Vermont has become the first US state to ban the weedkilling pesticide paraquat, a decision backed by lawmakers who cited research showing the chemical substantially increases the risk of Parkinson's disease, an incurable brain ailment. Governor Phil Scott signed the legislation on Tuesday, with the new law taking effect on 1 November. However, it includes a provision allowing state regulators to issue special permits for paraquat use on fruit-producing tree orchards, berries, and other "small fruit" crops until 31 December 2030.
Details of the Ban
The law also mandates annual data reporting on any paraquat use within the state and requires a state-funded study to explore alternatives to paraquat for farmers. Some lawmakers voiced concerns that the ban could hurt the competitiveness of Vermont farmers if the chemical remains legal in other states, and they argued that more research is needed to fully establish a link between paraquat and Parkinson's. However, others contended that the scientific evidence is robust and that the risks of not banning the chemical outweigh the benefits of keeping it on the market.
Scientific Evidence
Early versions of the law referenced multiple studies by the National Institutes of Health (NIH) demonstrating that paraquat exposure significantly increases the risk of Parkinson's disease. Lawmakers also noted that other NIH studies have linked paraquat to non-Hodgkin lymphoma and childhood leukemia. State Representative Michelle Bos-Lun stated during a 13 May House committee hearing, "There are so many factors that are pointing to the correlation between paraquat use and Parkinson's. We have to do something to phase this out. Our job is to support farmers and to support all Vermonters. My belief is that paraquat is causing harm to both."
Expert Opinions
Ray Dorsey, a neurologist who directs research into environmental causes of brain diseases at Atria Health and Research Institute, praised Vermont's action as "another step toward preventing this largely man-made disease." He noted that many countries have already banned paraquat and said it "is long overdue for the US to do the same." While Vermont is the first state to pass a ban, lawmakers in multiple other states have introduced similar legislation, and several federal lawmakers have also called for a nationwide ban on the chemical.
Background on Paraquat
Paraquat has been used in the United States since 1964 to kill broadleaf weeds and grasses. Although banned in several countries, it remains one of the most widely used herbicides in the US, applied to crops such as soybeans, cotton, corn, grapes, pistachios, peanuts, and many others. The chemical is extremely dangerous if ingested, even in small amounts, and regulators have issued warnings and restrictions due to poisoning risks. However, the link between paraquat and Parkinson's disease has been a subject of fierce debate.
Industry Response
Syngenta, the key manufacturer of paraquat for decades, has maintained that there is no credible evidence connecting the disease to its weedkiller. Nevertheless, numerous scientific studies have found that paraquat damages brain cells in ways that can lead to Parkinson's. Over 8,000 lawsuits are pending in US courts over the Parkinson's allegations. Syngenta has settled several cases without admitting liability and has been negotiating to settle a bulk of the ongoing cases. In April, the company announced it would stop making paraquat and would no longer attempt to sell paraquat products in the US and other countries, although generic versions remain available from other suppliers.
Public Health Implications
Bos-Lun remarked during the committee hearing, "If there is a chance that we could reduce the harm by making this step, it feels like that is a responsible thing to do. When I think about the people I've known who've had Parkinson's, we want to do everything we can to avoid that. Every case that we could prevent, that would be a blessing." According to the World Health Organization (WHO), the number of people suffering from Parkinson's has more than doubled in the last 25 years, and incidences are expected to continue rising. Parkinson's symptoms develop when dopamine-producing neurons in the brain degenerate, and the disease is progressive, leaving individuals unable to speak and move normally.
Historical Context
A trove of internal corporate records dating back several decades shows that Syngenta and its predecessor entities have grappled with concerns about paraquat's links to Parkinson's and other chronic health issues for years. The Guardian revealed many of Syngenta's internal files on paraquat in 2022 and 2023, showing that the company employed secretive tactics to hide or downplay research linking its chemical to the disease, discredit independent research, and influence regulatory decisions to protect paraquat sales. Dan Feehan, chief policy and government affairs officer for the Michael J Fox Foundation for Parkinson's Research (MJFF), a key group advocating for paraquat bans, stated, "The evidence linking paraquat exposure to increased Parkinson's risk is strong and has been building for decades. Other states should follow Vermont's lead – and the federal government has an obligation to protect all Americans with a national paraquat ban."
This story is co-published with the New Lede, a journalism project of the Environmental Working Group.
