Short-term tests of genotoxicity for 1,1,1-trichloroethane

Covalent binding of 14C-1,1,1-trichloroethane to macromolecules from rat and mouse liver, kidney, lung and stomach was analyzed under the same experimental conditions previously utilized in studying 1,1-dichloroethane and 1,1,2-trichloroethane. Labeling of DNA, RNA and proteins was very low both in in vivo interaction and in in vitro microsome-mediated binding. Interaction proceeded through the involvement of the P-450-dependent mixed function oxidase system from liver microsomes and, to a lesser extent, from lung microsomes. Covalent Binding Index of 1,1,1-trichloroethane in liver DNA was typical of very weak initiators. However, overall evaluation of the short-term assays available for 1,1,1-trichloroethane leads to limited evidence of genotoxicity. On the other hand, the evidence of 1,1,1-trichloroethane carcinogenicity in animals is still inadequate.