Mutagenic and genotoxic effects of carbosulfan in freshwater fish Channa punctatus (Bloch) using micronucleus assay and alkaline single-cell gel electrophoresis

Carbosulfan insecticide is widely used in agriculture and was recently proposed for treatment against pyrethroid-resistant mosquitoes. The mutagenic and genotoxic effect of carbosulfan was carried out in fish Channa punctatus using micronucleus (MN) test and comet assay. The 96 h LC₅₀, estimated by probit analysis in a semi-static bioassay experiment, was 0.268 mg l⁻¹. Based on the LC₅₀ value, three sub-lethal concentrations of carbosulfan (1/4th LC₅₀ = ∼67 μg l⁻¹, 1/2nd LC₅₀ = ∼134 μg l⁻¹ and 3/4th LC₅₀ = ∼201 μg l⁻¹) were selected and fishes were exposed to the said concentrations for 96 h and the samplings were done at regular intervals of 24 h for assessment of the MN frequencies and DNA damage. In general, significant effects (P < 0.01) from both concentrations and time of exposure were observed in exposed fishes. The MN induction was highest on 96 h at all the concentrations in the peripheral blood. Similar trend was observed for the DNA damage measured in terms of the percentage of tail DNA in the erythrocyte and gill cells. This study confirmed that the comet and micronucleus assays are useful tools in determining potential genotoxicity of water pollutants and might be appropriate as a part of monitoring program.