[Benzo(a)pyrene and the carcinogenic effect of coal tar]

The carcinogenic effects of coal tar and benzo(a)pyrene were compared. The agents were applied to murine skin, with coal tar dose being adjusted for benzo(a)pyrene. The carcinogenic effect of coal tar appeared higher than that of benzo(a)pyrene, the relative carcinogenic risk of the former being 3.2 times that of the latter. The coefficient of relative carcinogenic risk of coal tar calculated on the basis of TD56 regression coefficients for dose-effect relationship and mean latent period ratios was averagely 1.5.