The residue of certain pesticides found on fresh produce in the United States and Canada increase the odds of children developing attention deficit/hyperactivity disorder (ADHD) by 35 percent, according to a recently released study.
About 4.5 million children, ages 5 to 17, have been diagnosed with ADHD, according to the Centers for Disease Control and Prevention, and rates of diagnosis have risen by 3 percent a year between 1997 and 2006. The prevalence of medication treatment for ADHD is highest among children aged 9 to 12.
Exposure to the pesticides, organophosphates, has been linked to behavioral and cognitive problems in children in the past, but previous studies have focused on communities of farm workers and other high-risk populations, according to CNN.com.
Led by Maryse Bouchard in Montreal, researchers based at the University of Montreal and Harvard analyzed the levels of pesticide residue in the urine of more than 1,100 children ages 8 to 15 and found that those with the highest level of dialkyl phosphates, which are breakdown products of organophosphate pesticides, had the highest incidence of ADHD, according to Time.
Further, the study revealed that exposure, even at the low end, meant that children were twice as likely as those with undetectable levels to show symptoms of ADHD. Bouchard said she was surprised "to see an effect at lower levels of exposure.''
Until the recent findings, the causes and risks factors for developing ADHD were unknown, according to the CDC. But researchers said genetics might play an important role. Besides genetics, scientists are studying other possible causes, including brain injury, environmental exposure, such as lead alcohol and tobacco use during pregnancy; premature delivery and low birth weight.
Determining whether a child has ADHD is a multistep process, but signs and symptoms include daydreaming, not listening, easily distracted, forgetful, squirming or fidgeting, talking too much, and acting and speaking without listening.
The researchers of the pesticide study called for additional studies to determine the method and levels of exposure on commercial produce. Until then, they urged parents to feed their children organically grown fruits and vegetables. If not, parents should use a vegetable brush to reduce residue, according to the Time article.