SKIN TUMOR-INITIATING ACTIVITIES OF 12 ISOMERIC PHENOLS OF BENZO(A)PYRENE

Abstract

The skin tumor-initiating activities of the 12 isomeric phenols of benzo(a)pyrene (BP) were determined in mice by use of a 2-stage system of tumorigenesis. 11-Hydroxybenzo(a)pyrene was moderately active, whereas 2-hydroxybenzo(a)pyrene and BP were strong tumor initiators when applied topically to CD-1 mice and followed by twice-weekly applications of the promoter 12-O-tetradecanoylphorbol-13-acetate. 1-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10- and 12-hydroxybenzo(a)pyrene had less than 5% of the tumor-initiating activity of BP when the data were expressed as papillomas per mouse. After 30 wk of promotion, the number of papillomas per mouse was 8.4, 8.5 and 2.8, respectively, for animals treated with BP, 2-hydroxybenzo(a)pyrene and 11-hydroxybenzo(a)pyrene. A 5-wk latency period before the appearance of the 1st tumor was observed after application of 2-hydroxybenzo(a)pyrene or BP, whereas a slightly longer latency period of 7 wk was observed following application of 11-hydroxybenzo(a)pyrene. The time required for 50% of the animals to develop tumors was 13 wk for animals treated with BP and 15 wk for animals treated with 2- or 11-hydroxybenzo(a)pyrene.