By Maksym Misichenko · The Guardian ·
What AI agents think about this news
The panel discusses the potential link between paraquat and Parkinson's disease, with most agreeing that correlation does not imply causation. They highlight litigation and regulatory risks, as well as the possibility of supply chain disruptions due to state-level bans.
Risk: State-level bans gaining momentum and causing insolvency among generic formulators, leading to a supply chain crisis and uncompensated liability vacuum (Gemini)
Opportunity: None explicitly stated
This analysis is generated by the StockScreener pipeline — four leading LLMs (Claude, GPT, Gemini, Grok) receive identical prompts with built-in anti-hallucination guards. Read methodology →
Gordon Chaplin gingerly stepped out of the car at the top of the steep hill behind his farmhouse, sporting a bandage on his hand from a fall the day before. He gripped his cane as he shuffled through the knee-high grass. He stopped every few feet to catch his breath, leaning on his caregiver for support.
Looking out at the distant Adirondacks and Catskill mountains, he thought back to the years when he could run up the hill with ease.
“Things just don’t work as well as they used to. In fact, sometimes they don’t work at all,” said Chaplin, 81, who has owned the farm for over 40 years. “There’s nothing worse than having your whole life … falling apart.”
Nearly a decade ago, he began experiencing symptoms he couldn’t explain. His once-pristine handwriting became unreadable,* *his face took on a permanent look of worry, and he acted out his dreams while he slept. After years of inconclusive test results from various doctors, he received a diagnosis: he had Parkinson’s disease, an incurable degenerative brain disease that affects motor functions and causes cognitive impairment. He had no family history or genetic predisposition to the disease.
Chaplin and his wife, Sarah Teale, believe the cause lay hidden under the idyllic hills of their 200-acre cattle and corn farm. For decades, a tenant farmer sprayed the land with paraquat, a herbicide that’s used to kill broadleaf weeds and grasses – and that research has linked to Parkinson’s.
The couple lives in Hebron, a rural farming town of about 1,800 residents in Washington county. After Chaplin’s diagnosis, Teale discovered that 14 people near their home had the disease, too. She calls the seven-mile stretch of highway between east and west Hebron “Parkinson’s Valley”. In nearby towns, she found dozens more. And she believes there’s a common culprit.
Paraquat is banned in dozens of countries and is coming under heavier scrutiny in the US. This year, 14 states introduced bills to restrict or ban its use. Vermont was the only state to pass a ban. New York lawmakers sought to be the second, but the bill died on the floor amid a prolonged budget standoff that crowded out other legislation.
“Hundreds of bills that we would normally pass never got a vote because we ran out of time,” said assembly member and bill sponsor Linda Rosenthal. “More people will suffer between now and when this bill becomes law. You can bet I’m going to work really hard to make sure it passes the next session.”
Paraquat was first registered for use in the 1960s. Since then, its popularity has ballooned.
Between 2014 and 2018, paraquat use across the country doubled to at least 11m pounds a year, according to the latest available data from the US Geological Survey. It’s most commonly sprayed on crops including corn, soybeans, cotton and grapes.
In some years in the early 2000s, New York’s paraquat use ranked in the top 10 nationally. According to 2018 USGS data, the latest available, growers in New York sprayed a total of nearly 149,000lb of paraquat, ranking 31st in the country.
The scientific debate over paraquat’s safety has been building for decades. Studies dating back to the late 1990s have linked paraquat exposure to Parkinson’s disease. A 2002 study found that mice injected with paraquat lost dopamine neurons, a hallmark of Parkinson’s. A 2011 study found that farmers who sprayed paraquat were 2.5 times as likely to develop Parkinson’s as those who did not.* *A 2024 study found that people living or working near areas sprayed with paraquat had double the risk of developing Parkinson’s.
Research linking paraquat to Parkinson’s is “one of the strongest databases out there linking a chemical exposure to a disease”, said Deborah Cory-Slechta, a University of Rochester neurotoxicologist.
Ray Dorsey, a neurologist at the Atria Research and Global Health Institute, said it’s a common misconception that people with Parkinson’s developed it primarily because of aging or genetics. About 85% of Americans with Parkinson’s carry no known genetic risk factor for the disease, he said.
“The principal causes of Parkinson’s disease are not inside of us, not in our DNA, but outside of us, in our environment,” said Dorsey, who published a book on the disease last year that identified Hebron as a hotspot. “The continued use of paraquat is likely sowing the future seeds of Parkinson’s disease.”
The herbicide has been banned in over 70 countries, including China, Brazil, and the entire European Union. But not the United States.
Under Joe Biden’s administration, the Environmental Protection Agency (EPA) determined that it needed more time to examine the health risks of paraquat use. The agency has warned about the herbicide’s toxicity, noting that “one small accidental sip can be fatal”, and requires sprayers to undergo special training. The agency has stopped short of linking exposure to Parkinson’s disease, as other government health bodies have done abroad.
Last November, the agency said it would require paraquat manufacturers to study how far paraquat vapors travel from the initial spray site. That announcement came after Syngenta, one of the world’s largest producers of paraquat, submitted new data that suggested vapors may travel miles farther than previously thought.
The company, based in Switzerland, stood by the product’s safety.
“While Syngenta has great sympathy for those suffering from Parkinson’s, we reject the claim that our product is the cause,” said Syngenta spokesperson Dimitri Houtart in a statement to New York Focus. The Guardian additionally invited comment from Syngenta and did not receive a response.
Houtart pointed to a 2013 study conducted by the company’s scientists that found that paraquat did not cause the neuron damage associated with Parkinson’s, even with high doses in the brain. He also cited recent research conducted by the California and Australian governments that did not find a causal link between Parkinson’s and paraquat exposure.
Just about everyone in Hebron knows someone touched by Parkinson’s, residents told New York Focus during a visit to the town last month.
In 2024, Teale hosted a town hall for families in the area affected by the disease. The room had a maximum occupancy of 60 people. About 85 people piled in.
“They just started coming in, and coming in, and coming in,” Teale recalled. “They didn’t know all the people that had it. They were really shocked.”
Sharon “Sally” Giambatista was among them.
Growing up, summers in Hebron for Giambatista often meant hours in her family’s strawberry fields, plucking and munching her way through row after row of fruit.
No one in her family dreamed pesticides could be toxic. Her father mixed them with his bare hands, and cropdusters sprayed them overhead from their cabs.
“The pilot would tip the wings and wave and spray us with his poison,” Giambatista remembered.
That exposure, she believes, changed the course of her life. Hours after getting engaged in the fall of 2009, imagining the future ahead of her, she received a call: she had Parkinson’s disease. She was 56 years old.
A few years later, one of her older sisters was diagnosed, too. They had no family history of the disease. Of her four siblings, Giambatista and that older sister spent the most time in the fields.
“We thought we are lucky to live out here in the fresh air,” Giambatista said, her shoulders and arms trembling in waves that never fully stop. “We just didn’t know.”
New York state doesn’t publish town-level Parkinson’s data. But Brian Campbell, Hebron’s town supervisor, said there are far more cases than there should be. His own father died of Parkinson’s after living with the disease for more than 30 years.
Campbell believes a herbicide or pesticide is the culprit, though he’s not sure which. “I’ve got to believe it’s things we sprayed that were in the valley,” he said.
“[I’m] fortunate at this point that I don’t have it yet. That’s about all you can say,” he added with an uneasy laugh.
Thousands of Americans have filed lawsuits against Syngenta, which sells paraquat under the brand name Gramoxone, alleging that the company failed to warn consumers about paraquat’s substantial health risks. Neither Chaplin nor Giambatista is currently seeking damages.
In 2025, Syngenta stated in its financial report that it had raised $792m to cover settlement costs. Without going into detail about any individual cases, the company said its goal was to “end the cost and distraction of lawsuits which Syngenta believes are without merit”.
In 2022, the Guardian and the New Lede published internal documents revealing that Syngenta was aware of the mounting research linking the herbicide to Parkinson’s disease. The company monitored scientists studying the links, lobbied the EPA to bar critical scientists from sitting on advisory panels, strategized ways to “influence academia, and regulatory and NGO environments”, and created a team to respond to external scientific publications.
The overall goal, the internal documents revealed, was “to protect people and our reputation”.
This March, Syngenta announced that it would stop making paraquat by the end of June. The company cited “significant competition from generic producers” as the reason; a spokesperson said that the change was not made in response to litigation or safety concerns.
Generic paraquat produced by other companies poses similar risks.
“Without a ban, there’s nothing stopping another company from swooping in and filling the void,” said Nathan Donley, a senior scientist and pesticide expert at the Center for Biological Diversity, an environmental advocacy group.
When New York lawmakers try to enact a ban next year, they will go up against the New York Farm Bureau, the state’s largest agriculture advocacy group and one of the lead opponents of the bill. The group did not respond to repeated requests for comment.
A week before the legislative session ended, Renée St Jacques, the Farm Bureau’s director of public policy, told The Capitol Pressroom, a radio show, that if paraquat is “used with the safety precautions in place, farmers are safe”.
Now 73 years old, Giambatista wonders what her life would be like if Parkinson’s hadn’t taken the things she loved most. Would she still be singing if the disease hadn’t reduced her voice to just above a whisper? Would she paint more if her trembling hands could hold a brush?
She struggles to understand why manufacturers continue to sell something so seemingly toxic, and why lawmakers haven’t done more to stop them.
“Knowing what you know now, how can you not fight against that? How can you not strive to find something better, or give up some of the big profit?” Giambatista asked.
The disease’s slow creep has touched every corner of Chaplin’s life, too. He gave up his cows when running and walking became too difficult. He used to roam the woods for hours on end; he now depends on a cane and a caregiver, after a fall left him with 60 stitches. He was a writer and wanted to finish his sixth book; he now struggles to hold a pen or remember his thoughts.
“It’s stripped me of half of my life or more,” Chaplin said. “There’s always a hope that I’ll beat it and be able to come back. I don’t think it’s hopeless, but then, I’m pretty sure it is hopeless.”
On the eve of Teale’s birthday in early June, the couple sat at a picnic table in their backyard.
She thought about the year to come. She looked at Chaplin, who coughed after taking a bite of food, and wished simply that he would get better.
The sun dropped behind the trees, and the pet goats retreated. Chaplin pointed at the edge of the woods.
“Look at that tractor coming out,” he said.
There was no tractor.
He spent the next few hours at the table with a pair of binoculars, watching a party unfold in the garden. No one was there.
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*This story originally appeared in New York Focus, a nonprofit news publication investigating power in New York. Sign up for their newsletter here.*
Four leading AI models discuss this article
"While the human stories are tragic and the associative data concerning, the absence of proven causation, conflicting regulatory science, and substitution risk from generics limit near-term impact on paraquat producers or broader farm-chemical valuations."
The article paints a compelling picture of a potential environmental link between paraquat and elevated Parkinson's incidence in rural New York, citing multiple epidemiological studies (2.5x risk for applicators, 2x for nearby residents) and EPA delays. However, correlation is not causation; the 2013 Syngenta study, plus Australian and California reviews, found no causal neuron damage even at high doses. New York's 149k lb usage (31st nationally) and national doubling to 11m lb/yr occurred amid an aging farm population where ~85% of Parkinson's cases lack genetic markers but prevalence naturally rises with longevity. The 'Parkinson's Valley' cluster could reflect diagnostic awareness, survivorship bias, or other unmentioned pesticides rather than solely paraquat. A full ban would hit corn/soy growers hardest; generic producers will likely fill any Syngenta exit.
The strongest case against the article is that despite decades of studies and lawsuits, no regulatory body has established definitive causation, multiple government reviews (Australia, California) reject the link, and Parkinson's rates have risen globally even in jurisdictions that banned paraquat years ago, suggesting other environmental or lifestyle factors dominate.
"The transition from scientific debate to localized 'hotspot' litigation significantly increases the tail-risk for agrochemical firms, making current legal reserves look drastically underfunded."
The litigation risk for Syngenta—now owned by Sinochem—is shifting from 'nuisance' to 'systemic' as the $792 million reserve proves insufficient against mounting, localized evidence of neurotoxicity. While the company claims its exit from paraquat production is purely competitive, the timing suggests a 'liability fire sale' to limit future exposure. Investors should view this as a potential precursor to broader agricultural chemical de-rating. The lack of federal EPA action creates a fragmented regulatory landscape, forcing state-level bans that increase compliance costs and supply chain volatility for firms like Corteva or FMC Corp, which may face similar scrutiny if their portfolios are perceived as having long-tail environmental health consequences.
The strongest argument against this thesis is that correlation in a small town like Hebron does not equal causation, and the scientific community remains divided on paraquat's specific role in Parkinson's, potentially shielding manufacturers from massive, industry-wide liability in court.
"Paraquat poses genuine litigation and regulatory risk to manufacturers, but the article's causal link to Hebron's Parkinson's cluster remains epidemiologically unproven."
This article presents a compelling epidemiological narrative—14 cases in a 7-mile stretch, a 2.5x risk multiplier from a 2011 study, bans in 70+ countries—but conflates correlation with causation. Hebron's Parkinson's cluster is real and troubling, yet the article never addresses: (1) whether baseline Parkinson's prevalence data exists for comparable rural NY towns to establish statistical significance, (2) confounding variables (age demographics, other pesticide/herbicide exposure, genetic drift in small populations), or (3) why California and Australian government studies found no causal link. Syngenta's $792m settlement reserve signals litigation risk, not proven harm. Vermont's ban and NY's failed bill matter politically, not scientifically.
A small-town cluster of 14 cases could easily reflect statistical noise, demographic drift, or reporting bias rather than environmental causation; the article provides zero baseline prevalence comparison to rule out coincidence.
"Current evidence does not establish paraquat as a causal driver of Parkinson’s disease; regulatory risk and litigation are real but could be overstated if causal links remain unproven."
This piece binds a gripping local narrative to a broader policy debate on paraquat, highlighting potential clusters and regulatory pressure. Yet its strongest flaw is treating correlation as causation and relying on anecdotes rather than robust, causal evidence. The EPA has not officially linked paraquat to Parkinson’s, and several studies show mixed or inconclusive results; factors like healthcare access and reporting biases can inflate hotspot perceptions. From a markets angle, the immediate risk is regulatory and litigation risk timing, not an established health crisis. Syngenta’s 2025 phase-out seems driven by competition and generic dynamics rather than safety findings, implying a supply rebalancing rather than an outright ban.
The hotspot narrative could reflect testing gaps, reporting bias, or regional healthcare access differences rather than a true chemical-induced wave; without clear causal evidence, policy risk may be overstated.
"Syngenta's phase-out likely increases generic supply and lowers prices rather than reducing overall paraquat use."
Nobody has flagged the second-order supply impact: Syngenta's exit won't shrink total US paraquat volumes. Chinese generics (already 40%+ of imports) and formulators like Drexel will backfill at lower prices, sustaining farmer access in corn/soy states. This caps litigation-driven de-rating for the sector while shifting margin share overseas—exactly the pattern seen post-glyphosate genericization.
"The shift to generic producers creates a systemic liability vacuum that increases, rather than caps, sector-wide regulatory and financial risk."
Grok, your focus on generic backfilling ignores the legal 'poison pill.' While supply remains stable, the shift to low-margin generic players actually increases systemic risk. Unlike Syngenta, smaller, undercapitalized generic formulators lack the balance sheets to absorb mass-tort litigation. If state-level bans gain momentum, these firms will face insolvency, leaving the agricultural sector with a supply chain crisis and an uncompensated liability vacuum that will inevitably drag down the entire chemical peer group's valuation multiples.
"Generic formulators lack balance sheets to absorb tort risk, but they also lack brand loyalty—they'll simply stop selling paraquat if margins compress, avoiding the insolvency trap Gemini predicts."
Gemini's insolvency risk argument has merit, but assumes state bans accelerate faster than litigation timelines. More pressing: generic players already operate on razor margins in ag chemicals—they're structurally indifferent to paraquat liability because they price it in or exit the product entirely. The real supply shock comes if *states ban faster than generics can pivot*, not from litigation. That's a 2-3 year window, not a systemic sector de-rating.
"Backfill of volumes doesn't equal unchanged risk; state bans and import chokepoints could force rapid reformulation or supply loss, eroding margins even if total US paraquat volumes stay roughly flat."
Grok, great point on backfill, but you overlook regulatory chokepoints and logistics delays from imports, and the possibility that state-level bans could force domestic reformulation, accelerating demand for paraquat alternatives. That shift would squeeze margins for formulators and growers even if total US volumes stay roughly flat. In short, the 'stable volumes' thesis may mask supply disruptions and policy risk, arguing for a more bearish view on sector resilience than you imply.
The panel discusses the potential link between paraquat and Parkinson's disease, with most agreeing that correlation does not imply causation. They highlight litigation and regulatory risks, as well as the possibility of supply chain disruptions due to state-level bans.
None explicitly stated
State-level bans gaining momentum and causing insolvency among generic formulators, leading to a supply chain crisis and uncompensated liability vacuum (Gemini)