Free Consultation
(310) 207-3233
A 2026 UCLA health study found that long-term residential exposure to chlorpyrifos is associated with a more than 2.5x increased risk of developing Parkinson’s disease. The research, which combined human population data with laboratory experiments, was published in the peer-reviewed journal Molecular Neurodegeneration. The laboratory data showed how the pesticide can damage dopamine-producing brain cells.
The research coincides with legal claims related to chlorpyrifos exposure and its potential link to Parkinson’s disease. Wisner Baum chlorpyrifos attorneys represent people diagnosed with Parkinson’s after exposure to Lorsban, Dursban, and other chlorpyrifos-based products. Below, we break down what the UCLA Health study found and what it may mean for people affected by chlorpyrifos exposure.
The 2026 UCLA Health Study used data from the population-based Parkinson’s Environment and Genes (PEG) study. The PEG study looked at over 1600 people (829 patients with Parkinson’s disease and 824 controls) in the three Central California agricultural counties of Kern, Fresno, and Tulare.
Researchers then estimated ambient exposure over several decades based on where participants lived and worked using California’s pesticide use reports. To see the isolated effects of chlorpyrifos, researchers controlled for other potential pesticide exposures, including paraquat, glyphosate, and diazinon.
Using this information, researchers found that individuals with the highest long-term exposure to chlorpyrifos were over 2.5x more likely to be diagnosed with Parkinson’s disease compared to those who were not exposed.
The 2026 UCLA Health study builds upon previously published data that found individuals exposed to certain pesticides, including paraquat or rotenone were more than twice as likely to be diagnosed with Parkinson’s disease.
A 2011 study published in Environmental Health Perspectives found that participants with Parkinson’s disease were 2.5x more likely than the control group to have used the pesticides rotenone or paraquat. The study used data from the Agricultural Health Study, whose participants include private pesticide applicators and their spouses in Iowa and North Carolina. The findings supported years of animal studies that propose a link between pesticides and an increased risk of Parkinson’s.
A 2013 study published in the International Journal of Epidemiology found that household use of organophosphate pesticides was potentially associated with a higher risk of Parkinson’s disease with frequent use increasing the odds of developing the disease.
These earlier studies generally relied on statistical links in people and did not explain the exact mechanism of how exposure to the pesticide can increase a person’s risk of developing the disease. In order to address this, the UCLA team included data from animal laboratory studies.
The aim of the researchers was to isolate whether there may be an association between chlorpyrifos and Parkinson’s, rather than pesticides as a whole. The study’s senior author, Dr. Jeff Bronstein, a professor of neurology at UCLA Health, explained in a UCLA Health article, “This study establishes chlorpyrifos as a specific environmental risk factor for Parkinson's disease, not just pesticides as a general class.”
In addition to looking at human studies, UCLA researchers looked at laboratory experiments. The experiments showed that animals exposed to chlorpyrifos developed movement problems and lost dopamine-producing brain cells. The studies showed that the mice exposed to the pesticide had the same toxic protein (alpha-synuclein) buildup found in patients with Parkinson’s disease.
Experiments of zebrafish exposed to the pesticide showed that the pesticide disrupts the body's ability to clear damaged proteins from cells, a process known as autophagy. When the process was restored, neurons were protected. These experiments provided further evidence of an association between chlorpyrifos exposure and Parkinson’s.
Chlorpyrifos remains one of the most widely used pesticides in the United States. It has been sprayed on crops like corn, soybeans, citrus, and cotton for decades. While residential use was banned in 2000, with the phase-out completed in 2001, agricultural use remains in effect, although restricted.
Many people may be exposed to chlorpyrifos, especially individuals living and/or working near farming communities where the chemical is sprayed.
Exposure can occur from drift spray, contaminated water or soil, or direct handling. Due to chlorpyrifos potential link to Parkinson’s, the study’s researchers noted that people with a history of exposure — particularly those who lived or worked near treated fields for extended periods — may benefit from closer neurological monitoring.
It can take decades for a person to be diagnosed with Parkinson’s. The disease is slow-moving, although it often starts years before any symptoms show up. Because a diagnosis can surface years after exposure, many people do not associate any connection. While there may be many potential causes of Parkinson’s, it is important to consider environmental factors. Individuals who sustained long-term exposure to pesticides are encouraged to consult with an attorney to determine if they may be eligible to pursue legal action.
The latest research from UCLA Health shows a potential association between chlorpyrifos exposure and Parkinson’s disease. Attorneys are reviewing claims on behalf of people who were exposed to the pesticide and later diagnosed with the disease.
Wisner Baum is reviewing potential claims from farmworkers, agricultural employees, pesticide applicators, and others with a history of chlorpyrifos exposure who were later diagnosed with Parkinson’s disease. Eligibility to file a lawsuit, however, depends on the individual factors of the claim. Each situation is reviewed on a case-by-case basis.
Attorneys with the firm proudly represent clients nationwide who were exposed to chlorpyrifos and later diagnosed with Parkinson’s. If you or your loved one was affected by chlorpyrifos, contact the firm at (310) 207-3233 for a free, no-obligation case evaluation.
