A study published in an online medical journal of my field, Pediatrics, wound up in the headlines recently. “Study Links ADHD in Children to Pesticide Exposure.” Whoa! That sounded like bad news, for sure. With all the efforts to get our kids to eat more fresh fruits and vegetables, were we inadvertently causing another problem? Were parents going to storm my office irritated with conflicting advice — after all, in the last issue of InHealthNW, I wrote about helping kids eat more fresh fruits and veggies? I knew I’d better look into it more. But once again, the study, fetchingly titled “Attention-Deficit/Hyperactivity Disorder and Urinary Metabolites of Organophosphate Pesticides,” didn’t exactly show what the headlines proposed.
To summarize the actual study: A group of researchers in the field of environmental health, neurology and pediatrics in the United States and Canada attempted to see if there was a link between pesticide exposure and attention deficit hyperactivity disorder in children. To do this, they accessed a very good database of participants from the National Health and Nutrition Examination Survey (2000-04). This allowed them to evaluate an excellent cross section of American children. From this group they analyzed the data for 1,139 children ages 8-15, for whom they had data regarding ADHD diagnosis and urine metabolite levels for six common classes of pesticides. They also looked at the results of a phone interview attempting to diagnose ADHD which detected 119 kids who met criteria for one of three varieties of ADHD — 69 were of the inattentive variety, 21 hyperactive/impulsive and 29 exhibited a combination of symptoms.
The researchers then looked at levels of pesticide metabolites in the urine of these children to see if there was a correlation between higher levels and the various types of ADHD. The results seemed to indicate that kids with the highest levels of pesticide residue — about 10 times of the levels of kids in the low-residue group — were 55 percent more likely to exhibit ADHD of the hyperactive variety. By the way, kids with low-levels of pesticide residue were no more likely to exhibit ADHD than kids with no residue. And there was no association with the other two types of ADHD.
Reason enough to switch to organic produce? Not at all. This was a very small study — just 21 kids in the group that showed an association. The correlation between ADHD and urine metabolites was a very small one that was only revealed after some pretty hard-core statistical slicing and dicing of data — never mind the fact that a single phone interview is not a generally accepted way to diagnose ADHD. Or that a single urine sample of metabolites is hard-pressed to establish anything, particularly given the fact that these metabolites are completely cleared by the urine within six hours.
I’ll be very angry if a child misses a serving of fruits or vegetables because their parents can’t afford or do not have access to organic produce. If the consumer takes away the message that fruits and vegetables should be washed thoroughly before consuming, then fine. This study will no doubt lead to more research into the issues and could possibly even lead to a change in the way produce is distributed — perhaps giving it all an extra wash before it is sold. My point is that consumers of mass media, particularly those using the Internet, need to be careful about what influences their actions.
Matt Thompson is a pediatrician at the Kids Clinic in Spokane.