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.