Mutagenicity of some organophosphorus compounds at the ade6 locus of Schizosaccharomyces pombe.

12 organophosphorus insecticides were tested for toxicity and mutagenicity in the forward mutation test system ade6 of the yeast Schizosaccharomyces pombe. EMS and MMS were selected as positive controls. 3 compounds, dichlorvos, trichlorfon and paraoxon, showed a linear dose-response relationship. Among the other compounds investigated, methyl derivatives, though in general more toxic than ethyl derivatives, did not significantly increase the mutation frequency. Trichlorfon, tested in combination with malathion, methylparathion or methylazinphos (guthion), produced clearly synergistic effects for both toxicity and mutagenicity. The addition of S9 microsomal liver fraction decreased the efficiency of both single and combined treatments only where a dose-response relationship or a synergistic effect was obtained.