If illegal pesticides or pesticide residues above the tolerances are found, the FDA and USDA may remove the contaminated food from the market. The FDA and USDA test thousands of samples of domestic and imported raw produce, meats, and poultry each year for the presence of pesticides. The FDA also tests for pesticide residues in prepared foods using a Market Basket or Total Diet Study. Pesticide residue levels are highest following the last application before harvest. Sun, rain, the passage of time, and preparation techniques, including washing and cooking, all substantially decrease residue levels.
Pesticides are by definition poisonous to some type of organism.
They may also be toxic to humans in high enough concentrations. As with most substances, including medicines, vitamins, and even salt and spices, the level of exposure determines whether the pesticide is beneficial or harmful. For example, while small amounts of vitamin A are essential for good health, large doses can be fatal. The same is true of pesticides. The labels of all pesticides registered by the EPA carry detailed instructions for use.