Comparative evaluation of genotoxicity of captan in amphibian larvae (Xenopus laevis and Pleurodeles waltl) using the comet assay and the micronucleus test
Résumé
Captan (N-trichloromethylthio-4-cyclohexene-1,2-dicarboximide) is a fungicide used to inhibit the growth of many types of fungi on plants used as foodstuffs. The toxic and genotoxic potentials of captan were evaluated with the micronucleus test (MNT) and the comet assay (CA) using Xenopus laevis and Pleurodeles waltl larvae. Acute toxicity results showed that captan was toxic to X. laevis larvae exposed to 2 mg to 125 or 62.5 micro g captan/litre, depending on the nature of the water (reconstituted water containing mineral salts or mineral water) and to P. waltl exposed to 2 mg to 125 micro g captan/litre in both types of water. The MNT results obtained in mineral water showed that 62.5 micro g captan/litre was genotoxic to X. laevis but not genotoxic to P. waltl at all concentrations tested. CA established that the genotoxicity of captan to X. laevis and P. waltl larvae depended on the concentration, the exposure times and the comet parameters (tail DNA, TEM, OTM, and TL). The CA and MNT results were compared for their ability to detect DNA damage at the concentrations of captan and the exposure times applied. CA showed captan to be genotoxic from the first day of exposure. In amphibians, CA appears to be a sensitive and suitable method for detecting genotoxicity such as that caused by captan