Organic food for thought: lessening children's pesticide exposure. (Science Selections).

Parents concerned about the risk to their children's health posed by eating foods sprayed with organophosphorus (OP) pesticides may want to take note: Cynthia Curl and her colleagues at the University of Washington compared the OP pesticide metabolite levels of 39 Seattle preschool children and found that children who consumed organic fruits, vegetables, and juices had significantly lower OP pesticide exposure than those who consumed conventional foods [EHP 111:377-382]. They also concluded that consumption of organic produce and juice may shift children's OP pesticide exposure from a range of uncertain risk to a range of negligible risk, as defined by the U.S. Environmental Protection Agency's current guidelines. Studies suggest that chronic low-level exposure to OP pesticides may affect neurological functioning, neurodevelopment, and growth in children.

Consumption of produce and juice is possibly one of the main pathways by which children are exposed to pesticide residues. Children's diets often include more of these items than do adult diets. Children also eat more food per body mass than adults.

The scientists recruited families at a local chain supermarket selling mostly conventional products and a consumer cooperative selling mostly organic goods. Children aged 2-5 years were considered eligible for the study if their parents stated that the produce and juice they consumed was nearly all conventional or nearly all organic. Parents were later interviewed in the home about a variety of topics such as income, length of time at their current residence, and housekeeping practices, as well as any recent use of pesticides around the home, which could present an alternative route of exposure in the children (it was subsequently determined not to be a confounding factor). They were also asked how often their children sucked their thumbs, washed their hands, engaged in hand-to-mouth activity, and spent time outdoors. The parents kept food diaries for their children for three days, and collected as much of the urine produced by their children on the third day as they could. Most parents collected nearly all the urine their children produced.

It was rare for a family to eat 100% organically, so a 75% cutoff was employed: 18 children whose juice and produce servings were 75% or more organic were included in the "organic" category, and 21 children whose diets were 75% or more conventional were grouped into the "conventional" category. The children's urine samples were analyzed for five OP pesticide metabolites: dimethylphosphate, dimethylthiophosphate, dimethyldithiophosphate, diethylphosphate, and diethylthiophosphate. These metabolites can be grouped as dimethyl and diethyl metabolites.

The data showed that the median total dimethyl metabolite concentration was approximately six times higher for the children eating conventional diets than for the children eating organic diets. The median total diethyl metabolite concentration was the same across the two groups. Overall, the children eating primarily organic diets had significantly lower OP pesticide metabolite concentrations than did the children eating conventional diets.

This analysis did not allow the researchers to determine exactly which pesticides children were being exposed to. The metabolites measured are generic breakdown products of more than a dozen OP pesticides, and within that group there is more than a 100-fold difference in toxicity. The researchers did, however, calculate some simple dose estimates, and the results of those estimates suggest that consuming organic products may reduce a child's exposure level to below the Environmental Protection Agency's chronic reference doses for various OP pesticides, shifting exposures from a range of uncertain risk to a range of negligible risk.