Senior investigator Laboratory Chemical Pharmacology, National Cancer Institute, Bethesda, Maryland, 1963—1965. Chief Laboratory toxicology, Experimental Therapeutics, Chemotherapy Program, 1969—1972. Assistant professor pharmacology University Washington School Medicine, Seattle, 1965—1969, associate professor pharmacology, 1969.
Chief Laboratory Reproductive and Development Toxicology, National Institute Environmental Health Sciences, Research Triangle Park, North Carolina, 1972—1984. Assistant to director International Programs, 1970—1980. Senior policy analyst Office of Science and Technology Policy, The White House, Washington, 1977—1978.
Director Office Health Research, Office of Research and Development, Environmental Protection Agency, Washington, 1984—1985. Senior director toxicology Sterling-Winthrop Research Institute, since 1985. Member editorial board Toxicology and Applied Pharmacology, since 1973, Environmental Health Perspectives, since 1972, Pharmacology and Therapeutics-The International Encyclopedia Pharmacology and Therapeutics, since 1975, Journal Environmental Sciences and Health, since 1976, Journal Environmental Pathology and Toxicology, since 1977, Journal Toxicology and Environmental Health, since 1977, Fundamental and Applied Toxicology, since 1982.
Member Toxicology Advisory Board Raven Press, New York City, since 1977. Editor-in-chief Target Organ Toxicity Monograph Series, Raven Press, since 1981.
Member of American Association for the Advancement of Science, Society Toxicology (president 1982-1983), Western Pharmacology Society, Society Ecotoxicology and Environmental Safety, Society Study Reproduction, Society Risk Analysis, Society Occupational and Environmental Health, Society Experimental Biology and Medicine, Mount Desert Island Biological Laboratory Society, International Union Toxicology, International Union Pharmacology, International Society Study Xenobiotics, International Academy Environmental Safety, American Chemical Society (Division Chemical Health and Safety), American Society Andrology, American Society Pharmacology and Experimental Therapeutics, American Public Health Association, American Association Cancer Research, Rho Chi, Sigma Xi.