Genotoxicity evaluation of chlorpyrifos to amphibian Chinese toad (Amphibian: Anura) by Comet assay and Micronucleus test.

In the present study, the genotoxicity of chlorpyrifos was evaluated in the Chinese toad by using Comet assay and Micronucleus test (MN), as the potential tools for the assessment of genotoxicity. The first step was determined by the acute toxicity of chlorpyrifos. Tadpoles were exposed to the series of relatively high concentrations of chlorpyrifos for 96 h. LC(50) values at 24, 48, 72, and 96 h were 3.63, 1.17, 0.82, and 0.80 mgl(-1), respectively. Secondly, the Micronucleus test was used for detecting chromosome damage in Chinese toad tadpoles exposed to the sublethal concentrations of chlorpyrifos and methyl methane sulfonate (MMS), which indicated that they induced chromosomal lesion in erythrocytes of Bufo bufo gargarizans tadpoles. Thirdly, the significant (P < 0.05 concentration-dependent increase in DNA damage (as indicated by Tail DNA%, Tail length, Olive tail moment)) were observed in erythrocytes and liver cells of tadpoles exposed to the sublethal concentrations of chlorpyrifos and MMS by Comet assay. To our knowledge, this is the first report to describe the use of B. bufo gargarizans for genotoxicity assessment of chlorpyrifos.