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Microbiological mutagenicity studies of pesticides in vitro
Abstract:
14 pesticides were tested as pure compounds for the induction of point mutations in four strains of Salmonella typhimurium--TA1535, TA1536, TA1537 and TA1538--in the presence and in the absence of rat-liver microsomal fractions and for the induction of resistance to low concentrations of streptomycin in the filamentous bacterium, Streptomyces coelicolor. The technique used was essentially the so-called "spot test". The pesticides investigated were: aminotriazole, Benomyl, Captafol, Captan, Dichlorvos, Dalapon-Na, Dinobuton, Dodine, Ioxynil, Mecoprop, Neburon, Picloram, Triallate and Trichlorphon. In Salmonella, Captan and Triallate were mutagenic on the TA1535 strain; Dichlorvos and Trichlorphon were negative in the spot test but mutagenic after incubation in liquid cultures of strain TA1535. By using the S. coelicolor forward-mutation test, aminotriazole, Dichlorvos, Picloram, Trichlorphon and Triallate were mutagenic with the "spot test" technique; Captan showed a weak mutagenic activity with a "plate-incorporated" technique.
Insights
This study evaluated 14 pesticides for mutagenicity using Salmonella typhimurium and Streptomyces coelicolor. Several pesticides, including Captan, Triallate, Dichlorvos, and Trichlorphon, demonstrated mutagenic potential in these bacterial assays.
Area of Science:
- Environmental Toxicology
- Microbial Genetics
- Chemical Mutagenesis
Background:
- Pesticide safety assessment is crucial for environmental and human health.
- Bacterial mutagenicity assays are standard tools for preliminary genotoxicity screening.
- Understanding pesticide-induced mutations informs risk assessment and regulatory decisions.
Purpose of the Study:
- To assess the mutagenic potential of 14 different pesticides.
- To investigate pesticide-induced point mutations in Salmonella typhimurium strains.
- To evaluate pesticide effects on induced resistance in Streptomyces coelicolor.
Main Methods:
- Utilized the bacterial reverse mutation assay (Ames test) with Salmonella typhimurium strains TA1535, TA1536, TA1537, and TA1538.
- Employed the spot test technique for initial screening and liquid culture incubation for further analysis.
- Assessed forward mutation induction in Streptomyces coelicolor to low streptomycin concentrations.
Main Results:
- Captan and Triallate induced mutations in Salmonella typhimurium TA1535.
- Dichlorvos and Trichlorphon showed mutagenicity in liquid cultures of S. typhimurium TA1535, but not in the spot test.
- Aminotriazole, Dichlorvos, Picloram, Trichlorphon, and Triallate were mutagenic in the S. coelicolor forward-mutation test; Captan showed weak mutagenicity.
Conclusions:
- Several tested pesticides exhibit mutagenic activity in bacterial test systems.
- The choice of assay method (spot test vs. liquid culture) can influence the detection of mutagenicity.
- Findings highlight the need for comprehensive genotoxicity testing of pesticides.