Vermont has become the first US state to ban paraquat, amid concerns over studies linking the herbicide to Parkinson’s disease.
Phil Scott, the governor, signed the legislation on Tuesday.
The new law takes effect on November 1, although it allows state regulators to issue special permits for paraquat use on fruit-producing tree orchards, berries and other small fruit crops until December 31, 2030.
Michelle Bos-Lun, a state representative, told a House committee hearing on May 13: “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.”
Some lawmakers raised concerns that a ban could affect the competitiveness of Vermont farmers if the chemical remains available in other states.
They also said more research was needed to fully establish a link between paraquat and Parkinson’s.
Other supporters of the ban argued that the scientific evidence was well established and that the risks of not banning the chemical outweighed the risks of keeping it on the market.
Early versions of the law cited studies by the National Institutes of Health linking paraquat exposure to a substantially increased risk of Parkinson’s disease.
Lawmakers also noted that other NIH studies have linked paraquat to non-Hodgkin lymphoma and childhood leukaemia.
Ray Dorsey, a neurologist who directs research into environmental causes of brain diseases at Atria Health and Research Institute, said Vermont’s action was “another step toward preventing this largely man-made disease”.
He said many countries had banned paraquat and said it “is long overdue for the US to do the same”.
Although Vermont is the first US state to pass a ban, lawmakers in several other states have introduced legislation to ban paraquat.
Several federal lawmakers have also called for restrictions on the chemical.
Paraquat has been used in the US 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.
It is used in the production of crops including soybeans, cotton, corn, grapes, pistachios, peanuts and many other crops.
The chemical is known to be extremely dangerous if even a small amount is swallowed, and regulators have issued warnings and restrictions because of poisoning risks.
However, whether paraquat causes Parkinson’s disease remains contested.
Syngenta, a key maker of paraquat for decades, has maintained there is no credible evidence of a connection between the disease and its weedkiller.
Numerous scientific studies have found that paraquat damages brain cells in ways that can lead to Parkinson’s, and more than 8,000 lawsuits are pending in US courts over the allegations.
Syngenta has settled several cases without admitting liability before they went to trial and has been negotiating to settle a bulk of the ongoing cases.
In April, the company said it would stop making paraquat and would no longer try to sell paraquat products in the US and other countries, although generic versions remain available from other suppliers.
Bos-Lun said: “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.”
The number of people living with Parkinson’s has more than doubled in the past 25 years, according to the World Health Organization, and cases are expected to continue rising.
Parkinson’s symptoms develop when dopamine-producing neurons in the brain degenerate.
Dopamine is a chemical messenger involved in movement, motivation and other brain functions.
As the disease progresses, people can lose the ability to speak and move normally.
Internal corporate records dating back several decades have shown Syngenta and its predecessor companies examined concerns about possible links between paraquat and Parkinson’s, as well as other chronic health issues.
The Guardian reported in 2022 and 2023 that internal Syngenta files showed the company used tactics to hide or downplay research linking paraquat to Parkinson’s, 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, said: “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.”
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