Prenatal pesticide exposure linked to high ADHD risk

Exposure of women during pregnancy to organophosphate pesticides increases risk of attention deficit hyperactivity disorder (ADHA) in their children, a new study suggests.

The study published in in the Aug 19 issue of the journal Environmental Health Perspectives found prenatal levels of metabolites of these pesticides were significantly associated with attention problems in children at the age of five years.

For the study, Brenda Eskenazi, University of California - Berkeley professor of epidemiology and of maternal and child health followed more than 300 children enrolled in the Center for the Health Assessment of Mothers and Children of Salinas, which examined environmental pesticide exposures and sexual or reproductive health.

What Brenda Eskenazi and colleagues did was examine the association between the organophosphate pesticides as measured by maternal urinary dialkyl phosphate metabolites during pregnancy and attention-related outcomes among the Mexican-American children at the age of 3.5 years and five years.

The researchers found pesticide exposure during pregnancy was not significantly associated with risk of ADHD in children at the age of 3.5 years while the association was significant when the children grew to the age of five years.

Brenda Eskenazi explained that at the age of 3.5 years, diagnosis of ADHD is not easy, suggesting that prenatal exposure to pesticides can still have an impact on the children's behavior.

Organophosphate pesticides disrupt neurotransmitters, particularly acetylcholine, which plays an critical role in sustaining attention and short-term memory, according to a press release by the University of California - Berkeley.

ADHD may not be the only neurological disorder these pesticides can cause.  Early studies suggest that exposure to organophosphate insecticides may raise risk of neurodegenerative disease like Parkinson disease, according to Kamel F and Hoppin J.A. from the National Institute of Environmental Health Sciences.

In their report published in the June 2004 issue of Environmental Health Perspectives, Kamel and Hoppin urged more research on the relationship of pesticide-related neurotoxicity to neurodegenerative disease.

According to Marc Weisskopf of the Harvard School of Public Health and colleagues,  there are about 40 organophosphate pesticides allowed to be sold in the U.S. and these chemicals are made originally as chemical weapons because of their neurotoxicity.

Dr. Weisskpf et al. published a similar study earlier in Pediatrics saying that exposure to these pesticides may increase risk of attention-deficit/hyperactivity disorder or ADHD in children aged 8 to 15 years.

They found a 10-fold increase in one of the pesticides was linked with 50 percent elevated risk of developing ADHD among other things.