Mutagenic evaluation of trichlorfon using different assay methods with Salmonella typhimurium.

Evaluation of the mutagenicity of trichlorfon pesticide was carried out with strains TA1535, TA100, TA97, TA98 and TA104 of Salmonella typhimurium by means of several assay methods: (i) spot test; (ii) standard plate incorporation test; (iii) plate incorporation test with preincubation; (iv) fluctuation test and (v) fluctuation test with preincubation, with and without post-mitochondrial liver fraction (S9) from Wistar rats pretreated with phenobarbital and 5,6-benzoflavone as a metabolic activation system. Trichlorfon induced base-pair substitution mutations, and its mutagenic activity was decreased by the addition of S9 mix. The fluctuation test and fluctuation test with preincubation were the most sensitive assay methods for detecting the mutagenicity of trichlorfon.