NTP TECHNICAL REPORT ON THE TOXICOLOGY AND CARCINOGENESIS STUDIES OF PYRIDINE (CAS NO. 110-86-1) IN F344/N RATS, WISTAR RATS, AND B6C3F1 MICE (DRINKING WATER STUDIES) NATIONAL TOXICOLOGY PROGRAM P.O. Box 12233 Research Triangle Park, NC 27709 March 2000 NTP TR 470 NIH Publication No. 00-3960 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. Listings of all published NTP reports and ongoing studies are available from NTP Central Data Management, NIEHS, P.O. Box 12233, MD E1-02, Research Triangle Park, NC 27709 (919-541-3419). The Abstracts and other study information for 2-year studies are also available at the NTP’s World Wide Web site: http://ntp- server.niehs.nih.gov. NTP TECHNICAL REPORT ON THE TOXICOLOGY AND CARCINOGENESIS STUDIES OF PYRIDINE (CAS NO. 110-86-1) IN F344/N RATS, WISTAR RATS, AND B6C3F1 MICE (DRINKING WATER STUDIES) NATIONAL TOXICOLOGY PROGRAM P.O. Box 12233 Research Triangle Park, NC 27709 March 2000 NTP TR 470 NIH Publication No. 00-3960 U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service National Institutes of Health 2 Pyridine, NTP TR 470 CONTRIBUTORS National Toxicology Program NTP Pathology Working Group Evaluated and interpreted results and reported findings Evaluated slides, prepared pathology report on F344/N and Wistar rats (22 July 1997) J.K. Dunnick, Ph.D., Study Scientist D.A. Bridge, B.S. M.P. Jokinen, D.V.M., Chairperson J.R. Bucher, Ph.D. Pathology Associates International S. Botts, M.S., D.V.M., Ph.D. R.E. Chapin, Ph.D. Experimental Pathology Laboratories, Inc. J.R. Hailey, D.V.M. S. Ching, D.V.M., Ph.D. J.K. Haseman, Ph.D. SVC Associates, Inc. R.R. Maronpot, D.V.M. E.T. Gaillard, M.S., D.V.M. G.N. Rao, D.V.M., Ph.D. Experimental Pathology Laboratories, Inc. A. Radovsky, D.V.M., Ph.D. R.A. Herbert, D.V.M., Ph.D. C.S. Smith, Ph.D. National Toxicology Program P.B. Little, D.V.M., Ph.D., Observer G.S. Travlos, D.V.M. Pathology Associates International D.B. Walters, Ph.D. S. Platz, D.V.M., Ph.D., Observer K.L. Witt, M.S., Integrated Laboratory Systems Boehringer Ingelheim A. Radovsky, D.V.M., Ph.D. TSI Mason Research Institute National Toxicology Program Conducted studies, evaluated pathology findings for 13-week and A. Yoshida, D.V.M., Ph.D., Observer 2-year studies in rats and mice National Toxicology Program A.G. Braun, Sc.D., Principal Investigator, 13-week studies Evaluated slides, prepared pathology report on kidney step sections of male F344/N and Wistar rats (8 August 1997) M.R. Osheroff, Ph.D., Principal Investigator, 2-year studies C. Gamba-Vitalo, Ph.D. P.B. Little, D.V.M., Ph.D., Chairperson D. Norlin, Ph.D. Pathology Associates International F.M. Voelker, M.S., D.V.M. J.R. Hailey, D.V.M. National Toxicology Program PATHCO, Inc. J.R. Leininger, D.V.M., Ph.D. National Toxicology Program Histopathologic evaluation for 2-year studies in F344/N and Wistar rats J. Mahler, D.V.M. National Toxicology Program D.G. Goodman, V.M.D. A. Radovsky, D.V.M., Ph.D. P.K. Hildebrandt, D.V.M. National Toxicology Program Evaluated slides, prepared pathology report on mice (19 September Experimental Pathology Laboratories, Inc. 1996) Provided pathology quality assurance J.C. Seely, D.V.M., Chairperson J.F. Hardisty, D.V.M., Principal Investigator PATHCO, Inc. S. Botts, M.S., D.V.M., Ph.D. S. Botts, M.S., D.V.M., Ph.D. E.T. Gaillard, M.S., D.V.M. Experimental Pathology Laboratories, Inc. R. Cattley, V.M.D., Ph.D. Chemical Industry Institute of Toxicology Dynamac Corporation J.R. Leininger, D.V.M., Ph.D. Prepared quality assurance audits National Toxicology Program A. Nyska, D.V.M. S. Brecher, Ph.D., Principal Investigator National Toxicology Program A. Radovsky, D.V.M., Ph.D. National Toxicology Program Pyridine, NTP TR 470 3 Analytical Sciences, Inc. Biotechnical Services, Inc. Provided statistical analyses Prepared Technical Report R.W. Morris, M.S., Principal Investigator S.R. Gunnels, M.A., Principal Investigator S.R. Lloyd, M.S. J.R. Carlton, B.A. N.G. Mintz, B.S. G. Gordon, M.A. L.M. Harper, B.S. A.M. Macri-Hanson, M.A., M.F.A. 4 CONTENTS ABSTRACT ............................................................................ 7 EXPLANATION OF LEVELS OF EVIDENCE OF CARCINOGENIC ACTIVITY ................ 13 TECHNICAL REPORTS REVIEW SUBCOMMITTEE ... .................................... 14 SUMMARY OF TECHNICAL REPORTS REVIEW SUBCOMMITTEE COMMENTS . ........... 15 INTRODUCTION ....................................................................... 17 MATERIALS AND METHODS ........................................................... 25 RESULTS .............................................................................. 35 DISCUSSION AND CONCLUSIONS ....................................................... 67 REFERENCES.......................................................................... 73 APPENDIX A Summary of Lesions in Male F344/N Rats in the 2-Year Drinking Water Study of Pyridine ............................................................... 83 APPENDIX B Summary of Lesions in Female F344/N Rats in the 2-Year Drinking Water Study of Pyridine ............................................................... 115 APPENDIX C Summary of Lesions in Male Wistar Rats in the 2-Year Drinking Water Study of Pyridine ............................................................... 149 APPENDIX D Summary of Lesions in Male Mice in the 2-Year Drinking Water Study of Pyridine ............................................................... 189 APPENDIX E Summary of Lesions in Female Mice in the 2-Year Drinking Water Study of Pyridine ............................................................... 227 APPENDIX F Genetic Toxicology ........................................................ 261 APPENDIX G Hematology and Clinical Chemistry Results ... ................................ 275 APPENDIX H Organ Weights and Organ-Weight-to-Body-Weight Ratios ... .................... 285 APPENDIX I Reproductive Tissue Evaluations and Estrous Cycle Characterization .. ........... 289 APPENDIX J Determinations of Pyridine in Plasma......................................... 293 APPENDIX K Chemical Characterization and Dose Formulation Studies ....................... 295 Pyridine, NTP TR 470 5 APPENDIX L Water and Compound Consumption in the 2-Year Drinking Water Studies of Pyridine ............................................................... 313 APPENDIX M Ingredients, Nutrient Composition, and Contaminant Levels in NIH-07 Rat and Mouse Ration ............................................ 319 APPENDIX N Sentinel Animal Program .................................................. 323 6 Pyridine, NTP TR 470 7 ABSTRACT N PYRIDINE CAS No. 110-86-1 Chemical Formula: C5H5N Molecular Weight: 79.10 Synonyms: Azabenzene, azine Pyridine is used as a denaturant in alcohol and anti- died during week 1. Final mean body weights of freeze mixtures, as a solvent for paint, rubber, and 1,000 ppm males and females and 500 ppm females polycarbonate resins, and as an intermediate in the were significantly less than controls. Water consump- manufacture of insecticides, herbicides, and fungicides. tion by female rats exposed