Brief Communication: Tumor Initiation by Apparently Noncarcinogenic

SUMMARY-Three hydrocarbons previously reported to be nontumorigenic initiated tumor formation in mouse skin. In addition, chrysene, benz[a]anthracene, dibenz[a,danthracene, and benzo[e]pyrene pro-duced multiple papillomas when used as initiators in modest doses. Pyrene, anthracene, and anthanthrene showed borderline initiating activity. These findings generally agree with previously published calculations of the chemical reactivity of these and other unsubstituted aromatic hydrocarbons, which postulated that substitutions at different positions in the hydrocarbons represent competing processes of activation for carcinogenesis and detoxication.-J Natl Cancer Inst 50: 1717-1719,1973. IN SEVERAL ATTEMPTS to explain the car-cinogenicity of unsubstituted polycyclic aromatic hydrocarbons (1-4), a number of compounds ap-peared to be exceptions to the correlations drawn. However, from study of the literature (5) many of these apparent exceptions are compounds inade-quately tested. For this reason, I tested several com-mercially available hydrocarbons, including som