Mutagenic Activity of Thiocarbamate Herbicides in Salmonella typhimurium

Three thiocarbamate herbicides, diallate (S-(2,3-dichloroallyl)diisopropylthiocarbamate), triallate (S-(2,3,3-trichloroallyl)diisopropylthiocarbamate), and CDEC (2-chloroallyl-N,N-diethyldithiocarbamate), were evaluated for their ability to induce mutations in four histidine-requiring strains of Salmonella typhimurium (TA 100, TA 1535, TA 98, and TA 1538) with and without a rat liver microsomal activation system (Ames test). These herbicides were mutagenic in TA 100 and TA 1535 (base-pair substitution mutants) only in the presence of the liver microsomal preparation, indicating that the chemicals require metabolic activation for their conversion into active mutagens. None of the herbicides caused mutations in strains TA 98 and TA 1538 (frameshift mutants). Diallate was considerably more potent than triallate or CDEC, showing mutagenic activity at 1 μg/plate.