Harvard University: Pesticide Residues in Urine Linked to ADHD
By Jessica Berman
May 19, 2010
Scientists have found that exposure
to pesticide residues on vegetables and fruit may double a child's risk
of attention deficit hyperactivity disorder (ADHD) a condition that
causes inattention, hyperactivity, impulsivity or a combination of all
three in children.
Maryse Bouchard, Harvard
According to the U.S. Centers for Disease Control and Prevention,
between three and seven percent of school age children in the United
States have ADHD, which makes them impulsive and impairs concentration
in the classroom.
In the study, researchers with the University of Montreal and Harvard
University tested the urine of more than 1,100 children, between the
ages of eight and 15, looking for breakdown products of organophosphate
pesticides. 119 of the children in the study had been diagnosed with
"What we saw was that the higher the level of pesticide residues in the
urine, the higher the risk of ADHD in the children," said Maryse
Bouchard, who led the team of researchers.
Investigators found the risk of ADHD was almost double in youngsters
with higher levels of the most common breakdown metabolite, compared to
children with nearly undetectable levels.
Researchers say 40 organophosphate pesticides are registered with the
Organophosphates are among the most widely used pesticides by growers to
protect fruit and vegetables. Studies have showed that organophosphates
cause hyperactivity and cognitive defects in laboratory animals, as well
as neural changes.
Bouchard, who is with the University of Montreal's Department of
Environmental and Occupational Health, says she is not surprised by the
finding, although she cautions it is too early to draw any firm
"We can't affirm that exposure to pesticides is causing ADHD," she
added. "We would need a different kind of study to say that."
Goldman is with the Department of Environmental Health Sciences at Johns
Hopkins University School of Public Health in Baltimore. Goldman says
the use of pesticides, including organophosphates, is widespread in
developing countries, where children are exposed to high levels of
pesticides through farming.
"Those kids have much more serious, much more severe, neurological
problems," said Goldman. "So, we do see evidence of effects in those
Goldman says studies will probably now be conducted in other nations to
determine how pesticides affect brain development in children.
A 2008 study of produce in the United States found organophosphate
residues in 28 percent of frozen blueberry samples, 25 percent of fresh
strawberry samples and 19 percent of celery samples.
The new study on pesticides and attention deficit hyperactivity disorder
appears in the journal Pediatrics.