Key Takeaways
- The first California paraquat Parkinson's disease case, Anderson v. Syngenta AG, et al., has been scheduled for trial on March 1, 2027, in Contra Costa County Superior Court.
- Plaintiffs Keith and Cheryl Anderson allege that Mr. Anderson's repeated exposure to paraquat-containing herbicide products, including Gramoxone®, from approximately 1994 through 2022 on their California walnut farm caused him to develop Parkinson's disease, diagnosed in 2021.
- The lawsuit alleges that defendants Syngenta and Chevron knew or should have known for decades about paraquat's neurotoxic properties and failed to adequately warn users.
- Multiple epidemiological studies, including research from the federally funded Agricultural Health Study, have found elevated Parkinson's disease risk among agricultural workers exposed to paraquat.
- Paraquat remains widely used in U.S. agriculture despite being banned or restricted in dozens of other countries.
First California Paraquat Parkinson's Trial Scheduled for March 2027
A California court has set a March 1, 2027 trial date for the first paraquat Parkinson's disease case to proceed in the state. Anderson v. Syngenta AG, et al., filed in Contra Costa County Superior Court, is being closely watched as a potential bellwether case that could shape the outcome of thousands of similar claims filed by U.S. farmers and agricultural workers across the country.
The case is being brought by Wisner Baum LLP, a Los Angeles-based plaintiffs' law firm, alongside co-counsel R. Allen Smith Jr. of The Smith Law Firm. Attorneys Brent Wisner, Conor Kennedy, and Harrison E. James will serve on the trial team. The firm represents farmers, pesticide applicators, landscapers, and others who used paraquat-containing products and subsequently developed Parkinson's disease or Parkinsonism.
“These cases reveal a disturbing reality: Syngenta and Chevron knew for decades that paraquat destroyed the dopamine-creating cells in the brain — the very cells that, when dead, cause Parkinson's. It's reprehensible, and when a jury sees this evidence, most of which is still sealed from public scrutiny, there will be a reckoning,” said Brent Wisner, lead trial attorney and managing partner of Wisner Baum.
The Andersons' Case: Decades of Paraquat Exposure on a California Farm
Plaintiffs Keith and Cheryl Anderson allege that Mr. Anderson was repeatedly exposed to paraquat from around 1994 through 2022 while mixing, loading, spraying, and handling paraquat products, including Gramoxone®, on their California walnut farm. The complaint alleges the herbicide entered his body through inhalation, skin absorption, and ingestion during routine agricultural use. Mr. Anderson was diagnosed with Parkinson's disease in 2021.
The lawsuit alleges that manufacturers Syngenta and Chevron knew or should have known about paraquat's neurotoxic properties for decades, yet failed to adequately warn users about the associated health risks. Plaintiffs' attorneys contend that internal corporate documents obtained through discovery may reveal a longstanding awareness of paraquat's toxicity.
“Syngenta explicitly said that its stewardship of paraquat would involve the ‘placing of economics before safety,'” said Conor Kennedy, associate attorney at Wisner Baum. “This trial will be a critical opportunity to give agricultural workers and their families their day in court and to demand accountability from companies that have profited from a dangerous product for decades.”
Scientific Evidence Linking Paraquat to Parkinson's Disease
A substantial body of research has accumulated over the past two decades examining the relationship between paraquat exposure and Parkinson's disease risk. Laboratory studies have found that paraquat can cause oxidative stress and damage to dopamine-producing neurons. The Agricultural Health Study (AHS), a large federally funded cohort study of pesticide applicators, reported an elevated Parkinson's disease risk associated with paraquat exposure among agricultural workers. Subsequent research confirmed those findings, with leading Parkinson's disease researchers describing the accumulated data as persuasive, and a National Institutes of Health investigator noting it was about as strong as such evidence typically gets.
Parkinson's disease is a progressive neurological disorder affecting movement, coordination, and cognitive function. Its hallmarks include tremors, rigidity, slowed movement, and balance impairment. Nearly one million Americans are currently living with the disease, according to the Parkinson's Foundation. Some studies have also found elevated risk among people in rural areas and those who drink well water, findings that researchers have suggested may relate to pesticide runoff into agricultural water sources.
Regulatory Context: Widely Used in the U.S., Banned Elsewhere
Paraquat remains one of the most widely used herbicides in U.S. agriculture despite bans or restrictions in dozens of countries, including across the European Union. The divergence in regulatory treatment has attracted ongoing scrutiny from public health advocates and plaintiffs' attorneys alike.
“When you see a chemical banned across large parts of the world but still widely used in American agriculture, you have to wonder whether the system designed to protect public health is working the way it's supposed to,” Wisner said.
The March 2027 trial is expected to be the first opportunity for a California jury to directly evaluate the evidence linking paraquat exposure to Parkinson's disease — including internal documents that plaintiffs say have been largely shielded from public view. The case follows a pattern seen in prior mass tort litigation involving agrochemical manufacturers, where bellwether trials have played a significant role in shaping broader settlement dynamics.
