Release of pesticides into the environment and initial concentrations in soil, water, and plants

Considerable information exists as to the initial concentrations of pesticide residues to be expected in soils, plants, and water. Empirical or theoretical models have been developed for incorporating this data into exposure assessments for humans as well as terrestrial and aquatic wildlife. In addition, monitoring data exists for many older products, especially with respect to typical concentrations observed in food commodities for human consumption and in surface and ground waters. Estimated and observed concentrations of pesticides in these matrices have been routinely employed for more than 30 years in assessing the potential impacts of pesticides on a variety of biologically relevant endpoints. The same data will also prove useful for exposure assessments of endocrine active substances. There are some additional research needs, however. First, further research and development is needed to ensure that estimation and monitoring methods for pesticide concentrations in soil, water, and food are applicable and utilized for all important and relevant cultural, agronomic, and environmental conditions. This is especially true with respect to developing countries and tropical climates, which are often disproportionately ignored in favor of developing countries and temperate climates. Second, methodologies for collection of monitoring data and generation of modeled estimates for pesticide residues in soil, water, and food need to be carefully designed with the requirements of higher-tier, probabilistic exposure assessments in view. Although worst-case, point estimates or analyses may be useful for screening-level assessments, advanced assessments targeted at addressing the likelihood of biologically relevant exposures are urgently required by scientists and regulatory authorities for reaching sound risk assessment and management decisions.