Ecotoxicity testing of chemicals with particular reference to pesticides.

Ecotoxicity tests are performed on vertebrates and invertebrates for the environmental risk assessment of pesticides and other chemicals and for a variety of ecotoxicological studies in the laboratory and in the field. Existing practices and strategies in ecotoxicity testing are reviewed, including an account of current requirements of the European Commission for the testing of pesticides and the recent REACH (Registration, Evaluation, Authorisation and Restrictions of Chemicals) proposals for industrial chemicals. Criticisms of existing practices have been made on both scientific and ethical grounds, and these are considered before dealing with the question of possible alternative methods and strategies both for environmental risk assessment and for ecotoxicological studies more generally. New approaches from an ecological point of view are compared with recent developments in laboratory-based methods such as toxicity tests, biomarker assays and bioassays. With regard to the development of new strategies for risk assessment, it is suggested that full consideration should be given to the findings of earlier long-term studies of pollution, which identified mechanisms of action by which environmental chemicals can cause natural populations to decline. Neurotoxicity and endocrine disruption are two cases in point, and biomarker assays for them could have an important role in testing new chemicals suspected of having these properties. In a concluding discussion, possible ways of improving testing protocols are discussed, having regard for current issues in the field of environmental risk assessment as exemplified by the debate over the REACH proposals. The importance of flexibility and the roles of ecologists and ecotoxicologists are stressed in the context of environmental risk assessment.