ADHD (Attention-deficit/hyperactivity disorder) - A common neurodevelopmental disorder in children and adolescents. Frequently diagnosed in children with academic underachievement or behavioral problems.


Hallmarks are hyperactivity, impulsivity, and inattention that are beyond normal developmental expectations for a child’s age. Core symptoms interfere with attainment of many normal developmental milestones (academic, fine-motor, and social and adaptive skills).

Despite considerable research there is no scientific consensus about what causes Attention Deficit/Hyperactivity Disorder (ADHD). Some factors commonly considered include heredity and links with environmental exposures such as cigarette smoke, alcohol, drug use, lead and certain brain injuries. A few studies have also suggested links between ADHD and exposures to various pesticides. One ongoing study by Columbia University researchers has suggested that chlorpyrifos-specific prenatal exposures may contribute to ADHD in some way. However, inherent limitations in study design and exposure assessment limit the confidence that can be placed on these findings. The weight of the evidence demonstrates no link between chlorpyrifos and ADHD, and no data exist to substantiate such a claim.

Further Resources

“A Closer Look at Chlorpyrifos and Brain Scans”, Dow AgroSciences, 2012.

Li, A.A., et al., “Evaluation of epidemiology and animal data for risk assessment: chlorpyrifos developmental neurobehavioral outcomes.” Journal of Toxicology and Environmental Health, Part B Critical Reviews, 2012, Volume 15(2):109-184.

American Academy of Pediatrics: