Makers of Paraquat Herbicide Must Answer for Causing Parkinson’s Disease, Personal Injury Suits Claim


Agricultural workers are seeking to hold crop protection products manufacturer Syngenta AG liable for an herbicide they claim causes Parkinson’s disease.

Lawsuits filed in San Francisco Superior Court contend that Syngenta AG and Syngenta Crop Protection, LLC, Chevron USA, Inc., Wilbur-Ellis Company, LLC, their predecessors-in-interest, and 60 presently unknown entities violated various product liability and tort laws by making and selling a product they knew or should have known had harmful side effects.

The filings detail the history of paraquat’s creation in 1962, market entry into the United States, and regulatory approval. In support of their argument linking the herbicide and the disease, the filings cite numerous studies and point to scientific conclusions. They describe how “convergent lines of evidence (toxicology, animal experiments, and epidemiology) demonstrate that paraquat exposure generally can cause Parkinson’s disease.”

The complaints aver that “[t]he risk of contracting Parkinson’s disease from chronic, low-dose exposure to paraquat presented a substantial danger to users of paraquat when the product was used in a reasonably foreseeable manner.” The filings state that despite the United States Environmental Protection Agency’s (EPA) determination that paraquat met Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) registration criteria, paraquat may be misbranded, failing to advise users of exposal consequences. However, the filings make clear that the plaintiffs do not bring any FIFRA claims.

One complaint, filed by plaintiff David Hanse and his wife, claims that the plaintiff was exposed to the chemical when he worked at various central California farms from 1967 to 2011. His work reportedly included mixing, loading, applying, and cleaning up paraquat, in addition to supervising those processes. He was also allegedly exposed to the chemical in wind drift from crop dusting sprayers and when he rode the spray rig to monitor its progress. The complaint states that Hanse was diagnosed with Parkinson’s disease in 2018.

For plaintiff Hanse’s part, he claims that the defendants’ tortious conduct has caused him personal injuries and his wife to suffer loss of consortium. The personal injury plaintiffs all seek damages and attorneys’ fees, amongst other requests.

The plaintiffs are represented by Walkup, Melodia, Kelly & Schoenberger.