Parkinson's Pesticide Lawsuit: Claims, Evidence and Status
The Parkinson’s pesticide lawsuit is a group of product liability claims over paraquat and Parkinson’s disease. The science is unsettled. A 2020 Agricultural Health Study update reported no association, and EPA has not found a clear link at labeled use. Exposed people can file, and the claims sit in MDL 3004, called In re Paraquat Products Liability Litigation. Syngenta signed a letter agreement to resolve most of those claims. Paraquat is not banned in the United States and remains a restricted use pesticide. The Roundup Supreme Court ruling blocks failure-to-warn claims when EPA approved the label. Roundup cases differ from paraquat cases in the injury, the EPA position and the court.
What Is the Parkinson’s Pesticide Lawsuit?
The Parkinson’s pesticide lawsuit is a group of product liability claims over paraquat and Parkinson’s disease. The Parkinson’s pesticide lawsuits argue that manufacturers failed to warn users that paraquat could cause the disease. People diagnosed with Parkinson’s disease after paraquat exposure sue the manufacturers and distributors. Syngenta faces more than 8,000 such lawsuits across the United States. Cases proceed in both federal and state courts. In October 2026, the federal multidistrict litigation held 6,602 pending cases in the Southern District of Illinois. E Ray Dorsey of the University of Rochester Medical Center reviews the environmental toxicants behind such claims. The science stays disputed, because EPA describes the studies as varying in quality with conflicting results.
Which Pesticides Are Linked to Parkinson’s Disease?
The pesticides linked to Parkinson’s disease include Paraquat, Maneb, Mancozeb, Ziram, Benomyl, Diazinon, Chlorpyrifos and Dieldrin. Parkinson’s disease has several linked pesticides, and the sources tie each one to onset or progression.
The Parkinson’s Disease, Environment, and Genes study named six pesticides. Paraquat, maneb, ziram, benomyl, diazinon and chlorpyrifos contribute to onset and progression. The National Toxicology Program has identified paraquat exposure as a contributor to the disease. Controlled studies associate paraquat, maneb and mancozeb with twice the risk.
Dieldrin and benomyl inhibit the pathway that reduces the toxic dopamine residue DOPAL to a less toxic acid. The Agricultural Health Study follows more than 89,000 farmers and their spouses in North Carolina and Iowa. A 2025 study by E Ray Dorsey implicated certain pesticides, trichloroethylene, perchloroethylene and air pollution. These toxicants impair mitochondrial or lysosomal function. Uncertainties remain regarding relevant doses, timing and routes of exposure. Genetics explain 10 to 15 percent of cases, so pesticides are one factor among several.
Who Is Being Sued in the Parkinson’s Pesticide Lawsuit?
The defendants sued in the Parkinson’s pesticide lawsuit are Syngenta, Chevron Phillips Chemical Company and Chevron USA, Inc. They are the main defendants in most paraquat Parkinson’s cases. Syngenta and Chevron made, marketed and distributed paraquat in the United States.
Syngenta makes paraquat, and its Gramoxone herbicide brand is popular with US farmers. Chevron Phillips Chemical Company and Chevron USA, Inc distribute paraquat in the United States. Plaintiffs have filed lawsuits against Syngenta, Chevron, FMC and other parties responsible for manufacturing and distributing paraquat. Priyanshu Sharma wrote in Parkinsonism & related disorders about paraquat as a herbicide behind these claims.
Does Paraquat Cause Parkinson’s Disease?
It depends. The Agricultural Health Study cohort reported no association between paraquat and Parkinson’s disease in a 2020 update. EPA has not found a clear link from labeled uses. A cause here can mean a statistical association found in studies. Proof that paraquat caused one person’s disease is a separate claim.
A 2019 study by Wimonchat Tangamornsuksan found an association between paraquat exposure and Parkinson’s disease across 13 case-control studies. A population-based study of 829 patients and 824 community controls found higher odds near paraquat applications. C Berry wrote a 2010 study that calls human evidence limited and based on insufficient epidemiological data.
The 2020 update did not replicate 2011 findings. The Parkinson’s Disease, Environment, and Genes research links both pesticides and air pollution to higher risk. Living near applications can matter, since drift exposes residents without their knowledge.
How Does Paraquat Damage the Brain?
Paraquat damages the brain by driving oxidative stress that injures dopamine-producing neurons. Paraquat undergoes cyclic oxidation and reduction, and each cycle generates a reactive superoxide radical. That radical damages the neurons that make dopamine. Paraquat resembles MPP+, the toxic metabolite of MPTP, which induced parkinsonism in humans in 1983.
The main finding in brains of people with Parkinson’s disease is loss of dopaminergic neurons. A 2024 study by Priyanshu Sharma describes paraquat as a laboratory tool. Paraquat reproduces several Parkinson’s pathological features in cell and animal models. The mechanisms include oxidative stress, mitochondrial dysfunction and endoplasmic reticulum stress.
How Much Does Pesticide Exposure Raise Parkinson’s Risk?
Pesticide exposure raises the risk of Parkinson’s disease by 50 or more percent, per occupational meta-analyses. Parkinson’s disease risk rose by 33 to 80 percent in a review of 104 studies of pesticide and solvent exposure.
Parkinson’s disease risk rises in a dose-response manner as length of exposure increases. A 2017 study by Lars-Gunnar Gunnarsson found higher estimates with a hereditary taint or onset below age 60. That review reported that a funnel plot and bias test indicated some publication bias among smaller studies.
What Does the EPA Say About Paraquat and Parkinson’s Disease?
The United States Environmental Protection Agency has not found a clear link between labeled paraquat use and Parkinson’s disease. EPA reached this conclusion after a thorough review of the best available science under FIFRA. EPA states that many studies on paraquat and Parkinson’s disease range in quality and give conflicting results.
The EPA interim decision came in July 2021 and required mitigation measures. All registered paraquat products are Restricted Use Pesticides with no homeowner uses. In November 2025, EPA concluded that there is greater uncertainty about whether paraquat volatilizes than previously considered. EPA will issue a Data-Call In to paraquat manufacturers to resolve it. A registration review cycle lasts 15 years for each registered pesticide. C Berry of the University of London reached a similar view on the human evidence.
Paraquat ingestion is dangerous. One small sip can be fatal and there is no antidote. Illegal transfer to beverage containers causes 1 to 2 deaths per year in the United States.
Who Can File a Parkinson’s Pesticide Lawsuit?
Exposed people can file a Parkinson’s pesticide lawsuit. People exposed to paraquat after 1966 and later diagnosed with Parkinson’s disease qualify. Applicators and landscapers who sprayed paraquat qualify. Employees of companies that used paraquat qualify. Paraquat became fully available on the market in 1966, so exposure must come after that year.
Exposure routes include spraying paraquat, working at a company that used it, or living near sprayed farms. Drift near a farm can count as exposure. Lars-Gunnar Gunnarsson of the School of Medical Sciences reviewed occupational exposures behind Parkinson’s disease. An Environmental Working Group analysis shows paraquat is disproportionately sprayed in areas inhabited by Latino farmworkers and their families.
Filing deadline limits come from each state’s statute of limitations, which limits how long a claimant has to file. Relatives of people who died from paraquat exposure may bring claims too.
How Is Paraquat Exposure Proven in a Lawsuit?
To have paraquat exposure proven in a lawsuit, the plaintiff starts with the work and residential history. Collect medical records that confirm the diagnosis. Show the product was paraquat and not another herbicide. Gather purchase, applicator license or employer records. Add expert testimony linking the exposure to the disease.
A plaintiff must show exposure to paraquat and not another herbicide. Work history, residential history and medical records can establish that exposure. Wimonchat Tangamornsuksan of Naresuan University pooled 13 case-control studies on paraquat exposure. Nearby residents can be exposed without realizing it, so their proof relies on residential history and expert testimony. Agricultural workers and landscapers face a higher risk because they may have worked with or around paraquat for longer.
What Is the Paraquat Multidistrict Litigation?
The paraquat multidistrict litigation is MDL 3004, called In re Paraquat Products Liability Litigation. The paraquat MDL sits in the Southern District of Illinois. An MDL combines similar federal cases for pretrial proceedings before one judge. The paraquat MDL was established in 2021.
The paraquat MDL held 6,602 pending cases in October 2026. District Judge Nancy Rosenstengel largely denied Syngenta and Chevron’s motions in the paraquat MDL. She canceled the October 2023 trial date for the bellwether cases. Priyanshu Sharma wrote in 2024 that paraquat reproduces Parkinson’s features in laboratory models.
What Is the Philadelphia Paraquat Mass Tort?
The Philadelphia paraquat mass tort is a state court docket of paraquat cases in the Philadelphia Court of Common Pleas. The Philadelphia paraquat mass tort held 2,080 pending cases in October 2026. Judge Joshua Roberts oversees the paraquat mass tort in the Philadelphia Court of Common Pleas.
Judge Roberts declined to dismiss or remove more than 900 paraquat lawsuits pending before him. The defendants appealed to the Pennsylvania Superior Court. The first bellwether case settled on January 27, 2026, the night before trial. The state docket differs from the federal MDL because it runs in state court under its own judge. In 2010, C Berry judged the human evidence on paraquat to be limited.
Have Parkinson’s Pesticide Lawsuits Settled?
Yes. Parkinson’s pesticide lawsuits have settled in part, and Syngenta signed a letter agreement to resolve most MDL claims. The first Philadelphia bellwether case settled on January 27, 2026, the night before trial.
Syngenta reached a settlement with a retired landscaper on the eve of what would have been the first bellwether trial. Syngenta and Chevron agreed in 2021 to a $187.5 million settlement of claims by 7 men, who sued in 2017. Syngenta and lead counsel for thousands of plaintiffs signed a Letter Agreement in April 2025 intended to resolve the litigation. The agreement would not resolve all cases but could resolve the majority. The 2026 settlement terms are confidential. Lars-Gunnar Gunnarsson of Örebro University published a review of occupational exposures that frames the science behind such cases.
Is Paraquat Banned in the United States?
No. Paraquat is not banned in the United States and remains a restricted use pesticide. EPA keeps all registered paraquat products as Restricted Use Pesticides that only trained certified applicators may use. Those applicators cannot pass paraquat to workers under their supervision.
Paraquat is banned in around 70 countries but not in the United States. The European Union and China have banned paraquat. Vermont became the first state to ban paraquat in late May 2026. The Parkinson’s Foundation applauded Vermont for being the first state in the nation to ban it. The Environmental Working Group is sponsoring legislation that would ban paraquat in California. Other state laws restrict paraquat rather than ban it. In 2019, Wimonchat Tangamornsuksan reported an association between paraquat and Parkinson’s disease.
How Does the Roundup Supreme Court Ruling Affect Paraquat Cases?
The Roundup Supreme Court ruling affects paraquat cases by blocking failure-to-warn claims when EPA approved the label. Paraquat claims lose the failure-to-warn theory when EPA approved the label without the warning. FIFRA bars such suits under this rule.
The Supreme Court ruled 7-2 on June 25, 2026 in Monsanto v. Durnell. The ruling overturned a $1.25 million jury verdict won by Missouri resident John Durnell in 2023. Plaintiffs can still pursue design defect, manufacturing defect or fraudulent concealment claims. Monsanto proposed a $7.25 billion class settlement in February 2026 and plans to proceed with it. Bayer AG inherited the Roundup litigation when it bought Monsanto in 2018. The ruling does not dismiss pending paraquat suits. E Ray Dorsey of the Center for the Brain & Environment reviews the toxicant evidence these cases rely on.
How Do Roundup Lawsuits Differ From Paraquat Lawsuits?
Roundup lawsuits differ from paraquat lawsuits in the alleged injury, the EPA position and the court. Roundup plaintiffs allege non-Hodgkin lymphoma from the active ingredient glyphosate. Paraquat plaintiffs allege Parkinson’s disease.
| Attribute | Roundup (glyphosate) lawsuits | Paraquat lawsuits |
|---|---|---|
| Alleged injury | Non-Hodgkin lymphoma | Parkinson’s disease |
| EPA position on the health link | Not likely to cause cancer in humans when used as directed | No clear link found from labeled uses |
| Court venue | Northern District of California, Judge Vince Chhabria | Southern District of Illinois |
Glyphosate is the active ingredient in Roundup. EPA has determined it is not likely to cause cancer in humans when used as directed. The International Agency for Research on Cancer classified glyphosate as probably carcinogenic in 2015. Priyanshu Sharma of the University Institute of Pharma Sciences wrote about paraquat as a cause of Parkinson’s disease.
