ADHD in Children Linked to Pesticide Exposure_Scientific Study

UC study links pesticide exposure to ADHD

Thomas H. Maugh II, Los Angeles Times
Friday, August 20, 2010

A new study from UC Berkeley of children in the Salinas Valley adds to a growing body of evidence suggesting that exposure to organophosphate pesticides is a prime cause of attention deficit hyperactivity disorder.

The study, reported Thursday in the journal Environmental Health Perspectives, examines the effects of both prenatal and childhood exposure to the pesticides, which are widely used in the United States to control insects on food crops.

UC Berkeley epidemiologist Brenda Eskenazi and her colleagues have been studying more than 300 Mexican American children living in the heavily agricultural Salinas Valley.

Because they live in a farming community, the children are more likely than others to be exposed to the pesticides, but the problems resulting from environmental exposure are often first seen in those with the highest exposure.

Eskenazi and her team tested for levels of pesticide metabolites in urine in the mothers twice during their pregnancies and several times in the children after birth.

They then tested the children at ages 3 1/2 years and 5 years for attention disorders and ADHD, using the mothers' reports, performance on standardized computer tests and behavior ratings from examiners.

After correcting the data to account for lead exposure and other confounders, they found that each tenfold increase in pesticide levels in the mothers' urine was associated with a fivefold increase in attention problems as measured by the assays. The effect was more pronounced in boys than in girls.

The study comes three months after a Harvard study, looking at much lower levels of malathion in urine, found that a tenfold increase in pesticide levels was associated with a 55 percent increase in ADHD. The researchers believe that most of the children in the study were exposed to the malathion through food.

"It's known that food is a significant source of pesticide exposure among the general population," Eskenazi said in a statement. "I would recommend thoroughly washing fruits and vegetables before eating them, especially if you are pregnant."

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