A pesticide once sprayed in homes is leaving its mark on the brain. Researchers at Columbia University’s Mailman School of Public Health, Children’s Hospital Los Angeles, and USC’s Keck School of Medicine report that prenatal exposure to chlorpyrifos was linked to structural brain abnormalities and poorer motor function in 270 New York City children and adolescents.
The findings, published in JAMA Neurology, show dose-dependent disruptions in brain structure, metabolism, and motor control persisting into adolescence.
The study underscores the enduring consequences of exposure to organophosphate pesticides during pregnancy. Chlorpyrifos was widely used in homes until its residential ban in 2001. Agricultural use continues in many places, leaving farm workers, nearby communities, and consumers of nonorganic produce at risk of exposure.
“Current widespread exposures, at levels comparable to those experienced in this sample, continue to place farm workers, pregnant women, and unborn children in harm’s way. It is vitally important that we continue to monitor the levels of exposure in potentially vulnerable populations, especially in pregnant women in agricultural communities, as their infants continue to be at risk,” said Virginia Rauh, ScD, senior author on the study and the Jane and Alan Batkin Professor of Population and Family Health at Columbia Mailman School.
A closer look at the cohort
The children in the study were drawn from the Columbia Center for Children’s Environmental Health birth cohort, which originally enrolled more than 700 pregnant women between 1998 and 2006. The mothers, largely Dominican and African American residents of northern Manhattan and the South Bronx, had umbilical cord or maternal blood samples taken at birth to measure chlorpyrifos levels.
By ages 6 to 14, 270 of their children underwent magnetic resonance imaging and behavioral testing. These assessments provided a detailed window into brain structure, tissue microstructure, blood flow, metabolism, and motor function. Researchers controlled for confounding factors such as child age, sex, race and ethnicity, maternal education, material hardship, and home stress, with sensitivity analyses that also considered air pollution and maternal age.
Brain changes across multiple systems
The findings reveal a striking pattern: the higher the prenatal pesticide exposure, the greater the brain abnormalities observed. Children with higher chlorpyrifos levels had thicker frontal and temporal cortices but reduced white matter volumes beneath them, suggesting disruptions at the gray-white matter boundary.
Microstructural imaging showed altered fiber properties in the internal capsule, a white matter pathway critical for communication between motor regions. Blood flow across the brain was reduced, pointing to impaired metabolism, while spectroscopy revealed lower levels of N-acetyl-aspartate, an index of healthy neuron density.
Functionally, these brain changes translated into measurable deficits. Children exposed to more chlorpyrifos performed worse on fine motor speed and sequencing tasks, with both hands affected but especially the nondominant one.
“The disturbances in brain tissue and metabolism that we observed with prenatal exposure to this one pesticide were remarkably widespread throughout the brain. Other organophosphate pesticides likely produce similar effects, warranting caution to minimize exposures in pregnancy, infancy, and early childhood, when brain development is rapid and especially vulnerable to these toxic chemicals,” said first author Bradley Peterson, MD, Vice Chair for Research and Chief of Child & Adolescent Psychiatry in the Department of Psychiatry at the Keck School of Medicine of USC.
What might be driving these effects
Mechanistically, prior work suggests that oxidative stress and inflammation can impair mitochondria and disrupt maturation of glial cells that insulate nerve fibers. Such processes can alter cortical development and white matter integrity, consistent with the observed pattern of thicker cortex, reduced local white matter volumes, and internal capsule microstructural differences.
Caveats and implications
The authors note several limitations. Because the cohort was drawn from African American and Dominican mothers in New York City, findings may not generalize to all populations. The study did not account for postnatal exposures or genetic factors that influence pesticide metabolism. And as an observational study, it cannot prove causation, only strong associations.
Even so, the dose-response relationship, convergence of signals across multiple imaging modalities, and persistence of effects into adolescence provide strong evidence that chlorpyrifos exposure during pregnancy is linked to lasting brain changes. The results support minimizing pesticide exposures during pregnancy and early life, especially in agricultural communities where exposure risks can be higher.
JAMA Neurology. DOI: 10.1001/jamaneurol.2025.2818
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