On the heels of last week's strong report from pediatricians highlighting the harms pesticides can cause children's developing minds, a new study finds that pesticides are clearly harming adult brains, too.
In the "meta-analysis" published in Critical Reviews in Toxicology, scientists reviewed 14 separate studies of neurobehavioral changes linked to low-level organophosphate (OP) pesticide exposure. They found that workers exposed to OPs — particularly over long periods of time — had reduced working memory and were slower to process information.
Researchers chose the studies carefully since — as they note — findings on the effects of low-dose exposures are often considered "controversial." They included only those with control group comparisons, and only those that used psychomotor tests (more accurate than interviews) to evaluate impacts.
From fruit tree sprayers in New Jersey to greenhouse workers in Spain to sheep dippers in the UK, farmers, farmworkers and pesticide applicators exposed to OPs over long periods showed a range of neurological harms. Problems ranged from reduced reaction time and fine motor control to memory, attention and visuospatial deficits. Anxiety and emotional difficulties were often documented too.
The longer the period of exposure, the more likely brain function is affected. Greenhouse workers exposed for more than 10 years and sheep dippers with 14 years of exposure were most likely to be impaired.
Given the low-level dietary exposure we all experience over a lifetime, these findings are cause for real concern. Tests from the Center for Disease Control show, for example, that more than 93% of the U.S. population has breakdown products of the OP insecticide chlorpyrifos in our bodies.
The researchers specifically excluded studies looking at children since:
Children may be particularly susceptible to the effects of toxic substances because of their developing nervous system and lower capacity to detoxify specific OP compounds.
And they didn't want to skew the results. Plus, the impact of pesticides on children's brains and nervous systems has already been pretty darn well documented. Last month, PAN released A Generation in Jeopardy rounding up just this body of evidence.
And in last week's comprehensive review of pesticides' impacts on kids health by the American Academy of Pediatrics, findings were so strong that the doctors' group was compelled to release a set of urgent policy recommendations calling for government action (and pediatrician engagement) to reduce children's exposure.
Turns out, neurotoxicants are bad for brains, young and old alike.