Predicting pesticide mixtures in surface waters from a given crop

Organisms are rarely exposed to single toxicants; the typical situation found in the actual environment is the presence of a multitude of heterogeneous and potentially toxic substances acting simultaneously on natural freshwater ecosystems. This is the case, for instance, of pesticides that are repeatedly applied to the same agricultural areas in order to protect crop productions. As a consequence of drift or runoff processes, many of these may reach water bodies and may simultaneously act as a mixture on aquatic organisms or populations. Within the framework of the EU BEAM project (BEAM: bridging effect assessment of mixtures to ecosystem situations and regulations) this paper outlines the procedures adopted for developing a new methodology in order to define priority lists of pesticide mixtures involving surface water systems at EU level.