Children who are regularly consuming pesticide-treated fruits and vegetables, have a higher risk of developing attention-deficit hyperactivity disorder or (ADHD), new studies have indicated.

Even low levels of organochlorine exposure in-utero (while in gestation) have been found linked to the development of ADHD-like behaviour in children. Organophosphates are one of the most widely used pesticides in agriculture.

ADHD was associated with higher levels of intrauterine exposure to polychlorinated biphenyls (PCBs) and p,p’-dichloriphenyl dichloroethylene (a metabolite of the pesticide DDT). Both these pesticides have been banned from production in the United States for decades but they still persist in the environment.

On analysing data obtained from 1,139 children aged between eight to 15 years who took part in the National Health and Nutrition Examination Survey, about 10 percent (119) met the diagnostic criteria for ADHD, according to the study published in Pediatrics journal.

The organophosphate pesticide metabolites were measured in the urine samples of the children. Those children, whose urine showed the highest concentration of these metabolites, were more likely to have been diagnosed with ADHD than those with the lowest concentrations, researchers found.

The data further indicated that the risk of developing ADHD was 10 percent amongst those children with the lowest exposure and 20 percent for those with the highest.

In another study published in April in the American Journal of Epidemiology, it was found that children born to mothers who had exposure to pesticides had a higher risk of developing ADHD-like behaviour. The researchers studied data from children born between 1993 and 1998 to mothers who lived near a polychlorinated biphenyls-contaminated harbour in Massachusetts. The levels of organochlorine pesticides were measured from blood samples in each child’s umbilical cord.

Even though the women had experienced a rather average level of exposure to PCBs, their children were found at a greatest risk of developing ADHD-like behaviour when they reached at the age of eight.

This finding suggested that even low-level pre-natal exposure to these chemicals might raise the risk of ADHD in children, despite the fact that none of the umbilical cord blood tests had revealed excessive exposure to organochlorines, researchers noted.

The connection between childhood exposure to organophosphate pesticides and ADHD has been reported earlier also.