Chlorpyrifos (CPF) Exposure Linked to Abnormal Brain Development in Children: Study

In 2024, the EPA reversed a chlorpyrifos ban following a court ruling, meaning pregnant women in the U.S. are again at risk of exposure to the toxic insecticide.

Children exposed to certain pesticides during pregnancy are more prone to developmental delays affecting fine motor skills and hand-eye coordination, data from a new study warns.

According to findings published in the journal JAMA Neurology on August 18, prenatal exposure to chlorpyrifos, a type of pesticide widely used on fruits and vegetables, increased a child’s risk of suffering abnormalities to the structure of the brain and increased the risk of experiencing problems with motor skills.

Chlorpyrifos (CPF) is one of the most widely used insecticides in the world. Indoor residential CPF use was banned in 2011, but. it was still allowed for use in agriculture on non-organic fruits, vegetables and grains.

In 2021, the U.S. Environmental Protection Agency (EPA) issued a final rule banning the use of CPF on all food and crops, citing growing evidence of neurological harm, persistent developmental disorders and autoimmune diseases. 

However, following a U.S. Court of Appeals ruling last year, the EPA reversed the ban on CPF and reinstated all food and crop uses of chlorpyrifos. The agency said it planned to propose new restrictions, but those have not been announced since the reversal.

In the new study, researchers from Columbia University Mailman School of Public Health, Keck School of Medicine USC, and the Children’s Hospital Los Angeles examined prenatal exposure to CPF and long-term effects to the brain.

Led by Dr. Bradley S. Peterson, the team studied a sample of 270 teens from the Columbia Center for Children’s Environmental health birth cohort ages 6 to 14 years old from January 1998 to July 2015.

Of 727 pregnant women, 512 children had measurable levels of CPF in their umbilical cord blood at delivery. The children then underwent an MRI at 6 years old or later.

The data indicated exposure to CPF increased a child’s risk of suffering structural abnormalities to the brain and poor motor function, including holding and manipulating objects and their own hands, dressing, writing and other tasks.

In what appears to be a dose-specific response, often key in proving causation, higher prenatal exposure to CPF was linked with progressively greater changes in brain structure, function and metabolism. Exposed children also had progressively poorer measures of motor speed and motor programming, or the ability to execute coordinated movements like playing and writing.

Other changes researchers noticed in children exposed to CPF during pregnancy included reduced white matter volumes in the frontal, temporal and posteroinferior cortices of the brain. Those areas were also thicker.

CPF-exposed children also showed lower blood flow throughout the brain, and lower levels of neuronal density in white matter. Exposure to CPF caused widespread molecular, cellular and metabolic effects in the brain, the researchers determined.

Since CPF is known to cause oxidative stress and inflammation to the body, as well as impair mitochondria and the development of neurons, the researchers speculate these may be the avenues to how the chemical causes long-lasting changes to the brain structure and function. 

Prior research has also suggested that exposure during pregnancy is neurotoxic. 

As a result, a number of lawsuits were filed against CPF manufacturers following the 2021 ban, each alleging that the chemical caused brain damage, autism and other developmental harm to exposed children. Many of the plaintiffs in the lawsuits worked in the agriculture industry, coming into close contact with pesticide exposed foods during pregnancy.

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