were located. 2.6 INTERACTIONS WITH OTHER CHEMICALS Clinical reports of patients who underwent chloroform anesthesia indicated that premedication with morphine caused serious respiratory depression when chloroform was administered. Furthermore, thiopentone was associated with increased incidences of hypotension in chloroform-anesthetized patients. Several animal studies indicate that chloroform interacts with other chemicals within the organism. The lethal and hepatotoxic effects of chloroform were increased by dicophane (DDT) (McLean 1970) and phenobarbital in rats (Ekstrom et al. 1988; McLean 1970; Scholler 1970). Increased hepatotoxic and nephrotoxic effects were observed after interaction with ketonic solvents and ketonic chemicals in rats (Hewitt and Brown 1984; Hewitt et al. 1990) and in mice (Cianflone et al. 1980; Hewitt et al. 1979). The hepatotoxicity of chloroform was also enhanced by coexposure to carbon tetrachloride in rats (Harris et al. 1982) and by coexposure to ethanol in mice (Kutob and Plaa 1962). Furthermore, ethanol pretreatment in rats increased the in vitro metabolism of chloroform (Sato et al. 1981). Similarly, a mixture of cadmium and chloroform potentiated the cytotoxicity of each in in vitro experiments in rat hepatocytes (Stacey 1987a, 1987b). In contrast, mirex did not increase chloroform toxicity in mice (Hewitt et al. 1979). Disulfiram, an inhibitor of microsomal enzymes, decreases the hepatotoxicity of chloroform (Masuda and Nakayama 1982; Scholler 1970). Diethyldithiocarbamate and carbon disulfide pretreatment also protect against chloroform hepatotoxicity (Masuda and Nakayama 1982, 1983; Gopinath and Ford 1975), presumably by inhibiting microsomal enzymes. In general, chloroform toxicity can be influenced by chemicals that alter microsomal enzyme activity or hepatic glutathione levels. 2.7 POPULATIONS THAT ARE UNUSUALLY SUSCEPTIBLE A susceptible population will exhibit a different or enhanced response to chloroform than will most persons exposed to the same level of chloroform in the environment. Reasons include genetic make-up, developmental 65 2. HEALTH EFFECTS stage. health and nutritional status, and chemical exposure history. These parameters result in decreased function of the detoxification and excretory processes (mainly hepatic and renal) or the pre-existing compromised function of target organs. For these reasons we expect the elderly with declining organ function and the youngest of the population with immature and developing organs will generally be more vulnerable to toxic substances than healthy adults. Populations who are at greater risk due to their unusually high exposure are discussed in Section 5.6, "Populations With Potentially High Exposure.” Individuals who have hepatic or renal damage may be more susceptible to chloroform toxicity. Also, exhaustion and starvation may potentiate chloroform hepatotoxicity, as indicated in human clinical reports (Royston 1924: Townsend 1939) and in animal studies (Ekstrom et al. 1988; McMartin et al. 1981). Animal studies indicate that male mice and rats may be more susceptible to the lethal and renal effects of chloroform than female mice and rats (Deringer et al. 1953; Torkelson et al. 1976). The greater susceptibility of adult male animals is associated with testosterone levels in the animals (Deringer et al. 1953). Whether or not human males would be more susceptible than human females to the harmful effects of chloroform is not known. 2.8. METHODS FOR REDUCING TOXIC EFFECTS This section will describe clinical practice and research concerning methods for reducing toxic effects of exposure to chloroform. However, because some of the treatments discussed may be experimental and unproven, this section should not be used as a guide for treatment of exposures to chloroform. When specific exposures have occurred. poison control centers and medical toxicologists should be consulted for medical advice. 2.8.1 Reducing Peak Absorption Following Exposure Human exposure to chloroform may occur by inhalation, ingestion, or by dermal contact. General recommendations for reducing absorption of chloroform include removing the exposed individual from the contaminated area and removing the contaminated clothing. If the eyes and skin were exposed. they are flushed with water. In order to reduce absorption of ingested chloroform, emesis may be considered unless the patient is comatose. is convulsing. or has lost the gag reflex. Controversy exists concerning use of emesis because of the rapid onset of central nervous system depression, the risk of aspiration of vomit into the lungs, and the relative ineffectiveness of this method. Gastric lavage is also used. In comatose patients with absent gag reflexes, an endotracheal intubation may be performed in advance to reduce the risk of aspiration pneumonia. 2.8.2 Reducing Body Burden Chloroform is not stored in the human body (see Section 2.3). The half-life of chloroform in humans has been calculated as 7.9 hours following inhalation exposure (Gordon et al. 1988). Furthermore, an oral exposure study found most of the chloroform dose being eliminated within 8 hours postexposure (Fry et al. 1972). Hepatic and pulmonary first pass effect was reported in humans (Chiou 1975). Despite a relatively fast clearance of chloroform from the body, toxic effects may develop in exposed individuals. However, no method is commonly used to enhance the elimination of the absorbed dose of chloroform. Although there is evidence that ethanol pretreatment of rats can increase the in_vitro metabolism of chloroform (Sato et al. 1981). such treatment would not be recommended, because it is known that coexposure to ethanol increases the hepatotoxicity of chloroform (Kutob and Plaa 1962) and might be expected to increase central nervous system depression as well. 66 2. HEALTH EFFECTS 2.8.3 Interfering with the Mechanism of Action for Toxic Effects Target organs of chloroform toxicity are the central nervous system, liver, and kidneys (see Section 2.2). In addition, respiratory, cardiovascular, and gastrointestinal effects have been reported. Studies in animals also indicated that chloroform exposure may induce reproductive and developmental effects and cause cancer. Several studies investigated the possible mechanism for chloroform induced toxicity (see Section 2.4). Proposed mechanisms of chloroform toxicity and potential mitigations based on these mechanisms are discussed below. The potential mitigation techniques mentioned are all experimental in nature. One of the possible mechanisms of chloroform toxicity is thought to be linked to its high lipid solubility and its ability to bind covalently to lipids (Testai et al. 1987). For example, neurotoxic and respiratory effects of chloroform may be due to the interaction of chloroform with gangliosides in neuronal membranes (Harris and Groh 1985) and phospholipids in the surfactant monolayer of the lower respiratory tract (Enhoming et al. 1986), respectively. Another proposed reaction of chloroform and lipids would result in the formation of conjugated dienes which are indicative of lipid peroxidation (De Groot and Noll 1989). Some authors reported that conjugated dienes may play a key role in the hepatotoxicity induced by haloalkanes (Comporti 1985; Recknagel et al. 1982). Others, however, argue that lipid peroxidation alone is not responsible for all changes found in the liver following chloroform exposure (Brown et al. 1974b; Lavigne and Marchand 1974). Instead, the mechanism of chloroform-induced liver and kidney toxicity was proposed to involve metabolism to the reactive intermediate, phosgene, which binds to lipids and proteins of the endoplasmatic reticulum (Pohl et al. 1980a, 1980b). The toxicity of chloroform is increased by inducers of cytochrome P-450 such as phenobarbital (Scholler 1970). The involvement of cytochrome P-450 is further supported by the finding that disulfiram (Scholler 1970) and methoxsalen (Letteron et al. 1987), both inhibitors of microsomal enzymes, decreased the liver injury caused by chloroform in rats and mice. respectively. In addition, pretreatment with diethyldithiocarbamate and carbon disulfide protected mice against chloroform hepatotoxicity as indicated by biochemical and histopathological results (Masuda and Nakayama 1982, 1983; Gopinath and Ford 1975). Similarly, pretreatment of mice with methoxsalen (Lettcron et al. 1987) and piperonyl butoxide (Kluwe and Hook 1981) reduced the chloroform induced nephrotoxicity. Further research to determine which isozymes of P-450 are involved in metabolism to the more harmful metabolite, phosgene, as well as which isozymes are involved in enhancing the elimination of chloroform could lead to the development of strategies designed to selectively inhibit specific P-450 isozymes, and thus reduce the toxic effects of chloroform. Administration of chloroform to laboratory animals resulted in the depletion of renal glutathione, indicating that glutathione reacts with reactive intermediates. thus reducing the kidney damage otherwise caused by the reaction of these intermediates with tissue macromolecules (Hook and Smith 1985; Smith and Hook 1983, 1984; Smith et al. 1984). Similarly, chloroform treatment resulted in the depletion of hepatic glutathione and alkylation of macromolecules (Docks and Krishna 1976). Other studies demonstrated that sulfhydryl compounds such as L- cysteine (Bailie et al. 1984) and reduced glutathione (Kluwe and Hook 1981) may provide protection against nephrotoxicity induced by chloroform. The sulfhydryl compound N-acetylcysteine is an effective antidote for poisoning by acetaminophen, which, like chloroform, depletes glutathione and produces toxicity by reactive intermediates. All mitigations of the chloroform induced toxicity cited above are experimental. Further studies would be needed for implications of any of these methods to humans. 67 2. HEALTH EFFECTS 2.9 ADEQUACY OF THE DATABASE Section 104(i)(5) of CERCLA directs the Administrator of ATSDR (in consultation with the Administrator of EPA and agencies and programs of the Public Health Service) to assess whether adequate information on the health effects of chloroform is available. Where adequate information is not available, ATSDR, in conjunction with the National Toxicology Program (NTP), is required to assure the initiation of a program of research designed to determine the health effects (and techniques for developing methods to determine such health effects) of chloroform. The following categories of possible data needs have been identified by a joint team of scientists from ATSDR, NTP, and EPA. They are defined as substance-specific informational needs that if met would reduce or eliminate the uncertainties of human health assessment. This definition should not be interpreted to mean that all data needs discussed in this section must be filled. In the future, the identified data needs will be evaluated and prioritized, and a substance-specific research agenda will be proposed. 2.9.1 Existing Information on Health Effects of Chloroform The existing data on health effects of inhalation, oral, and dermal exposure of humans and animals to chloroform are summarized in Figure 2-4. The purpose of this figure is to illustrate the existing information concerning the health effects of chloroform. Each dot in the figure indicates that one or more studies provide information associated with that particular effect. The dot does not imply anything about the quality of the study or studies. Gaps in this figure should not be interpreted as "data needs” information (i.e.. data gaps that must necessarily be filled). As seen from Figure 2-4. information is available regarding death, systemic effects, and neurological effects in humans after inhalation and oral exposure to chloroform. In addition, information is available regarding carcinogenic effects in humans after oral exposure to chlorinated drinking water. Information is available regarding dermal effects in humans after exposure to chloroform. Inhalation and oral studies in animals provide data on death, systemic effects after acute and intermediate duration exposurc. immunological effects. neurological effects, developmental effects, reproductive effects, and genotoxic effects. Information is available regarding systemic effects and carcinogenic effects in animals after oral exposure to chloroform. In addition, data regarding death and acute systemic effects in animals after dermal exposure to chloroform were located in the available literature. 2.9.2 Identification of Data Needs Acute-Duration Exposure. Clinical reports indicate that the central nervous system, cardiovascular system, stomach, liver, and kidneys in humans were target organs of chloroform toxicity after inhalation and oral exposure to chloroform (Schroeder 1965; Smith et al. 1973; Whitaker and Jones 1965). These findings are supported by results obtained from acute inhalation and oral exposure studies in animals in which target organs identical to those observed in human studies (central nervous system, liver, and kidney) were identified (Culliford and Hewitt 1957; Jones et al. 1958; Lehmann and Flury 1943; Lundberg et al. 1986; Moore et al. 1982). The data are sufficient to derive an MRL for acute oral exposure. An acute inhalation MRL was derived based on a LOAEL for developmental effects (delayed ossification) in rats (Schwetz et al. 1974). Lethality studies were conducted in rats and mice after acute inhalation exposure (Deringer et al. 1953; Gehring 1968; Lundberg et al. 1986; Smyth et al. 1962). Similarly, lethal doses were identified after single oral exposure in rats and mice (Bowman et al. 1978: Chu ct al. 1982b; Jones et al. 1958; Kimura et al. 1971; Smyth et al. 1962). Information regarding dermal 68 2. HEALTH EFFECTS FIGURE 2-4. Existing Information on Health Effects of Chloroform SYSTEMIC > Oral ® & Inhalation | ® | ® | ® | ® ® ® @ ® Dermal HUMAN SYSTEMIC 8 & & § Inhalation | ® | ® | ® oj|0o(0|O0|O Oral O00 00000 | OG O Dermal oO ANIMAL @ Existing Studies 113035-1 69 2. HEALTH EFFECTS effects in humans and animals after exposure to chloroform is limited. Degenerative changes in the kidney tubules of rabbits were reported in one dermal study (Torkelson et al. 1976). Toxicokinetic data regarding dermal exposure are limited; however, there is evidence that chloroform can be absorbed through the skin (Tsuruta 1975). Due to its lipophilic quality, chloroform is likely to be distributed in the organism, after dermal exposure, in patterns similar to those for inhalation and oral exposure. Information regarding acute dermal exposure in rodents would be useful to identify target organs and threshold levels of chloroform toxicity. Additional acute inhalation studies conducted at lower exposure levels would help to identify a NOAEL for acute inhalation exposure. The information regarding chloroform toxicity is useful to populations residing at or near hazardous waste sites, that might be subject to acute exposure. Intermediate-Duration Exposure. An occupational study suggests that the liver is a target organ of chloroform toxicity after inhalation exposure of intermediate duration (Phoon et al. 1983). No data were located regarding intermediate-duration oral and dermal exposure in humans. Several studies were located regarding chloroform toxicity in animals after oral exposure (including three 90-day studies in rats, three 90-day studies in mice, and a >6-week oral study in dogs) (Bull et al. 1986; Chu et al. 1982a, 1982b; Heywood et al. 1979; Jorgenson and Rushbrook 1980; Klaunig et al. 1986; Munson et al. 1982; Palmer et al. 1979); fewer data were located regarding inhalation exposure (Torkelson et al. 1976), and no data were located regarding dermal exposure. In animals, the target organs for chloroform toxicity were identified as the central nervous system, liver, and kidneys. An intermediate-duration oral MRL was derived based on liver effects in dogs. An inhalation MRL was not derived because toxic hepatitis may occur in humans at exposure levels lower than those tested in animals. Pharmacokinetic data regarding dermal exposure to chloroform are limited. but it is known that chloroform can be absorbed through the skin. Intermediate-duration dermal studies in animals would provide information about chloroform toxicity via this exposure route. The information would be useful for populations living at or near hazardous waste sites, that may be exposed to chloroform for intermediate durations. Chronic-Duration Exposure and Cancer. Information regarding chronic inhalation exposure to chloroform in humans is limited to occupational studies (Bomski et al. 1967; Challen et al. 1958). The liver and central nervous system are target organs of chloroform toxicity. Regarding chronic oral exposure in humans, limited information is available from a case study reporting hematological, hepatic, and renal effects in an individual who used a cough medicine containing chloroform for 10 years (Wallace 1958) and from a follow-up study of individuals who used a mouthwash containing chloroform for <5 years (De Salva et al. 1975). Animal data indicate that the central nervous system, liver, and kidneys are target organs of chloroform toxicity after chronic oral exposure (Heywood et al. 1979; Jorgenson et al. 1985; NCI 1976; Roe et al. 1979; Tumasonis et al. 1985; 1987). The data are sufficient to derive a chronic oral MRL. No studies were located regarding chloroform toxicity in humans and animals after dermal exposure to chloroform and in animals after inhalation exposure to chloroform. Considering the similar pattern of chloroform toxicity after inhalation and oral exposures for acute and intermediate durations, similar target organs in animals after chronic inhalation exposure to chloroform may be predicted. Nonetheless, studies designed to assess the chronic toxicity of chloroform in animals after inhalation and dermal exposure would be useful to establish dose-response relationships. This information is important to humans occupationally exposed or exposed to contaminated air, water, or soil at or near hazardous waste sites. Epidemiology studies suggest a possible association between chloroform in drinking water and cancer risk. Increased incidences of colon and bladder cancer were identified in separate populations exposed to chlorinated water. Studies in rats and mice indicate that oral exposure to chloroform causes cancer (Jorgenson et al. 1985; NCI 1976: Roe et al. 1979; Tumasonis et al. 1985; 1987). No data were located regarding carcinogenicity in humans and animals following inhalation and dermal exposure to chloroform. Nonctheless. pharmacokinetic data 70 2. HEALTH EFFECTS indicate similar toxicokinetics of chloroform after inhalation and oral exposure; therefore, similar targets for carcinogenic effects may be predicted. Data were located suggesting different effects of chloroform depending on the vehicle and method of oral administration. Chloroform in com oil administered by gavage caused an increased incidence of liver tumors (NCI 1976), while administration of a higher same dose in drinking water did not (Jorgenson et al. 1985). It was demonstrated, however, that chloroform uptake is much slower from the oil vehicle (Withey et al. 1983). Therefore, the higher cancer incidence cannot be explained merely by the levels of chloroform in tissues. Furthermore, chloroform acted as a promoter rather than an initiator of preneoplastic foci in a rat liver bioassay (Deml and Oesterle 1985). In contrast, some studies indicate that chloroform inhibits the growth of tumors induced by known carcinogens (Daniel et al. 1989; Herren-Freund and Pereira 1987). Animal studies also suggest an epigenetic mechanism for the carcinogenicity of chloroform. Because of these differences. further studies on the possible mechanism of chloroform carcinogenicity would be useful. Genotoxicity. Chloroform has been tested for genotoxicity in several in vitro and in_vivo experiments. Its potency to induce mutations seems to be weak. No induction of reverse mutations was observed in prokaryotic systems (Gocke et al. 1981, Kirkland et al. 1981; San Augustin and Lim-Sylianco 1978; Simmon et al. 1977; Uehleke et al. 1977; Van Abbe et al. 1982; Varma et al. 1988). Mixed results were obtained in the induction of mutations in human lymphocytes and Chinese hamster cells in vitro (Kirkland et al. 1981; Mitchell et al. 1988; Perocco and Pradi 1981; White et al. 1979). Nonetheless, an increase in sperm anomalies and sister chromatid exchanges in the bone marrow of rodents was observed after in vivo exposure (Land et al. 1979, 1981; Morimoto and Koizumi 1983). Cytogenetic analysis of peripheral lymphocytes from exposed individuals would provide useful information about the ability of chloroform to induce mutations in humans. Reproductive Toxicity. No information was located regarding reproductive effects in humans exposed to chloroform via any route or in animals exposed by the dermal route. Increased resorptions were observed in rats and mice after inhalation exposure to chloroform during gestation (Murray et al. 1979; Schwetz et al. 1974) and in rats and rabbits after oral exposure (Thompson et al. 1974). In addition to effects in dams, abnormal sperm were found in mice after inhalation exposure (Land et al. 1979, 1981). Furthermore, exposure-related gonadal atrophy was observed in both sexes of rats following oral exposure to chloroform (Palmer et al. 1979). The results suggest that reproductive organs are a target of chloroform toxicity in animals; however, some inhalation and oral studies in animals do not report any effects. More studies assessing the reproductive function in animals would be uscful for the purpose of extrapolating the data to human exposure. Developmental Toxicity. No studies were located regarding developmental effects in humans exposed to chloroform via any route. Animal data indicate that chloroform can cross the placenta. Fetotoxicity effects (decreased birth weight. decreased fetal crown-rump length, increased resorptions) and teratogenicity (acaudate fetuses with imperforate anus, cleft palates) were observed in rats and mice after inhalation exposure to chloroform (Murray et al. 1979; Schwetz et al. 1974). An acute inhalation MRL was derived from a LOAEL for developmental effects (delayed ossification) in rats. Oral exposure to chloroform induced fetotoxicity in rats and rabbits (Ruddick et al. 1983; Thompson et al. 1974). Degeneration of the epididymal ductal epithelium (not affecting the fertility) was observed in mice in the F, generation in a two-generation oral reproductive study (Gulati et al. 1988). No information is available regarding the developmental toxicity of chloroform after dermal exposure. Data regarding developmental toxicity in experimental animals (especially after oral and dermal exposure) would be useful to identify the possible risk for humans. Immunotoxicity. No data were located regarding immunological effects in humans after inhalation, oral, or dermal exposurc to chloroform. The data obtained from animal studies are limited to one inhalation study in mice and three oral studies in rats and mice (Aranyi et al. 1986; Chu et al. 1982b; Munson et al. 1982). Depressed humoral and cell-mediated immunity were detected: however, the chloroform induced changes were Ia 2. HEALTH EFFECTS more serious in the acute exposure study than in the intermediate-duration study, indicating that the changes may be transient. Studies regarding skin sensitization with chloroform were not performed. A battery of immune function tests has not been performed in humans or in animals, but would provide helpful information to support or refute the limited evidence for chloroform immunotoxicity. Neurotoxicity. The central nervous system is a target organ for chloroform toxicity in humans after inhalation and oral exposure. The neurotoxic effect is well documented in studies of patients exposed to chloroform via anesthesia (Featherstone 1947; Smith et al. 1973; Whitaker and Jones 1965) or of individuals who intentionally and accidentally ingested the chemical (Piersol et al. 1933; Schroeder 1965; Storms 1973). Lower chloroform doses produced neurological effects during occupational exposure (Challen et al. 1958). Similarly, neurotoxicity is reported in animal studies involving inhalation and oral exposure to chloroform (Bowman et al. 1978; Jones et al. 1958; Lehmann and Flury 1943). A battery of neurobehavioral tests was conducted in mice after oral exposure to chloroform (Balster and Borzelleca 1982). No data were located regarding chloroform neurotoxicity in humans or animals after dermal exposure to chloroform. Animal studies involving dermal exposure to chloroform would be useful for risk assessment of occupational exposure. In addition, more information regarding the mechanism of chloroform induced neurotoxicity and structural alterations produced in the central nervous system would be helpful. Epidemiological and Human Dosimetry Studies. Populations may be exposed to chloroform in the workplace, near hazardous waste sites containing chloroform, from chlorinated water, and from various consumer products that contain chloroform. Limited information was obtained from occupational studies reporting central nervous system and liver effects in exposed workers (Bomski et al. 1967; Challen et al. 1958; Phoon et al. 1983). Reliable dosimetry data correlating occupational exposure with signs of toxic effects would be useful. Epidemiology studies suggest an association between chloroform levels in drinking water and colon, rectal, and bladder cancer in humans (Alavnja et al. 1978; Cantor et al. 1978; Young et al. 1981). All of these studies were limited by a lack of attention to important details (e.g., migration, exposure to other carcinogens). Better designed and better conducted epidemiology studies of occupational exposure would be helpful. The information can be useful to populations living near hazardous waste sites where chloroform is present. Biomarkers of Exposure and Effect. Methods for detecting chloroform in exhaled breath, blood. urine, and tissues are available. Nevertheless. it is difficult to correlate chloroform levels in biological samples with exposure, because of the volatility and short half-life of chloroform in biological tissues. Several studies monitored chloroform levels in environmentally exposed populations (Antoine et al. 1986; Hajimiragha et al. 1986; Peoples et al. 1979); however, the measured levels probably reflect both inhalation and oral exposure. Moreover, increased tissue levels of chloroform or its metabolites may reflect exposure to other chlorinated hydrocarbons. Studies to better quantitate chloroform exposure would enhance the database. No biomarkers were identified that are useful to characterize effects induced by exposure to chloroform. The target organs of chloroform toxicity are the central nervous system, the liver, and kidneys; however, damage to these organs may result from exposure to other chemicals. More effort to identify subtle biochemical changes to serve as biomarkers of effects of chloroform exposure would be useful in detecting early, subtle signs of chloroform-induced damage. Absorption, Distribution, Metabolism, and Excretion. Human data indicate that chloroform absorption from the lungs is rapid and fairly complete (Lehmann and Hasegawa 1910; Smith et al. 1973). The data also indicate that absorption after oral exposure is fairly complete for both animals and humans (Brown et al. 1974a; Fry et al. 1972; Taylor et al. 1974). Although there are no experimental data regarding dermal absorption in humans, some data have been extrapolated from mouse studies (Tsuruta 1975). The rate of absorption following 72 2. HEALTH EFFECTS oral or inhalation exposure is rapid (within 1-2 hours). Additional studies investigating the rate of dermal absorption would be useful to quantitate dermal absorption and to compare information from oral and inhalation studies. Data are available regarding the distribution of chloroform in humans and animals after inhalation and oral exposure to chloroform (Brown et al. 1974a; Chenoweth et al. 1962; Cohen and Hood 1969; Corley et al. 1990; Danielsson et al. 1986; Feingold and Holaday 1977; Taylor et al. 1974). It appears that distribution following oral exposure is similar to that following inhalation exposure. Another well-conducted animal study focusing on distribution and excretion after dermal exposure would be useful to assess exposure via this route. The metabolic pathway of chloroform is well understood. It appears that both the mode of oral administration and the vehicle affect metabolism. Additional data investigating the mode and vehicle of administration would be useful in order to understand the role of these factors in the mechanism of chloroform’s toxicity. In addition, the fate of the reactive metabolites of chloroform should be monitored. The excretion of chloroform and its metabolites is understood, based on human and animal data derived from oral and inhalation studies (Brown et al. 1974a; Corley et al. 1990; Fry et al. 1972; Taylor et al. 1974). The major route of chloroform elimination is pulmonary, but minor pathways are through enterohepatic circulation, urine, and feces. There are no human or animal data regarding excretion of dermally applied chloroform. Comparative Toxicokinetics. Target organs for chloroform distribution appear to be similar in humans and animals. according to inhalation studies (Corley et al. 1990; Feingold and Holaday 1977). Nonetheless, human and animal studies indicate that there are large interspecies differences in chloroform metabolism (Brown et al. 1974a: Corley et al. 1990). Marked, sex-related differences in tissue distribution and covalent binding to tissue macromolecules in mice also have been observed (Taylor et al. 1974). Excretion data indicate that humans and nonhuman primates excrete chloroform in the breath primarily as unchanged chloroform; mice eliminated almost 80% of an oral chloroform dose as carbon dioxide (Brown et al. 1974a). Thus, toxicokinetic data indicate that it may be difficult to compare the toxicokinetics of chloroform in animals with that in humans. There is a large number of oral studies. relatively few inhalation studies, and almost no dermal studies regarding the toxicokinetics of chloroform. Quantitative toxicokinetic studies in several animal species involving exposure to chloroform via all three routes. especially inhalation and dermal, would complete the database. Methods for Reducing Toxic Effects. General procedures such as flushing the skin with water following dermal exposure and emesis or gastric lavage following oral exposure may be used to reduce absorption of chloroform. However. specific mechanisms to prevent absorption of chloroform have not been identified. Such mechanisms might be beneficial because they might be more effective than general procedures and might involve less risk than procedures such as emesis. Ways to enhance elimination of chloroform from the body are not known. Although chloroform is eliminated fairly rapidly, methods to accelerate elimination without producing toxic metabolites would be helpful in reducing toxicity. The mechanism by which chloroform produces toxicity appears to involve metabolism by phenobarbital-inducible isozymes of cytochrome P-450 to phosgene (Pohl et al. 1980a, 1980b). Development of methods to selectively inhibit the P-450 isozymes responsible for this reaction might reduce chloroform toxicity. There is also evidence that glutathione conjugates with reactive products of chloroform metabolism, providing protection from damaging effects (Docks and Krishna 1976; Hook and Smith 1985). Development of a method to maintain high tissue glutathione levels following exposure to chloroform might have a mitigating effect on toxicity. Therefore, although no treatments are currently available to block the toxic action of chloroform or repair damage caused by this chemical, there are indications that further research in this area would enable identification of such treatments. 73 2. HEALTH EFFECTS 2.9.3 On-going Studies A study investigating the effects of anesthetics on membrane proton permeability is in progress (Deamer 1990). Model and biological membranes will be used to measure changes in pH gradients under the influence of chloroform and other anesthetics. The role of cytochrome P-450 in the activation of halomethanes (chloroform and carbon tetrachloride) will be studied in vitro in microsomal fractions from rats and gerbils (Ebel 1990). Chloroform and carbon tetrachloride nephrotoxicity will be studied in_vitro using isolated human and rabbit proximal tubule segments (Hjelle 1990). 75 3. CHEMICAL AND PHYSICAL INFORMATION 3.1 CHEMICAL IDENTITY Data regarding the chemical identity of chloroform are reported in Table 3-1. 3.2 PHYSICAL AND CHEMICAL PROPERTIES The physical and chemical properties of chloroform are reported in Table 3-2. 76 3. CHEMICAL AND PHYSICAL INFORMATION TABLE 3-1. Chemical Identity of Chloroform Characteristic Information Reference Chemical name Trichloromethane SANSS 1990 Synonym(s) Metheny! chloride, IARC 1979 methane trichloride, methyl trichloride formyl trichloride Registered trade name(s) Freon 20, R 20, IARC 1979 R 20 refrigerant Chemical formula CHCl, HSDB 1990 Chemical structure h IARC 1979 Ci —-C—Ci Cl Identification numbers: CAS registry 67-66-3 HSDB 1990 NIOSH RTECS FS 9100000 HSDB 1990 EPA hazardous waste UO44 HSDB 1990 OHM/TADS 7216639 HSDB 1990 DOT/UN/NA/IMCO shipping Chloroform; UN 1888 HSDB 1990 HSDB 56 HSDB 1990 NCI CO2686 HSDB 1990 CAS = Chemical Abstracts Services: DOT/UN/NA/IMCO = Department of Transportation/United Nations/ North America/International Maritime Dangerous Goods Code; EPA = Environmental Protection Agency; HSDB = Hazardous Substances Data Bank; NCI = National Cancer Institute; NIOSH = National Institute for Occupational Safety and Health; OHM/TADS = Oil and Hazardous Materials/Technical Assistance Data System: RTECS = Registry of Toxic Effects of Chemical Substances 77 3. CHEMICAL AND PHYSICAL INFORMATION TABLE 3-2. Physical and Chemical Properties of Chloroform Property Information Reference Molecular weight 119.38 Deshon 1979 Color Colorless Hawley 1981 Physical state Liquid Deshon 1979 Melting point -63.2°C Deshon 1979 Boiling point 61.3°C Deshon 1979 Density: at 20°C 1.485 g/cm? Hawley 1981 Odor Pleasant, ethereal, Deshon 1979 nonirritating Odor threshold: Water 2.4 ppm (W/V) Amoore and Hautula 1983 Air 85 ppm (v/v) Amoore and Hautula 1983 Solubility: Water at 25°C 7.22x10° mg/L Banerjee et al. 1980 Organic solvent(s) Partition coefficients: Log K,.. Log K Vapor pressure at 20°C Henry's law constant: at 20°C at 24.8°C Autoignition temperature Flashpoint Flammability limits Conversion factors ppm (v/v) to mg/m’ in air (20°C) mg/m? to ppm (v/v) in air (20°C) Explosive limits Miscible with principal organic solvents 1.97 1.65 159 mmHg 3.0x10 5 atm-m3/mol 3.67x10° atm-m*/mol >1,000°C None No data ppm (v/v) = 4.96 mg/m’ mg/m = 0.20 ppm (v/v) No data Deshon 1979 Hansch and Leo 1985 Sabljic 1984 Boublik 1984 Nicholson et al. 1984 Gosett 1987 Deshon 1979 Deshon 1979 No data No data v/v = volume per volume; w/v = weight per volume 79 4. PRODUCTION, IMPORT, USE, AND DISPOSAL 4.1 PRODUCTION During 1989, 523.6 million pounds of chloroform were produced (USITC 1989). The chloroform demand was increased 10% during both 1988 and 1989 because of a higher demand for fluorocarbon-22, which is the major chemical produced from chloroform. The demand increase for fluorocarbon-22 resulted from the Montreal Protocol, which listed fluorocarbon-22 as one of the few fluorocarbons not restricted by the international agreement designed to reduce the usage of ozone-depleting chemicals (CMR 1989). The manufacturers and sites of chloroform production listed for 1990 include the following: Dow Chemical U.S.A., Freeport, Texas, and Plaquemine, Louisiana; LCP Chemicals Division, Hanlin Group, Inc., Moundsville, West Virginia; Occidental Petroleum Corp., Belle, West Virginia; and Vulcan Materials Co., Geismar, Louisiana, and Wichita. Kansas (SRI 1990). Table 4-1 is a compilation of release data from 1988 regarding the maximum amounts of chloroform on site at facilities that manufacture or process the chemical (TRI88 1990). The chlorination of methane and the chlorination of methyl chloride produced by the reaction of methanol and hydrogen chloride are the two common methods for commercial chloroform production (Ahlstrom and Steele 1979: Deshon 1979). The methanol process accounts for =92% of the production capacity, while the methane process accounts for only 8%. The Vulcan Materials Co. in Wichita, Kansas, is the only production facility listed above that uses the methane process. and this process is used for one-third of the plant's annual production capacity (SRI 1990). 4.2 IMPORT/EXPORT Twenty-four million pounds of chloroform were imported into the United States in 1988. In 1985, the United States imported 27.6 million pounds (12.5 billion grams) of chloroform (CMR 1989; HSDB 1990). According to these data, the amount of chloroform imported into the United States decreased slightly from 1985 to 1988. Current export volumes for chloroform were not located. A 1988 export volume of 40 million pounds was estimated using the 8% figure of the exported chloroform and the demand of 500 million pounds, which includes exports (CMR 1989). In 1985. 33.5 million pounds (15.2 billion grams) were exported (HSDB 1990). According to these estimated data. the amount of chloroform exported between the years 1985 and 1988 increased. 43 USE Major chloroform uses include the following: fluorocarbon-22 (chlorodifluoromethane), 90% of the total production (refrigerants, 70%; fluoropolymers. 30%); export, 8%: and miscellaneous, 2% (CMR 1989). Chemical plants that manufacture fluorocarbon-22 are operated by Allied-Signal Inc. in Baton Rouge, Louisiana, and El Segundo, California; Atochem North America in Calvert City, Kentucky; and E.I. du Pont de Nemours and Company in Louisville, Kentucky, and Montague, Michigan (SRI 1990). Chloroform has been used in the past as a solvent or an extraction solvent for fats, oils, greases, resins, lacquers. rubber, alkaloids, gums, waxes, gutta- percha. penicillin, vitamins, flavors, floor polishes, and adhesives in artificial silk manufacture, as a dry cleaning spot remover. in fire extinguishers, as an intermediate in the manufacture of dyes and pesticides, and as a fumigant (Deshon 1979; Windholz 1983). Chloroform was previously used as an anesthetic, but it has been replaced by safer and more versatile materials (Deshon 1979). The U.S. Food and Drug Administration banned chloroform use in drug. cosmetic. and food packaging products in 1976 (Windholz 1983). This ruling did not include drug products that contain chloroform in residual amounts resulting from its use as a processing solvent in manufacturing or its presence as a by-product from the synthesis of drug ingredients (IARC 1979). 80 4. PRODUCTION, IMPORT, USE, AND DISPOSAL TABLE 4-1. Facilities That Manufacture or Process Chloroform® Range of maximum amounts on site b Number of in thousands d State facilities of pounds Activities and uses AK 2 (N° 0-0.09 1,5, 6 AL 10 0.1-9,999 1, 3,5, 6, 10, 13 AR 6 0-9,999 1. 5.6, 7, AZ 1 0.1-0.9 1, 5 CA 10 0-999 1, 5,6,7, 11, 13 co 1 10-99 5, 1 CT 1 10-99 1" FL 5 (2)° 0-0.09 1,5, 6 GA 4 0-9 1. 5, 6 ID 1 1-9 1, 6 IL 1 100-999 1" IN 1 10-99 1 KS 2 100-9,999 1, 4, 6,7 KY 6 0-9,999 1, 3.5.7, 10 LA 13 0-9,999 1,2,3,.4,5,46,7,13 MD 1 0-0.09 1, 'S ME 7 0-99 1, 5, 6, 13 MI 5 0-9,999 1, 5,7, 13 MN 2 0.1-0.9 1: 5 MO 2 10-999 1" MS 3 0-9 1, 5, 6 MT 1 0.1-0.9 1:5 NC 5 0.1-999 1, 5,6, 1" NH 1 0.1-0.9 1, 6 NJ 5 0-9,999 1, 5,7, 1 NY 4 0.1-999 1. 5, 10, 11, 13 OH 4 0.1-999 4, 5, 10, 12, 13 OK 1 0-0.09 5 OR 3 0-0.9 1 5 PA 7 0-999 1, 5, 6, 1" PR 6 0.1-999 1, 12 SC 3 0-0.9 1, 5 ™ 2 (1° 0-0.09 1,5 TX 12 0-9,999 1, 4,5,6,7, 11, 13 VA 4 (NE 0.1-999 1, 5, 1 WA 10 0-9 1, 5, 6 WI 12 0-99 1, 5,7, 11, 13 WV 3 (Nn 1,000-9,999 1, 4, 11 81R188 1990 Post office state abbreviations Cbata in TRI are maximum amounts on site at each facility. dactivities/Uses: 1. produce 8. as a formulation component 2. import 9. as an article component 3. for on-site use/processing 10. for repackaging only 4. for sale/distribution 11. as a chemical processing aid 5. as a byproduct 12. as a manufacturing aid 6. as an impurity 13. ancillary or other use 7. as a reactant ENumber of facilities reporting "no data" regarding maximum amount of the substance on site. 81 4. PRODUCTION, IMPORT, USE, AND DISPOSAL 44 DISPOSAL According to the 1988 Toxics Release Inventory (TRI), the amount of chloroform released to land is only a small fraction of the total amount of chloroform released to the environment by facilities that produce and process the chemicals (see Section 5.2.3) (TRI88 1990). In addition, transfer of chloroform to off-site location and discharges to publicly-owned treatment works appear to be relatively minor, with the exception of transfers and discharges from a handful of facilities. The TRI data should be used with caution since only certain types of facilities are required to report. This is not an exhaustive list. Chloroform has been identified as a hazardous waste by EPA, and disposal of this waste is regulated under the Federal Resource Conservation and Recovery Act (RCRA) (EPA 1988a, 1989b). Specific information regarding federal regulations on chloroform disposal on land is available in the Code of Federal Regulations (EPA 1988a, 1989b). Ultimate disposal of chloroform, preferably mixed with another combustible fuel, can be accomplished by controlled incineration. Care must be exercised to ensure complete combustion to prevent phosgene formation, and an acid scrubber will be needed to remove the haloacids produced. Chloroform also is a potential candidate for liquid injection incineration. Because chloroform has been used in some pesticides, the disposal of containers for these pesticides may be relevant. Combustible containers from organic or many metallo-organic pesticides could be disposed of in pesticide incinerators or in specified landfill sites. Noncombustible containers could be disposed of in a designated landfill or recycled (HSDB 1990). No data were located regarding the approximate amounts of chloroform disposal. 83 5. POTENTIAL FOR HUMAN EXPOSURE 5.1 OVERVIEW Chloroform is both a man-made and naturally occurring compound, although anthropogenic sources are responsible for most of the chloroform in the environment. Chloroform is released into the environment as a result of its manufacture and use, its formation in the chlorination of drinking water, municipal and industrial waste water, and swimming pool and spa water, and from other water treatment processes involving chlorination. Most of the chloroform released into the environment will eventually be released into the atmosphere. Much smaller amounts will eventually be released into groundwater. Volatilization from water and soil is a major source of chloroform release to the atmosphere. Volatilization half-lives from water for a model shallow river and pond are 3.5 and 44 hours, respectively. In the atmosphere, chloroform may be transported long distances before ultimately being degraded by indirect photochemical reactions (half-life of =80 days). The compound has been detected in ambient air in locations that are remote from anthropogenic sources. Chemical hydrolysis and biodegradation are not significant chloroform removal processes from water and soil. Because of its low soil adsorption and significant water solubility, chloroform will readily leach from soil into groundwater. In groundwater, chloroform is expected to persist for a long time. The general population is exposed to chloroform by ingesting water and food, inhaling contaminated air, and possibly through dermal contact with chloroform-containing water. Generalizations can be made concerning the chloroform concentrations in the environment. Background air concentrations appear to be in the sub-ppb range, but certain urban, indoor, and source-dominated areas appear to have elevated concentrations when compared to background concentrations. Drinking water levels as high as 311 ppb have been reported in public water supplies, although most of the reported concentrations ranged between 2 and 44 ppb. Levels in drinking water derived from groundwater contaminated with leachate from landfills and hazardous waste sites can be much higher. No information was located regarding the concentrations found in ambient soil. Chloroform has also been detected in the ppb range in certain foods. Occupational exposure to higher than background levels of chloroform can be expected to occur in various occupations, although very little quantitative exposure data were located. Populations with the highest potential exposures appear to be workers employed in the manufacturing and use industries, persons living near industries and facilities that manufacture or use chloroform, operators and individuals who live near municipal and industrial waste water treatment plants and incinerators and paper and pulp plants. and persons that derive their drinking water from groundwater sources contaminated with leachate from hazardous waste sites. Chloroform has been identified in at least 646 of the 1,300 NPL hazardous waste sites, including 6 in Puerto Rico. that have been proposed for inclusion on the NPL (HAZDAT 1992). However, it is not known how many of the 1,300 NPL sites have been evaluated for chloroform. As EPA evaluates more sites, the number of sites at which chloroform is found may change. The frequency of these sites within the United States can be seen in Figure 5.1. 5.2 RELEASES TO THE ENVIRONMENT 5.2.1 Air Quantitative data or estimates of current chloroform releases to the atmosphere are lacking. Direct release to the atmosphere is expected to occur during the manufacture, loading, and transport of chloroform (EPA 1985a, 1985b). Indirect chloroform releases are expected to result from its use in the manufacture of fluorocarbon-22, fluoropolymers. pharmaceuticals. ethylene dichloride, dyes, and fumigants (Deshon 1979; EPA 1985a, 1985b; Windholz 1983). Some of these uses may have been banned. Chloroform releases result from its formation and subsequent volatilization from chlorinated waters including drinking water, municipal and industrial waste waters, FIGURE 5-1. FREQUENCY OF NPL SITES WITH CHLOROFORM CONTAMINATION * JHNSOdX3 NVWNH HOH TVILN3LOd S FREQUENCY BEFFH 1 TO 7 SITES HHH 9 TO 20 SITES l 25 TO 30 SITES BH 5 0 67 SITES v8 85 5. POTENTIAL FOR HUMAN EXPOSURE process waters and effluent from the bleaching of pulp in pulp and paper mills, cooling tower water, and swimming pool and whirlpool spa water (Benoit and Jackson 1987; EPA 1985a, 1985b; Hoigne and Bader 1988). Increased release rates of the chloroform in waters can be expected from chloroform-containing waters that are heated (e.g., water used for cooking, showers, swimming pools, and spas). Aeration and use of groundwater contaminated with chloroform is a potential source of emission to the atmosphere (Crume et al. 1990). Chloroform is released as a result of the hazardous and municipal waste treatment. The chloroform released may have initially been present in the waste or possibly formed during chlorination treatment (Corsi et al. 1987; EPA 1990: Namkung and Rittmann 1987). Releases may also occur from hazardous waste sites and sanitary landfills where chloroform was disposed of, and from municipal and hazardous waste incinerators that burn chloroform- containing wastes or form chloroform during the combustion process (LaRegina et al. 1986; Travis et al. 1986). Table 5-1 lists air releases data from facilities in the United States that produce and process chloroform, according to the 1988 TRI (TRI88 1990). It appears from the data that nearly all of the chloroform released to the environment is released to the atmosphere. The TRI data should be used with caution since only certain types of facilities are required to report. This is not an exhaustive list. In the past, minor releases may have resulted from the use of consumer products (e.g., certain air deodorizers and cleaning products) that contained chloroform as a component or residual product (Bayer et al. 1988; Wallace et al. 1987a). 5.2.2 Water Quantitative data or estimates of current chloroform releases to natural waters are lacking. Direct release to water is expected via waste waters generated during chloroform manufacture and its use in the manufacture of other chemicals and materials (EPA 1985a). Direct emission sources are expected to be relatively minor contributors to total chloroform emissions to water relative to the formation of chloroform that results from the chlorination of drinking water (EPA 1985a). Since chlorination to disinfect water supplies is nearly universal, chloroform contamination resulting from chlorination will also be nearly universal (see discussion on levels monitored or estimated in water in Section 5.4.2). The 1988 TRI data in Table 5-1 appear to indicate that only a small fraction of the chloroform released to the environment is released to water (TRI88 1990). The TRI data should be used with caution since only certain types of facilities are required to report. This is not an exhaustive list. Other chloroform emission sources tend to be relatively isolated point sources. Chlorination of municipal and industrial waste waters at municipal and industrial waste water treatment plants, process waters and effluent from the bleaching of pulp in pulp and paper mills, cooling tower water, and swimming pool and whirlpool spa water will also result in chloroform formation (Benoit and Jackson 1987; EPA 1985a, 1985b, 1990; Hoigne and Bader 1988). The use of modern treatment facilities may reduce the amounts of chloroform released to environmental waters. This has been demonstrated at a modern kraft pulp mill (Paasivirta et al. 1988); however, much of the chloroform removed from the waste water may be released to the atmosphere by volatilization. Release of chloroform to groundwater has resulted from improper disposal of chloroform-containing waste at hazardous waste sites (Clark et al. 1982; Dewalle and Chian 1981; Harris et al. 1984; Sawhney 1989). An additional minor source of water contamination may be atmospheric rainout since chloroform has been found in rainwater (Kawamura and Kaplan 1983). Other sources of chloroform release to surface water include breweries, thermal combustion of plastics, reaction of dissolved chlorine with sediment and other materials in water, biological production by marine algae, and the reaction of chlorinated pollutants with humic materials in natural waters (EPA 1985a). ilities Releases to the Envirorment from F That Manufacture or Process Chloroform TABLE 5-1. b Range of reported amounts released in thousands of pounds off-site waste transfer POTW transfer d Total Environment Number of Underground injection Land Water facilities Air state® 86 5. POTENTIAL FOR HUMAN EXPOSURE w - o ~N oN 0 © Fits! s Minn ~ oN wee om” ~m 3 OO oon o-ocominycoco coffo-RoPnocdovcToco o ’ , . . ‘ + C0000 aINOOONM-O0000OR060060000060 © = © . » mm < N S " wv eS 9 cocococcodococococonoSoRs coBol--o™280o CE COO 0OMO000000000000R000000000000 oc = o ~ oO 0 oN — © ~ oN «© 0 ~ ~ . ~N 0 “oe . . . ~ Oo +0 -— ~ sy VN FON Dono NNTS 2 + CQ CANN eM -— ~ o NOC +N Msgs we Sew 0 = nO NN AN RDP I ONIN GE Ge NDT. NOoMNNADN OQ SNN—Ne-OY SUR ROONT NI OS mM . . . -— ce= «eo “oe EES BK) LC . rn ome NN noo Ba - mm oneoo © - oN ~N Mm -0 wn 0 ~N -— Mm mm © Nm = o Mm 0 «© onNCMr-oO0OCO00OO--OONCO-OC0O0COoONGOM COOMOO000000000000000060006600660 - mM wv ~ Q N : +O N00 ~~ ~ NO _ © SNe T= N © N-o®ore-r-ocor-NoNy orcoNANoNNCO ON Ta, © COOONOOIO-OOOOMOOOVNROBOOONOOOY - o - oo ~N oc - - oN ne ~ -— Mm COCO OOOO OOOO OPPOOOOD ' CC OOO OOOO OOOOOOOOOOOOOdotdobdo Lag] mM 0 ~N oO ~ © . . . < LS 838 rNINTNOON SnsgYnMnee o ~ ‘Nn «0 0 MO «+ +m oO Nine S Mo RENNIN Ne nN CTEM ICFOOANNRNNr~rNNOIT~ANNNONO= NON Me — ' ' , 1 , . . ‘ J ’ . . ' . ’ ’ . . ’ . ‘ ' . ' ‘ 1) ’ . ’ . . . “se oe eae <3 Oo — + eo ”m “On < © ER —MMNe—O 0 NNN noo - MM -— ownnmMmoo oO po ~ oN : od Ww 0 wv -— TABLE 5-1 (Continued) Range of reported amounts b released in thousands of pounds off-site Number of Underground Total d POTW waste state facilities injection Water Land Environment transfer transfer ™ 0-0 1.7-2.1 0-3.9 34.1-345.6 0-0 0-3 ™ 0-0 0-11 0-0.8 0-224.8 0-100 0-7.6 VA 0-0 0.6-2.6 0-0.7 46.3-1,224 0-0 0-0.3 WA 0-0 0.3-100 0-2.9 16.7-473.2 0-0 0-0.8 Wl 0-0 0-14 0-3.6 0.5-102 0-16 0-85 wv 0-0 0.5-24 0-0.1 300.7-604 0-0.1 0.1-14.2 81R188 1990 ata in TRI are maximum amounts released by each facility. chundred pounds, except those quantities >1 million pounds which have been rounded to the nearest thousand pounds. Jo DLicty owned treatment works Post office state abbreviation ®The sum of all releases of the chemical to air, land, water, and underground injection wells by a given facility. Quantities reported here have been rounded to the nearest 3HNSOdX3 NYWNH HO4 TVILN3LOd 'S L8 88 5. POTENTIAL FOR HUMAN EXPOSURE Data from the Contract Laboratory Program Statistical Database (CLPSD) indicate that chloroform has been detected in surface water and groundwater samples taken at an estimated 4% and 15%, respectively, of NPL hazardous waste sites included in the database. The geometric mean concentrations in surface water and groundwater were 10 and 9.5 pg/L, respectively, for the positive samples (CLPSD 1989). The information used from the CLPSD includes data from NPL sites only. 5.2.3 Soil Quantitative data or estimates of current chloroform releases to soil are lacking. Chloroform release to soil has occurred at hazardous waste sites containing improperly disposed wastes where chloroform has leached through soil to groundwater (Clark et al. 1982; Dewalle and Chian 1981; Harris et al. 1984; Sawhney 1989). Land disposal of sludge from municipal and industrial waste water treatment plants may also result in chloroform release to soil (EPA 1990). Direct land disposals of chloroform-containing wastes may have occurred in the past, but land disposals of chloroform wastes are currently subject to restrictive regulations (EPA 1988a, 1989b). An additional minor source of soil contamination may be atmospheric rainout since chloroform has been found in rainwater (Kawamura and Kaplan 1983). Data from the CLPSD indicate that chloroform has been detected in soil samples taken at an estimated 10% of NPL hazardous waste sites included in the CLPSD. The geometric mean concentration was 12.5 pg/kg for the positive samples (CLPSD 1989). The information used from the CLPSD includes data from NPL sites only. The 1988 TRI data in Table 5-1 appear to indicate that only a very small fraction of the chloroform released to the environment is released to land (TRI88 1990). The TRI data should be used with caution since only certain types of facilities are required to report. This is not an exhaustive list. 5.3 ENVIRONMENTAL FATE 5.3.1 Transport and Partitioning Based upon a vapor pressure of 159 mmHg at 20°C, chloroform is expected to exist almost entirely in the vapor phase in the atmosphere (Boublik et al. 1984; Eisenreich et al. 1981). Large amounts of chloroform in the atmosphere may be removed by wet deposition since chloroform is highly soluble in water. This is confirmed by its detection in rainwater (Kawamura and Kaplan 1983). Most of the chloroform removed in precipitation, however, is likely to reenter the atmosphere by volatilization. Since chloroform is relatively nonreactive in the atmosphere, long-range transport within the atmosphere is possible. This is confirmed by the detection of chloroform in air samples from remote areas of the world (Class and Ballschmidter 1986). The dominant fate process for chloroform in surface waters is volatilization. Chloroform present in surface water is expected to rapidly volatilize to the atmosphere. An experimental half-life range of 18-25 minutes has been measured for volatilization of chloroform from a 1-ppm solution with a depth of 6.5 cm that was stirred with a shallow pitch propeller at 200 rpm at 25°C under still air (=0.2 mph air currents) (Dilling 1977; Dilling et al. 1975). Using the Henry's law constant, a half-life of 3.5 hours was calculated for volatilization from a model river 1 meter deep flowing at 1 meter/second, with a wind velocity of 3 meters/second, and neglecting adsorption to sediment (Lyman et al. 1982). A half-life of 44 hours was estimated for volatilization from a model pond using EXAMS (1988). Based on a measured soil organic carbon sorption coefficient (K_ .) of 45, chloroform is not expected to significantly adsorb to sediment or suspended organic matter in surface water (Sabljic 1984). This prediction is supported by sediment monitoring data that indicate that this compound has not been detected, or was detected at very low concentrations. in sediment (Bean et al. 1985; Ferrario et al. 1985; Helz and Hsu 1978). Little or 89 5. POTENTIAL FOR HUMAN EXPOSURE no chloroform concentration was observed on peat moss, clay, dolomite limestone, or sand added to water (Dilling et al. 1975). Chloroform slightly adsorbed to aquifer solids in laboratory studies utilizing different amounts of two different aquifer materials with K_ values ranging from 63.4 to 398. The authors reported higher adsorption with increasing organic content of the solids (Urchin and Mangels 1986). K_. values ranging from 45 to 80 in soil have been experimentally determined for chloroform (Sabljic 1984; Wilson et al. 1981). Chloroform does not bioconcentrate in aquatic organisms based upon measured bioconcentration factors (BCF) of 6 and 8 for bluegill sunfish (Lepomis macrochirus) (Barrows et al. 1980; Veith et al. 1980). A BCF of 690 experimentally determined for the bioconcentration of chloroform in the green algae (Selenastrum capricornutum) suggests that the compound has a slight tendency to concentrate in aquatic plants (Mailhot 1987). No data regarding the biomagnification potential of chloroform were found. Based upon the observed BCF, however, significant biomagnification of chloroform is apparently unlikely. In soil, the dominant transport mechanism for chloroform near the surface will probably be volatilization because of its high volatility and low soil adsorption. This prediction is supported by laboratory studies in which 75% of the chloroform initially present in water volatilized when applied to a fine sandy soil, and 54% of the chloroform volatilized from a soil column during a percolation study utilizing a sandy soil (Piwoni et al. 1986; Wilson et al. 1981). All or nearly all of the remaining chloroform travelled through the soil because of its low adsorption onto soil. The leaching potential of chloroform is further confirmed by the detection of chloroform in groundwater. especially at hazardous waste sites (Clark et al. 1982; Dewalle and Chian 1981; Harris et al. 1984; Sawhney 1989). 5.3.2 Transformation and Degradation 5.3.2.1 Air The vapor-phase reaction of chloroform with photochemically generated hydroxyl radicals is the dominant degradation process in the atmosphere. The rate constant for this process at 25°C has been experimentally determined as 1.0x10"'3 cm*/molecule-second. which corresponds to a half-life of =80 days based upon a 12-hour sunlit day in a typical atmosphere containing 1x10° hydroxyl radicals/cm’ (Hampson 1980; Singh et al. 1981). Breakdown products from reaction with hydroxyl radicals probably include phosgene and hydrogen chloride (Atkinson 1985). Chloroform is more reactive in photochemical smog conditions where the approximate half-life is 11 days (Dimitriades and Joshi 1977). Direct photolysis of chloroform will not be a significant degradation process in the atmosphere. Chloroform solutions sealed in quartz tubes and exposed to sunlight for 1 year degraded at almost the same rate as solutions in sealed tubes stored in the dark, which indicated that very little or no photodegradation of the compound had occurred (Dilling et al. 1975). This is expected because chloroform does not absorb light at wavelengths >290 nm (Hubrich and Stuhl 1980). 5.3.2.2 Water Chloroform has generally been observed to resist biodegradation in aqueous aerobic screening tests. Little or no degradation was observed during 25 weeks in aqueous aerobic screening tests utilizing primary sewage effluent inocula (Bouwer et al. 1981a). No chloroform degradation was observed in aerobic biofilm column studies (Bouwer et al. 1981b). Significant degradation of chloroform (46-49% loss in 7 days, at least some of which was apparently due to volatilization) in aerobic screening tests utilizing settled domestic waste water as inoculum was reported (Tabak et al. 1981). Under the proper conditions, chloroform appears to be much more susceptible to anaerobic biodegradation. Degradation of chloroform under anaerobic conditions was more rapid at lower chloroform concentrations (81% and 99% degradation after 2 and 16 weeks. respectively, at 16 ppb): a more 90 5. POTENTIAL FOR HUMAN EXPOSURE gradual degradation was observed at higher concentrations (25% and 78% degradation after 2 and 16 weeks, respectively, at 157 ppb) (Bouwer et al. 1981a). No degradation was observed, however, when chloroform was incubated with aquifer material under anaerobic conditions for 27 weeks (Wilson et al. 1981). Hydrolysis will not be a significant degradation process in water based upon rate constants experimentally determined at 25°C that correspond to half-lives ranging from 1,850 to 3,650 years at pH 7, and from 25 to 37 years at pH 9 (Jeffers et al. 1989; Mabey and Mill 1978). Direct photolysis of chloroform will not be a significant degradation process in surface waters because the compound does not absorb light at wavelengths >290 nm (Hubrich and Stuhl 1980). The reaction rate of chloroform with hydrated electrons photochemically produced from dissolved organic matter has been predicted to correspond to a near-surface half-life of =44 days based upon an experimentally determined rate constant and a hydrated electron concentration of 1.2x10°'7 mol of hydrolyzed electrons/L (Zepp et al. 1987). This latter process is probably too slow to effectively compete with volatilization as a removal process from surface waters. 5.3.23 Soll Little information was located regarding the degradation of chloroform in soil. Based upon data for degradation in water, chemical degradation in soil is not expected to be significant. The available soil data suggest that chloroform biodegradation rates in soil may vary depending upon conditions. In soil column studies, the chloroform present in the influent secondary waste water appeared to pass through the column nearly unchanged even though some of the other organic compounds present were apparently biodegraded, which indicated that the waste water was not too toxic to the microorganisms in the soil (Bouwer et al. 1981b). In contrast to these studies, significant degradation of chloroform (33% removed in 6 days) was observed in fine sandy soil in sealed bottles; however, the chloroform may have been cometabolized by methylotropic bacteria already present in the soil. The aerobic degradation was even faster in methane-enriched soil (Henson et al. 1988). Such biooxidation of chloroform was also observed under methanogenic conditions in batch experiments using an inoculum derived from activated sludge and in a continuous-flow laboratory scale column. using a methanogenic fixed film derived from primary sewage effluent (Bouwer and McCarty 1983). Overall, biodegradation in soil is not expected to compete with the predicted rapid rate of volatilization from soil. 5.4 LEVELS MONITORED OR ESTIMATED IN THE ENVIRONMENT 5.4.1 Air Data from the most recent study located (1982-1985 air samples) reported that the hagkground level of chloroform concentrations over the northern Atlantic ocean ranges from 2x10 to 5x10 ppm (Class and Balischmidier 1986). This range does not differ significantly from the range reported for 1976-1979 (1.4-4x107 ppm) and the range reported from the 1957 update of the National Ambient Volatile Organic Compounds Database (NAVOCDB), which was 2x10 ppm (Brodzinski and Singh 1982; EPA 1988b; Singh 1977; Singh et al. A779). The maximum and background levels found in seven U.S. cities between 1980 and 1981 were 5.1x1073 and 2x10°% ppm, respectively (Singh et al. 1982). Average atmospheric levels in U.S. cities ranged from 2x10 iD 2x1073 ppm between 1980 and 1981. The median concentration reported between 1977 and 1980 is 7.2x10°3 ppm, and the median reported in the 1987 update of the NAVOCDB is 6x10 ppm (Brodzinski and Singh 1982; EPA 1988b; Singh et al. 1981, 1982; Wallace et al. 1986a, 1986b, 1988). The median concentration for source-dominated areas in the United States is 8.2x107* pom for data reported between 1977 and 1980. and this figure does not differ significantly from the 5.1x10™* reported in the 1987 update of the NAVOCDB (Brodzinski and Singh 1982; EPA 1988b). Certain source-dominated areas contained 91 5. POTENTIAL FOR HUMAN EXPOSURE much higher chloroform levels. The ambient air concentrations outside homes in Love Canal, New York, in 1978 ranged from 2x10% to 2.2x10°2 ppm, and the maximum concentration found in ambient air at 20 California municipal landfills was 0.61 ppm (Barkley et al. 1980; Wood and Porter 1987). Concentrations ranging from 29x10* 10 6x1073 ppm were found in air samples taken from five hazardous waste sites in New Jersey (LaRegina et al. 1986). Ambient air samples measured near a hazardous waste landfill contained <1x1073 ppm chloroform. All these data indicate that chloroform levels in air can be much higher in areas near hazardous waste sites (Stephens et al. 1986). Other source-dominated areas that may have ambient air chloroform concentrations significantly higher than background levels include areas near facilities that treat hazardous and municipal waste, as well as areas near contaminated groundwater and municipal and hazardous waste incinerators (Corsi et al. 1987; EPA 1990; LaRegina et al. 1986; Namkung and Rittmann 1987; Travis et al. 1986). Typical median indoor air concentrations of chloroform range from =2x10 to 4x10 ppm (Barkley et al. 1980; Pellizzari et al. 1986; Wallace et al. 1987c, 1989). Chloroform concentration ratios of indoor air to outdoor air range from <1 to 25 (Pellizzari et al. 1986). One of the most significant indoor sources of chloroform is chlorinated tap water, and taking showers is expected to contribute a substantial amount to the indoor chloroform levels (Andelman 1985a, 1985b; Wallace 1987). 5.4.2 Water Recent monitoring data regarding the presence of chloroform in surface water, sediments, and groundwater were not located. The most recent monitoring data that were obtained involved chloroform levels in drinking water. Finished drinking water collected in 1988 from 35 sites across the United States contained median concentrations of chloroform ranging from 9.6 to 15 pg/L (Krasner et al. 1989). The range of interquartile ranges was 2-44 ppb in water with a maximum detected value of 136 ppb in water (EPA/AMWA 1989). Data from earlier studies indicate a wide range of concentrations have been found in drinking water supplies. The reported chloroform concentrations that were detected ranged from trace levels to 311 pg/L, with one study reporting a median concentration of 16.7 pg/L and another study reporting a geometric mean concentration of 1.81 pg/L. Most of the concentrations ranged between 22 and 68 pg/L (Brass et al. 1977, EPA/AMWA 1989; Furlong and D'Itri 1986: Kasso and Wells 1981; Krasner et al. 1989; Rogers et al. 1987; Symons et al. 1975). Chloroform can be expected to exist in virtually all chlorinated drinking water supplies. The main source of chloroform found in municipal drinking water is the chlorination of naturally occurring humic materials found in raw water supplies (Bellar et al. 1974; Cech et al. 1982). Factors that can increase the amount of chloroform in drinking water include seasonal effects (high summer values) and increased contact time between chlorine and humic material. Sources of water with high humic material content will contain higher levels of chloroform. The chloroform concentration increases with time and this indicates that concentrations of the compound increase as the water moves through the distribution system (Kasso and Wells 1981). Drinking water derived from groundwater, especially groundwater at or near hazardous waste sites and landfills, may contain higher levels of chloroform than normally encountered in drinking water derived from surface water. Chloroform levels ranging from 2.1 to 1,890 pg/L have been observed in drinking water derived from wells near a hazardous waste dump (Clark et al. 1982). The leachate from one solid waste landfill contained 21,800 pg chloroform/L; drinking water obtained from wells in the vicinity of the landfill had chloroform levels of 0.3-1.6 pg/L (Dewalle and Chian 1981). Data from the most recent study of Kansas groundwater sampled in 1986 indicate concentrations ranging from =0.3 to 91 pg/L in both raw and treated groundwater; the average and median concentrations in the treated water were 7.6 and 0.5 pg/L. respectively (Miller et al. 1990). Forty-five percent of the sample sites in a national groundwater supply survey had detectible levels of chloroform, and median and maximum concentrations were 1.5 and 300 pg/L, respectively (Westrick et al. 1989). 92 5. POTENTIAL FOR HUMAN EXPOSURE Current surface water monitoring data are lacking. The highest concentrations observed in surface waters of the United States sampled before 1984 were 394 and 120 pg/L. These concentrations were observed in rivers in highly industrialized cities (Ewing et al. 1977; Pellizzari et al. 1979). Typical concentrations for most sites that are not heavily industrialized appear to range from trace levels to =22 pg/L (Ohio River Valley Sanitation Commission 1980, 1982). Data from EPA's STORET database indicate that chloroform was detected in 64% of 11,928 surface water sample data points at a median concentration of 0.30 pg/L (Staples et al. 1985). Low levels of chloroform have been found in sediment samples. Chloroform was found in sediment samples taken in 1980 from the three passes of Lake Pontchartrain, Louisiana, at concentrations ranging from 1.7 to 18 ng/kg (wet weight basis) (Ferrario et al. 1985). Chloroform was found at concentrations ranging from 30 to 80 ng/kg (dry weight basis) in sediment samples exposed to chlorinated electrical power plant cooling water; the control samples that were not exposed to cooling water contained nearly the same amounts of chloroform (Bean et al. 1985). Data from EPA's STORET database indicate that chloroform was detected in 8% of 425 sediment sample data points at a median concentration of <5.0 pg/kg (Staples et al. 1985). Chloroform has been found in rainwater collected in Los Angeles, California, during 1982 at 0.25 pg/L (Kawamura and Kaplan 1983). Data from the CLPSD indicate that chloroform has been detected in the surface water and groundwater taken at an estimated 4% and 15%. respectively, of the NPL hazardous waste sites included in the CLPSD. The geometric mean concentrations for surface water and groundwater were 10 and 9.5 pg/L, respectively, for the positive samples (CLPSD 1989). The information used from the CLPSD includes data from NPL sites only. According to an earlier study. chloroform was detected in groundwater samples from 28% of 178 RCRA hazardous waste sites (Plumb 1987). 5.4.3 Soil Adequate soil monitoring data were lacking. It can be predicted that chloroform contamination occurs at hazardous waste sites where chloroform-containing leachate moves through the soil to groundwater. An explanation of the lack of data results from the fact that any chloroform in the soil is expected to either rapidly volatilize or leach. Data from the CLP statistical database indicate that chloroform has been found in soil at 9.93% of the hazardous waste sites compiled in the database at a median concentration of 12.5 pg/kg (CLPSD 1989). The information from the CLP statistical database includes data from NPL sites only. 5.4.4 Other Environmental Media Chloroform has been detected in various foods at the following concentrations: soft drinks and beverages (2.7-178 ng/kg); dairy products (7-1110 pg/kg): oils and fats (traces <12 pg/kg); dried legumes (6.1-57.2 pg/kg); and grains and milled grain products (1.4-3000 pg/kg) (Abdel-Rahman 1982; Entz et al. 1982; Graham and Robertson 1988: Heikes 1987; Heikes and Hopper 1986; Lovegren et al. 1979). In a study of various foods, 41% of 231 samples contained chloroform at levels ranging from 4 to 312 pg/kg: the average level was 52 pg/kg (Daft 1988a). In another broad study, 55% of 549 samples contained between 2 and 830 pg/kg. The average level in this study was 71 pg/kg (Daft 1989). The chloroform concentration observed in other foods ranged from 6.1 to 1,110 pg/K. The highest amounts were found in butter (1,110 pg/kg), mixed cereal (220. pg/kg). infant/junior food (230 pg/kg). and cheddar cheese (83 pg/kg) (Heikes 1989). 93 5. POTENTIAL FOR HUMAN EXPOSURE Chloroform has been detected in the air above outdoor and indoor pools and in spas at maximum concentrations of 2.8x10°2, 5.0x10°2, and 5.2x10°2 ppm, respectively; water concentrations ranged between 4 and 402, 3 and 580, and <0.1 and 530 pg/L, respectively (Armstrong and Golden 1986). In another study, air samples above whirlpool spas treated with chlorine disinfectant contained chloroform at concentrations ranging from 8x10 to 1.5x10°! ppm; the concentration in the water ranged from 15 to 674 pg/L (Benoit and Jackson 1987). Chloroform has been detected at <37 pg/L in the cooling water of a nuclear reactor; a concentration of 50 pg/L was detected 0.75 miles downstream from the reactor cooling tower in one study (Hollod and Wilde 1982). 5.5 GENERAL POPULATION AND OCCUPATIONAL EXPOSURE The general population is probably exposed to chloroform through drinking water and beverages, eating food, inhaling contaminated air, and through dermal contact with water (e.g., while showering, bathing, cleaning, washing, swimming). All humans are expected to be exposed to at least low levels of chloroform. Accurate, current estimates of the daily intake of chloroform by various exposure routes are not available or possible due to the lack of appropriate current monitoring data. Typical levels of atmospheric exposure in remote, urban, and source-dominated areas range from 2x10 to 5x10°5, 6x10°5 10 2x1073, and 8.2x10* 10 2.2x10°2 ppm, respectively (Barkley et al. 1980; Brodzinski and Singh 1982; Class and Balschmidter 1986; EPA 1988a: Singh et al. 1981, 1982; Wallace et al. 1986a, 1986b, 1988; Wood and Porter 1987). Exposure via ingestion of contaminated drinking water is expected to be extensive since most U.S. drinking water supplies are chlorinated. Typical levels in drinking water range from 2 to 68 pg/L (Brass et al. 1977; EPA/AMWA 1989; Furlong and D'Itri 1986; Kasso and Wells 1981; Krasner et al. 1989; Rogers et al. 1987; Symons et al. 1975). Although data regarding levels in food are rather scant. typical average chloroform levels in certain foods are estimated to range from 52 to 71 pg/L (Daft 1988. 1989). Assuming an average daily intake of 20 m?/day of air. the average daily intake of chloroform by inhalation in remote, urban, and source-dominated areas can be estimated to range from 2 to §, 6 10 200. and 82 to 2.200 pg/day. respectively. Assuming an average intake of 2 L of drinking water/day. the probable average daily intake of chloroform via ingestion of drinking water can be estimated to range from 4 10 88 pg/day. No estimate of daily exposure via ingestion of contaminated food is possible due to a lack of data regarding the level of chloroform in total diet samples. The contributions to exposure from inhalation and ingestion of drinking water routes appear to be of a similar order of magnitude. These estimates. however, are included only to roughly assess the relative significance of exposure routes. Although data is available from various studies regarding concentrations of chloroform found in human tissues, blood. and expired air, only limited data is available that compares these concentrations to measured or estimated environmental exposure levels. Furthermore, no correlation has been made between these measured human tissue concentrations and the corresponding environmental exposure levels (see discussion of Biomarkers Used to Identify or Quantify Exposure to Chloroform in Section 2.5.1 for a discussion of the relationship between chloroform exposure levels and concentrations found in humans). Much of the data available is from the Total Exposure Assessment Methodology (TEAM) studies in which the concentration of chloroform was measured in personal air samples and exhaled human breath (Wallace 1987; Wallace et al. 1984; Wallace et al. 1986ba; Wallace et al. 1986b. Wallace et al. 1988). For example, in one TEAM study, the ratios of the concentrations of chloroform detected in personal air samples to those found in human exhaled breath air varied from 0.66 (0.86 to 1.3 ppb, respectively) to 13.3 (0.80 to 0.06 ppb, respectively) (Wallace 1987) (see discussion of Biomarkers in Section 2.5.1 for more data regarding concentrations found in humans, including data obtained during autopsies). Limited current data were located regarding occupational exposure to chloroform. Although some of the exposure levels encountered in workplaces may be comparable to exposure the worker receives in his own home, there are probably many specific jobs that expose the workers to significantly higher levels of chloroform. These occupations include persons who work at or near source-dominated areas such as chemical plants and other 94 5. POTENTIAL FOR HUMAN EXPOSURE facilities that manufacture or use chloroform, operators of chlorination processes in drinking water plants, people who work at or near waste water treatment plants and paper and pulp plants, and people around other facilities where large amounts of chloroform are released, such as hazardous and municipal waste incinerators. Persons working at waste water an other treatment plants can be exposed to significant levels of chloroform. A maximum level of 3.8x10°3 ppm was found in the air at an activated sludge waste water treatment plant (Lurker et al. 1983). Maintanonce, workers, SHOTANIS, and life guards at indoor pools and spas may encounter maximum concentrations of 5.0x102 and 1.5x10°! ppm, respectively (Armstrong and Golden 1986; Benoit and Jackson 1987). Persons who use tap water often, especially if it is heated and/or sprayed (e.g., water used for cleaning, washing clothes and dishes, showering. and cooking), may be exposed to higher than background levels. For example, levels in personal air samples as high as 2.2x102 and 1.1x10°2 ppm have been measured during household cleaning activities and showering (Wallace et al. 1987d). Persons using certain cleaning agents and pesticides in enclosed spaces with poor ventilation or persons working where these materials are used may be exposed to relatively high levels of chloroform. A National Occupational Exposure Survey (NOES) conducted by NIOSH from 1981 to 1983 estimated that 95,778 workers in the United States are potentially exposed to chloroform (NIOSH 1989). The NOES database does not contain information on the frequency, concentration, or exposure duration of workers; it only provides estimates of the number of workers potentially exposed to chemicals in the workplace. 5.6 POPULATIONS WITH POTENTIALLY HIGH EXPOSURES All humans are exposed to low concentrations of chloroform. Those with potentially high exposures are workers employed in chloroform manufacturing and use industries. Person living in certain source-dominated areas may be at risk for higher than background exposures to chloroform. These may include persons living near industries and facilities that manufacture and use chloroform, municipal and industrial waste water treatment plants and incinerators, paper and pulp plants, and persons who derive their drinking water from groundwater sources contaminated with leachate from hazardous waste sites. The chloroform concentrations reported at NPL hazardous waste sites in surface water, groundwater, and soil are low based upon data compiled in the CLP Statistical Data Base (CLPSD 1989). If these concentrations are indicative of the concentrations at NPL sites, these media may not be sources of potentially high exposure to those populations surrounding the sites. No air monitoring data are available for the sites in CLPSD, however. Previously reported air monitoring data from landfills and other waste sites (see Section 5.4.1) suggest that potentially high exposure may occur via inhalation of contaminated air near hazardous waste sites. Other exceptions include people who obtain their drinking water from wells contaminated with chloroform that leached from the sites and perhaps people who live in homes built directly on top of former waste sites. Although many, if not most, of the drinking water supplies contaminated solely by leached chloroform will probably contain levels lower or comparable to that in normal treated drinking water (e.g., <1.6 ppb in water) (de Walle and Chian 1981) versus 2-44 ppb in water in chlorinated supplies (EPA/AMWA 1989), much higher levels have been found (1.890 ppb in water from wells near a waste dump) (Clark et al. 1982). 5.7 ADEQUACY OF THE DATABASE Section 104(i)(5) of CERCLA directs the Administrator of ATSDR (in consultation with the Administrator of EPA and agencies and programs of the Public Health Service) to assess whether adequate information on the health effects of chloroform is available. Where adequate information is not available, ATSDR, in conjunction with NTP, is required to assure the initiation of a program of research designed to determine the health effects (and techniques for developing methods to determine such health effects) of chloroform. 95 5. POTENTIAL FOR HUMAN EXPOSURE The following categories of possible data needs have been identified by a joint team of scientists from ATSDR, NTP, and EPA. They are defined as substance-specific informational needs that if met would reduce or eliminate the uncertainties of human health assessment. This definition should not be interpreted to mean that all data needs discussed in this section must be filled. In the future, the identified data needs will be evaluated and prioritized, and a substance-specific research agenda will be proposed. 5.7.1 Identification of Data Needs Physical and Chemical Properties. As reported in Table 3-2, the physical and chemical properties of chloroform have been characterized sufficiently to permit estimation of its environmental fate. Production, Import/Export, Use, and Release and Disposal. Data regarding the production methods and current, past, and projected future production volumes are available (SRI 1990; TRI88 1990; USITC 1989); however, data regarding current import and export volumes, use, release, and disposal patterns are lacking. Use, release, and disposal data are useful to determine where environmental exposure to chloroform may be high. General disposal information is adequately detailed in the literature, and information regarding disposal regulations of chloroform is available (EPA 1988a, 1988b). According to the Emergency Planning and Community Right-to-Know Act of 1986, 42 U.S.C. Section 11023, industries arc required to submit chemical release and off-site transfer information to the EPA. The Toxics Release Inventory (TRI). which contains this information for 1987, became available in May of 1989. This database will be updated yearly and should provide a list of industrial production facilities and emissions. Environmental Fate. Experimental data are available regarding the transport and partitioning properties of chloroform (Bean et al. 1985; Clark et al. 1982: Class and Ballschmidter 1986; Dilling 1977; Ferrario et al. 1985; Piwoni et al. 1986: Sawhney 1989). Chloroform partitions mainly into the atmosphere and into groundwater. It can be transported long distances in air. Data are available regarding the degradation of chloroform in the atmosphere. but less is known about degradation rates in water and soil (Bouwer et al. 1981a, 1981b; Dilling et al. 1975: Hampson 1980; Henson et al. 1988; Jeffers et al. 1989; Singh et al. 1981; Tabak et al. 1981; Wilson et al. 1981). Hydrolysis and direct photodegradation are not significant removal processes. Although data regarding biodegradation rates in natural media are lacking. volatilization is expected to dominate over biodegradation as a removal process from surface water and near-surface soil. Chloroform seems relatively persistent in the atmosphere and groundwater. The environmental fate of chloroform appears to be sufficiently determined by the available data. Bioavallability from Environmental Media. Chloroform is absorbed following inhalation, oral, and dermal contact. Toxicity studies of exposure to chloroform in air, water, and food demonstrated the bioavailability of chloroform by these routes. Data regarding its bioavailability from soil are lacking, but near-surface soil concentrations can be expected to be low due to volatilization (Piwoni et al. 1986; Wilson et al. 1981). Additonal information regarding the volatilization of chloroform from soil would be useful to confirm the predicted, limited significance of this exposure route. Food Chain Bioaccumulation. Data are available that indicate that chloroform does not bioconcentrate in aquatic organisms (Barrows et al. 1980; Veith et al. 1980); however, data are lacking for plants and other animals as well as for the biomagnification potential of chloroform in terrestrial and aquatic food chains. Additional information on bioconcentration and biomagnification could be useful in establishing the significance of food chain bioaccumulation as a route of human exposure. 96 5. POTENTIAL FOR HUMAN EXPOSURE Exposure Levels in Environmental Media. All humans are exposed to at least low levels of chloroform via inhalation of contaminated air, and most humans are exposed by drinking contaminated water. Estimates from intake via inhalation and ingestion of drinking water, based on limited data, are available (see Section 5.5). Exposure from foods cannot be estimated, due to the lack of data. Current information on exposure to chloroform from water, air, and foods, especially for workers or people who live near manufacturing and use facilities, water and waste water treatment plants, municipal and industrial incinerators, hazardous waste sites, and other sources of significant release, in addition to data regarding exposure levels in indoor air would be useful. Exposure Levels In Humans. Data regarding exposure levels in humans are incomplete and are not current. Chloroform has been found in human blood and expired air of both occupationally and nonoccupationally exposed groups and in breast milk of nonoccupationally exposed groups (Hajimiragha et al. 1986; Pellizzari et al. 1982; Wallace et al. 1987a). A detailed recent database of exposure would be helpful in determining the current exposure levels, thus allowing an estimation of the average daily dose associated with various scenarios, such as living near a point source of release, drinking contaminated water, or working in a contaminated place. Exposure Registries. No exposure registries for chloroform were located. This compound is not currently one of the compounds for which a subregistry has been established in the National Exposure Registry. The compound will be considered in the future when chemical selection is made for subregistries to be established. The information that is amassed in the National Exposure Registry facilitates the epidemiological research needed to assess adverse health outcomes that may be related to the exposure to this compound. 5.7.2 On-going Studies A study regarding the global tropospheric modeling of trace gas distributions that is in progress may lead to further knowledge about atmospheric exposure levels (FEDRIP 1990). As part of the Third National Health and Nutrition Evaluation Survey (NHANES III). the Environmental Health Laboratory Sciences Division of the Center for Environmental Health and Injury Control, Centers for Disease Control. will be analyzing human blood samples for chloroform and other volatile organic compounds. These data will give an indication of the frequency of occurrence and background levels of these compounds in the general population. 97 6. ANALYTICAL METHODS The purpose of this chapter is to describe the analytical methods that are available for detecting and/or measuring and monitoring chloroform in environmental media and in biological samples. The intent is not to provide an exhaustive list of analytical methods that could be used to detect and quantify chloroform. Rather, the intention is to identify well-established methods that are used as the standard methods of analysis. Many of the analytical methods used to detect chloroform in environmental samples are the methods approved by federal organizations such as EPA and the National Institute for Occupational Safety and Health (NIOSH). Other methods presented in this chapter are those that are approved by groups such as the Association of Official Analytical Chemists (AOAC) and the American Public Health Association (APHA). Additionally, analytical methods are included that refine previously used methods to obtain lower detection limits, and/or to improve accuracy and precision. 6.1 BIOLOGICAL MATERIALS Methods for analyzing chloroform in all biological matrices are listed in Table 6-1. None of these methods has been standardized by an organization or federal agency. These methods all use gas chromatography (GC) with various detection methods as an analytical technique. This technique is sufficiently sensitive to measure background levels of chloroform in the general population as well as chloroform levels at which health effects might occur after short-term or long-term exposure. However, many studies do not report the method detection limit and/or the recovery percentage for the method. For more information regarding the use of GC methods and detectors. see Section 6.2. There are adequate methods of analysis for known metabolites of chloroform such as phosgene, which is determined following trapping by cysteine (Pohl et al. 1980b) 6.2 ENVIRONMENTAL SAMPLES As with all extremely volatile chemicals, it is essential to take precautions during sampling, storage, and analysis to avoid loss of chloroform. Analytical methods for determining chloroform in environmental samples are presented in Table 6-2. The common method used for the preconcentration of chloroform for the determination of its levels in air is adsorption on a sorbent column, although at least one method is available that uses a nonpreconcentrated sample directly for the analysis (Bureau of International Technique des Solvants Chlores 1976). The disadvantages of the sorption tubes are that sorption and desorption deficiencies may not be 100% and that the background impurities in the sorbent tubes may limit the detection limit for samples at low concentrations (Cox 1983). The most common method for the determination of chloroform levels in water, sediment, soil, and aquatic species is the purging of the vapor from the sample or its suspension in a solvent with an inert gas and trapping the desorbed vapors in a sorbent trap. Subsequent thermal desorption is used for the quantification of its concentration. All of the methods listed for the analysis of environmental samples utilize gas chromatography (GC) with various detection methods. The two methods that provide the lowest detection limits are halide-specific detectors (e.g., Hall electrolytic conductivity detector) and mass spectrometer (EPA 1986a; Ho 1989; Lopez-Avila et al. 1987; Ramus et al. 1984). The advantage of halide specific detectors is they are not only very sensitive but are also specific for halide compounds. The mass spectrometer, on the other hand, provides additional confirmation of the presence of a compound through the ionization patterns and is desirable when a variety of compounds are required to be identified and quantified. The disadvantage of halide-specific detectors for their inability to detect and quantify nonhalogen compounds can be greatly overcome by using other detectors (e.g., photoionization detector) in series (Lopez-Avila et al. 1987). High-resolution gas chromatography (HRGC) with capillary columns coupled with mass spectrometry (MS) provides better resolution and increased sensitivity for volatile compounds than packed columns. In this method, desorbed compounds are cryogenically trapped onto the head of the TABLE 6-1. Analytical Methods for Determining Chloroform in Biological Materials Sample detection Percent Sample matrix Preparation method Analytical method limit recovery Reference Exhaled air Sample collected in Tedlar HRGC/FID and No data No data Krotoszynski et al. (breath) bag preconcentrated by HRGC/MS 1979 Tenax-GC, thermal desorption Whole blood Purge-and-trap and thermal GC/MS <0.5 pg/L No data Antoine et al. 1986 desorption Adipose tissue Purge-and-trap and thermal GC/Hall with No data 100% at 0.6 Peoples ct al. 1979 and serum desorption GC/MS confirmation pg/L (serum); No data (tissue) Whole blood Solvent extraction HRGC/ECD with No data 99% at 50 pg/L Kroneld 1986 HRGC/MS confirmation Serum and Purge-and-trap and thermal GC/Hall with GC/MS 0.05 pg/L No data Pfaffenberger et al. adipose tissue desorption confirmation for serum 1980 Water, serum, Solvent extraction HRGC/ECD 1 pg/L for 100.3% at 50 Reunanen and Kroneld and urine serum and pg/L (water); 1982 urine 103% at 2.5 pg/L (serum); 141% at 2.3 pg/L (urine) SQOHL3N TVOILATYNY 9 86 TABLE 6-1 (Continued) Sample detection Percent Sample matrix Preparation method Analytical method limit recovery Reference Blood. urine, Purge-and-trap, thermal GC/HSD or GC/MS 0.10 pg/L No data EPA 1985a and tissue desorption (blood and urine) ECD = electron capture detector; FID = flame ionization detector; GC = gas chromatography; Hall = Hall electrolytic conductivity detector; HRGC = high-resolution gas chromatography; HSD = electrolytic conductivity conductor; MS = mass spectrometry SAOHL3N TVIILATYNY 9 66 TABLE 6-2. Analytical Methods for Determining Chloroform in Environmental Samples Sample detection Percent Sample matrix Preparation method Analytical method limit recovery Reference Volatile food Direct injection of head- GC/ECD or MS 4.2 pg/kg No data Entz et al. 1982 components space gas (beverages); 12.5 pg/kg No data (dairy products); 18 pg/kg No data (meats); 28 pg/kg No data (fats/oils) Drinking water Direct injection or purge- GC/ECD, 1 pg/L (direct); 103-126% at Nicholson et al. 1977 and-trap on GC column GC/Hall 0.1 pg/L (purge- 35-70 pg/L (automated) and-trap) (direct); 91-106% at 35-70 pg/L (purge-and-trap) Drinking water Purge-and-trap and thermal GC/MS 0.1 pg/L No data Coleman et al. 1976 desorption Drinking water None (direct injection) GC/MS 0.1 pg/L No data Fujii 1977 Seawater and Solvent extraction with GC/ECD 80 ng/L No data Bureau International freshwater pentane, extract dried with sodium sulfate Technique des Solvants Chlores 1976 SAOHL3N TVOILATVNY 9 00} TABLE 6-2 (Continued) Sample detection Percent Sample matrix Preparation method Analytical method limit recovery Reference Water Permeation through a GC/FID 74.0 pg/L No data Blanchard and Hardy silicon polycarbonate 1986 membrane into an inert gas stream and directed to GC port Air Adsorption on charcoal, GC/FID (NIOSH 0.7 mg/m’ 97% at NIOSH 1987 desorption with carbon method 1003) for 15 L sample 100-416 mg/m> disulfide Ambient air Tenax GC adsorption and GC/FID or ECD No data No data Parsons and Mitzner and stacks thermal desorption 1975 Air Sample collected in flask, GC/ECD 15 pg/m> No data Bureau of Intemational GC sample removed by Technique des Solvants syringe Chlores 1976 Water, soil, Solvent extraction GC/FID (screening 800-1,000 pg/L No data EPA 1988c and sediment test) (EPA-CLP) (water); 3.24 ng/g (soil and sediment) Water, soil, Purge-and-trap thermal GC/MS 5 pg/L (water); No data EPA 1988c and sediment desorption (EPA-CLP) 5 ng/g (soil and sediment) Tap water Solvent extraction HRGC/ECD with No data No data Kroneld 1986 HRGC/MS confirmation SAOHL3IW TVYOILATYNY 9 104 TABLE 6-2 (Continued) Sample detection Percent Sample matrix Preparation method Analytical method limit recovery Reference Water Solvent extraction HRGC/ECD 1 pg/L for 100.3% at Reunanen and Kroneld serum and urine 50 pg/L 1982 Groundwater, Direct injection of head- GC/HSD or FID 0.05 pg/L 102% at EPA 1986a liquid, and space gas (EPA method (EPA method 8010) 0.44-50 pg/L solid matrices 5020) or preconcentration by purge-and-trap and thermal desorption (EPA method 5030) Waste water Preconcentration by purge- GC/HSD or MS 0.05 pg/L 102% at EPA 1982 and-trap method and (EPA methods 601 (for HSD); 0.44-50 pg/L thermal desorption and 624) 1.6 pg/L (for HSD); (for MS) 101% at 10-100 pg/L (for MS) Solid and liquid Sample dispersed in a GC/ECD and FID No data 105% at Lopez-Avila et al. waste, soil glycol; purged, and trapped in series 5S pg/L 1987 in Tenax/silica/charcoal; thermally desorbed Drinking water Purge and trap in Tenax/ GC-Hall and FID 0.02 pg/L 98% Ho 1989 silica/charcoal; thermally in series desorb Finished drinking/ Purge and trap in Tenax/ GC-Hall (EPA No data No data EPA 1986b raw source water silica/charcoal/thermally method 502.1) desorb SAOHL3N TVOILATVNY 9 col TABLE 6-2 (Continued) Sample detection Percent Sample matrix Preparation method Analytical method limit recovery Reference Finished drinking/ Purge and trap in Tenax/ Subambient No data No data EPA 1986b raw source water silica/charcoal; thermally programmable desorb HRGC-MS (EPA method 524.1) Finished drinking/ Purge and trap in Tenax/ Cryofocusing (oxide 0.03 pg/L 90% at EPA 1986b raw source water silica/charcoal; thermally or narrow bore); (wide bore); 0.5-10 pg/L desorb HRGC-MS 0.04 pg/L (wide bore); (EPA method 524.2) (narrow bore) 105% at 0.5 pg/L (narrow bore) Food Extract composited, table- GC-ECD/Hall 5 ng/g (ECD); 15-161% Daft 1988a, 1989 ready food with isooctane 5 ng/g (Hall) or acetone-isooctane), most extracts directly injected into GC, extracts of other samples (fat content 21-70%) are passed through a micro-Florisil column before injection into GC CLP = Contract Laboratory Program; ECD = electron capture detector; EPA = Environmental Protection Agency; FID = flame ionization detector; GC = gas chromatography; Hall = Hall electrolytic conductivity detector; HRGC = high-resolution gas chromatography; HSD = electrolytic conductivity detector; MS = mass spectrometry; NIOSH = National Institute for Occupational Safety and Health SAQOHL3IN TVOILATYNY 9 £01 104 6. ANALYTICAL METHODS capillary column. This HRGC-MS method overcomes some common problems involved in analyses of excessively complex samples, samples with large ranges of concentrations, and samples that also contain high- boiling compounds (Dreisch and Munson 1983; EPA 1986a). Standardized methods include EPA Method 8010 for analysis of chloroform in groundwater, liquid, and solid matrices, and the moist air method. The reproducibility of the methods listed in Table 6-2 is generally acceptable and will vary with the identity of the researcher(s) and laboratories doing the analyses. Probable interferences for the methods of analysis includes contamination from chloroform vapors in the laboratory. For this reason, it is often recommended that the laboratories doing the analysis should not contain chloroform (or any other solvent being tested for) (EPA 1982; EPA 1986a; EPA 1986b). Other interferences include those volatile compounds that have similar retention times in the various GC columns used. This problem is often eliminated by the analytical methods by analyzing the samples with two different types of GC columns such that the retention times will not be coincidental in both columns. Refer to the references cited in Table 6-2 and the text for specific information regarding reproducibility and potential interferences. 6.3 ADEQUACY OF THE DATABASE Section 104(i)(5) of CERCLA directs the Administrator of ATSDR (in consultation with the Administrator of EPA and agencies and programs of the Public Health Service) to assess whether adequate information on the health effects of chloroform is available. Where adequate information is not available, ATSDR, in conjunction with NTP, is required to assure the initiation of a program of research designed to determine the health effects (and techniques for developing methods to determine such health effects) of chloroform. The following categories of possible data needs have been identified by a joint team of scientists from ATSDR, NTP, and EPA. They are defined as substance-specific informational needs that if met would reduce or eliminate the uncertainties of human health assessment. This definition should not be interpreted to mean that all data needs discussed in this section must be filled. In the future, the identified data needs will be evaluated and prioritized, and a substance-specific research agenda will be proposed. 6.3.1 Identification of Data Needs Methods for Determining Biomarkers of Exposure and Effect. No biomarker that can be associated quantitatively with chloroform exposure has been identified (see Section 2.5.1). Although chloroform levels can be determined in biological samples, the relationship between these levels and the exposure levels has not been quantitatively determined. Furthermore, the presence of chloroform in a biological sample may have resulted from the metabolism of another chlorinated hydrocarbon. If a biomarker of exposure for this compound in a human tissue or fluid was available and a correlation between the level of the biomarker and exposure existed, it could be used as an indication of the levels and extent of chloroform exposure. Further information regarding the accuracy of sample recovery for the methods of chloroform analysis would be useful in interpreting monitoring data. No biomarker of effect that can be associated quantitatively and directly to chloroform exposure has been identified (see Section 2.5.2). If biomarkers of effect were available for this compound and a correlation between the level or intensity of the biomarker of effect and the exposure level existed, it could be used as an indication of the levels and extent of chloroform exposure. Methods for Determining Parent Compounds and Degradation Products in Environmental Media. Methods for determining chloroform in the environment are available. These include methods for drinking water 105 6. ANALYTICAL METHODS (Banchard and Hardy 1986; EPA 1986b. Ho 1989; Kroneld 1986; Nicholson et al. 1977), air (NIOSH 1987; Parsons and Mitzner 1975), and foods (Daft 1988a, 1989; Entz et al. 1982)—-the media of most concern for human exposure. The precision, accuracy, reliability, and specificity of the methods are well documented and well suited for the determination of low levels of chloroform and levels at which health effects occur. There is not much information regarding the degradation products of chloroform in the environment. 6.3.2 On-going Studies The Environmental Health Laboratory Sciences Division of the Center for Environmental Health and Injury Control, Centers for Disease Control, is developing methods for the analysis of chloroform and other volatile organic compounds in blood. These methods use purge and trap methodology and magnetic sector mass spectrometry which gives detection limits in the low parts per trillion range. 107 7. REGULATIONS AND ADVISORIES The International Agency for Research on Cancer (IARC), national, and state regulations and guidelines regarding human exposure to chloroform are summarized in Table 7-1. Chloroform is regulated by the Clean Water Act Effluent Guidelines for the following industrial point sources: electroplating, organic chemicals, steam electric, asbestos, timber products processing, metal finishing, paving and roofing, paint formulating, ink formulating, gum and wood, carbon black, metal molding and casting, coil coating, copper forming, and electrical and electronic components (EPA 1988a). An MRL of 0.009 ppm has been derived for acute inhalation exposure to chloroform. The MRL is based on a LOAEL of 30 ppm for developmental effects in rats exposed to chloroform during gestation (Schwetz et al. 1974). An MRL of 0.2 mg/kg/day has been derived for acute oral exposure to chloroform. The MRL is based on a NOAEL of 17.3 mg/kg for liver and kidney effects in mice exposed to a single gavage dose of chloroform in oil (Moore et al. 1982). An MRL of 0.1 mg/kg/day has been derived for intermediate duration oral exposure to chloroform. The MRL is based on a NOAEL of 15 mg/kg/day for liver effects (increased SGPT) in dogs exposed to chloroform in toothpaste for 26 weeks (Heywood et al. 1979). An MRL of 0.01 mg/kg/day has been derived for chronic oral exposure to chloroform based on a LOAEL for liver effects (increased SGPT) in dogs administered 15 mg/kg/day chloroform in toothpaste in capsules for 7.5 years (Heywood et al. 1979). The chronic oral RfD for chloroform is also 0.01 mg/kg/day, based on the LOAEL for liver effects in dogs administered 15 mg/kg/day chloroform (Heywood et al. 1979; IRIS 1992). 108 7. REGULATIONS AND ADVISORIES TABLE 7-1. Regulations and Guidelines Applicable to Chloroform Agency Description Information References INTERNATIONAL IARC Carcinogenic classification Group 2B* IARC 1987 NATIONAL Regulations: a. Air EPA OAQPS Intent to list under Section 112 of Yes EPA 1985¢ Clean Air Aa (40 CFR 61.01) OSHA PEL-TWA 2 ppm OSHA 1989 (9.78 mg/m?) (29 CFR 1910) b. Water: EPA PQL 0.5 pg/L EPA 1987a (40 CFR 264 and 270) c. Other: EPA OERR RQ (Ruled) 10 pounds EPA 1989¢ (54 CFR 155) Threshold planning quantity 10,000 pounds EPA 1987b Guidelines: a. Air ACGIH TLV-TWA 10 ppm ACGIH 1992 49 mg/m?) NIOSH STEL (60 minutes) 2 ppm NIOSH 1990 (9.78 mg/m?) b. Water: EPA ODW Individual lifetime cancer risk 10° 60 pg/L IRIS 1992 c. Non-specific media EPA q,* (oral) 6.1x10> (mg/kg/day)! IRIS 1992 q;* (inhalation) 8.1x10°2 (mg/kg/day)! RIS 1992 [2.3x10°° (pg/m3)}) RfD (chronic oral) 0.01 mg/kg/day IRIS 1992 Cancer classification B2® IRIS 1992 STATE Regulations and Guidelines: a. Air: Acceptable ambient air concentrations Arizona 60 pg/m> (1 hr) NATICH 1992 16 pg/m> (24 hr) 0.043 pg/m’ (1 yr) California (Monteray) 0 NATICH 1992 Connecticut 250 pg/m’ (8 hr) NATICH 1992 109 7. REGULATIONS AND ADVISORIES TABLE 7-1 (Continued) Agency Description Information References STATE (continued) Florida (Fort Lauderdale) 500 pg/m> (8 hr) NATICH 1992 Florida (Pinellas Co.) 97.8 pg/m> (8 hr) 23.5 pg/m’ (24 hr) 0.043 pg/m> (1 yr) Indiana 1200 pg/m> (8 hr) NATICH 1992 0.043 pg/m?> (1 yr) Kansas 0.0435 pg/m’ (1 yr) NATICH 1992 Kentucky 1.276E-02 pounds (1 hr) State of Kentucky 1986 Massachusetts 133 pg/m> (24 hr) NATICH 1992 0.04 pg/m® (1 yr) Maryland 0 NATICH 1992 Maine 0.043 pg/m> (1 yr) NATICH 1992 Michigan 0.04 pg/m? (1 yn) NATICH 1992 North Carolina 4.3 pgm? (1 yr) NATICH 1992 North Dakota 0 NATICH 1992 Nevada 1190 pg/m> (8 hr) NATICH 1992 New York 167 pg/m> (1 yr) NATICH 1992 Oklahoma 97 pg/m* (24 hr) NATICH 1992 Pennsylvania (Philadelphia) 120 pg/m> (1 yr) NATICH 1992 Rhode Island 0.04 pg/m® (1 yr) NATICH 1992 South Carolina 250 pg/m> (24 hr) NATICH 1992 Texas 98 pg/m> (30 min) NATICH 1992 10 pg/m® (1 yr) Virginia 490 pg/m® (24 hr) NATICH 1992 Vermont 0.043 pg/m> (1 yr) NATICH 1992 b. 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Fed Proc 35:1125-1132. *Wallace CJ. 1950. Hepatitis and nephrosis due to cough syrup containing chloroform. Calif Med 73:442-443. *Wallace LA. 1987. The total exposure assessment methodology (TEAM) study. EPA 600/56-87/002. Wallace LA. 1989. The total exposure assessment methodology (TEAM) study: An analysis of exposures, sources, and risks associated with four volatile organic chemicals. J Am Coll Toxicol 8:883-895. *Wallace LA, Pellizzari E, Hartwell T, et al. 1984. Personal exposure to volatile organic compounds. I. Direct measurements in breathing-zone air, drinking water, food, and exhaled breath. Environ Res 35:293-319. *Wallace L, Pellizzari E, Sheldon L, et al. 1986a. The total exposure assessment methodology (TEAM) study: Direct measurement of personal exposures through air and water for 600 residents of several U.S. cities. In: Cohen Y, ed. Pollutants in a multimedia environment. New York, NY: Plenum Press, 289-315. *Wallace L, Pellizzari E, Hartwell T, et al. 1986b. Concentrations of 20 volatile organic compounds in the air and drinking water of 350 residents of New Jersey compared with concentrations in their exhaled breath. J Occup Med 28:603-608. *Wallace LA, Pellizzari ED, Hartwell TD, et al. 1987a. The TEAM study: Personal exposures to toxic substances in air, drinking water, and breath of 400 residents of New Jersey, North Carolina, and North Dakota. Environ Res 43:290-307. *Wallace LA, Pellizzari E, Leaderer B, et al. 1987b. Emissions of volatile organic compounds from building materials and consumer products. Atmos Environ 21:385-395. *Wallace L, Jungers R, Sheldon L, ei al. 1987c. Volatile organic chemicals in 10 public-access buildings. EPA 600/D-87/152. *Wallace LA, Hartwell TD, Permitt K, et al. 1987d. The influence of personal activities on exposure to volatile organic compounds. In: Proceedings of the 4th International Conference: Indoor Air Quality and Climate, Germany, 2-181 to 2-185. *Wallace LA, Pellizzari ED, Hartwell TD, et al. 1988. The California TEAM study: Breath concentrations and personal exposures to 26 volatile compounds in air and drinking water of 188 residents of Los Angeles, Antioch, and Pittsburgh, CA. Atmos Environ 22:2141-2163. *Wallace LA, Pellizzari ED, Hartwell TD, et al. 1989. The influence of personal activities on exposure to volatile organic compounds. Environ Res 50:37-55. Walter CB. 1982. Safe handling of chemical carcinogens, mutagens, teratogens, and highly toxic substances. Ann Arbor, MI: Ann Arbor Science. 138 8. REFERENCES *Westrick JJ, Mello JW, Thomas RF. 1989. The groundwater supply survey. Journal of the American Water Works Association 76:52-59. *Whitaker AM, Jones CS. 1965. Report of 1500 chloroform anesthetics administered with a precision vaporizer. Anesth Analg 44:60-65. *White AE, Takehisa S, Eger EI, et al. 1979. Sister chromatid exchanges induced by inhaled anesthetics. Anesthesiology 50:426-430. Wikberg JES, Hede AR, Post C. 1987. Effects of halothane and other chlorinated hydrocarbons on a,-adenoceptors in the mouse cortex. Pharmacol Toxicol 61:271-277. *Wilson J, Enfield CG, Dunlap WJ, et al. 1981. Transport and fate of selected organic pollutants in a sandy soil. J Environ Qual 10:501-506. *Windholz M, Ed. 1983. The Merck index. 10th ed. Rahway, NJ: Merck and Co., 300-301. *Withey JR, Collins BT, Collins PG. 1983. Effect of vehicle on the pharmacokinetics and uptake of four halogenated hydrocarbons from the gastrointestinal tract of the rat. J Appl Toxicol 3:249-253. Wolf CR, Mansuy D, Nastainczyk W, et al. 1977. The reduction of polyhalogenated methanes by liver microsomal cytochrome P450. Mol Pharmacol 13:698-705. *Wood JA, Porter ML. 1987. Hazardous pollutants in class II landfills. J Air Pollut Control Assoc 37:609-615. Yang RSH, Rauckman EJ. 1987. Toxicological studies of chemical mixtures of environmental concern at the National Toxicology Program: Health effects of groundwater contaminants. Toxicology 47:15-34. *Young TB, Kanarek MS, Tsiatis AA. 1981. Epidemiologic study of drinking water chlorination and wisconsin female cancer mortality. J Natl Cancer Inst 67:1191-1198. *Zepp RG, Braun AM, Hoigne J, et al. 1987. Photoproduction of hydrated electrons from natural organic solutes in aquatic environments. Environ Sci Technol 21:485-490. Zogorski JS. 1984. Experience in monitoring domestic water sources and process waters for trace organics. J Environ Sci Health A19:233-249. 139 9. GLOSSARY Acute Exposure -- Exposure to a chemical for a duration of 14 days or less, as specified in the Toxicological Profiles. Adsorption Coefficient (K,.) -- The ratio of the amount of a chemical adsorbed per unit weight of organic carbon in the soil or sediment to the concentration of the chemical in solution at equilibrium. Adsorption Ratio (Kd) -- The amount of a chemical adsorbed by a sediment or soil (i.e., the solid phase) divided by the amount of chemical in the solution phase, which is in equilibrium with the solid phase, at a fixed solid/solution ratio. It is generally expressed in micrograms of chemical sorbed per gram of soil or sediment. Bioconcentration Factor (BCF) -- The quotient of the concentration of a chemical in aquatic organisms at a specific time or during a discrete time period of exposure divided by the concentration in the surrounding water at the same time or during the same period. Cancer Effect Level (CEL) -- The lowest dose of chemical in a study, or group of studies, that produces significant increases in the incidence of cancer (or tumors) between the exposed population and its appropriate control. Carcinogen -- A chemical capable of inducing cancer. Ceiling Value -- A concentration of a substance that should not be exceeded, even instantaneously. Chronic Exposure -- Exposure to a chemical for 365 days or more, as specified in the Toxicological Profiles. Developmental Toxicity -- The occurrence of adverse effects on the developing organism that may result from exposure to a chemical prior to conception (either parent), during prenatal development, or postnatally to the time of sexual maturation. Adverse developmental effects may be detected at any point in the life span of the organism. Embryotoxicity and Fetotoxicity -- Any toxic effect on the conceptus as a result of prenatal exposure to a chemical; the distinguishing feature between the two terms is the stage of development during which the insult occurred. The terms, as used here, include malformations and variations, altered growth, and in utero death. EPA Health Advisory -- An estimate of acceptable drinking water levels for a chemical substance based on health effects information. A health advisory is not a legally enforceable federal standard, but serves as technical guidance to assist federal, state, and local officials. Immediately Dangerous to Life or Health (IDLH) -- The maximum environmental concentration of a contaminant from which one could escape within 30 min without any escape-impairing symptoms or irreversible health effects. Intermediate Exposure -- Exposure to a chemical for a duration of 15-364 days, as specified in the Toxicological Profiles. Immunologic Toxicity -- The occurrence of adverse effects on the immune system that may result from exposure to environmental agents such as chemicals. In Vitro -- Isolated from the living organism and artificially maintained, as in a test tube. 140 9. GLOSSARY In_Vivo -- Occurring within the living organism. Lethal Concentration; i) (LC; ¢) -- The lowest concentration of a chemical in air which has been reported to have caused death in humans or animals. Lethal Concentrations) (LCgg) — A calculated concentration of a chemical in air to which exposure for a specific length of time is expected to cause death in 50% of a defined experimental animal population. Lethal Dose; ) (LD) -- The lowest dose of a chemical introduced by a route other than inhalation that is expected to have caused death in humans or animals. Lethal Doses, (LDgy) -- The dose of a chemical which has been calculated to cause death in 50% of a defined experimental animal population. Lethal Times (LTg,) -- A calculated period of time within which a specific concentration of a chemical is expected to cause death in 50% of a defined experimental animal population. Lowest-Observed-Adverse-Effect Level (LOAEL) -- The lowest dose of chemical in a study, or group of studies, that produces statistically or biologically significant increases in frequency or severity of adverse effects between the exposed population and its appropriate control. Malformations -- Permanent structural changes that may adversely affect survival, development, or function. Minimal Risk Level -- An estimate of daily human exposure to a dose of a chemical that is likely to be without an appreciable risk of adverse noncancerous effects over a specified duration of exposure. Mutagen -- A substance that causes mutations. A mutation is a change in the genetic material in a body cell. Mutations can lead to birth defects, miscarriages, or cancer. Neurotoxicity -- The occurrence of adverse effects on the nervous system following exposure to chemical. No-Observed-Adverse-Effect Level (NOAEL) -- The dose of chemical at which there were no statistically or biologically significant increases in frequency or severity of adverse effects seen between the exposed population and its appropriate control. Effects may be produced at this dose, but they are not considered to be adverse. Octanol-Water Partition Coefficient (K,,) -- The equilibrium ratio of the concentrations of a chemical in n- octanol and water, in dilute solution. Permissible Exposure Limit (PEL) -- An allowable exposure level in workplace air averaged over an 8-hour shift. q;* -- The upper-bound estimate of the low-dose slope of the dose-response curve as determined by the multistage procedure. The q,* can be used to calculate an estimate of carcinogenic potency, the incremental excess cancer risk per unit of exposure (usually pg/L for water, mg/kg/day for food, and pg/m3 for air). Reference Dose (RfD) -- An estimate (with uncertainty spanning perhaps an order of magnitude) of the daily exposure of the human population to a potential hazard that is likely to be without risk of deleterious effects during a lifetime. The RfD is operationally derived from the NOAEL (from animal and human studies) by a 141 9. GLOSSARY consistent application of uncertainty factors that reflect various types of data used to estimate RfDs and an additional modifying factor, which is based on a professional judgment of the entire database on the chemical. The RfDs are not applicable to nonthreshold effects such as cancer. Reportable Quantity (RQ) -- The quantity of a hazardous substance that is considered reportable under CERCLA. Reportable quantities are (1) 1 pound or greater or (2) for selected substances, an amount established by regulation either under CERCLA or under Sect. 311 of the Clean Water Act. Quantities are measured over a 24-hour period. Reproductive Toxicity -- The occurrence of adverse effects on the reproductive system that may result from exposure to a chemical. The toxicity may be directed to the reproductive organs and/or the related endocrine system. The manifestation of such toxicity may be noted as alterations in sexual behavior, fertility, pregnancy outcomes. or modifications in other functions that are dependent on the integrity of this system. Short-Term Exposure Limit (STEL) -- The maximum concentration to which workers can be exposed for up to 15 min continually. No more than four excursions are allowed per day, and there must be at least 60 min between exposure periods. The daily TLV-TWA may not be exceeded. Target Organ Toxicity -- This term covers a broad range of adverse effects on target organs or physiological systems (e.g., renal, cardiovascular) extending from those arising through a single limited exposure to those assumed over a lifetime of exposure to a chemical. Teratogen — A chemical that causes structural defects that affect the development of an organism. Threshold Limit Value (TLV) -- A concentration of a substance to which most workers can be exposed without adverse effect. The TLV may be expressed as a TWA, as a STEL, or as a CL. Time-Weighted Average (TWA) -- An allowable exposure concentration averaged over a normal 8-hour workday or 40-hour workweek. Toxic Dose (TDg,) -- A calculated dose of a chemical, introduced by a route other than inhalation, which is expected to cause a specific toxic effect in 50% of a defined experimental animal population. Uncertainty Factor (UF) -- A factor used in operationally deriving the RfD from experimental data. UFs are intended to account for (1) the variation in sensitivity among the members of the human population, (2) the uncertainty in extrapolating animal data to the case of human, (3) the uncertainty in extrapolating from data obtained in a study that is of less than lifetime exposure, and (4) the uncertainty in using LOAEL data rather than NOAEL data. Usually each of these factors is set equal to 10. A-1 APPENDIX A USER'S GUIDE Chapter 1 Public Health Statement This chapter of the profile is a health effects summary written in nontechnical language. Its intended audience is the general public especially people living in the vicinity of a hazardous waste site or substance release. If the Public Health Statement were removed from the rest of the document, it would still communicate to the lay public essential information about the substance. The major headings in the Public Health Statement are useful to find specific topics of concern. The topics are written in a question and answer format. The answer to each question includes a sentence that will direct the reader to chapters in the profile that will provide more information on the given topic. Chapter 2 Tables and Figures for Levels of Significant Exposure (LSE) Tables (2-1, 2-2, and 2-3) and figures (2-1 and 2-2) are used to summarize health effects by duration of exposure and endpoint and to illustrate graphically levels of exposure associated with those effects. All entries in these tables and figures represent studies that provide reliable, quantitative estimates of No-Observed-Adverse-Effect Levels (NOAELS), Lowest-Observed- Adverse-Effect Levels (LOAELs) for Less Serious and Serious health effects, or Cancer Effect Levels (CELs). In addition, these tables and figures illustrate differences in response by species, Minimal Risk Levels (MRLs) to humans for noncancer end points, and EPA's estimated range associated with an upper-bound individual lifetime cancer risk of 1 in 10,000 to 1 in 10,000,000. The LSE tables and figures can be used for a quick review of the health effects and to locate data for a specific exposure scenario. The LSE tables and figures should always be used in conjunction with the text. The legends presented below demonstrate the application of these tables and figures. A representative example of LSE Table 2-1 and Figure 2-1 are shown. The numbers in the left column of the legends correspond to the numbers in the example table and figure. LEGEND See LSE Table 2-1 (1). Route of Exposure One of the first considerations when reviewing the toxicity of a substance using these tables and figures should be the relevant and appropriate route of exposure. When sufficient data exist, three LSE tables and two LSE figures are presented in the document. The three LSE tables present data on the three principal routes of exposure, i.e., inhalation, oral, and dermal (LSE Table 2-1, 2-2, and 2-3, respectively). LSE figures are limited to the inhalation (LSE Figure 2-1) and oral (LSE Figure 2-2) routes. (2). Exposure Duration Three exposure periods: acute (14 days or less); intermediate (15 to 364 days); and chronic (365 days or more) are presented within each route of exposure. In this example. an inhalation study of intermediate duration exposure is reported. (3). 4). (5). (6). (7). (8). 9). (10). (11). {12}. A-2 APPENDIX A Health Effect The major categories of health effects included in LSE tables and figures are death. systemic, immunological, neurological, developmental, reproductive. and cancer. NOAELs and LOAELs can be reported in the tables and figures for all effects but cancer. Systemic effects are further defined in the "System" column of the LSE table. Key to Figure Each key number in the LSE table links study information to one or more data points using the same key number in the corresponding LSE figure. In this example, the study represented by key number [8 has been used to define a NOAEL and a Less Serious LOAEL (also sce the two "181" data points in Figure 2-1). Species The test species, whether animal or human, are identified in this column. Exposure Frequency/Duration The duration of the study and the weekly and daily exposure regimen are provided in this column. This permits comparison of NOAELs and LOAELSs from different studies. In this case (key number 18), rats were exposed to [substance x] via inhalation for 13 weeks, 5 days per week, for 6 hours per day. System This column further defines the systemic effects. These systems include: respiratory, cardiovascular, gastrointestinal, hematological, musculoskeletal, hepatic. renal, and dermal/ocular. "Other" refers to any systemic effect (e.g., a decrease in body weight) not covered in these systems. In the example of key number 18, one systemic effect (respiratory) was investigated in this study. NOAEL A No-Observed-Adverse-Effect Level (NOAEL) is the highest exposure level at which no harmful effects were seen in the organ system studied. Key number 18 reports a NOAEL of 3 ppm for the respiratory system which was used to derive an intermediate exposure, inhalation MRL of 0.005 ppm (see footnote "b"). LOAEL A Lowest-Observed-Adverse-Effect Level (LOAEL) is the lowest exposure level used in the study that caused a harmful health effect. LOAELs have been classified into "Less Serious" and "Serious" effects. These distinctions help readers identify the levels of exposure at which adverse health effects first appear and the gradation of effects with increasing dose. A brief description of the specific end point used to quantify the adverse effect accompanies the LOAEL. The "Less Serious” respiratory effect reported in key number 18 (hyperplasia) occurred at a LOAEL of 10 ppm. Reference The complete reference citation is given in Chapter 8 of the profile. CEL A Cancer Effect Level (CEL) is the lowest exposure level associated with the onset of carcinogenesis in experimental or epidemiological studies. CELs are always considered serious effects. The LSE tables and figures do not contain NOAELs for cancer, but the text may report doses which did not cause a measurable increase in cancer. Footnotes Explanations of abbreviations or reference notes for data in the LSE tables are found in the footnotes. Footnote "b" indicates the NOAEL of 3 ppm in key number 18 was used to derive an MRL of 0.005 ppm. A-3 APPENDIX A LEGEND See LSE Figure 2-1 LSE figures graphically illustrate the data presented in the corresponding LSE tables. Figures help the reader quickly compare health effects according to exposure levels for particular exposure duration. (13). (14). (15). (16). (17). (18). (19). Exposure Duration The same exposure periods appear as in the LSE table. In this example, health effects observed within the intermediate and chronic exposure periods are illustrated. Health Effect These are the categories of health effects for which reliable quantitative data exist. The same health effects appear in the LSE table. Levels of Exposure Exposure levels for each health effect in the LSE tables are graphically displayed in the LSE figures. Exposure levels are reported on the log scale "y" axis. Inhalation exposure is reported in mg/m* or ppm and oral exposure is reported in mg/kg/day. NOAEL In this example, 18r NOAEL is the critical end point for which an intermediate inhalation exposure MRL is based. As you can see from the LSE figure key, the open-circle symbol indicates a NOAEL for the test species (rat). The key number 18 corresponds to the entry in the LSE table. The dashed descending arrow indicates the extrapolation from the exposure level of 3 ppm (see entry 18 in the Table) to the MRL of 0.005 ppm (see footnote "b" in the LSE table). CEL Key number 38r is one of three studies for which Cancer Effect Levels (CELs) were derived. The diamond symbol refers to a CEL for the test species (rat). The number 38 corresponds to the entry in the LSE table. Estimated Upper-Bound Human Cancer Risk Levels This is the range associated with the upper-bound for lifetime cancer risk of 1 in 10,000 to 1 in 10,000,000. These risk levels are derived from EPA’s Human Health Assessment Group's upper-bound estimates of the slope of the cancer dose response curve at low dose levels (q,"). Key to LSE Figure The Key explains the abbreviations and symbols used in the figure. LICIU CE XJ 2 hi 0 0% 0 "se "re ee %e %e 2% % ® o , o! $ cleo, a ole 1 F > TABLE 2-1. Levels of Significant Exposure to [Chemical x] - Inhalation Exposure LOAEL (effect) Key to frequency/ NOAEL Less serious Serious figure? Species duration System (ppm) (ppm) (ppm) Reference }— INTERMEDIATE EXPOSURE oe BF ; [4}— 18 Rat 13 wk Resp 3 10 (hyperplasia) Nitschke et al. 5d/wk 1981 6hr/d CHRONIC EXPOSURE Cancer ul 5 J 38 Rat 18 mo 20 (CEL, multiple Wong et al. 1982 => > 5d/wk organs) > Thr/d 39 Rat 89-104 wk 10 (CEL, lung tumors, NTP 1982 5d/wk nasal tumors) 6hr/d 40 Mouse 79-103 wk 10 (CEL, lung tumors, NTP 1982 5d/wk hemangiosarcomas) 6hr/d 2 The number corresponds to entries in Figure 2-1. [12}— b Used to derive an intermediate inhalation Minimal Risk Level (MRL) of 5 x 1073 ppm; dose adjusted for intermittent exposure and divided by an uncertainty factor of 100 (10 for extrapolation from animal to humans, 10 for humen variability). CEL = cancer effect level; d = day(s); hr = hour(s); LOAEL = lowest-observed-adverse-effect level; mo = month(s); NOAEL = no- observed-adverse-effect level; Resp = respiratory; wk = week(s) vv : ° 8 AA o%e’ oe’ oe’ hy 5 o® oe? O50 oe o® e’0%e 0% 0s" ” B—F—— INTERMEDIATE CHRONIC (15-364 Days) (2365 Days) Systems Bysbarric # JS ra, --~ A A ss Ld Sf s 3] wom -_— he iin 10,000 1000 | 100 f@ie @" gy, Buse Oi (Qne GeO» PT Ome Bsa Ose Dee Ore o™ Oe On y i —f8 wb Ow @n= On One Os Ow Ome Ox On Ge [re] —-- —_— Qe Ow " ’ ’ or } ' 104 ' 04 Jesumorma upper. —3§] oo 3 108 Pound Hamen ' Canoe Fish ooo | 3 Key 100 vn + Ra © 10AEL te series affects (ardmahs) . 00001 |- "Meuse ( LOAEL tor fas sarioue eftecm (arma) rit nk tt tr 10-7 » a. s NOAEL (erdmaie) & sliects othe Bhan cance 000001 : a, CEL - Cancw Elect Love! — _ hve rasmber nest 1 each pani Gan sspands ie entries bn Tetse 2 | * Doses sepwesart he lowes! 60s tasied por Shady Nhat produced o henardgenic repens and 60 nat brgly $20 cshiorus of © Suesheld ke Bw sence end paint FIGURE 2-1. Levels of Significant Exposure to [Chemical X]-Inhalation Vv XION3ddY Sv A-6 APPENDIX A Chapter 2 (Section 2.4) Relevance to Public Health The Relevance to Public Health section provides a health effects summary based on evaluations of existing toxicological, epidemiological, and toxicokinetic information. This summary is designed to present interpretive, weight-of-evidence discussions for human health end points by addressing the following questions. 1. What effects are known to occur in humans? 2. What effects observed in animals are likely to be of concern to humans? 3. What exposure conditions are likely to be of concern to humans, especially around hazardous waste sites? The section discusses health effects by end point. Human data are presented first, then animal data. Both are organized by route of exposure (inhalation, oral, and dermal) and by duration (acute, intermediate, and chronic). In vitro data and data from parenteral routes (intramuscular, intravenous, subcutaneous, etc.) are also considered in this section. If data are located in the scientific literature, a table of genotoxicity information is included. The carcinogenic potential of the profiled substance is qualitatively evaluated, when appropriate, using existing toxicokinetic, genotoxic, and carcinogenic data. ATSDR does not currently assess cancer potency or perform cancer risk assessments. MRLs for noncancer end points if derived, and the end points from which they were derived are indicated and discussed in the appropriate section(s). Limitations to existing scientific literature that prevent a satisfactory evaluation of the relevance to public health are identified in the Identification of Data Needs section. Interpretation of Minimal Risk Levels Where sufficient toxicologic information was available, MRLs were derived. MRLs are specific for route (inhalation or oral) and duration (acute, intermediate, or chronic) of exposure. Ideally, MRLs can be derived from all six exposure scenarios (e.g., Inhalation - acute, -intermediate, -chronic; Oral - acute, -intermediate, - chronic). These MRLs are not meant to support regulatory action, but to aquaint health professionals with exposure levels at which adverse health effects are not expected to occur in humans. They should help physicians and public health officials determine the safety of a community living near a substance emission, given the concentration of a contaminant in air or the estimated daily dose received via food or water. MRLs are based largely on toxicological studies in animals and on reports of human occupational exposure. MRL users should be familiar with the toxicological information on which the number is based. Section 2.4, “Relevance to Public Health," contains basic information known about the substance. Other sections such as 2.6, “Interactions with Other Chemicals" and 2.7, "Populations that are Unusually Susceptible” provide important supplemental information. MRL users should also understand the MRL derivation methodology. MRLs are derived using a modified version of the risk assessment methodology used by the Environmental Protection Agency (EPA) (Barnes and Dourson, 1988: EPA 19894) to derive reference doses (RfDs) for lifetime exposure. A-7 APPENDIX A To derive an MRL, ATSDR generally selects the end point which, in its best judgement, represents the most sensitive human health effect for a given exposure route and duration. ATSDR cannot make this judgement or derive an MRL unless information (quantitative or qualitative) is available for all potential effects (e.g., systemic, neurological, and developmental). In order to compare NOAELs and LOAELS for specific end points, all inhalation exposure levels are adjusted for 24hr exposures and all intermittent exposures for inhalation and oral routes of intermediate and chronic duration are adjusted for continous exposure (i.e., 7 days/week). If the information and reliable quantitative data on the chosen end point are available, ATSDR derives an MRL using the most sensitive species (when information from multiple species is available) with the highest NOAEL that does not exceed any adverse effect levels. The NOAEL is the most suitable end point for deriving an MRL. When a NOAEL is not available, a Less Serious LOAEL can be used to derive an MRL, and an uncertainty factor (UF) of 10 is employed. MRLs are not derived from Serious LOAELs. Additional uncertainty factors of 10 each are used for human variability to protect sensitive subpopulations (people who are most susceptible to the health effects caused by the substance) and for interspecies variability (extrapolation from animals to humans). In deriving an MRL, these individual uncertainty factors are multiplied together. The product is then divided into the adjusted inhalation concentration or oral dosage selected from the study. Uncertainty factors used in developing a substance-specific MRL are provided in the footnotes of the LSE Tables. ACGIH ADME atm ATSDR BCF BSC C CDC CEL CERCLA CFR CLP cm CNS d DHEW DHHS DOL ECG EEG EPA EKG F Fy FAO FEMA FIFRA fpm ft FR g GC gen HPLC hr IDLH IARC ILO in Kd kg kkg K K L oC ow B-1 APPENDIX B ACRONYMS, ABBREVIATIONS, AND SYMBOLS American Conference of Governmental Industrial Hygienists Absorption, Distribution, Metabolism, and Excretion atmosphere Agency for Toxic Substances and Disease Registry bioconcentration factor Board of Scientific Counselors Centigrade Centers for Disease Control Cancer Effect Level Comprehensive Environmental Response, Compensation, and Liability Act Code of Federal Regulations Contract Laboratory Program centimeter central nervous system day Department of Health, Education, and Welfare Department of Health and Human Services Department of Labor electrocardiogram electroencephalogram Environmental Protection Agency see ECG Fahrenheit first filial generation Food and Agricultural Organization of the United Nations Federal Emergency Management Agency Federal Insecticide, Fungicide, and Rodenticide Act feet per minute foot Federal Register gram gas chromatography generation high-performance liquid chromatography hour Immediately Dangerous to Life and Health International Agency for Research on Cancer International Labor Organization inch adsorption ratio kilogram metric ton organic carbon partition coefficient octanol-water partition coefficient liter L.C LC, LCso LD, LD, LOAEL LSE m mg min mL mm mmHg mmol mo mppcf MRL MS NIEHS NIOSH NIOSHTIC ng nm NHANES nmol NOAEL NOES NOHS NPL NRC NTIS NTP OSHA PEL pg pmol PHS PMR ppb ppm ppt RfD RTECS sec SCE SIC SMR B-2 APPENDIX B liquid chromatography lethal concentration, low lethal concentration, 50% kill lethal dose, low lethal dose, 50% kill lowest-observed-adverse-effect level Levels of Significant Exposure meter milligram minute milliliter millimeter millimeters of mercury millimole month millions of particles per cubic foot Minimal Risk Level mass spectrometry National Institute of Environmental Health Sciences National Institute for Occupational Safety and Health NIOSH’s Computerized Information Retrieval System nanogram nanometer National Health and Nutrition Examination Survey nanomole no-observed-adverse-effect level National Occupational Exposure Survey National Occupational Hazard Survey National Priorities List National Research Council National Technical Information Service National Toxicology Program Occupational Safety and Health Administration permissible exposure limit picogram picomole Public Health Service proportionate mortality ratio parts per billion parts per million parts per trillion recommended exposure limit Reference Dose Registry of Toxic Effects of Chemical Substances second sister chromatid exchange Standard Industrial Classification standard mortality ratio STEL STORET TLV TSCA TRI TWA U.S. UF yr WHO wk Q RIAA NIV YV = 57 on™ oa B-3 APPENDIX B short term exposure limit STORAGE and RETRIEVAL threshold limit value Toxic Substances Control Act Toxics Release Inventory time-weighted average United States uncertainty factor year World Health Organization week greater than greater than or equal to equal to less than less than or equal to percent alpha beta delta gamma micron microgram C-1 APPENDIX C PEER REVIEW A peer review panel was assembled for chloroform. The panel consisted of the following members: Dr. Richard Bull, Associate Professor of Toxicology and Pharmacology, College of Pharmacy, Washington State University, Pulman, Washington; Dr. Derek Hodgson, Vice President for Research, University of Wyoming, Laramie, Wyoming; and Dr. Nancy Reiches, Private Consultant, Columbus, Ohio. These experts collectively have knowledge of chloroform’s physical and chemical properties, toxicokinetics, key health end points, mechanisms of action, human and animal exposure, and quantification of risk to humans. All reviewers were selected in conformity with the conditions for peer review specified in Section 104(i)(13) of the Comprehensive Environmental Response, Compensation, and Liability Act, as amended. Scientists from the Agency for Toxic Substances and Disease Registry (ATSDR) have reviewed the peer reviewers’ comments and determined which comments will be included in the profile. A listing of the peer reviewers’ comments not incorporated in the profile, with a brief explanation of the rationale for their exclusion, exists as part of the administrative record for this compound. A list of databases reviewed and a list of unpublished documents cited are also included in the administrative record. The citation of the peer review panel should not be understood to imply its approval of the profile’s final content. The responsibility for the content of this profile lies with the ATSDR. ¥ U.S. GOVERNMENT PRINTING OFFICE: 1993 738-201 EALTH LIBRARY PUBLIC HEALTH LIBRA JAN 03 1994 U.C. BERKELEY LIBRARIES (09547735