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….”

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