The Montreal Gazette:
MONTREAL – Children exposed to common pesticides used on fruits and vegetables could have a higher risk of attention-deficit/hyperactivity disorder, a new study has found.
The risk is present even at very low exposure, said lead author Maryse Bouchard of the Université de Montréal, a post-doctoral student at Harvard University.
Apart from a handful of studies on the subject that looked at specific groups with high exposure – for example, children of agricultural workers or living near crop fields – there previously was little data about pesticides and children’s health, Bouchard said.
“This is the average American child ... with no particular source of exposure that we know of,” Bouchard said of the study published in the journal Pediatrics Monday.
Bouchard’s findings show exposure is harmful even at levels commonly found in children’s environment.
Children are uniquely sensitive to pesticides – even small amounts can affect brain development. Pound for pound of body weight, infants and children eat, drink and breathe more than adults.
Bouchard and her colleagues looked at a sample of 1,139 children between 8 and 15 years and their measures of urine for metabolites of pesticides known as organophosphates.
The compounds turned up in the urine of 94 per cent of the children.
Those with higher residues of pesticide in their urine were at higher risk of attention-deficit/hyperactivity disorder – for which they were taking medication, Bouchard said.
Parents said their children had learning difficulties and behaviour problems including inattention, hyperactivity, and impulsivity.
The surprise, Bouchard said, was that the effect was noted at really low levels of pesticides.
“They had double the risk compared to those with no detectable levels of pesticide,” Bouchard said.
Organophosphate compounds have been used as insecticides in agriculture and in chemical warfare.
Some pesticides persist in the body. But not organophosphates. These are metabolized and eliminated quickly, which means that if found in urine, exposure had occurred within a few days, explained Robin Walker of the Canadian Institute of Child Health and chair of the pediatric health unit for the Canadian Pediatrics Society.
“That means that the children who had the highest levels probably were ingesting the pesticide in a fairly continuous fashion,” said Walker, who did not participate in the study.
“That’s worrisome. We’re not talking about acute toxicity. We’re much more concerned about the impact on the developing organism of low-level, continuous exposure.”
While earlier studies have shown links between pesticides and a broad range of neurdevelopmental issues, Bouchard’s team honed in on ADHD, behaviour and cognitive function.
The study does not prove pesticides cause ADHD but the link is significant, Walker said.
Also, the study did not determine how children were exposed, but researchers speculate the major source is diet and the environment.
Researchers noted high concentrations of pesticide were previously found in frozen blueberries, strawberries and celery.
Children are smaller, shorter, closer to the ground. Also, they tend to play in grass and dirt, and put toys and hands in their mouths, activities that can significantly increase their exposure to pesticides.
Plus, their bodies are not fully developed and they may not be able to excrete toxins like adults do.
People can limit pesticide exposure by eating organically grown foods, washing fruits and vegetables before eating them and reducing the use of pesticides in their homes and gardens.
The study is further proof that provinces should follow Quebec’s lead in banning lawn and garden pesticides, Walker said.