People who eat organic produce may have lower levels of some pesticides in their bodies than people who eat similar amounts of conventionally grown fruits and veggies, according to a new study.

The study is among the first to predict adult exposures to organophosphate pesticides based on people's usual diets, the researchers said. Organophosphates are the pesticides commonly used on conventionally grown produce.

Scientists studied nearly 4,500 people from six cities in the United States, and collected dietary information, including the types and amounts of produce eaten in the past year and how often participants ate organic foods. The researchers estimated pesticide exposure by comparing typical intake of specific food items with average pesticide residue levels for those items. [9 Snack Foods: Healthy or Not?]

To check their estimates, the scientists compared the calculated pesticide exposures to the levels of breakdown products from pesticides excreted in the urine of a subset of participants.

When matched on produce intake, people who reported eating organic fruits and veggies at least occasionally had significantly lower levels of pesticide residue in their urine than people who almost always ate conventionally grown produce.

Those who "often or always" ate organic fruits and vegetables averaged approximately 65 percent lower levels of pesticide metabolites in their urine than those who "rarely or never" ate organic.

Organophosphate pesticides degrade quickly in the body, so a urine test alone can only detect a person's exposures in the past day or two. But "by combining with information on typical diet, we can begin to estimate a person's long-term exposures," said study author Cynthia Curl, an environmental health scientist at Boise State University in Idaho.

Still, the findings may not represent a person's total exposure to pesticides. While organophosphates are the most commonly used insecticides on conventionally grown fruits and vegetables, the researchers did not estimate exposure to other types of pesticides that could have been applied to the produce.

Compared to guidelines set by the U.S. Environmental Protection Agency, the results of this study "do not suggest unacceptable risk" from organophosphate pesticides, even for people with the highest exposure levels, the researchers wrote in the study.

However, current guidelines were devised in large part to protect farm workers from acute poisoning and may not adequately reflect the risks associated with lower levels of exposure to organophosphate pesticides or to mixtures of pesticides that may be part of the diet. "Researchers are just beginning to understand these risks," Curl said.

Recent studies in mothers and children have suggested that prenatal organophosphate pesticide exposure may be associated with attention problems and developmental delays in children.

The new "research provides another piece of evidence that consumption of organic foods may reduce pesticide exposure," said Jonathan Chevrier, an epidemiologist at McGill University in Montreal, Canada, who was not involved with the study.

Some types of conventionally grown produce are lower in pesticides than others. For those interested in reducing exposure to pesticides, Curl suggested using the Environmental Working Group's "Dirty Dozen" list to see which fruits and vegetables tend to contain more pesticides. "This can help [people] pick and chose when to buy organic," she said.

The findings were published online Feb. 5 in the journal Environmental Health Perspectives.

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