Paraquat Lawsuit Timeline: 1962–2026
Six decades of science, regulation, corporate change, and litigation — condensed to a working chronology.
ICI commercializes paraquat as Gramoxone
Imperial Chemical Industries introduces paraquat dichloride as a non-selective contact herbicide under the Gramoxone brand. The product rapidly displaces older soil-applied herbicides for pre-plant burndown.
First U.S. EPA registration (then USDA)
Paraquat is registered for U.S. agricultural use. Re-registration follows EPA's creation in 1970.
Early acute toxicity literature
First case reports of acute paraquat poisoning establish the compound's high acute toxicity profile, particularly for pulmonary effects after ingestion.
U.S. drug-enforcement paraquat spraying controversy
Mexican marijuana fields are aerially sprayed with paraquat under U.S.-funded programs, prompting consumer-exposure controversy.
Early Parkinson's hypothesis
MPTP-induced parkinsonism in heroin users (described by Langston and colleagues) sparks scientific interest in environmental causes of Parkinson's. Researchers note structural similarity between MPP+ and paraquat.
Switzerland bans paraquat
Switzerland — home of Syngenta's eventual headquarters — bans paraquat. Other European countries follow over the next decade.
Zeneca spin-off
ICI Agrochemicals becomes Zeneca in a corporate restructuring. Paraquat remains a flagship product.
Syngenta AG formed
Zeneca's agrochemicals division merges with Novartis's agrochemicals division to form Syngenta AG, headquartered in Basel, Switzerland.
European Union bans paraquat
The EU bans paraquat following litigation by Sweden challenging earlier authorization.
Tanner case-control studies
Caroline Tanner and colleagues publish a series of case-control studies reporting elevated odds ratios for Parkinson's disease among individuals with documented paraquat exposure.
Agricultural Health Study Parkinson's findings
The Agricultural Health Study, a large prospective cohort of licensed pesticide applicators in Iowa and North Carolina, reports elevated Parkinson's incidence among applicators with paraquat exposure.
ChemChina acquires Syngenta
China National Chemical Corporation (ChemChina) acquires Syngenta in a $43 billion deal. Syngenta remains headquartered in Basel.
EPA Interim Registration Review Decision
EPA permits continued paraquat use under Restricted Use rules with additional label warnings about Parkinson's risk and new applicator training requirements.
MDL 3004 created
The Judicial Panel on Multidistrict Litigation creates MDL 3004 — In re: Paraquat Products Liability Litigation — before Chief Judge Nancy J. Rosenstengel in the Southern District of Illinois.
Philadelphia mass tort program organized
Paraquat cases begin to consolidate in the Philadelphia Court of Common Pleas Complex Litigation Center, eventually growing to a docket of approximately 1,799 cases before Judge Joshua Roberts.
Mallory v. Norfolk Southern
U.S. Supreme Court upholds Pennsylvania's consent-by-registration jurisdiction statute against Due Process Clause challenge, opening Pennsylvania state court to out-of-state plaintiffs against registered corporations.
Daubert rulings in MDL 3004
Federal court issues rulings on plaintiffs' causation experts in MDL 3004. Procedural posture continues to shape settlement leverage on both sides.
Syngenta announces settlement framework
Syngenta publicly announces a settlement framework covering a substantial portion of pending federal paraquat claims. Framework operates through a qualified settlement fund with points-based allocation. Does not bind Chevron or extinguish opt-out liability.
Supreme Court declines Syngenta's PA jurisdiction challenge
U.S. Supreme Court declines to hear Syngenta's challenge to Pennsylvania consent-by-registration jurisdiction. PA state court remains open to qualifying non-PA plaintiffs.
Philadelphia bellwether settles on courthouse steps
First paraquat bellwether case in the Philadelphia mass tort program settles confidentially on the courthouse steps, minutes before jury selection. Settlement amount sealed. Re-prices the entire Philadelphia docket.
Syngenta discontinues U.S. paraquat production
Syngenta announces it will discontinue U.S. production of paraquat. Existing stocks continue to be sold under EPA Restricted Use rules. Discontinuation does not extinguish liability for past exposures.
Related reading: Litigation Overview · Syngenta · Chevron