[Effect of 7,8-benzoflavone on the incidence of skin tumors induced by polycyclic hydrocarbons].

Tumours were induced in CBA mice or (C57BL X CBA)F1 hybrids by the application of benz(a)pyrene (BP), 6-methylBP, 6-formylBP or 7,12-dimethylbenzanthracene (DMBA) to the skin. 7,8-benzoflavone (BF) used in combination with the mentioned agents decreased the carcinogenic action of methyl-substituted hydrocarbons--DMBA and 6-methylBP and had no effect on the carcinogenic action of BP and 6-formylBP. It is suggested that the inhibitory action of BF on carcinogenesis induced by methyl-substituted hydrocarbons was due to the inhibited oxidation of the methyl group.