Hexachlorocyclohexane-induced tumorigenicity in mice under different experimental conditions

Continuous administration of 500 ppm hexachlorocyclohexane (HCH) in the diet induced 100% liver tumors in mice, but none were observed in rats and hamsters treated with the same dose of HCH. In Swiss male mice, tumor incidence at earlier ages was greater than that observed in corresponding age groups of Swiss female mice. It was further observed that in Swiss females, sex hormones retarded the tumorigenic effect of HCH; in BALB/c mice a similar phenomenon was not observed.