Trends in ambient concentrations of agrochemicals in humans and the environment of the United States.
Uses of pesticides and related agrochemicals have been regulated in the United States since 1948. The United States government has supported human and environmental monitoring for pesticides and selected toxic chemicals for the past 15 yr. The initial ambient monitoring systems were designed to determine average concentrations of pesticides and related chemicals in human and environmental media on a nationwide basis and determine changes in these concentrations over time. The results of these surveys showed that almost all of the general human population and various environmental components contained low concentrations of chlorinated pesticides. As the Environmental Protection Agency (EPA) restricted many uses of the chlorinated pesticides, the organophosphorous and carbamate pesticides which replaced them were not as easily monitored by ambient surveys. Special monitoring studies had to be done more frequently to produce data on these compounds which were not as persistent or accumulative in the environment. Currently, a re-evalution has begun to determine pesticide monitoring data needs for the next 5 to 10 yr, modify existing ambient surveys, and plan needed short-term studies to efficiently meet regulatory data needs. Ambient monitoring for trends in chemical levels in humans and the environment will continue in the United States at a reduced level, and many exposure data needs will be met with use-specific monitoring studies.