Metabolic activation of haloalkanes and tests in vitro for mutagenicity

1. During incubation of 14CCl4, 14CHCl3, [14C]halothane, or 14CCl3F with liver microsomes and NADPH, considerable radioactivity is bound irreversibly to endoplasmic protein and lipid. However, no 14C was detected in the ribosomal RNA. 2. None of the four haloalkanes studied induced mutations after incubation with liver microsomes and the bacterial tester strains S. typhimurium TA 1535 and TA 1538. 3. Very low or no activity was associated with soluble protein or RNA added to incubation mixtures of the four haloalkanes with liver microsomes.