Syngenta settles bellwether US trial over paraquat links to Parkinson’s

On the eve of the opening of what would have been a bellwether US trial over allegations that a widely used weed killer causes Parkinson’s disease, paraquat-maker Syngenta reached a settlement with the retired landscaper who blamed the company for his diagnosis with the incurable brain disease.

The trial, which was set to open Wednesday in Philadelphia, was to be the first public examination of evidence that Syngenta’s paraquat weed killing products can cause Parkinson’s. Syngenta’s paraquat-based Gramoxone herbicide brand is popular with US farmers.

The case was expected to spotlight decades of scientific research and a cache of internal corporate files related to the safety of paraquat and specifically the impacts exposure to the chemical can have on the brain. It was expected to be closely watch as US regulators are in the middle of a years-long review of paraquat and there are growing calls for a US ban on paraquat because of health concerns. New legislation seeking bans on paraquat were introduced this month in Pennsylvania, Missouri and Vermont.

Paraquat has been used in the United States since 1964 as a tool to kill broadleaf weeds and grasses. Though banned in several countries, it remains popular with US farmers for use in growing soybeans, cotton, and corn as well as in growing grapes, pistachios, peanuts and many other crops.

The chemical is known to be extremely dangerous to anyone who ingests even a small amount, and regulators have issued warnings and placed restrictions on its use because of poisoning risks. But whether or not it causes Parkinson’s disease is a matter of fierce debate. Syngenta maintains that there is no credible evidence of a connection between the disease and its weed killer.

Still, more than 8,000 lawsuits have been filed across the US against Syngenta by people alleging paraquat exposure caused them to develop Parkinson’s. Several other trials are planned later this year, though Syngenta has been negotiating to settle a bulk of the cases.

So far, Syngenta has settled each case set for trial before the trial takes place, paying more than $187 million to settle one multi-plaintiff case.

Alongside Syngenta as a defendant in the nationwide litigation is Chevron, which distributed paraquat products made by Syngenta for many years before ending the arrangement in 1986. Chevron has no involvement in the business any longer, and maintains it should not be part of the litigation. Both companies deny any liability.

The terms of the settlement in the Philadelphia case were not disclosed. The plaintiff in that case, 77-year-old Bill Mertens, operated a landscaping business in the 1980s and 1990s, mixing and spraying paraquat as part of his work, his lawsuit states. Mertens wore personal protective clothing and equipment but still was exposed by inhaling paraquat and through his clothes and skin, according to the lawsuit. He was diagnosed with Parkinson’s in 2021.

“Chevron and Syngenta are very bad companies who hurt a lot of people with their killing agent, paraquat,” said Aimee Wagstaff, lead lawyer for Mertens. “On the eve of opening, the parties have decided that resolution is the best path for this particular matter. We are very happy with the result for our clients and are already looking forward to holding these companies accountable when we begin our next trial in April.”

Chevron declined to comment. Syngenta did not respond to a request for comment.