Growing public concern for pesticide residues in drinking water has resulted in tighter federal and state regulations to prevent ground-water contamination. There are many uncertainties in estimating human exposure risk, yet standards are being set to protect human health. In the last several years, drinking water health standards have been developed for a number of pesticides, often at levels of a few μg L−1 or less. Ground-water monitoring studies, first required by the U.S. Environmental Protection Agency in 1984, have now become an integral requirement to support registration of pesticides shown to have leaching potential. Regulators are now faced with deciding the extent to which pesticides can still be used while continuing to meet legal requirements to protect the public and preserve ground-water resources. The implications are that pesticide use may be severely limited in regions with ground-water resources considered especially vulnerable to contamination, dramatically affecting the type of agricultural practices and crops grown in these regions.
