In vivo and in vitro binding of alpha- and gamma-hexachlorocyclohexane to mouse liver macromolecules.

alpha-Hexachlorocyclohexane (alpha-HCH) but not gamma-HCH, produces a strong neoplastic response in HPB strain mouse liver. In vivo and in vitro binding studies with 14C-labelled HCH isomers showed no preferential binding of the alpha-HCH isomer to protein or DNA. Moreover, the binding of both isomers to DNA in vivo or in vitro occurred only at very low levels, a result consistent with the lack of mutagenic activity associated with these compounds. The results suggest that the neoplastic response observed with alpha-HCH results from a non-genotoxic mechanism.