June 25, 2010

Do Pesticides and Allergens Cause ADHD?

By Mary Beth Sammons

In the United States alone, an estimated 4.5 million children ages 5 to 17 have been diagnosed with attention deficit hyperactivity disorder, according to the Centers for Disease Control and Prevention, and rates of diagnosis have risen 3 percent a year between 1997 and 2006. Yet it is unclear what is causing this increase. New research is investigating many avenues. One of them is environmental factors such as pesticides and allergens.

In a study published in the journal Pediatrics, researchers studied 1,139 children ages 8 to 15. All of the children studied had measurable residue of pesticides commonly used on fruits and vegetables. Diet is a major source of pesticide exposure in children, according to the National Academy of Sciences, and much of this exposure comes from the common kid-friendly fruits and vegetables, such as blueberries, strawberries and celery. In a 2008 government report, detectable concentrations of malathion (a pesticide commonly used in agriculture, residential landscaping and mosquito abatement) were found in 28 percent of frozen blueberry samples, 25 percent of fresh strawberry samples and 19 percent of celery samples.

In the Pediatrics study, researchers found that for every tenfold increase in the urinary concentration of pesticide residue, there was a 35 percent increase in the chance that the child would develop ADHD. The effect was seen even in kids who had a very low level of detectable, above-average pesticide residue.

Unlike other studies of pesticidal impact, this one looked at the average exposure to pesticides in the general population of children and not at a specialized group such as children who live on farms, according to lead author Maryse Bouchard of the University of Montreal.

Because certain pesticides leave the body after three to six days, the presence of residue shows that exposure is likely constant, Bouchard said. The study found that children with the kind of metabolites left in the body after malathion exposure were 55 percent more likely to be diagnosed with ADHD. Almost universally, the study found detectable levels: The compounds turned up in the urine of 94 percent of the children. Children may be especially prone to the health risks of pesticides because they're still growing and may consume more pesticide residue than adults, relative to their body weight.

More research is needed to confirm the findings, says Bouchard. But the take-home message for parents, she says, is to give kids organic produce as much as you can and to wash fresh fruits and vegetables -- organic or not -- thoroughly.

An unpublished 2008 study out of Emory University found that in children who switched to organically grown fruits and vegetables, urine levels of pesticide compounds dropped to undetectable or close to undetectable levels.

Denver immunologist Dr. Isaac Melamed is studying another effect that may contribute to ADHD: the inflammation caused by all allergies including food, pollen and dust. In his unpublished study, he found that the inflammation caused by an allergic reaction may contribute to ADHD. Therefore, he says, by controlling a child's exposure to allergens, parents may be able to better control ADHD. Melamed says that although much more study needs to be done on this, in his private practice, he has controlled his patients' ADHD by limiting allergic triggers.

Remember that all of this research is in the very early stages and needs to be studied more thoroughly before it can be confirmed.

-http://www.aolhealth.com/condition-center/adhd/pesticides-allergens?