Genotoxic and reproductive effects of an industrially contaminated soil on the earthworm Eisenia Fetida

Polluted soil sampled from a former coking plant in Lorraine (France) was studied for its genotoxicity and reproductive effects on the Eisenia fetida earthworm. Genotoxicity was investigated by means of the single-cell gel electrophoresis (comet) assay on the coelomocytes of earthworms after 4 and 10 days of exposure to the soil. DNA damage and a decline in the number of coelomocytes extruded from earthworms were observed at coking plant soil concentrations of 20 and 40% (w/w) in ISO soil. These soil concentrations had previously been shown to significantly reduce cocoon and juvenile productions after 28 and 56 days of earthworm exposure, respectively. The results showed that genotoxic pollutants in the tested soil were still bioavailable despite the age of the contaminated soil. Similar values of the no-observed-effect concentration (NOEC) corresponding to 10% of the contaminated soil and of the lowest soil concentration tested inducing effects (LOEC) corresponding to 20% of the contaminated soil were obtained from reproductive and genotoxicity endpoints. Among the soil pollutants measured, polycyclic aromatic hydrocarbons (PAHs) appeared to be the most likely source of the genotoxicity recorded, although effects of metals could not be excluded. Measurement of genotoxicity in earthworms could complement the existing standardized tests used in the ecotoxicological assessment of the risk associated with contaminated soils.