Prenatal pesticide exposure linked to brain abnormalities

Researchers from the Columbia University Mailman School of Public Health, Children’s Hospital Los Angeles and the Keck School of Medicine of USC have reported a link between prenatal exposure to the widely used insecticide chlorpyrifos (CPF) and structural brain abnormalities, as well as poorer motor function, in New York City children and adolescents. Their findings, published in the journal JAMA Neurology, are said to be the first to demonstrate enduring and widespread molecular, cellular and metabolic effects in the brain, as well as poorer fine motor control among youth with prenatal exposure to the insecticide.

The 270 children and adolescents assessed were participants in the Columbia Center for Children’s Environmental Health birth cohort study — conducted from January 1998 to July 2015 — and were born to Latino and African-American mothers residing in a northern Manhattan neighbourhood. They had measurable quantities of CPF in their umbilical cord blood and were assessed by brain imaging and behavioural tests between the ages of six and 14 years.

Progressively higher insecticide exposure levels were significantly associated with progressively greater alterations in brain structure, function and metabolism, as well as poorer measures of motor speed and motor programming. Links between higher CPF and greater anomalies across different neuroimaging measures suggest that prenatal exposure produces enduring disturbances in brain structure, function and metabolism in direct proportion to the level of exposure.

“The disturbances in brain tissue and metabolism that we observed with prenatal exposure to this one pesticide were remarkably widespread throughout the brain,” said first author Dr Bradley Peterson, Vice Chair for Research and Chief of Child & Adolescent Psychiatry in the Department of Psychiatry at the Keck School of Medicine. “Other organophosphate pesticides likely produce similar effects, warranting caution to minimise exposures in pregnancy, infancy and early childhood, when brain development is rapid and especially vulnerable to these toxic chemicals.”

Exposure to CPF was mostly attributable to indoor residential spraying for pests, which was prevalent in the inner-city neighbourhood before residential use was banned by the US EPA in 2001. It was later banned from agricultural use on all food crops in August 2021, but this ban was challenged and overturned in late 2023 — meaning toxins can still be carried by outdoor air and dust near agricultural areas.

“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,” said senior author Virginia Rauh, the Jane and Alan Batkin Professor of Population and Family Health at the Mailman School. “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.”

Dr Rudrarup Bhattacharjee, a postdoctoral researcher from The University of Adelaide, said the study provides “compelling evidence that prenatal exposure to chlorpyrifos has enduring neurodevelopmental consequences — particularly in white matter and cortical organisation of the brain”.

According to Bhattacharjee, “White matter abnormalities are increasingly recognised as a central feature in conditions such as intellectual disability, autism spectrum disorder and ADHD, underscoring how disruptions to axonal development and myelination can have profound effects on cognition and motor function. What stands out here is the clear demonstration that such structural and metabolic vulnerabilities can arise not only from genetic insults but also from environmental exposures during critical periods of brain development … reinforcing the urgent need for stronger public health protections.”

Image credit: iStock.com/simonkr