109 Mutation Research, 60 (1979) 109--113 © Elsevier/North-Holland Biomedical Press Short Communication MUTAGENESIS OF HUMAN CELLS BY 3-METHYLCHOLANTHRENE RODGER D. CURREN *, CHARLES J. HOMER **, PAUL J. PRICE *** and AARON E. FREEMAN $ Microbiological Associates, Torrey Pines Research Center, 2945 Science Park Road, La Jolla, CA 92037 (U.S.A.) (Received 2 June 1978) (Revision received 25 October 1978) (Accepted 6 November 1978) A major goal of research in carcinogenesis and mutagenesis is the identifica- tion of deleterious chemicals in our environment and the quantitation of their biological action. A few of the systems which are presently available to do this are in vivo rodent bioassays, prokaryotic mutation assays, and in vitro mutation and transformation assays with non-human mammalian cells. Although correla- tions have been made among the results of such diversified tests [2,4,13,18], the more difficult problem of the relevance of these tests to the occurrence of human cancer remains. One logical aid would be the development of mutation and transformation screens utilizing human cells. If correlations could be found between the results of the previously mentioned tests and tests employing human cells, then the degree of relevance of all such tests to human cancer might be extrapolated. However, the development of transformation assays using normal diploid human cells has proved difficult [9,10]. Mutational sys- tems in human cells have been explored, but to date only direct-acting mutagens have been successfully used in such systems [1,10,19]. This means that many classes of compounds requiring metabolic activation, e.g., polycyclic aromatic hydrocarbons (PAH), have not been detected as mutagens in human cells. We * Present address: Dep~Lrtment of Biochemical Oncology. Microbiological Associates, 5221 River Road, Bethesda, MD 20016 (U.S.A.) ** Present address: Monitor Labs, 4202 Sorrento Valley Blvd., San Diego, CA 92037 (U.S.A.) *** Present address: Section of Cell Production and Media, Center for Disease Control, 1600 Clifton Road, Atlanta GA 30333 (U.S.A.) Present address: La Jolla Cancer Research Foundation, 2945 Science Park Road, La Jolla, CA 92037 (U.S.A.)