Parkinson’s risk increases with exposure to common chemical, study suggests
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New research suggests that a pesticide commonly used in the United States food supply has been linked to Parkinson’s disease.
A UCLA study published in the journal Springer Nature Link suggests that exposure to chlorpyrifos could increase the risk of neurological disease.
The chemical is often used in agricultural products such as soybeans, fruit and nut trees, broccoli, cauliflower and other row crops, according to the U.S. Environmental Protection Agency.
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The study compared 829 people with Parkinson’s to 824 people without the disease over a 45-year period, focusing on their proximity to chlorpyrifos.
The researchers also conducted experiments with mice, in which the mice inhaled the pesticide as humans would for 11 weeks. Experiments were also carried out with zebrafish to study brain damage at the cellular level.
Chlorpyrifos is often used in agricultural products such as soybeans, fruit and nut trees, broccoli, cauliflower and other row crops, according to the U.S. Environmental Protection Agency. (iStock)
In humans, the study revealed that long-term exposure to chlorpyrifos led to a 2.5-fold increased risk of Parkinson’s.
In mice, exposure to the pesticide caused movement problems similar to Parkinson’s symptoms, loss of dopamine-producing neurons, increased brain inflammation, and accumulation of harmful proteins.
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According to the study’s press release, the zebrafish suffered death and brain cell damage related to a failure in the cell’s “cleaning system.”
Dr. Jeff Bronstein, director of the UCLA Movement Disorders Program and professor of neurology and molecular toxicology, noted that previous studies in humans also suggested an association between chlorpyrifos exposure and Parkinson’s.
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“[We were] “I was surprised that the mechanism of toxicity was evident in both mice and zebrafish,” he said. “We rarely find such consistent results in different animal models.”
One researcher commented that consistency in results between human and animal subjects is “rare.” (iStock)
The researcher emphasized that the association between pesticide exposure and Parkinson’s was “very strong,” and the longer a person was exposed, the greater the risk.
“People should avoid exposure to CPF and similar (organophosphate) pesticides by not using them at home, eating organic produce, and washing fruits and vegetables before eating them,” Bronstein said.
Limitations of the study
The study had some limitations, the researchers acknowledged, primarily that it was observational, meaning it shows an association but cannot prove causality.
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It also estimated exposure based on participants’ location and did not measure diet, indoor exposure, or personal lifestyle behaviors. Furthermore, results from animal models cannot be directly translated to humans.
There was also the possibility that chlorpyrifos was used in conjunction with other chemicals, meaning it could be difficult to measure its specific impact, the study noted.
Chlorpyrifos is used to control different types of pests, such as termites, mosquitoes and roundworms, among crops. (iStock)
Industry reaction
Chlorpyrifos is used to control different types of pests, such as termites, mosquitoes and roundworms, among crops, according to the National Pesticide Information Center (NPIC) at Oregon State University.
People can be exposed to the pesticide by inhaling it or consuming contaminated water or food.
In 2021, the EPA banned the use of chlorpyrifos on food crops, but a federal appeals court overturned that decision in 2023, allowing its use on some crops to resume while regulators review the rule.
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In January 2026, EPA issued an update outlining plans to move forward with a rule that would ban most uses of chlorpyrifos.
“Chlorpyrifos is subject to registration review, a process required by FIFRA (the Federal Insecticide, Fungicide, and Rodenticide Act) in which registered pesticides are thoroughly evaluated every 15 years against current safety standards and the most recent scientific evidence,” the EPA said in a statement to News Digital.
“EPA is currently developing a revised assessment of the human health risks of chlorpyrifos as part of that review, and will consider this study along with any other relevant submissions,” the agency said in a statement to News Digital. (Getty)
“EPA is currently developing a revised assessment of the human health risks of chlorpyrifos as part of that review, and will consider this study along with any other relevant submissions. When science requires stronger protections or tolerance reversals, EPA will act without hesitation and without delay.”
News Digital has reached out to several manufacturers of the chemical for comment.
“People should avoid exposure to CPF and similar pesticides.”
Corteva, an Indiana agrochemical company formed in 2019 through the merger of Dow Chemical and DuPont, announced in 2020 that it would end production of chlorpyrifos within a year, citing declining sales.
In April 2022, the German chemical company BASF requested the cancellation of its pesticide registrations for products containing chlorpyrifos.
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“BASF does not manufacture chlorpyrifos and does not have any pesticide registration issued by the US EPA for products containing chlorpyrifos,” the company told News Digital.
No Corteva or BASF products were included in the study linking chlorpyrifos to Parkinson’s disease.
Angelica Stabile is a lifestyle reporter for News Digital.