Syngenta to Stop Paraquat Production Amid Parkinson’s Lawsuits & Safety Concerns

Syngenta, a global chemical company, announced Tuesday it will cease production of its paraquat-based weed killer by the end of June. The decision comes amid mounting legal challenges linking the pesticide to Parkinson’s disease, though the company cites market factors as the primary driver. This move represents a significant development in a long-running debate over the safety of paraquat, a herbicide widely used in American agriculture for decades.

For farmers, paraquat has been valued for its effectiveness in controlling a broad spectrum of weeds in crops like soybeans, cotton, corn, grapes, pistachios and peanuts. However, its use has been banned in over 50 countries, including throughout Europe, due to concerns about its toxicity. The United States remains a key market for the product, and other companies continue to manufacture generic versions of the herbicide.

A History of Controversy and Litigation

The core of the controversy lies in the potential link between paraquat exposure and the development of Parkinson’s disease. Numerous scientific studies have indicated that paraquat can damage cells in the brain in ways that are consistent with the pathology of Parkinson’s. More than 8,000 lawsuits are currently pending in US courts, alleging that Syngenta failed to adequately warn users about these risks. The company has settled some cases, and has been negotiating to settle a larger portion of the claims.

Internal documents obtained by The New Lede and The Guardian revealed that Syngenta was aware of research linking paraquat to Parkinson’s disease decades ago and actively sought to influence scientific information and public opinion regarding those links. These revelations have fueled criticism of the company’s handling of the safety concerns.

What the Science Says – and Doesn’t Say

Syngenta maintains that the evidence linking paraquat to Parkinson’s disease is “fragmentary” and “inconclusive”. While studies have demonstrated a correlation between exposure and increased risk, establishing a definitive causal link remains complex. Parkinson’s disease is a multifactorial condition, meaning it likely arises from a combination of genetic predisposition and environmental factors. Isolating the specific contribution of paraquat is challenging.

Michael Okun, chair of neurology at the University of Florida, described the announcement as a “public health milestone,” emphasizing the importance of advocacy and data in driving change. However, it’s crucial to understand that ceasing paraquat production doesn’t automatically eliminate the risk. Exposure can occur through various pathways, including drift from application to neighboring fields and potential contamination of water sources.

Regulatory Response and Ongoing Evaluation

The US Environmental Protection Agency (EPA) has previously stated that there was “insufficient” evidence to definitively link paraquat to Parkinson’s disease. However, the agency has indicated it will re-evaluate existing data in light of new information. The EPA’s assessment process involves reviewing scientific studies, considering public comments, and conducting risk assessments to determine whether the benefits of paraquat use outweigh the potential risks.

Several states have also introduced legislation to ban paraquat, reflecting growing concerns at the local level. These efforts underscore the increasing pressure on regulators to address the potential health risks associated with the herbicide.

Implications for Farmers and Weed Management

Syngenta’s decision to discontinue paraquat production will likely prompt farmers to seek alternative weed control methods. These may include other herbicides, mechanical weeding, and integrated pest management strategies. The transition could present challenges, as paraquat is known for its rapid and non-selective action, making it a convenient tool for many growers. The availability and cost of alternative solutions will be key factors in determining the impact on agricultural practices.

Nathan Donley, environmental health science director with the Center for Biological Diversity, pointed out that while Syngenta’s exit is positive, other companies will likely continue to supply generic versions of paraquat as long as it remains approved for use. This highlights the need for broader regulatory action to address the risks associated with the herbicide.

What to Expect Moving Forward

The future of paraquat regulation in the United States remains uncertain. The EPA’s ongoing evaluation of the scientific evidence will be critical in determining whether further restrictions or a complete ban are warranted. Continued monitoring of Parkinson’s disease incidence among agricultural workers and individuals living near treated fields will also be essential.

Ray Dorsey, a neurologist and director of the Atria Research Institute’s Center for the Brain and the Environment, emphasized that this decision is a victory for the Parkinson’s community and a testament to the power of advocacy. He hopes it will encourage further research into the environmental causes of brain diseases and lead to more proactive measures to protect public health.

This story is co-published with the New Lede, a journalism project of the Environmental Working Group