Toxicity of aromatic hydrocarbons on normal human epidermal cells in vitro.

cultures has not yet been demonstrated, the cytotoxic response suggests that the cells possess a microsomal aryl hydroxylase system, which may also be capable of the conversion of the hydrocarbon to an active carcinogen. MATERIALS AND METHODS Pieces of normal adult human abdominal skin, approximately 4 mm square and 1 mm thick, were grown in a clot of chick embryo extract and plasma (Baltimore Biological Laboratory, Baltimore, Md.) on the bottom of plastic Petn dishes, either directly on the plastic or on glass coverslips (8). The tissues were immersed in Eagle's minimal essential medium containing 10% fetal calf serum, penicillin (100 units/ml), streptomycin (100 units/mi), and mycostatin (100 units/mi). Cultures were gassed with a 95% air-5% CO2 mixture and incubated at 37°.The medium was changed every 3 to 4 days. After a period of 10 to 1 1 days, during which a sizable epithelial outgrowth had appeared, cultures were photographed. The normal medium was then removed and medium containing hydrocarbon was added. The hydrocarbons (Eastman Organic Chemicals, Rochester, N. Y.) were initially dissolved in acetone (1 mg/S ml) and added to the medium to achieve a final concentration of 1 @zg of hydrocarbon and 0.004 g of acetone per ml. The hydrocarbons and their solutions were stored in the dark at 4°and handled under red or amber filtered lighting. The cultures were divided into 4 groups, those containing the carcinogens MCA or BP and controls containing pyrene or normal medium. The controls consisting of only normal culture fluid contained no acetone, because preliminary experiments showed that, in concentrations up to 0.008 g/ml, acetone had no detectable effect on culture growth or cell morphology. The cultures were exposed to the hydrocarbon solutions for 4 days in the dark, after which they were rinsed through 4 baths of normal culture fluid at 37°.After rinsing, the cultures were placed in fresh fluid. From this point, they were periodically exposed to normal laboratory lighting conditions for examination and photography. The culture medium was changed every 3 to 4 days. Cultures were maintained for 3 months after exposure to the carcinogen. SUMMARY Outgrowth cultures of normal human epidermis were continuously exposed for 4 days to the aromatic hydrocarbons 3-methylcholanthrene and benzo [a] pyrene at a concentration of 1 j.tg/ml. After exposure to the hydrocarbons, the amount of epithelial outgrowth was markedly reduced in 10 of 13 3-methylcholanthrene and 14 of 14 benzo [a] pyrene cultures …