California lawsuit alleges years of pesticide drift contributed to an early-onset Parkinson’s diagnosis.
A newly filed California lawsuit is putting chlorpyrifos back into the spotlight as questions continue about the insecticide’s potential neurological effects and its remaining agricultural uses in the United States.
Wisner Baum LLP has filed a lawsuit in Los Angeles County Superior Court on behalf of a Los Angeles County man diagnosed with early-onset Parkinson’s disease. The complaint alleges that years of exposure to chlorpyrifos from nearby commercial nurseries contributed to his illness.
The lawsuit names Corteva, Inc., Corteva Agriscience LLC and The Dow Chemical Company, alleging the companies designed, manufactured, marketed, sold or distributed chlorpyrifos products while failing to adequately investigate or communicate potential long-term neurological risks.
Three commercial nurseries, Abeja Nursery, Azul & Verde Nursery and ABC Nursery, Inc., are also named as defendants.
The allegations have not been proven in court.
Lawsuit focuses on alleged pesticide drift
According to the complaint, the plaintiff was exposed to chlorpyrifos while living near commercial nursery operations in Los Angeles County from approximately 2003 through 2020.
The lawsuit alleges that one residence was about 20 feet from a nursery between 2003 and 2013, with no barrier separating the properties. At another residence, the plaintiff’s backyard fence allegedly directly bordered a commercial nursery.
Attorneys contend that the nursery defendants failed to take reasonable precautions to prevent pesticide drift and other off-site exposure, including adequate buffers and application controls.
“People living near pesticide applications should not have to guess what is being sprayed or whether it could affect their health,” said Sasha Shariati, a Wisner Baum attorney representing the plaintiff. “This case will examine what the defendants knew, how they communicated about chlorpyrifos, and whether reasonable precautions could have reduced exposure to nearby residents.”
The complaint seeks compensatory and punitive damages and includes claims involving negligent failure to warn, negligent design, strict liability design defect, general negligence and trespass.
Parkinson’s research adds another dimension
Chlorpyrifos is an organophosphate insecticide that affects the nervous system by inhibiting acetylcholinesterase, an enzyme important to normal nerve function.
The new lawsuit comes as researchers examine whether long-term exposure may also be associated with Parkinson’s disease.
Recent research involving California agricultural communities reported that people with high long-term residential exposure to chlorpyrifos were more than 2.5 times as likely to develop Parkinson’s disease compared with people without that exposure.
That finding is important, but it should not be interpreted as proof that chlorpyrifos causes every individual case of Parkinson’s disease. Epidemiological studies examine associations among populations, while individual disease risk can involve numerous environmental, genetic and other factors.
Wisner Baum alleges the manufacturers failed to adequately investigate long-term neurological effects and communicate potential risks through channels including training, advertising and sales information.
“Chlorpyrifos manufacturers had decades to study what this chemical does to the human nervous system,” Shariati said. “This lawsuit seeks to hold them accountable for what they knew and what they chose not to tell the public.”
What U.S. farmers should know
Although chlorpyrifos has been the subject of substantial regulatory action, its U.S. regulatory history is more complicated than a straightforward nationwide ban.
The U.S. Environmental Protection Agency’s 2021 rule revoked food tolerances for chlorpyrifos, but the U.S. Court of Appeals for the Eighth Circuit vacated that rule in November 2023 and sent the matter back to EPA. Chlorpyrifos tolerances were subsequently reinstated.
Since then, registrants have voluntarily cancelled most food and feed uses.
EPA-approved amended labels currently retain food uses involving 11 crops: alfalfa, apples, asparagus, tart cherries, citrus, cotton, peaches, soybeans, strawberries, sugar beets and spring and winter wheat. Those uses are also subject to geographic and application restrictions.
EPA’s registration review of chlorpyrifos remains ongoing in 2026.
For growers, pesticide applicators and agricultural employers, the developing litigation is another reminder of the importance of following current product labels and application restrictions, maintaining pesticide application records and observing requirements intended to reduce off-target exposure.
Those practices can be especially important where agricultural land borders homes, businesses, schools or other populated properties.
California ended almost all chlorpyrifos use
The lawsuit involves alleged exposure that occurred before California effectively removed chlorpyrifos from agricultural use.
California reached an agreement with manufacturers in 2019 to end sales of chlorpyrifos products to growers by February 6, 2020. Growers were prohibited from possessing or using affected products after December 31, 2020.
Before the final phase-out, California imposed measures including restrictions on aerial applications and buffer requirements.
Global phase-out approaching
Chlorpyrifos is also facing tighter controls internationally.
In 2025, parties to the Stockholm Convention on Persistent Organic Pollutants agreed to list chlorpyrifos in Annex A of the Convention for elimination, subject to specific exemptions.
The listing is scheduled to enter into force on December 16, 2026. Parties registered for specific exemptions may continue certain uses under the Convention’s provisions.
The global action adds another layer to the changing regulatory environment for an insecticide that was widely used in agriculture for decades.
Litigation could put agricultural exposure under greater scrutiny once again
For U.S. agriculture, the latest case may be significant beyond the individual plaintiff.
Earlier chlorpyrifos health concerns focused heavily on developmental and neurological effects associated with childhood and prenatal exposure. The emerging Parkinson’s litigation shifts some of the attention toward long-term adult exposure involving agricultural workers, pesticide applicators and people living close to areas where chlorpyrifos was historically applied.
Whether the allegations against Corteva, Dow and the nursery defendants ultimately succeed will be determined through the legal process.
However, the combination of ongoing research, changing pesticide regulations and new litigation means chlorpyrifos is likely to remain an important issue for agricultural employers, pesticide applicators and growers even as its available uses continue to narrow.