Editors' ChoiceNEUROTOXICITY

Pesticides Perturb Prenatal Brain

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Science Translational Medicine  30 May 2012:
Vol. 4, Issue 136, pp. 136ec95
DOI: 10.1126/scitranslmed.3004352

Pesticides protect your food from bugs, but they may be damaging to the fetal human brain. Chlorpyrifos (CPF), for instance, is a broad-spectrum organophosphate insecticide that has been in use since 1965 and has been linked to neurodevelopmental and behavioral alterations in animals. CPF readily crosses the placenta, and its toxicity is thought to result from inhibiting cholinesterase, an enzyme involved in the metabolism of neurotransmitters. Yet, the specific effects of CPF on the human brain remain unclear. In order to better understand this, Rauh and colleagues used magnetic resonance imaging (MRI) to look at the brains of children exposed to CPF before birth.

The authors studied children, 5 to 11 years of age, who either had “low” or “high” levels of prenatal CPF exposure as measured in umbilical cord blood collected at the time of delivery. The “high” CPF group was defined as those children with exposure in the upper 25% of the study population, and the “low” CPF group was below this threshold. Using MRI, Rauh et al. found that the brain appeared differently in children with higher levels of exposure. These abnormalities included enlargement of several structures involved in critical cognitive and behavioral processes, decreased IQ scores in children demonstrating enlargement of specific regions of the brain, and loss of normal gender-specific structural differences in brain morphology. Several studies have attempted to examine what level of CPF exposure is considered “safe” and not likely to cause deleterious health problems. All 40 children in the study, including those deemed to have high levels of in utero CPF exposure, had CPF contact as a result of routine daily living in an urban environment. Their blood levels were comparable with what has been reported as background rates in presumed healthy individuals. The results from Rauh et al. suggest that even routine exposure to CPF may be toxic for the developing brain, and the damaging effects are long-lasting, extending into at least early adolescence. Although larger prospective, comprehensive studies are needed to fully understand the relationship between CPF and neurotoxicity, avoiding pesticides might be a safe bet for pregnant women.

V. A. Raugh et al., Brain anomalies in children prenatally exposed to a common organophosphate pesticide. Proc. Natl. Acad. Sci. U.S.A. 109, 7871–7876 (2012). [Abstract]

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