New research from UCLA indicates that prolonged exposure to the pesticide chlorpyrifos may significantly increase the risk of developing Parkinson’s disease.
Recent findings from UCLA have established a concerning link between prolonged exposure to the pesticide chlorpyrifos and an increased risk of Parkinson’s disease. This study, published in the journal Springer Nature Link, draws on evidence from both human and animal research.
Chlorpyrifos is a pesticide commonly utilized in the United States agricultural sector, particularly on crops such as soybeans, fruit and nut trees, broccoli, and cauliflower, as noted by the U.S. Environmental Protection Agency (EPA).
The study analyzed data from 829 individuals diagnosed with Parkinson’s disease and 824 control subjects without the disease over a span of 45 years, focusing on their proximity to chlorpyrifos. Additionally, researchers conducted experiments on mice, which were exposed to the pesticide through inhalation for 11 weeks, mimicking human exposure. Zebrafish were also used in experiments to investigate cellular brain damage.
Results from the human study indicated that long-term exposure to chlorpyrifos was associated with a more than 2.5-fold increase in the risk of developing Parkinson’s disease. In animal studies, mice exhibited movement difficulties akin to Parkinson’s symptoms, experienced a loss of dopamine-producing neurons, and showed increased brain inflammation along with the accumulation of harmful proteins. Zebrafish, on the other hand, suffered from brain cell death and damage linked to a failure in the cell’s cleanup mechanisms.
Dr. Jeff Bronstein, director of the Movement Disorders Program at UCLA and a professor of neurology and molecular toxicology, expressed surprise at the consistency of the toxicity mechanisms observed across both mice and zebrafish. “We rarely find such consistent results in different animal models,” he stated.
Bronstein emphasized that the correlation between pesticide exposure and Parkinson’s disease is “very strong,” noting that the risk increases with the duration of exposure. He advised the public to minimize exposure to chlorpyrifos and similar organophosphate pesticides by avoiding their use at home, opting for organic produce, and thoroughly washing fruits and vegetables before consumption.
While the study presents compelling evidence, the researchers acknowledged certain limitations. The observational nature of the study means it can only establish an association rather than prove causation. Furthermore, exposure estimates were based on participants’ locations without accounting for dietary habits, indoor exposure, or personal lifestyle factors. The study also noted that chlorpyrifos is often used in conjunction with other chemicals, complicating the assessment of its specific impact.
Chlorpyrifos is employed to manage various pests, including termites, mosquitoes, and roundworms, in agricultural settings, according to the National Pesticide Information Center at Oregon State University. Individuals can be exposed to the chemical through inhalation or by consuming contaminated food or water.
In 2021, the EPA banned the use of chlorpyrifos on food crops, but a federal appeals court overturned this decision in 2023, allowing its use to resume on certain crops while the agency revisits the regulation. In January 2026, the EPA announced plans to advance a rule that would prohibit most uses of chlorpyrifos.
“Chlorpyrifos is subject to registration review, a process required under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), in which registered pesticides are evaluated every 15 years against current safety standards and the latest scientific evidence,” the EPA stated in a communication to Fox News Digital. “The EPA is currently developing a revised human health risk assessment for chlorpyrifos as part of that review and will consider this study alongside any other relevant submissions. Where the science calls for stronger protections or tolerance revocations, the EPA will act without hesitation and without delay.”
Fox News Digital reached out to several manufacturers of chlorpyrifos for comments. Corteva, an Indiana-based agrichemical company formed in 2019 through the merger of Dow Chemical and DuPont, announced in 2020 its decision to cease production of chlorpyrifos, citing declining sales. In April 2022, the German chemical company BASF requested the cancellation of its pesticide registrations for products containing chlorpyrifos. BASF clarified that it does not manufacture chlorpyrifos and does not hold any pesticide registrations issued by the U.S. EPA for chlorpyrifos-containing products.
No products from Corteva or BASF were included in the study linking chlorpyrifos to Parkinson’s disease, according to the research findings.
This study underscores the importance of ongoing research into the health impacts of pesticides and the need for regulatory bodies to consider new evidence in their assessments.
For more information, refer to the study published in Springer Nature Link.