Prenatal Exposure to Chlorpyrifos Linked to Significant Brain Abnormalities in Children

A major new study published in JAMA Neurology has revealed strong evidence that prenatal exposure to the widely used pesticide chlorpyrifos (CPF) is associated with measurable abnormalities in brain structure, function, and metabolism in children aged 6 to 14 years. The research, based on a longitudinal cohort from northern Manhattan and the South Bronx, analyzed MRI scans and neurodevelopmental outcomes of 270 children whose mothers had documented CPF levels at delivery.

Chlorpyrifos, an organophosphate insecticide still used globally, has long been suspected of affecting early brain development. However, until now, its specific effects on the human brain have not been well characterized. This study provides some of the clearest evidence to date.

Major Findings

Researchers found that higher prenatal chlorpyrifos exposure was consistently associated with:

Thicker frontal, temporal, and posteroinferior cortices
Reduced white matter volumes in the same regions
Altered microstructure of the internal capsule, shown through higher fractional anisotropy and lower diffusivity
Significantly reduced cerebral blood flow across the brain
Lower neuronal density in deep white matter pathways
Poorer fine-motor performance and motor programming skills

These patterns were observed across multiple advanced imaging techniques—including anatomical MRI, diffusion tensor imaging, arterial spin labeling, and MR spectroscopy—making the findings particularly robust.

Study Details

The cohort consisted of children born to Dominican and African American mothers enrolled between 1998 and 2006. CPF levels were measured from umbilical cord or maternal plasma samples. Children underwent MRI scanning starting at age 6, and researchers analyzed structural, metabolic, and functional parameters along with cognitive assessments.

Why This Matters

The findings indicate that chlorpyrifos exposure in the womb may disrupt normal neuronal development by altering the balance between cortical gray matter and white matter, impairing brain metabolism, and affecting microstructural maturation of motor pathways. Behavioral differences were observed primarily in motor coordination tasks, aligning with the imaging abnormalities.

What the Study Doesn’t Do

The authors do not infer causation and do not extend conclusions beyond the data collected. They also did not assess postnatal chlorpyrifos exposure or concurrent exposure to other pesticides.

Conclusion

This landmark study highlights important associations between prenatal chlorpyrifos exposure and detectable abnormalities in childhood brain development. As pesticides continue to be used worldwide, these findings may support future regulatory decisions and reinforce the urgency of minimizing prenatal exposure to neurotoxic chemicals.

Reference

Peterson BS, Delavari S, Bansal R, et al. Brain Abnormalities in Children Exposed Prenatally to the Pesticide Chlorpyrifos. JAMA Neurol. 2025;82(10):1057–1068. doi:10.1001/jamaneurol.2025.2818