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Pesticides and ADHD: Study fails to establish a causal link

As if it weren’t bad enough that farmers are accused of causing all manner of environmental ills while providing the U.S. with the most abundant and cheapest food on the planet, now the anti-pesticide contingent wants to make them responsible for kids having ADHD.

They’re making media hay with the study by a team of scientists at the University of Montreal and Harvard, who say their findings, published in the journal Pediatrics, show an association between exposure to organophosphate pesticides and attention deficit hyperactivity disorder.

The researchers, who studied 1,139 children 8 years to 15 years of age, representative of the general population in the U.S. and Canada, say their findings show that children with higher urinary levels of organophosphate metabolites were more likely to meet the diagnostic criteria for ADHD.

According to the National Institutes of Mental Health, ADHD, is one of the most common mental disorders of children. The Centers for Disease Control and Prevention estimates 4.5 million children ages 5 to 17 have been diagnosed and the number has been increasing at 3 percent per year.

Children with the disorder have impaired functioning in multiple settings, including home and school, and in relationships with peers. If untreated, the disorder can have long-term adverse effects into adolescence and adulthood.

Scientists have been puzzled by the causes of ADHD. Some studies have suggested that genes play a large role. Like many other illnesses, scientists say, the disorder probably results from a combination of factors. In addition to genetics, they have looked at possible environmental factors, and are studying how brain injuries, nutrition, and the social environment might contribute to ADHD.

While most of the mainstream media and the anti-ag/anti-pesticide groups played up the story, most did not mention that the study’s leader, Maryse Bouchard of the University of Montreal, emphasized that the findings show only an association — not a direct causal link to pesticide exposure.

In other words, a correlation between pesticide exposure and ADHD doesn’t prove that pesticides are a factor in causing the disorder. And nobody’s going to feed pesticides to kids in controlled tests to try and prove it or disprove it.

“ADHD is a serious disorder that affects many families,” CropLife America, which represents the crop protection industry, said in a statement, “but our review of the Pediatrics story leads us to believe much more research is needed to ascertain if there is a direct link between exposure to organophosphate pesticides and the development of ADHD in children. All crop protection products are extensively reviewed by regulatory agencies before approval for market use.”

Anti-pesticide groups have jumped on the study as another call to move to organic agriculture, asserting anew that organic food is higher in nutrients and safer than conventionally-produced food and that the government should encourage farmers to switch to organic methods — a totally unworkable solution in terms of feeding a burgeoning world population


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