The Paraquat Parkinson's Lawsuit: A Complete Overview

What is paraquat?

Paraquat dichloride is a non-selective contact herbicide first commercialized by Imperial Chemical Industries (ICI), now Syngenta AG, in the 1960s under the Gramoxone brand. It is one of the most heavily used "burndown" herbicides in U.S. agriculture — applied before planting corn, soybeans, cotton, and other row crops to kill existing vegetation. Paraquat is fast-acting, broad-spectrum, and inexpensive, which made it the dominant pre-plant herbicide for decades.

More than 60 countries — including the European Union, China, Brazil, and Switzerland (Syngenta's home country) — have banned paraquat. The U.S. EPA permits paraquat under Restricted Use rules: only certified applicators may buy or apply it. EPA's 2021 Interim Registration Review Decision required new label warnings about Parkinson's risk and additional applicator training, but did not restrict paraquat further.

How exposure happens

Most paraquat Parkinson's claimants were exposed occupationally — not in a single acute poisoning, but through years of repeated low-level dermal and inhalation exposure during routine agricultural work. The principal exposure routes:

• Mixing and loading. Paraquat is sold as a concentrate that must be mixed with water. Mixers and loaders work directly with the most concentrated form of the product.
• Application. Ground sprayers, hand-held sprayers, and aerial application all produce paraquat mist that can be inhaled or absorbed dermally.
• Equipment cleanup. Tank rinsing, hose flushing, and nozzle servicing produce repeated low-level contact.
• Re-entry. Workers who re-enter treated fields before the re-entry interval expires have documented elevated exposure.
• Drift. Paraquat drift from ground or aerial application has been documented in residences within drift distance of treated fields.

How paraquat causes Parkinson's disease

Paraquat is a redox-cycling compound. Inside cells, it accepts an electron, becomes a free radical, and donates that electron to oxygen — producing superoxide and other reactive oxygen species (ROS). Dopaminergic neurons in the substantia nigra of the brain are unusually vulnerable to oxidative stress because of their high mitochondrial demand, low antioxidant reserves, and reliance on dopamine itself (a redox-active molecule). Repeated paraquat exposure causes selective loss of these neurons — the same neurons whose progressive loss defines Parkinson's disease.

The peer-reviewed literature on the paraquat-Parkinson's link is mature. The Agricultural Health Study and multiple case-control studies have reported elevated Parkinson's incidence among workers with documented paraquat exposure, with effect sizes that increase with cumulative exposure. Read the full medical overview →

The defendants: Syngenta and Chevron

Syngenta AG is the principal global manufacturer of paraquat. Syngenta is the corporate successor to ICI Agrochemicals and Zeneca; the company was formed in 2000 in a merger with Novartis Agribusiness and was acquired by ChemChina in 2017. Syngenta is headquartered in Switzerland — a country that banned paraquat in 1989. More on Syngenta →

Chevron U.S.A. distributed paraquat in the United States under the Gramoxone brand for decades under arrangement with Syngenta's predecessor companies. As a distributor, Chevron shares product liability with the manufacturer. The April 2025 Syngenta settlement framework does not bind Chevron. More on Chevron →

MDL 3004: the federal hub

Federal paraquat Parkinson's cases are consolidated in In re: Paraquat Products Liability Litigation, MDL No. 3004, before Chief Judge Nancy J. Rosenstengel in the Southern District of Illinois. Thousands of cases are pending. The MDL handles coordinated pretrial proceedings — discovery, expert work, motion practice — but each plaintiff retains an individual claim and an individual recovery. MDL 3004 is not a class action.

Bellwether trials, Daubert rulings on causation, and the court's handling of expert reports have shaped the negotiating posture of both sides. The MDL's procedural posture determines when individual cases get worked up, when trials happen, and what causation evidence is admissible. Read MDL status update →

The Philadelphia state court mass tort

The Philadelphia Court of Common Pleas operates one of the most influential mass tort dockets in the United States. Its paraquat program — administered through the Complex Litigation Center under specialized case management orders before Judge Joshua Roberts — currently hosts approximately 1,799 active paraquat cases. The docket grows steadily as Pennsylvania's consent-by-registration jurisdiction becomes more widely understood.

The Philadelphia program moves cases faster than typical federal MDL bellwether tracks. The January 2026 Philadelphia bellwether settled confidentially on the courthouse steps, minutes before jury selection — a strong indicator of how Syngenta and Chevron view Philadelphia jury risk. Defendants do not settle bellwether cases on the courthouse steps when they like their odds. Full PA advantage breakdown →

The April 2025 Syngenta settlement framework

In April 2025, Syngenta publicly announced a settlement framework for a substantial portion of pending federal paraquat claims. The framework structures resolution through a court-supervised qualified settlement fund with points-based allocation that weighs factors including documented exposure history, age at diagnosis, severity of Parkinson's symptoms, comorbid conditions, and economic losses.

The framework does not extinguish liability for cases that opt out, and it does not bind Chevron. Pennsylvania state court claimants with strong facts may elect to prosecute in Philadelphia rather than opt into the federal framework — a strategic choice that depends on individual case strength and timing tolerance. Read the settlement framework breakdown →

Monsanto v. Durnell and federal preemption

Defendants in pesticide litigation routinely argue that state-law failure-to-warn claims are preempted by the federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). Monsanto v. Durnell, in the Roundup litigation, tests how aggressively defendants can use FIFRA preemption to shut down failure-to-warn claims. Whatever the Supreme Court ultimately decides will be applied by analogy in paraquat. A more aggressive preemption ruling would not eliminate paraquat claims — most include design defect and negligence theories that do not depend on label adequacy — but would narrow some theories and affect settlement valuations.

March 2026: Syngenta discontinues U.S. paraquat production

In March 2026, Syngenta announced that it would discontinue U.S. production of paraquat. The company framed the decision in commercial terms. Plaintiffs' counsel framed it in litigation terms. Both are right — and neither changes the fact that anyone exposed before March 2026 and diagnosed with Parkinson's disease retains a claim. Existing stocks of paraquat-based herbicides will continue to be sold and applied in the U.S. until exhausted, subject to EPA Restricted Use rules.

Litigation timeline 2021–2026

• 2021: MDL 3004 created by the Judicial Panel on Multidistrict Litigation
• 2023: Mallory v. Norfolk Southern upholds Pennsylvania consent-by-registration jurisdiction
• 2023–2024: Daubert rulings on plaintiffs' causation experts in MDL 3004
• April 2025: Syngenta announces settlement framework for federal paraquat inventory
• October 2025: U.S. Supreme Court declines to review Syngenta's challenge to Pennsylvania jurisdiction
• January 2026: First Philadelphia bellwether settles on the courthouse steps
• March 2026: Syngenta announces U.S. paraquat production discontinuation

For a fuller chronology going back to paraquat's 1962 introduction, see Paraquat Lawsuit Timeline.

What this means if you have a claim

Statutes of limitations continue to run regardless of where the litigation stands. The Syngenta settlement framework operates on a fixed registration window. Pennsylvania state court eligibility is currently broad, but defendants continue to test the doctrine.

The single most useful action you can take this month is a free case review. It takes 15 to 30 minutes by phone, costs nothing, and locks in your place while options remain open. Check your eligibility →