Validation of avoidance assays for the screening assessment of soils under different anthropogenic disturbances.

A chemical characterization of the soil compartment per se does not supply any information about the synergistic/antagonistic effects of mixtures of chemicals, resulting in an under- or overestimation of the risks. Therefore the existence of rapid and ecologically relevant toxicity assays becomes of paramount importance, allowing the evaluation of invertebrate's behavioural parameters with equal consequences in terms of functionality of the edaphic community. The aim of this study was to evaluate the sensitivity of avoidance assays, with the earthworm Eisenia andrei, in discriminating natural soils under different anthropogenic disturbances. Although earthworms were able to discriminate soils with similar contamination, it is nonetheless questionable whether the preference for some soils is determined by the reduced bioavailability of contaminants, the great affinity of the species for organic matter-rich soils, or the inability of chemoreceptors to detect some contaminants from complex environmental mixtures, usually present in natural contaminated soils.