Thursday, August 19, 2010

ADHD Linked to Pesticide Exposure

No, this post isn't directly about birth, but I believe it's important to spread the word about a new study in the journal Pediatrics: Attention-Deficit/Hyperactivity Disorder and Urinary Metabolites of Organophosphate Pesticides. The most heavily used pesticide in the United States is an oraganophosphate, and it is rated for use at schools and on playgrounds. Organophosphate pesticides are also commonly used on fruits and vegetables. 

I highly encourage you to check out the study for yourself; the entire text is availabe for free at the link above.  Here's the meat of it:

Methods Cross-sectional data from the National Health and Nutrition Examination Survey (2000–2004) were available for 1139 children, who were representative of the general US population. A structured interview with a parent was used to ascertain ADHD diagnostic status, on the basis of slightly modified criteria from the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition.

Results One hundred nineteen children met the diagnostic criteria for ADHD. Children with higher urinary dialkyl phosphate concentrations, especially dimethyl alkylphosphate (DMAP) concentrations, were more likely to be diagnosed as having ADHD. A 10-fold increase in DMAP concentration was associated with an odds ratio of 1.55 (95% confidence interval: 1.14–2.10), with adjustment for gender, age, race/ethnicity, poverty/income ratio, fasting duration, and urinary creatinine concentration. For the most-commonly detected DMAP metabolite, dimethyl thiophosphate, children with levels higher than the median of detectable concentrations had twice the odds of ADHD (adjusted odds ratio: 1.93 [95% confidence interval: 1.23–3.02]), compared with children with undetectable levels.

Conclusions These findings support the hypothesis that organophosphate exposure, at levels common among US children, may contribute to ADHD prevalence. Prospective studies are needed to establish whether this association is causal.
In case you're wondering about organophosphates, Wikipedia has a good article that offers more information. Even better is this factsheet on the National Resources Defence Council's website:

"Almost 25,000 of these incidents [acute poisoning] involved children under 6, who are particularly vulnerable to organophosphate poisoning, and at least 482 resulted in hospitalization.

More alarming, studies in animals now show that even a single, low-level exposure to certain organophosphates, during particular times of early brain development, can cause permanent changes in brain chemistry as well as changes in behavior, like hyperactivity. Chlorpyrifos (the chemical in the insecticide Dursban), for example, decreases the synthesis of DNA in the developing brain, leading to drops in the number of brain cells. If these findings pertain to humans, it may mean that early childhood exposures to chlorpyrifos can lead to lasting effects on learning, attention, and behavior -- just as were seen with another environmental neurotoxin, lead.

Even with these factors in mind, many people may not consider organophosphate poisoning a serious worry, assuming they can avoid exposing their children to these chemicals by keeping them away from the lawn and garden after insecticides have been applied. But in addition to outdoor exposure, people, children included, also receive exposure to organophosphate and carbamate insecticides indoors and through food."
This factsheet goes on to discuss indoor exposure and offers a list of fruits and vegetables that are commonly treated with organophosphate pesticides.

Finally, with all this in mind, you may be interested in the list the Environmental Working Group (EWG) has compiled of The Dirty Dozen and The Clean Fifteen to help you prioritize which fruits and vegetables to buy organic.

Christina @ Birthing Your Baby
Independent Childbirth Classes for Central Maine
Mamas & Muffins: New Moms Group

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