Distinctive fingerprints of genotoxicity induced by As, Cr, Cd, and Ni in a freshwater fish.

Genotoxicity of three toxic elements (chromium, cadmium, nickel) and a metalloid (arsenic) has been studied in a freshwater fish, Channa punctatus using micronuclei (MN) test, comet assay, and erythrocyte nuclear alterations (ENAs) as fingerprints of genotoxicity. These tests yielded different results suggesting involvement of different mechanisms for their genotoxicity. While highest frequency of blebbed nuclei was observed in chromium-treated fish (6.5 ± 0.76), lowest was observed in cadmium-treated fish (4.0 ± 1.0). Maximum number of notched nuclei was recorded in arsenic-treated fish (5.5 ± 1.15) whereas highest numbers of lobed nuclei were found in cadmium-treated fish (4.5 ± 0.13). These differences might be attributed to selective bioaccumulation and chemodynamics of each element. Other parameters used to determine genotoxicity viz.: lipid peroxidation and DNA damage also suggested different mechanisms of their genotoxicity. It is suggested that an integrative approach, using a battery of tests for determining genotoxicity, should be made while making environmental health risk assessment and ecotoxicological studies of these toxic elements.