Earthworm bioassays: Adopting techniques from aquatic toxicity testing

Current theories suggest that the effective concentration of soil contaminants is that fraction that resides in the hydrosphere of soil particles; therefore, parallels may be drawn between toxicity testing in soil, sediment and water. Certain practices and concepts used in aquatic toxicity testing may be adapted into soil toxicity testing procedures and increase the general understanding of the toxicity of soil contaminants. The use of lethality thresholds or incipient lethal levels (ILLs) would increase the accuracy of the estimation of toxicity and kinetics in varying soil types, as well as providing validation for a key bioassay assumption. The use of toxicant kinetics and critical body residues (CBR) in relation to toxicity endpoints may provide a more suitable estimate of toxic dose than the soil concentrations of contaminants, especially for hydrophobic organic chemicals, and also provide a means for both examining the bioavailability of soil contaminants and estimating the influence of modifying factors.