Vermont Becomes First State To Ban Toxic Weedkiller Paraquat After Decades Of Neurological Concerns

Vermont has now banned the highly toxic herbicide paraquat, and is the first state in the country to do so. Governor Phil Scott signed the bill into law on May 26, 2026, which prohibits sales and use beginning November 1, 2026, with phased exemptions and transition periods for orchards, berries, and small fruit. By December 31, 2030, the herbicide will no longer be used for any crops in the state of Vermont.

Paraquat is a Restricted Use Pesticide in the US and requires certified applicators. Consuming or inhaling as little as one teaspoon of paraquat can lead to death, and there is no antidote for Paraquat poisoning. Poisoning can occur from improper storage or transfer into unmarked containers. Serious side effects from paraquat poisoning include rapid multi-organ failure and damage to the kidneys, liver, and heart.

There has been a known association between long-term paraquat exposure and Parkinson’s Disease for over three decades and multiple research studies that show people who live or work near areas with high levels of paraquat spraying have a higher likelihood of getting Parkinson’s. A 2011 NIH-funded study found farmworkers exposed to paraquat were 2.5 times more likely to develop the disease.

70 countries have banned the chemical across the world, including all 27 countries in the European Union, the United Kingdom, Switzerland, and Brazil. There is a domestic ban in China and the product is not sold, manufactured, or readily available in Canada.

Companies like Chevron who distributed paraquat dating back to the 1970s had internal research and worker reports raising concerns about potential neurological effects and possible brain accumulation. Over 50 years later and the chemical is still being used in the US with Vermont being the first state to take definitive action against the chemical.

In 2018, there was an estimated 17 million pounds of paraquat applied onto US farmland, which is more than double the amount used in 2008.

The most well-known brand that uses Paraquat as an active ingredient is Gramoxone, which is manufactured by Syngenta. The company announced in April that it will be ceasing global production of the herbicide by the end of June and will stop selling the product by the end of 2026. The company expressed that competition from smaller manufacturers and brands played a role in its decision to stop producing the herbicide. Those brands are expected to fill in the gaps when Syngenta ceases production at the end of this month.

In 2022, an investigative collaboration between The New Lede and The Guardian revealed that Syngenta and its predecessor company had documented evidence of paraquat’s potential to accumulate in brain tissue. The company had investigated possible neurological effects and found adverse effects on brain tissue, but allegedly withheld that information from regulators and downplayed similar findings by independent scientists according to the New Lede/Guardian report.

Chevron was a distributor for Syngenta and predecessor companies (Imperial Chemical Industries) and was concerned about liability for neurological harms dating back to 1975 – over 50 years ago. Chevron representatives were concerned about central nervous system damage and noted there were sore throat and nosebleeds occurring for workers in the plant. Chevron stopped distributing the chemical in 1986 and noted competition as the primary reason rather than harms caused by the product. This mirrors Syngenta’s recent statements about ceasing production of the chemical this month.

Chevron was looking to obtain “more positive data” to counter the looming data that would be used against them in court. An ICI scientist said he did not believe a “satisfactory investigation” could be made, but they could develop a plan.

The journalistic investigation found that Chevron, ICI, and Syngenta all downplayed known links and mechanisms that paraquat could cross the blood-brain barrier while creating a public relations plan to tell regulators and the public that the chemical is safe.

There are more than 6,000 pending lawsuits in the federal multidistrict litigation with more cases in state courts. Plaintiffs are arguing that manufacturers failed to warn about Parkinson’s risks despite internal knowledge. Independent studies also found a connection to Parkinson’s and those studies were reviewed by the EPA, but the federal agency concluded that there was not enough to show a causal link.

Pesticide and herbicide manufacturers face liability primarily from failure-to-warn lawsuits, but they argue that EPA approval of the warning label is preemption and protects them from these types of liability claims. That is precisely the case that is going before the Supreme Court this session with Bayer’s preemption claim for glyphosate. If the court rules in favor of Bayer,

If the court issues a ruling in favor of Bayer, then any ongoing failure-to-warn cases would be ruled in favor of the manufacturer based on the Supreme Court’s precedent. Any cases won by the plaintiff that are actively being appealed by the manufacturer would also likely be overturned in favor of the producer based on the Supreme Court’s decision.

Bayer has reformulated some versions of Roundup to remove glyphosate in favor of diquat, which is considered a similar herbicide to paraquat. The HighWire reported about the Friends of the Earth evaluation that found the diquat formulation is 45 times more toxic than the glyphosate version. Podcaster Dana Parish told The HighWire about her dog’s poisoning from diquat spraying at her California HOA. About 300,000 pounds of diquat is used annually in the US. All European Union nations and the United Kingdom banned the use of diquat in 2019 and 2020.