Concentrations of two organophosphate pesticides -- malathion and chlorpyrifos -- declined substantially in the bodies of elementary school-age children during a five-day period when organic foods were substituted for conventional foods.

The findings suggest that children are exposed to organophosphate chemicals mainly through food, not through spraying in homes or other sources. In 2001, the U.S. Environmental Protection Agency banned most residential uses of chlorpyrifos but has left most agricultural uses unrestricted. Three other organophosphate pesticides that are not widely used on farms and are more highly restricted by the EPA were undetectable in most of the children, according to the study, directed by Emory's Chensheng Lu.

Organic foods can be expensive and sometimes difficult to find. But parents can minimize their children's exposure if they substitute organic products for those that contain the most residue. Experts advise parents to wash produce and peel skins if they buy conventional foods, but for foods that cannot be peeled, such as grapes and strawberries, organic may be a wise choice.