Pesticides are used on food crops and meat produced from domestic animals. The residues contained within domestically produced food are monitored closely by the EPA, whereas those for imported food are tracked by the Animal and Plant Health Inspection Service (APHIS) of the U.S. Department of Agriculture (USDA). Scientists determine the highest dose of a pesticide that might be ingested by animals (birds and mammals, including humans) to cause adverse health effects but not death; this is called the maximum tolerated dose (MTD). They also determine the no-observable-effect level (NOEL) and identify the amount of pesticides that may be safely consumed by humans, in terms of milligrams per kilogram of body weight, over a seventy-year lifetime. In calculating an acceptable exposure for a pesticide, scientists usually include a safety factor of one hundred below the NOEL, assuming a lifetime of exposure to the pesticide. Such calculations take for granted that a pesticide is applied to all labeled crops, at recommended rates, and that the treated food will be consumed daily for a lifetime. Pesticides that have been demonstrated to cause cancer in laboratory animals are not granted tolerance, or approved for application to food crops, based on legislation from Section 409, the so-called Delaney clause, of the federal Food, Drug and Cosmetic Act.
The Food and Drug Administration (FDA) and USDA, in addition to many states, have monitoring programs for pesticide residues in food. They sample approximately 1 percent of the national food supply. For every pesticide, the FDA conducts a total diet study (a market-based survey) to more accurately assess the exposure of the human population to pesticides. Similar calculations are made for exposure to pesticides that may reach drinking water through percolation into groundwater or runoff into waterways.
These adverse effects of pesticides on humans and wildlife have resulted in research into ways of reducing pesticide use. The most important of these is the concept of integrated pest management (IPM), first introduced in 1959. This combines minimal use of the least harmful pesticides, integrated with biological and cultural methods of minimizing pest losses. It is linked with using pesticides only when threshold levels of pest attacks have been identified. There is also a move toward sustainable agriculture which aims to minimize use of pesticides and fertilizers based on a systems approach. SEE also Agriculture; Bioaccumulation; Carson, Rachel; DDT (Dichloro-diphenyl trichloroethane); Endocrine Disruption; Integrated Pest Management; Persistent Bioaccumulative and Toxic Chemicals (PBTs); Persistent Organic Pollutants (POPs); WAter Pollution.
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U.S. Environmental Protection Agency Web site. "Pesticides." Available from http:// www.epa.gov/pesticides.
Clive A. Edwards
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