Proposed Policy for Differentiated Hazard Evaluation of Pesticides in Surface211 Waters: Exposure Concentrations Simulated by TOXSWA and Ecotoxicological Hazards 211 of Pesticides in Field Ditches and Main Watercourses

摘要

The consequences of a proposed new policy concerning pesticides in surface water211u001ewere explored. In small watercourses, the water quality standards defined in the 211u001eUniform Principles (UP) are allowed to be temporarily exceeded, provided that the 211u001eaquatic ecosystem recovers within a few months. In the main watercourses, the UP 211u001estandards will be strictly upheld. Exposure concentrations in a small and a main 211u001ewatercourse were calculated with the TOXSWA model for a designed standardized 211u001epolder. These concentrations were compared with the ecotoxicolgical standards for 211u001ethe three standard aquatic test organisms. It was found that at present about 30% 211u001eof the authorized pesticides in the Netherlands comply with the UP standards. 211u001eImplementation of the new policy, including an application-free zone of 6 m along 211u001emain watercourses, would raise this number to about 50%.