Studies on the genotoxicity of endosulfan in different tissues of fresh water fish Mystus vittatus using the comet assay.

Endosulfan, a widely used organochlorine pesticide, is readily bio-accumulative in fishes and can be indirectly harmful to human populations. Limited efforts have been made to study long-term genotoxic effects of endosulfan in different tissues of fish using gentoxicity biomarkers. Therefore, the current investigation was undertaken to detect single-cell DNA strand breaks induced by endosulfan in the fresh water teleost fish Mystus vittatus using the comet assay. The LC(50) value of technical grade endosulfan was first determined for the fish species in a semistatic system, and on the basis of the LC(50) value, the sublethal and nonlethal concentrations were determined. The DNA damage was measured in gill, kidney, and erythrocytes as the percentage of DNA in comet tails of fish specimens exposed to the sublethal and nonlethal concentrations of endosulfan. In general, significant effects (p < 0.01) from both concentration and time of exposure were observed in exposed fishes. It was found that all the tissues at all concentrations exhibited the highest DNA damage on day 1, after which there was a nonlinear decline in the percentage of tail DNA. The comparison of DNA damage among the tissues at different concentrations could not show the sensitivity of particular tissue to endosulfan. The current study explored the utility of the comet assay for in vivo laboratory studies using fish species to screen the genotoxic potential of chemical agents.