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J. Soc. Cosmet. Chem., 29, 727-732 (November 1978) Regulatory considerations concerning mutagenesis ALBERT C. KOLBYE, JR. Bureau of Foods, Food and Drug Administration, U.S. Department of Health, Education, and Welfare, Washington, D.C. 20204. Received June 8, 1977. Presented at Annual Scientific Seminar, Society of Cosmetic Chemists, May 1977, Montreal, Canada. As the study of mutagenesis has developed over the past decade, our understanding of mutagenesis and related phenomena has undergone a rapid evolution that may have profound implications for public health. This rapid evolution is also compelling us to reconsider our methods of testing substances for their potential adverse effect on human health and their implications for regulatory decisions. Thus a series of questions have arisen for which society must find answers. I shall attempt to formulate several of the questions and to explain some of the scientific and regulatory considerations that determine the utility of presently available test systems for regulatory decision-making. Society's concern about preventing cancer and genetic damage is readily understood in terms of public health, but in my judgment this concern may not always be properly directed. The chief question is not primarily whether mutagenesis assay systems are useful for identifying compounds that have the potential for causing genetic damage in future generations, although that is a major question in itself. Instead, the question is whether the results of mutagenesis testing alone can enable us to decide if a substance poses an appreciable risk for inducing cancer in humans. The scope of that question covers many related issues. For example, are the biological phenomena associated with positive results in mutagenesis assay systems relevant to cancer induction in humans? My answer is both "yes" and "no, not necessarily." I answer "yes" because induction of mutations in the DNA of somatic cells appears to be associated with an important pathway in the cancer induction pattern in experimental animals by many chemical "carcinogens." Furthermore, certain human cancers appear to be associated with exposure (primarily occupational) to chemicals all of which have the properties associated with the quality of carcinogenicity and, by definition from the results of mutagenesis tests, of mutagenicity as well. Hence we could label some of these substances "carcinomutagens" or "mutacarcinogens." The current leaders of this school of thought include Drs. Ames and McCann. They have accomplished a great deal by expanding their system so that many compounds can be tested rapidly, at moderate cost, and with results that are reproducible by independent laboratories. Their test system (1) has many attractive features, including the capability of assessing mutagenic potency quantitatively over a very wide range. Furthermore, their system is 727