Peculiarities of carcinogenesis under simultaneous oral administration of benzo(a)pyrene and o-cresol in mice.

A modifying influence of ortho-cresol (o-cresol) on the carcinogenic effect of benzo(a)pyrene (BaP) with combined oral administration to CC57Br mice had been found. During simultaneous administration of o-cresol (1 mg) and BaP (1 mg), the incidence of tumors, the multiplicity of tumors, and the degree of malignancy all increased, but the latency was shortened. When o-cresol was administered before or after BaP (in identical doses), the carcinogenic effect was weakened. When o-cresol (10 mg) and BaP (5 mg) were administered simultaneously, the incidence of malignant tumors was similar to controls receiving BaP only (13.8%), indicating inhibition of carcinogenesis.