NTP TECHNICAL REPORT ON THE TOXICOLOGY AND CARCINOGENESIS STUDIES OF BROMODICHLOROMETHANE (CAS NO. 75-27-4) IN MALE F344/N RATS AND FEMALE B6C3F1 MICE (DRINKING WATER STUDIES) NATIONAL TOXICOLOGY PROGRAM P.O. Box 12233 Research Triangle Park, NC 27709 February 2006 NTP TR 532 NIH Publication No. 06-4468 National Institutes of Health Public Health Service U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES FOREWORD The National Toxicology Program (NTP) is an interagency program within the Public Health Service (PHS) of the Department of Health and Human Services (HHS) and is headquartered at the National Institute of Environmental Health Sciences of the National Institutes of Health (NIEHS/NIH). Three agencies contribute resources to the program: NIEHS/NIH, the National Institute for Occupational Safety and Health of the Centers for Disease Control and Prevention (NIOSH/CDC), and the National Center for Toxicological Research of the Food and Drug Administration (NCTR/FDA) Established in 1978, the NTP is charged with coordinating toxicological testing activities, strengthening the science base in toxicology, developing and validating improved testing methods, and providing information about potentially toxic substances to health regulatory and research agencies, scientific and medical communities, and the public. The Technical Report series began in 1976 with carcinogenesis studies conducted by the National Cancer Institute. In 1981, this bioassay program was transferred to the NTP. The studies described in the Technical Report series are designed and conducted to characterize and evaluate the toxicologic potential, including carcinogenic activity, of selected substances in laboratory animals (usually two species, rats and mice). Substances selected for NTP toxicity and carcinogenicity studies are chosen primarily on the basis of human exposure, level of production, and chemical structure. The interpretive conclusions presented in NTP Technical Reports are based only on the results of these NTP studies. Extrapolation of these results to other species including characterization of hazards and risks to humans requires analyses beyond the intent of these reports. Selection per se is not an indicator of a substance’s carcinogenic potential. The NTP conducts its studies in compliance with its laboratory health and safety guidelines and Food and Drug Administration (FDA) Good Laboratory Practice Regulations, and must meet or exceed all applicable federal, state, and local health and safety regulations. Animal care and use are in accordance with the Public Health Service Policy on Humane Care and Use of Animals. Studies are subjected to retrospective quality assurance audits before being presented for public review. NTP Technical Reports are indexed in the NIH/NLM PubMed database and are available free of charge electronically on the NTP website (http://ntp.niehs.nih.gov) or in hardcopy upon request from the NTP Central Data Management group at [email protected] or (919) 541-3419. NTP TECHNICAL REPORT ON THE TOXICOLOGY AND CARCINOGENESIS STUDIES OF BROMODICHLOROMETHANE (CAS NO. 75-27-4) IN MALE F344/N RATS AND FEMALE B6C3F1 MICE (DRINKING WATER STUDIES) NATIONAL TOXICOLOGY PROGRAM P.O. Box 12233 Research Triangle Park, NC 27709 February 2006 NTP TR 532 NIH Publication No. 06-4468 National Institutes of Health Public Health Service U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES 2 CONTRIBUTORS National Toxicology Program NTP Pathology Working Group Evaluated and interpreted results and reported findings Evaluated slides and prepared pathology report on rats (December 10, 2002) R.L. Melnick, Ph.D., Study Scientist P.H. Long, D.V.M., Ph.D., Chairperson R.A. Herbert, D.V.M., Ph.D., Study Pathologist Pathology Associates, A Charles River Company D.W. Bristol, Ph.D. Laboratories, Inc. J.R. Bucher, Ph.D. N. Allison, D.V.M. J.R. Hailey, D.V.M. Experimental Pathology Laboratories, Inc. G.E. Kissling, Ph.D. R.A. Herbert, D.V.M., Ph.D. R.R. Maronpot, D.V.M. National Toxicology Program F.M. Parham, Ph.D. G.D. Hill, D.V.M., Ph.D. S.D. Peddada, Ph.D. National Toxicology Program C.S. Smith, Ph.D. A. Nyska, D.V.M. National Toxicology Program G.S. Travlos, D.V.M. G. Pearse, B.V.M.&S. K.L. Witt, M.S. National Toxicology Program J.C. Peckham, D.V.M., M.S., Ph.D. Southern Research Institute Experimental Pathology Laboratories, Inc. Conducted studies and evaluated pathology findings C. Picut, V.M.D., J.D. Integrated Laboratory Systems C.D. Hébert, Ph.D., Principal Investigator (2-Year Studies) W.R. Richter, D.V.M., M.S., Principal Investigator Evaluated slides and prepared pathology report on mice (October 24, 2002) (2-Year Studies) J.D. Prejean, Ph.D., Principal Investigator (3-Week Studies) P.H. Long, D.V.M., Ph.D., Chairperson J.E. Heath, D.V.M. Pathology Associates, A Charles River Company P.R. Farnell, D.V.M., M.S., Ph.D. K.Y. Cimon, D.V.M., M.S. R.B. Thompson, D.V.M., Ph.D. Experimental Pathology Laboratories, Inc. R.A. Herbert, D.V.M., Ph.D. Experimental Pathology Laboratories, Inc. National Toxicology Program G.D. Hill, D.V.M., Ph.D. Provided pathology review National Toxicology Program D.E. Malarkey, D.V.M., Ph.D. M.H. Hamlin, II, D.V.M., Principal Investigator National Toxicology Program N. Allison, D.V.M. G. Pearse, B.V.M.&S. K.Y. Cimon, D.V.M., M.S. National Toxicology Program J.C. Peckham, D.V.M., M.S., Ph.D. J.C. Peckham, D.V.M., M.S., Ph.D. J.C. Seely, D.V.M. Experimental Pathology Laboratories, Inc. J.C. Seely, D.V.M. Dynamac Corporation Experimental Pathology Laboratories, Inc. Prepared quality assurance audits Y. Tani, D.V.M., Ph.D., Observer National Toxicology Program S. Brecher, Ph.D., Principal Investigator Biotechnical Services, Inc. Constella Group Prepared Technical Report Provided statistical analyses S.R. Gunnels, M.A., Principal Investigator P.W. Crockett, Ph.D., Principal Investigator L.M. Harper, B.S. L.J. Betz, M.S. P.A. Gideon, B.A. K.P. McGowan, M.B.A. E.S. Rathman, M.S. J.T. Scott, M.S. D.C. Serbus, Ph.D. 3 CONTENTS ABSTRACT . 5 EXPLANATION OF LEVELS OF EVIDENCE OF CARCINOGENIC ACTIVITY . 8 TECHNICAL REPORTS REVIEW SUBCOMMITTEE . 9 SUMMARY OF TECHNICAL REPORTS REVIEW SUBCOMMITTEE COMMENTS . 10 INTRODUCTION . 11 MATERIALS AND METHODS . 21 RESULTS . 29 DISCUSSION AND CONCLUSIONS . 45 REFERENCES . 53 APPENDIX A Summary of Lesions in Male Rats in the 2-Year Drinking Water Study of Bromodichloromethane . 61 APPENDIX B Summary of Lesions in Female Mice in the 2-Year Drinking Water Study of Bromodichloromethane . 101 APPENDIX C Genetic Toxicology . 143 APPENDIX D Clinical Pathology Results . 163 APPENDIX E Organ Weights and Organ-Weight-to-Body-Weight Ratios . 167 APPENDIX F Chemical Characterization and Dose Formulation Studies . 171 APPENDIX G Water and Compound Consumption in the 2-Year Drinking Water Studies of Bromodichloromethane . 185 APPENDIX H Ingredients, Nutrient Composition, and Contaminant Levels in NIH-2000 Rat and Mouse Ration . 189 APPENDIX I Sentinel Animal Program . 193 APPENDIX J Single-Dose Toxicokinetic Studies in F344/N Rats and B6C3F1 Mice . 197 APPENDIX K Physiologically Based Pharmacokinetic Model and Dose-Response Analyses . 211 4 Bromodichloromethane, NTP TR 532 SUMMARY Background Bromodichloromethane occurs as a by-product of the chlorination of drinking water. In earlier studies, bromodichloromethane caused cancer of the intestine and kidney in rats and of the liver and kidney in mice when doses of the chemical dissolved in corn oil were deposited in the stomachs of the animals. We studied the effects of bromodichloromethane in drinking water on male rats and female mice to see if the same effects occurred. Methods We gave drinking water containing 175, 350, or 700 mg of bromodichlomethane per liter of water to groups of 50 male rats and female mice for two years. Control animals received the same tap water with no chemical added. At the end of the study tissues from more than 40 sites were examined for every animal. Results Body weights and survival of animals receiving bromodichloromethane were similar to those of the control animals. No cancers or nonneoplastic lesions occurred more frequently as a result of exposure to bromodichloromethane in drinking water. Conclusions We conclude that bromodichloromethane in the drinking water did not cause cancer in male rats or female mice. 5 ABSTRACT Br H C Cl Cl BROMODICHLOROMETHANE CAS No. 75-27-4 Chemical Formula: CHBrCl2 Molecular Weight: 163.83 Synonym: Dichlorobromomethane Bromodichloromethane is a by-product of the chlorina­ bromodichloromethane (equivalent to average daily tion of drinking water. It is formed by the halogen sub­ doses of approximately 0, 6, 12, 20, 38, or 71 mg bro­ stitution and oxidation reactions of chlorine with modichloromethane/kg body weight) in drinking water naturally occurring organic matter (e.g., humic or for 3 weeks. All rats survived to the end of the study. fulvic acids) in water containing bromide. The mean body weight gains of 350 and 700 mg/L rats Bromodichloromethane has been shown to be carcino­ were significantly less than that of the controls. genic at multiple sites in rats (large intestine and kidney) Concentration-related decreases in water consumption and in mice (liver and kidney) after administration by were evident during the first week on study. Relative gavage in corn oil. To further characterize its dose- kidney weights of rats in the 175, 350, and 700 mg/L response relationships for evaluations of human risk, groups were significantly greater than that of the con­ bromodichloromethane was nominated to the NTP by trols. There were no significant chemical-related the United States Environmental Protection Agency for histopathological changes. toxicity and carcinogenicity studies in rats and mice by drinking water exposure. Male F344/N rats and female B6C3F1 mice were exposed to bromodichloromethane 3-WEEK STUDY IN MICE (greater than 98% pure) in drinking water for 3 weeks or Groups of 10 female B6C3F1 mice were exposed to tar­ 2 years.