Study Links Common Pesticide with ADHD in Boys
New research indicates that exposure to common, supposedly “safe” pesticides called pyrethroids, may increase the risk that young boys may be diagnosed with attention deficit hyperactivity disorder (ADHD). That’s disappointing, because these pesticides have been promoted as safer alternatives to older, still-more-dangerous pesticides, such as organophosphates. In particular, say researchers, exposure to pyrethroids was linked to increases in hyperactivity and impulsiveness, rather than inattentiveness.
Researchers at Cincinnati Children's Hospital Medical Center published their findings recently in the online journal Environmental Health. "Given the growing use of pyrethroid pesticides and the perception that they may represent a safe alternative, our findings may be of considerable public health importance," says Tanya Froehlich, MD, a developmental pediatrician at Cincinnati Children's and the study's corresponding author.
Older organophosphate pesticides were finally banned by the Environmental Protection Agency (EPA) for home use in 2000-2001. That step was welcomed, but it has led to increased use of ostensibly safer pyrethroid pesticides. Although pyrethroids are not as acutely toxic as organophosphates, many scientists have expressed concern about their apparent effects on the brain. Specifically, animal research has shown that exposure to pyrethroids affects the production of the brain messenger chemical, dopamine. Among other things, dopamine is believed to play an important role in behaviors associated with ADHD.
Researchers looked at a compound called 3-PBA in a single urine specimen obtained from subjects. 3-PBA is a biomarker that indicates previous exposure to pyrethroids. Boys with this biomarker were three times more likely to have ADHD compared to boys without the chemical. Hyperactivity and impulsivity both increased by 50 percent for every 10-fold increase in the marker chemical among boys.
“We found an association between increasing pyrethroid pesticide exposure and ADHD,” wrote researchers, “which may be stronger for hyperactive-impulsive symptoms compared to inattention and in boys compared to girls. Given the growing use of pyrethroid pesticides, these results may be of considerable public health import.”
Melissa Wagner-Schuman, Jason R Richardson, Peggy Auinger, Joseph M Braun, Bruce P Lanphear, Jeffery N Epstein, Kimberly Yolton, Tanya E Froehlich. Association of pyrethroid pesticide exposure with attention-deficit/hyperactivity disorder in a nationally representative sample of U.S. children. Environmental Health, 2015; 14 (1) DOI: 10.1186/s12940-015-0030-y