Now a new study published in Pediatrics, the journal of the American Academy of Pediatrics, links pesticide use with the rise in ADHD disorders among children. The study's authors examined data on over 1,100 children, and determined that elevated levels of pesticide metabolites in the urine was associated with a diagnosis of ADHD. In fact, children with levels higher than the median of the most commonly detected metabolite (known as dimethyl thiophosphate), were twice as likely to be diagnosed as ADHD compared with children that had undetectable levels of the metabolite. The elevated risk factor remained even after controlling for confounding variables like gender, age, race/ethnicity, poverty/income ratio and others. The pesticides studied belong to a class of compounds known as organophosphates. Time explains:

[Study author Maryse] Bouchard's analysis is the first to home in on organophosphate pesticides as a potential contributor to ADHD in young children. But the author stresses that her study uncovers only an association, not a direct causal link between pesticide exposure and the developmental condition. There is evidence, however, that the mechanism of the link may be worth studying further: organophosphates are known to cause damage to the nerve connections in the brain — that's how they kill agricultural pests, after all. The chemical works by disrupting a specific neurotransmitter, acetylcholinesterase, a defect that has been implicated in children diagnosed with ADHD. In animal models, exposure to the pesticides has resulted in hyperactivity and cognitive deficits as well.