brain Archives

October 27, 2022

Amid calls for ban on weed killer linked to Parkinson’s, a battle over science

By Carey Gillam

When US regulators issued a 2019 assessment of the widely used farm chemical paraquat, they determined that even though multiple scientific studies linked the chemical to Parkinson’s disease, that work was outweighed by other studies that did not find such links. Overall, the weight of scientific evidence was “insufficient” to prove paraquat causes the brain disease, officials with the US Environmental Protection Agency (EPA) declared.

The EPA reiterated its assessment in a 2021 report. The agency said after extensive analysis of numerous factors, including concerns about Parkinson’s risk, it determined farmers could safely continue to apply the weed killer across millions of US acres to help in the production of soybeans, corn, cotton and an array of other crops.

The determination has been significant for Syngenta, the longtime maker of paraquat weed killers. The company is facing calls in the US for a paraquat ban, as well as more than 2,000 legal claims brought by farmers and others alleging they developed Parkinson’s disease because of their exposure to paraquat.

Syngenta cites the EPA assessment of the science on paraquat in defense of the pesticide, and says scientific research “does not support” a causal relationship between the chemical and the disease. On a Syngenta-run paraquat information website, the company highlights several studies it says also backs that position, including many conducted by company scientists or by outside scientists who received company funding for their work.

Last week the Guardian and The New Lede reported that internal corporate records show Syngenta had knowledge of science linking paraquat to Parkinson’s decades ago but sought both to refute the evidence with various secret tactics. The documents are available at the Paraquat Papers Media Library.

US farmworker, health and environmental advocacy groups say in contrast to the corporate science, research conducted by independent scientists provides abundant evidence of paraquat’s ability to cause Parkinson’s and other health dangers, and the EPA is improperly discounting that body of research.

More than 50 groups have called for the US to follow the lead of dozens of other countries in banning paraquat. The Michael J. Fox Foundation for Parkinson’s Research submitted a petition to the EPA with 107,000 signatories calling for a ban. The foundation cited a study that found people exposed to paraquat in their teens or as young adults had an increased Parkinson’s risk of 200 to 600 percent, depending on the overall exposure.

October 20, 2022

Secret “Paraquat Papers” reveal corporate tactics to protect weed killer linked to Parkinson’s disease

By Carey Gillam and Aliya Uteuova

For more than 50 years, Swiss chemical giant Syngenta has manufactured and marketed a widely used weed killing chemical called paraquat, and for much of that time the company has been dealing with external concerns that long-term exposure to the chemical may cause the dreaded, incurable brain ailment known as Parkinson’s disease.

Syngenta has repeatedly told customers and regulators that scientific research does not prove a connection between its weed killer and the disease, insisting that the chemical does not readily cross the blood-brain barrier, and does not affect brain cells in ways that cause Parkinson’s.

But a cache of internal corporate documents dating back to the 1950s obtained by The New Lede in a reporting collaboration with the Guardian suggests that the public narrative put forward by Syngenta and the corporate entities that preceded it has at times contradicted the company’s own research and knowledge.

And though the documents reviewed do not show that Syngenta’s scientists and executives accepted and believed that paraquat can cause Parkinson’s, they do show a corporate focus on strategies to protect product sales, refute external scientific research and influence regulators.

In one defensive tactic, the documents lay out how the company worked behind the scenes to try to keep a highly regarded scientist from sitting on an advisory panel for the US Environmental Protection Agency (EPA). The agency is the chief US regulator for paraquat and other pesticides. Company officials wanted to make sure the efforts could not be traced back to Syngenta, the documents show.

And the documents show that insiders feared they could face legal liability for long-term, chronic effects of paraquat as long ago as 1975. One company scientist called the situation “a quite terrible problem,” for which “some plan could be made….”