NATIONAL TOXICOLOGY PROGRAM Technical Report Series No. 447 TOXICOLOGY AND CARCINOGENESIS STUDIES OF ACETONITRILE (CAS NO. 75-05-8) IN F344/N RATS AND B6C3F, MICE (INHALATION STUDIES) 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. 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 studieswere conducted in compliance with Food and Drug Administration (FDA)Good Laboratory Practice Regulations, and all aspectsof 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. These NTP Technical Reports are available for sale from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Road, Springfield, VA 22161 (703-487-4650). Single copies of this Technical Report are available without charge while supplies last from NTP Central Data Management, NIEHS, P.O. Box 12233, MD El-02, Research Triangle Park, NC 27709 (919-541-3419). \ Listings of all published NTP reports and ongoing studies are also available from NTP Central Data Management. The Abstracts and other study information for 2-year studies are also available on the NTP’s World Wide Web site: http://ntp-server.niehs.nih.gov. NTP TECHNICAL REPORT ON THE TOXICOLOGY AND CARCINOGENESIS STUDIES OF ACETONITRILE (CAS NO. 75-05-8) IN F344/N RATS AND B6C3Fl MICE (INHALATION STUDIES) NATIONAL TOXICOLOGY PROGRAM P.O. Box 12233 ResearchTrianglePark,NC27709 April 1996 NTP TR 447 NIH Publication No. 96-3363 U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service National Institutes of Health 2 Acetonitrile, NTP TR 447 CONTRIBUTORS National Toxicology Program NTP Pathology Working Group Evaluated and interpreted results and reported findings Evaluated slides, prepared pathology report on rats (30 June 1992) C.J. Alden, Ph.D. G.A. Boorman, D.V.M., Ph.D. M.P. Jokinen, D.V.M., Chair D.A. Bridge, B.S. Pathology Associates, Inc. J.R. Bucher, Ph.D. J. Cullen, V.M.D., Ph.D. M.R. Elwell, D.V.M., Ph.D. North Carolina State University T.J. Goehl, Ph.D. C. David, D.V.M. North Carolina State University J.K. Haseman, Ph.D. E.T. Gaillard, M.S., D.V.M. H.A. Herbert, D.V.M., Ph.D. Experimental Pathology Laboratories, Inc. G.N. Rao, D.V.M., Ph.D. J.R. Hailey, D.V.M. J.H. Roycroft, Ph.D. National Toxicology Program G.S. Travlos, D.V.M. C.C. Shackelford, D.V.M., MS., Ph.D. D.B. Walters, Ph.D. National Toxicology Program K.L. Witt, M.S., Oak Ridge Associated Universities R.C. Sills, D.V.M., Ph.D. National Toxicology Program Battelle Pacific Northwest Laboratories K. Takahashi, D.V.M., MSc., Ph.D. National Toxicology Program Conducted studies, evaluated pathology findings Evaluated slides, prepared pathology report on mice B.J. Chou, D.V.M., Ph.D., PrincipalInvestigator (14 July 1992) R.A. Miller, D.V.M., Ph.D. H.A. Ragan, D.V.M., Ph.D. M.P. Jokinen, D.V.M., Chair S.E. Rowe, D.V.M., MS. Pathology Associates, Inc. R.B. Westerberg, Ph.D. D. Dixon, D.V.M., Ph.D. National Toxicology Program E.T. Gaillard, MS., D.V.M. Experimental Pathology Laboratories, Inc. Experimental Pathology Laboratories, Inc. Provided pathology quality assurance J.R. Hailey, D.V.M. National Toxicology Program J.F. Hardisty, D.V.M., PrincipalInvestigator K.T. Morgan, B.V.Sc., Ph.D. E.T. Gaillard, M.S., D.V.M. Chemical Industry Institute of Toxicology C.C. Shackelford, D.V.M., M.S., Ph.D. Dynamac Corporation National Toxicology Program Prepared quality assurance audits Biotechnical Services, Inc. PrincipalInvestigator S. Brecher, Ph.D., Prepared Technical Report Analytical Sciences, Inc. D.D. Lambright, Ph.D., PrincipalInvestigator Provided statistical analyses J.R. Beverly, B.A. N.F. Fisher, M.A., M.P.H. R.W. Morris, MS., PrincipalInvestigator G. Gordon, M.A. N.G. Mintz, B.S. S.R. Gunnels, M.A. S. Rosenblum, MS. 3 CONTENTS ABSTRACT ................................................................... 5 EXPLANATION OF LEVELS OF EVIDENCE OF CARCINOGENIC ACTMTY ............... 9 TECHNICAL REPORTS REVIEW SUBCOMMITTEE ................................... 10 SUMMARY OF TECHNICAL REPORTS REVIEW SUBCOMMITTEE COMMENTS ........... 11 INTRODUCTION .............................................................. 13 MATERIALS AND METHODS .................................................... 21 RESULTS .................................................................... 31 DISCUSSION AND CONCLUSIONS ................................................ 55 REFERENCES ................................................................ 59 APPENDIXA Summary of Lesions in Male Rats in the 2-Year Inhalation Study of Acetonitrile ..................................................... 65 APPENDIXBSummary of Lesions in Female Rats in the 2-Year Inhalation Study of Acetonitrile .................................................... 107 APPENDIXCSummary of Lesions in Male Mice in the 2-Year Inhalation Study of Acetonitrile .................................................... 143 APPENDIXD Summary of Lesions in Female Mice in the 2-Year Inhalation Study of Acetonitrile .................................................... 177 APPENDIXE Genetic Toxicology ................................................. 219 APPENDIXF Organ Weights and Organ-Weight-to-Body-WeightRatios .................... 229 APPENDIXG Hematology and Thyroid Hormone Assay Results .......................... 237 APPENDIXH Chemical CharacterizationandGeneration of ChamberConcentrations ......... 241 APPENDIXI Ingredients.Nutrient Composition. andContaminant Levels in NIH-07 Rat and Mouse Ration ..................................... 259 APPENDIXJ Sentinel Animal Program ............................................ 265 4 Acetonitrile, NTP TR 447 5 ABSTRACT CH,CN ACETONITRILE CAS NO. 75-05-8 Chemical Formula: C,H,N Molecular Weight: 41.05 Synonyms: Cyanomethane, ethanenitrile, ethyl nitrile, methanecarbonitrile, methyl cyanide, nitrile of acetic acid Acetonitrile is used primarily as a solvent in extrac- concentrations up to andincluding 800 ppm,the final tive distillation and crystallization of pharmaceutical mean body weights and body weight gains were and agricultural products and as a catalyst in chemi- generally similar tothose of the controls.At cal reactions.It was nominatedfor testing by the 1,600 ppm, body weight gain was lower and the final NationalCancerInstitutedueto its presence in mean body weights of both males and females were drinking water supplies and the environment, due to significantly lower than those of the controls. Hypo- lack of information on the carcinogenicity of alkyl activity and ruffled fur were observed during the first cyanides, and becauseof widespread worker exposure. week of the study in males receiving 800 ppm and Male and female F344/N rats and B6C3Fl mice were males and females receiving 1,600 ppm. Additional exposed to acetonitrile (atleast 99% pure) by inhala- clinical findings in 1,600 ppm males that died during tionfor 13 weeks or 2 years. Genetic toxicology week 1 were ataxia, abnormalposture,andclonic studieswereconducted in Salmonella typhimurium, convulsions. Clinical pathology findings included cultured Chinese hamster ovary cells, and peripheral nonresponsive, normocytic, normochromic anemia in blood of B6C3Fl mice exposed to acetonitrilefor 1,600 ppm males and females andin800ppm 13 weeks. females, and decreased triiodothyronine(T3)concen- trations in 1,600 ppm females. Absolute and relative thymus weights were significantly lower than thoseof the controls in