ABSTRACT
The origin of the study of cancer induction by chemicals is often ascribed to the London surgeon Sir Percival Pott,1 who over 200 years ago postulated that the high incidence of epithelioma of the scrotum among chimney sweeps was due to their excessive exposure to soot. Thus, at the very outset it was obvious, unfortunately as a result of human exposure, that chemical carcinogens are markedly organ specific. The great mass of animal data subsequently generated during the 50 years following these early observations has shown this to be a general rule among nearly all classes of chemical carcinogens. Polycyclic aromatic hydrocarbons as a class act locally, i.e., tumors arise at the site of application. Mouse skin is particularly sensitive to these agents, papillomas, and later carcinomas developing on the treated areas after topical application. In summary, polycyclic aromatic hydrocarbons appear to be carcinogenic to most species and most tissues where they can accumulate and act over a prolonged period.
