Life cycle impact assessment of pesticides on human health and ecosystems

The development of methodologies to assess the effects of pesticides in a consistent way and to enable comparison with the impacts from other agricultural practices is urgently needed. This paper describes a life cycle assessment method to determine the impact of pesticides on human health and ecosystems. The approach considers a full-fate analysis and the exposure to toxic pollutants through different media and pathways, including residues in food, based on the behavior of the pesticides in air and the importance of transfers between soil and surface or ground waters. For human toxicity, estimates of pesticide residues show that food intake results in the highest toxic exposure, about 10(3) to 10(5) times higher than that induced by drinking water or inhalation. Better evaluation practices of pesticide residues in food need to be established in priority. For the "no effect concentration (NEC)" used as a reference for both terrestrial and aquatic ecotoxicity, extrapolation methods are developed on the basis of experimental data. Extrapolation coefficients for risk assessment are to be used with caution; an intra-species extrapolation factor of 10 explained the relationship between acute (LC50) and chronic (NOEC) ecotoxicity, whereas it was not suitable for inter-species extrapolation. The method is applied to a case study of five fungicides that have the same function on wheat. Results obtained for the 100 most commonly used pesticides in Switzerland are presented. It is demonstrated that the comparison of pesticides is feasible, the pollution sources of highest concern being identifiable and the best environmental management practices thereby promoted without penalizing the crop itself. (C) 2002 Elsevier Science B.V. All rights reserved.