Potential toxicity and genotoxicity of soils around a high impacted site

The importance of earthworms in testing the adverse effects of chemicals on soil biota has been recognised by various environmental organisations and resulted in a set of standard toxicity tests. Recently, there is growing interest in the use of biomarkers as a new complementary approach providing more information about the stress response of the organisms to pollutants. The aim of the present work was to apply an integrated approach of toxicity tests (mortality and reproduction rates) and genotoxic biomarkers (micronuclei and comet assay) on the bioindicator organism Eisenia foetida in the assessment of arsenic contamination risk around a national high impacted site (Termo-Electric Central, Cerano, Brindisi, Italy). The animals were exposed to soil samples obtained from 20 sites in the area around the Central. The exposure was carried out for two weeks (acute toxicity test) and for four weeks for the reproduction test. The adults were then removed from the soil and the newborns were counted after further 4 weeks. On the adults exposed for 4 weeks micronuclei and comet assay were performed on coelomatic cells. Obtained results excluded the presence of acute toxicity in all the sampled sites but revealed the presence of relevant chronic toxicity in some sites. Micronuclei and comet assay data showed a high significant (P<0.01) correlation with chronic toxicity test and with arsenic concentration in the soil. The study suggests the applicability of the proposed integrated approach of genotoxicity biomarkers and chronic toxicity test in the assessment of arsenic risk contamination in the soil.