“…That PAHs potentially play an important role in human cancer is suggested by their widespread environmental prevalence,2,3 their relatively high tumorigenic potency, and their broad spectrum of activity in animal tissues. 4 Significant levels of benzo [o]pyrene and other carcinogenic PAHs are present in urban air, in auto exhaust, and in many common foods.2'3 As a class, the PAHs rank second only to mycotoxin mold metabolites, e.g., aflatoxin, in relative carcinogenic potency. Moreover, PAHs are uniquely capable of selectively inducing diverse tumors in animal tissues, including mammary carcinoma, leukemia, sarcoma, etc., dependent upon the experimental conditions employed.…”