Risk assessment and ecotoxicology: the case of pesticides

The assessment of ecotoxicological risks associated with chemical substances is one of the applications of ecotoxicology. In order to provide decision-makers and managers with the information necessary for a reasoned and objective assessment of the risks associated with the presence in the environment of toxic substances resulting from human activities, it is essential to develop and disseminate validated, effective assessment tools and to expand the available knowledge base through dedicated experiments or field monitoring. Following a brief overview of what pesticides are and a summary of current knowledge on their fate and effects in aquatic environments, we present here the general principles of ecotoxicological risk assessment and its application to pesticides, whether prior to their placing on the market (a priori assessment) or after (a posteriori assessment).