Chlorpyrifos, a chlorinated organophosphate (CPF), is among the most widely used insecticides worldwide. In the United States, it remains a fixture in agriculture, showing up in nonorganic fruits, vegetables, grains, and even in the air and dust near farm fields, despite a ban on residential use since 2001. Globally, its use continues at scale.
Now, researchers at Columbia University’s Mailman School of Public Health have uncovered troubling evidence: prenatal exposure to chlorpyrifos is linked to measurable changes in brain structure and reduced motor skills in children and teens growing up in New York City.
As scientists uncover the hidden costs of this everyday chemical, the focus shifts from what’s on our plates to what’s affecting the future health of our children.
A 1960s pesticide icon
Chlorpyrifos (CPF) was introduced in 1965 by Dow Chemical and quickly became one of the most widely used pesticides in agriculture. Valued for its ability to kill insects on crops like corn, soybeans, and fruit, it was also sprayed in homes and schools for decades.
From farming staple to public health concern
Its popularity spread rapidly thanks to its effectiveness and low cost, making it a staple of modern farming. But as research advanced, scientists began linking long-term exposure to serious health risks, especially in children.
Hidden health risks
A number of studies soon revealed that CPF exposure can harm the brain and nervous system, leading to lower IQ, developmental delays, and behavioral problems in children, even at low levels over time.
Uncovering the hidden impact of CPF
And now, a groundbreaking study led by Columbia University, Children’s Hospital Los Angeles, and USC’s Keck School of Medicine is the first to show that prenatal exposure to CPF leaves lasting molecular and metabolic changes in the human brain.
How CPF travels through the body
When pesticides enter our bodies through food, touch, or air, pregnant women face a unique risk: CPF can cross the placenta, reaching the fetus at up to four times the levels found in maternal tissues, and then penetrate the developing brain.
What animal studies tell us about pesticides
Animal studies reveal that even low-level exposure to CPF and similar pesticides, below the dose that harms insects, can disrupt brain development.
What animal studies tell us about pesticides
In rodents, it hinders neuron growth, interferes with synapse formation, and even triggers cell death.
What CPF does to the brain
Early exposure to CPF appears especially harmful to glial cells, the brain’s support network. Studies show it first triggers abnormal growth and swelling, and later leads to widespread scarring known as astrogliosis.
The brain’s “support crew”
While neurons handle the electrical signals that let us think, move, and feel, glial cells keep everything running smoothly. They nourish neurons, clear away waste, and help repair damage. Think of them as the maintenance team that keeps the brain’s communication network in top shape.
What is astrogliosis?
Astrogliosis, a type of scarring in the brain that may result from early exposure to CPF, occurs when glial cells swell and multiply, forming a dense web of tissue. While this response is meant to protect the brain, excessive scarring can disrupt healthy function.
How CPF disrupts the brain at a cellular level
Researchers say CPF harms the brain by sparking stress inside cells, fueling inflammation, disrupting energy production in mitochondria, and altering how brain cells respond to growth signals.
Tracking CPF exposure
The study tracked 270 children from the Columbia Center for Children’s Environmental Health birth cohort. All were born in New York City to Latino and African-American mothers, offering a deeper look at the communities most often exposed to environmental risks.
Chemicals at birth, effects years later
Every child in the study showed traces of CPF in their umbilical cord blood at birth. Years later, between ages six and 14, researchers followed up with brain scans and behavioral tests to track possible impacts.
Exposure leaves its mark
The findings revealed a distinct trend: children exposed to higher levels of the insecticide before birth showed more significant changes in both brain structure and function compared to their peers.
How early exposure shapes the brain
Building on earlier evidence that prenatal CPF exposure can disrupt skills like intelligence, focus, and socialization, researchers predicted strong links to brain regions tied to these abilities.
Dose matters in brain impact
Prenatal exposure to CPF was found to alter brain structure, function, and even metabolism. The higher the exposure, the greater the disruption, pointing to a clear dose-response effect.
Farm use persists
For this group of children, indoor pesticide use was the primary source of exposure. While the EPA banned chlorpyrifos in households back in 2001, the chemical is still widely used in farming, especially on non-organic produce and grains.
A decline after the ban
After the household ban, CPF exposure steadily fell. Products were pulled from shelves, leftover supplies ran out, and carbamate-based pesticides largely took their place in American homes.
Exposure beyond the home
But even with the household ban in place, farm workers and nearby communities remain at risk. Ongoing agricultural use means CPF can drift into the air and dust, leaving those close to fields exposed.
Air pollution shows a parallel story
Earlier work with this same group of children revealed nearly identical results tied to prenatal exposure to air pollution, reinforcing the idea that environmental factors can also shape brain development from the very beginning.
CPF’s unique impact
The study shows CPF affects the brain on its own. Its influence didn’t overlap with air pollution, and the results stayed the same even after factoring in other pollutants.
A common pathway of harm
Even though these chemicals are different, many harm the brain in similar ways. Studies show that inflammation and cell damage are key, whether the exposure comes from CPF pesticides, air pollution (PM2.5), or pollutants from burning fuels (PAHs).
Protecting the most vulnerable
Virginia Rauh, ScD, senior author of the study, warns that current exposure levels still endanger farm workers, pregnant women, and unborn children. She stresses the need to closely monitor vulnerable groups, especially expectant mothers in farming communities, since their infants remain at risk.
Caution across pesticides
Other organophosphate pesticides may cause similar harm, making it crucial to limit exposure during pregnancy, infancy, and early childhood, times when the brain grows quickly and is most vulnerable to toxic chemicals.
Study scope and limitations
There are some limitations to the study. With participants drawn from urban Dominican and African-American mothers and their children, the results might not represent experiences in other communities or regions.
Addressing potential selection bias
Some selection bias was possible, since not all cohort members were reached or agreed to MRI scans. Still, participants were similar to the full group in demographics and long-term cognitive outcomes, so bias appears limited.
Risks may outweigh benefits
There's no doubt: pesticides such as CPF may boost crop yields, but mounting evidence shows they can damage brain development, harm wildlife, and contaminate soil and water, posing risks far beyond the fields.
Safer farming practices take root
Fortunately, farmers are slowly embracing integrated pest management, crop rotation, and natural predators to fight pests. These revolutionary methods cut back on chemicals while safeguarding harvests, proving that healthier farming is achievable close to home.
Farming for a sustainable tomorrow
Farmers worldwide are testing organic practices, biopesticides, and precision tools. By blending natural solutions with modern technology, they’re paving the way toward cleaner water, healthier food, and a future built on sustainability.
