For the past several decades, as hundreds of thousands of children have been diagnosed with attention deficit/hyperactivity disorder (ADHD) and prescribed medicines to treat it, doctors, researchers, and concerned parents have been trying to figure out why.
Some blamed the disorder’s rise on over-diagnosis, saying that doctors were too quick to write off normal amounts of youthful energy as a disorder. Others pointed the finger at vaccines, refusing to vaccinate their children for fear of burdening them with a disorder down the line. But a new study, written about in Time today, says that pesticides may have played a major role in causing ADHD among 4.5 million children in the U.S. ages 5 to 17.
A team of researchers from University of Montreal and Harvard University tested the urine of 1,100 children ages 8 to 15 to analyze the levels of pesticide residue. The results were unsettling: those with the highest levels of dialkyl phosphates (a breakdown product of pesticides called organophosphates) had the highest incidence of ADHD. With each tenfold increase in urinary concentration of pesticides, the odds of developing ADHD raised 35 percent. And kids with urine samples high in pesticide residues weren’t the only ones affected; kids with low levels of pesticides in their urine were twice as likely to reveal symptoms of a learning disorder as those with undetectable levels.