Genotoxic effects of nickel, trivalent and hexavalent chromium on the Eisenia fetida earthworm

The aim of this study was to examine genotoxic effects of nickel (Ni = 105 mg kg−1), trivalent and hexavalent chromium (Cr = 491 mg kg−1) on the Eisenia fetida earthworm after 2 and 4 d of exposure to two different spiked soils (an artificial (OECD) and a natural one). DNA damages were evaluated on the earthworm’s cœlomocytes using the comet assay. After an exposure into OECD spiked soils, Ni did not induce genotoxic effect whereas Cr(III) and Cr(VI) revealed to be genotoxic after 2 d of exposure. After 4 d of exposure, only Cr(VI) still induced significant damages. In natural spiked soils, nickel and Cr(III) revealed to be genotoxic after 2 and 4 d of exposure. Concerning Cr(VI) toxicity, all the earthworms died after 1 d of exposure. These results underline the importance to take into account the nature and the speciation of metallic pollutants, although the experiment has been performed on spiked soil with higher bioavailibity than in contaminated natural soil.