ABSTRACT
Little data are available on the occurrence of pesticide transformation products in surface waters overall, however, because transformation products of only 15 pesticides were targeted in the reviewed studies. Agriculture accounts for 75 percent of total pesticide use in the United States and is the primary source of pesticides to surface waters in most areas. To obtain a complete national perspective on pesticides in surface waters, long-term, systematic monitoring studies that target a wide range of pesticides and transformation products must be done. Future pesticide-monitoring efforts will need to respond to changes in the types of pesticides, methods of application, chemical characteristics, and geographic patterns of use. Analytical methods will need to be developed and improved, and different types of monitoring approaches will need to be applied. Little data are available on the effects of observed concentrations of newly used pesticides on aquatic or terrestrial biota.
