Determining exposure dose in soil: the effect of modifying factors on chlorinated benzene toxicity to earthworms

This study describes the comparison of multiple approaches for estimating the median lethal concentration of selected chlorinated benzenes (CBs) from an homologous series yielding acute toxicity to the earthworm Eisenia andrei in Webster soil. The coefficients of variation were significantly lower for solid-phase microextraction (SPME), tissue residue, and hexane-extractable based CB exposure estimates compared to nominal CB exposure estimates. The range of CB exposure estimates based on SPME, tissue residue, or nominal was narrower than lethal concentration exposure estimates based on hexane-extractable CBs. Despite the insignificant difference between the coefficients of variation for SPME and hexane-extractable based measures of CB exposure, the results of this study suggest that the use of SPME based estimates of exposure may improve the accuracy of ecological risk assessment when used an alternative to hexane-extractable (total soil CBs) due to a narrower range of medial lethal concentrations when comparing equipotent compounds.