NTP TECHNICAL REPORT ON THE TOXICOLOGY AND CARCINOGENESIS STUDIES OF CHLORAL HYDRATE (CAS NO. 302-17-0) IN B6C3F1 MICE (GAVAGE STUDIES) NATIONAL TOXICOLOGY PROGRAM P.O. Box 12233 Research Triangle Park, NC 27709 February 2002 NTP TR 502 NIH Publication No. 02-4436 U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service National Institutes of Health FOREWORD The National Toxicology Program (NTP) is made up of four charter agencies of the U.S. Department of Health and Human Services (DHHS): the National Cancer Institute (NCI), National Institutes of Health; the National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health; the National Center for Toxicological Research (NCTR), Food and Drug Administration; and the National Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control and Prevention. In July 1981, the Carcinogenesis Bioassay Testing Program, NCI, was transferred to the NIEHS. The NTP coordinates the relevant programs, staff, and resources from these Public Health Service agencies relating to basic and applied research and to biological assay development and validation. The NTP develops, evaluates, and disseminates scientific information about potentially toxic and hazardous chemicals. This knowledge is used for protecting the health of the American people and for the primary prevention of disease. The studies described in this Technical Report were performed under the direction of the NIEHS and were conducted in compliance with NTP laboratory health and safety requirements and must meet or exceed all applicable federal, state, and local health and safety regulations. Animal care and use were in accordance with the Public Health Service Policy on Humane Care and Use of Animals. The prechronic and chronic studies were conducted in compliance with Food and Drug Administration (FDA) Good Laboratory Practice Regulations, and all aspects of the chronic studies were subjected to retrospective quality assurance audits before being presented for public review. These studies are designed and conducted to characterize and evaluate the toxicologic potential, including carcinogenic activity, of selected chemicals in laboratory animals (usually two species, rats and mice). Chemicals selected for NTP toxicology and carcinogenesis studies are chosen primarily on the bases of human exposure, level of production, and chemical structure. The interpretive conclusions presented in this Technical Report are based only on the results of these NTP studies. Extrapolation of these results to other species and quantitative risk analyses for humans require wider analyses beyond the purview of these studies. Selection per se is not an indicator of a chemical’s carcinogenic potential. Details about ongoing and completed NTP studies are available at the NTP’s World Wide Web site: http://ntp-server.niehs.nih.gov. Abstracts of all NTP Technical Reports and full versions of the most recent reports and other publications are available from the NIEHS’ Environmental Health Information Service (EHIS) http://ehis.niehs.nih.gov (800-315-3010 or 919-541-3841). In addition, printed copies of these reports are available from EHIS as supplies last. A listing of all the NTP Reports printed since 1982 appears on the inside back cover. NTP TECHNICAL REPORT ON THE TOXICOLOGY AND CARCINOGENESIS STUDIES OF CHLORAL HYDRATE (CAS NO. 302-17-0) IN B6C3F1 MICE (GAVAGE STUDIES) NATIONAL TOXICOLOGY PROGRAM P.O. Box 12233 Research Triangle Park, NC 27709 February 2002 NTP TR 502 NIH Publication No. 02-4436 U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service National Institutes of Health 2 CONTRIBUTORS The studies on chloral hydrate were conducted at the FDA’s National Center for Toxicological Research under an interagency agreement between the FDA and the NIEHS. The studies were designed and monitored by a Toxicology Study Selection and Review Committee, composed of representatives from the NCTR and other FDA product centers, NIEHS, and other ad hoc members from other government agencies and academia. The interagency agreement was designed to use the staff and facilities of the NCTR in testing of FDA priority chemicals and to provide FDA scientists and regulatory policymakers information for hazard identification and risk assessment. Toxicology Study Selection National Center for Toxicological Research, and Review Committee Food and Drug Administration Conducted studies, evaluated and interpreted results and pathology B.A. Schwetz, D.V.M., Ph.D., Chairperson findings, and reported findings National Center for Toxicological Research W.T. Allaben, Ph.D. F.A. Beland, Ph.D., Study Scientist National Center for Toxicological Research W.T. Allaben, Ph.D. F.A. Beland, Ph.D. J.R. Appleget, B.S. National Center for Toxicological Research R.W. Benson, B.S. J.R. Bucher, Ph.D. D.W. Gaylor, Ph.D. National Institute of Environmental Health Sciences J.F. Contrera, Ph.D. R.L. Kodell, Ph.D. Center for Drug Evaluation and Research, N.A. Littlefield, Ph.D. Food and Drug Administration J.M. Reed, M.S. D.W. Gaylor, Ph.D. K.L. Witt, M.S., Integrated Laboratory Systems, Inc. National Center for Toxicological Research W.M. Witt, D.V.M., Ph.D. K.J. Greenlees, Ph.D. Center for Veterinarian Medicine, Food and Drug Administration Conducted chemical analyses of feed and purity of the agent R.J. Lorentzen, Ph.D. Center for Food Safety and Applied Nutrition, W.M. Cooper, B.S. Food and Drug Administration F.E. Evans, Ph.D. F.D. Sistare, Ph.D. J.P. Freeman, Ph.D. Center for Drug Evaluation and Research, T.M. Heinze, M.S. Food and Drug Administration T.C. Schmitt, B.S. P.H. Siitonen, B.S. Bionetics Prepared animal feed and cared for mice Pathology Associates International J. Carson, B.S. Evaluated pathology findings A. Matson, B.S. M. Moore T.J. Bucci, V.M.D., Ph.D. C.V. Okerberg, D.V.M., Ph.D. J.R. Latendresse, D.V.M., Ph.D. Chloral Hydrate, NTP TR 502 3 Experimental Pathology Laboratories, Inc. R.O.W. Sciences, Inc. Provided pathology quality assurance Provided experimental support and statistical analyses J.F. Hardisty, D.V.M., Principal Investigator J. Armstrong, B.S. C.C. Shackelford, D.V.M., M.S., Ph.D. M. Austen, M.S. D.L. Barton, M.S. NTP Pathology Working Group B. Bryant Evaluated slides, prepared pathology report on mice K. Carroll (25 August, 1999) X. Ding, M.S. C.C. Shackelford, D.V.M., M.S., Ph.D., Chairperson S. Goldman Experimental Pathology Laboratories, Inc. J.M. Gossett, M.S. T.J. Bucci, V.M.D., Ph.D. C.C. McCarty, B.S. Pathology Associates International W.A. McCracken, M.S. M.R. Elwell, D.V.M., Ph.D. B. Spadoni Covance Laboratories B.T. Thorn, M.S. J.F. Hardisty, D.V.M. Experimental Pathology Laboratories, Inc. R.A. Herbert, D.V.M., Ph.D. Biotechnical Services, Inc. National Toxicology Program Prepared Technical Report J.R. Latendresse, D.V.M., Ph.D. Pathology Associates International S.R. Gunnels, M.A., Principal Investigator C.V. Okerberg, D.V.M., Ph.D. L.M. Harper, B.S. Pathology Associates International D.C. Serbus, Ph.D. R.W. Trotter, D.V.M. W.D. Sharp, B.A., B.S. Pathology Associates International R.A. Willis, B.A., B.S. P.A. Yount, B.S. 4 CONTENTS ABSTRACT ......................................................................... 5 EXPLANATION OF LEVELS OF EVIDENCE OF CARCINOGENIC ACTIVITY ............... 9 TECHNICAL REPORTS REVIEW SUBCOMMITTEE ..................................... 10 SUMMARY OF TECHNICAL REPORTS REVIEW SUBCOMMITTEE COMMENTS ........... 11 INTRODUCTION .................................................................... 13 MATERIALS AND METHODS ......................................................... 23 RESULTS .......................................................................... 35 DISCUSSION AND CONCLUSIONS .................................................... 67 REFERENCES ...................................................................... 73 APPENDIX A Summary of Lesions in Regimen A Female Mice in the 2-Year Gavage Study of Chloral Hydrate ...................................................... 83 APPENDIX B Summary of Lesions in Regimen B Female Mice in the 2-Year Gavage Study of Chloral Hydrate ...................................................... 99 APPENDIX C Summary of Lesions in Regimen C Female Mice in the 2-Year Gavage Study of Chloral Hydrate ...................................................... 121 APPENDIX D Summary of Lesions in Regimen D Female Mice in the 2-Year Gavage Study of Chloral Hydrate ...................................................... 135 APPENDIX E Summary of Lesions in Regimen E Male Mice in the 2-Year Gavage Study of Chloral Hydrate ...................................................... 149 APPENDIX F Genetic Toxicology ...................................................... 163 APPENDIX G Liver Weights and Liver-Weight-to-Body-Weight Ratios ....................... 175 APPENDIX H Chemical Characterization and Dose Formulation Studies ...................... 179 APPENDIX I Ingredients, Nutrient Composition, and Contaminant Levels in NIH-31 Rat and Mouse Ration .......................................... 189 APPENDIX J Sentinel Animal Program ................................................ 193 5 ABSTRACT Cl OH Cl C C OH Cl H CHLORAL HYDRATE CAS No. 302-17-0 Chemical Formula: C2H3Cl3O2 Molecular Weight: 165.42 Synonyms: Trichloracetaldehyde monohydrate; 1,1,1-trichloro-2,2-ethanediol; 2,2,2-trichloro-1,1-ethanediol Trade names: Aquachloral Supprettes; Noctec; Somnos Chloral hydrate is used medically as a sedative or 2 years after the initial