Pesticides and Attention-Deficit/Hyperactivity Disorder

Results from a cross-sectional study support an association between organophosphate exposure in children and ADHD but cannot confirm causality.

Children are exposed to organophosphate pesticides primarily in food and drinking water. These pesticides might be particularly toxic to developing brains. Using data derived from a national health survey, investigators assessed the relation between exposure to organophosphates and development of attention-deficit/hyperactivity disorder (ADHD). Exposure was determined from one urinary sample, and ADHD was diagnosed by structured parent interview.

Among the 1139 children (age range, 8–15 years), 119 were diagnosed with ADHD. Most children (94%) had detectable levels of at least one of six urinary metabolites of organophosphates. The association between total exposure to organophosphates (total urinary metabolite concentrations) and ADHD approached statistical significance (adjusted odds ratio, 1.21; 95% confidence interval, 0.97–1.51). Exposure to a group of three related metabolites was significantly associated with ADHD (AOR, 1.55). In an analysis restricted to the most commonly detected metabolite, children with levels above the median detectable concentration were significantly more likely to have ADHD than children with levels below the detection limit (AOR, 1.93).

Comment: The authors note a number of study limitations, including assessment of exposure from a single urine sample and the possibility that children with ADHD engage in behaviors that expose them to higher levels of organophosphates. In addition, although a structured parental interview was used to make the diagnosis of ADHD, information from other sources was not available. These results are likely to fuel concern that exposure to pesticides adversely affects development in children. However, causality cannot be confirmed with this type of study design.

— Howard Bauchner, MD

Published in Journal Watch Pediatrics and Adolescent Medicine June 2, 2010

Citation(s):

Bouchard MF et al. Attention-deficit/hyperactivity disorder and urinary metabolites of organophosphate pesticides. Pediatrics 2010 Jun; 125:e1270. (http://dx.doi.org/10.1542/peds.2009-3058)

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