A METHOD FOR ASSESSING SUBLETHAL EFFECTS OF CONTAMINANTS IN SOILS TO THE EARTHWORM, EISENIA-FOETIDA

We developed and tested a procedure that allows quantification of the effects of soil contaminants on earthworm (Eisenia foetida) growth and reproduction. The procedure monitors isolated pairs of earthworms and generates a higher ratio of data per organism than other commonly use d procedures. It also incorporates an accurate technique for measuring adult growth, has high sensitivity compared to the Organization for E conomic Cooperation and Development (OECD) 14-d acute toxicity test, a nd is cost effective. We applied the method to a variety of soil-testi ng problems. A food-and-substrate trial using artificial soil demonstr ated the sensitivity of the method and the need for food supplementati on to stimulate earthworm reproduction. Application of the procedure t o assess efficacy of a soil bioremediation technology revealed the adv antage of measuring both growth and reproduction and highlighted the u sefulness of a single integrated measure of these two responses. The m ethod also was used as a fast-screening analysis for field soils in a large-scale ecological risk assessment. Finally, a reference toxicant, used in dilution series, demonstrated that responses of E. foetida us ing our method were similar to their responses in the OECD artificial- soil test method. The results of this study indicate that this procedu re can be used both for regulatory and compliance needs within the fra mework of ecological risk assessment.