Earthworm toxicology: From acute to chronic tests

The International Workshop on Earthworm Ecotoxicology (1991) offered the opportunity to synthesize the state of the art about the standardization of (eco)toxicological tests. It showed the need to improve the standardization of laboratory tests, especially for chronic assays. Such chronic tests need to avoid, or at least limit, the artefacts resulting from interferences between soil components (e.g. organic matter, sand, kaolinite, levilite), earthworm food, soil microorganisms and the chemical tested. The effects of test medium variables, especially pH changes and ionizable chemicals, are also crucial considerations. In order to ensure the goals of standardization and reproducibility for chronic tests, then one must provide an easy to prepare synthetic substrate and provide food in a non-aseptic environment using non-axenic earthworms. This paper deals with these improvements and describes a new synthetic medium, the procedure to make chronic tests and the monitoring of changes resulting from interferences due to the medium and chemicals.