Internal documents have exposed Syngenta’s decades-long strategy to protect sales of paraquat as evidence grew linking the widely-used herbicide to Parkinson’s disease. Help us push lawmakers to join 58 other countries and finally end its use in the United States. Action Alert!
Syngenta and its former American sales partner Chevron USA are being sued by thousands of farm workers who claimed they developed Parkinson’s disease from paraquat exposure. A judge in that case ordered the two companies to surrender thousands of internal papers, handwritten memos and emails dating back decades. The Guardian and The New Lede reviewed these files and found that Syngenta’s public stance on paraquat doesn’t always match what the company has said and done behind closed doors. We cannot allow the EPA to drag its feet on yet another dangerous chemical that endangers public health but benefits corporate profits.
While these documents do not indicate that Syngenta privately believes paraquat causes Parkinson’s, they do show voices inside the company have long worried what a potential link might mean. Syngenta spent years working to dissuade the public, influence regulators and muddle the science, all to protect its blockbuster product. The files also reveal Syngenta’s successful behind-the-scenes efforts to keep an influential scientist off a key Environmental Protection Agency panel.
The issue isn’t whether paraquat is dangerous – even the EPA considers it highly toxic. A small sip is enough to kill you and there is a long history of people consuming it for suicide. Users are advised to wear gloves, boots and other protective clothing when they apply paraquat and no one in the United States can buy it unless certified in its use. Scientists pushed for odd coloring and foul odors to be added to it so people didn’t drink it by accident. One expert has called it the “most deadly killer since the atom bomb.”
Far more countries currently ban paraquat than allow it, including the United Kingdom, where it’s made, and Switzerland and China, home of Syngenta and its new corporate parent ChemChina. But United States regulators continue to give the chemical a green light, despite mounting evidence linking paraquat to long-term health problems, most notably Parkinson’s disease.
Parkinson’s is the fastest-growing neurological condition on the planet, with cases worldwide expected to double in the next two decades. It has been ranked among the top 15 causes of death in the United States, where 60,000 new cases are reported each year. The disease develops when brain cells that make dopamine stop working or die, leading to tremors, limb stiffness, balance issues and difficulty moving. These symptoms worsen over time.
The documents show that a scientist for Syngenta predecessor Imperial Chemical Industries (ICI) raised a red flag in 1958, several years before paraquat was introduced. The researcher told a colleague about an internal study that lab animals exposed to the paraquat-related substance dipyridyl appeared to have central nervous system problems. Further animal research in the 1960s and 1970s pointed in this same direction, though the company always claimed that high doses given to rats and mice in these tests wouldn’t translate to a human risk.
By the 1970s, concerns were growing about field workers who used paraquat. The documents show that Chevron pressed ICI for assurance about paraquat’s safety after some of its own employees developed nosebleeds, sore throats and other issues. Chevron leaders circulated a 1985 memo that Canadian researchers found an “extraordinarily high correlation” between Parkinson’s and use of paraquat and other pesticides. Chevron left the paraquat business the following year. While the company maintains that market forces drove the move, internal memos indicate top executives worried about the long-term liability of continuing to sell the product.
As outside scientists built more connections between paraquat and Parkinson’s disease, Syngenta countered with research of its own. Company scientists would replicate those independent studies, but used alternative counting methods and avoided measuring paraquat levels in the brain. This allowed Syngenta to say its own tests never found definitive evidence linking the herbicide to Parkinson’s, making the overall body of research less conclusive in the eyes of the public – and regulators.
The EPA twice considered adding pesticide expert Dr. Deborah Cory-Slechta to its advisory panels. She has done extensive work on the effects of paraquat on laboratory animals. Internal documents show Syngenta fought hard to discredit Dr. Cory-Slechta and derail her appointment, saying that having her on the committee would be “a real disaster.” Syngenta did much of this work through advocate Crop Life, shielding much of the company’s direct involvement. Dr. Cory-Slechta was ultimately never nominated.
A few years ago, it looked like the EPA was finally ready to act on paraquat. In 2019, the agency sought public comment on the chemical and later recommended a ban on nearly all aerial applications of it. In 2021 however, the agency reversed itself and re-registered paraquat for 15 years with only limited new restrictions on application protocols and a stronger warning label.
A number of environmental and healthcare advocates sued the EPA over that decision, accusing it of largely basing its findings on evidence provided by the Agricultural Handler Exposure Task Force, an agricultural chemical advocacy group that includes Syngenta as one of its founders. The agency asked a judge this fall for permission to reconsider its decision and pledges to re-review the evidence and issue a revised report next year. Tired of waiting, many of the same advocates in the EPA lawsuit called on California and other states to take action on their own.
We agree with them that enough evidence points to a connection between paraquat and Parkinson’s disease to justify urgent action. Syngenta’s campaign to muddle the growing body of research cannot be allowed to succeed. Another year of delays caused by the EPA’s reliance on industry-friendly data means another year where paraquat can be applied to 15 million acres across America and the foods we eat that grow there. Given the EPA’s track record on PFAS, glyphosate, and other hazardous chemicals it allows on the market, we cannot trust the agency to do the right thing without public pressure.
Action Alert! Write to Congress and the EPA, telling them to ban paraquat now. Please send your message immediately.
