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Ag Giant Resisted Efforts to Change Toxic Weed Killer Formula to Protect Profits

Internal corporate documents dating back to 1968 detail the need to make the ubiquitous herbicide safer for humans.

A sign of Swiss farm chemicals powerhouse Syngenta is seen at the company's headquarters on July 23, 2015, in Basel.

While the toxic weed killer Paraquat, branded by Syngenta as Gramoxone, is part of the daily routine for many agricultural workers across the country, the Environmental Protection Agency (EPA) warns users on a government website that one small accidental sip can be fatal and there is no antidote. Regulators in the United States are grappling with a wave of research linking Paraquat to a less immediately apparent effect — Parkinson’s disease. And Syngenta — the Swiss-headquartered, Chinese-owned agrochemical company that now manufactures the weed killer — is currently facing litigation on that issue, though it denies responsibility.

Although first synthesized in 1882, Paraquat was not widely used as a herbicide until the middle of the 20th century. Today, though, it is used in more than 120 countries on more than 100 crops, including soybeans, wheat, rice, bananas, oranges, coffee and sugar cane. It gained notoriety after the United States government paid to have it sprayed on cannabis fields in Mexico during the late 1970s. One study conducted in 1978 found that 21 percent of the marijuana samples tested were found to be contaminated with the herbicide Paraquat.

According to a study published in Environmental Health, Paraquat is implicated in around 100 poisoning incidents in the U.S. each year, resulting in at least 17 deaths by acute poisoning over the last 20 years. As a result of its deadliness, more than 60 countries have already banned Paraquat, including Switzerland, the home base of the Paraquat maker Syngenta, which has banned the chemical since 1989. However, it is still popular and accessible to farmers in many countries, including the United States, and the toll from Paraquat poisonings is estimated at well into the thousands.

As more evidence emerges that gene alterations are involved in the early onset of Parkinson’s disease, the role of highly hazardous pesticides in the pathogenesis of this disease becomes intensely debated. In 2011, the journal Environmental Health Perspectives, in association with the National Institute of Environmental Health Sciences, published results from a case-control study of Parkinson’s disease cases in relation to pesticide exposure, and Paraquat emerged as a significant concern.

Syngenta states it is just one of the hundreds of companies worldwide that have registered Paraquat for sale. But now, hundreds of internal corporate documents, which date back to 1968, detail how the need for a safer formulation of Syngenta’s popular Paraquat-based product Gramoxone has been the subject of in-depth company discussions for decades. Analysis and data over the issue, as well as the arguments about the accuracy of evidence presented to regulators to avoid bans, are now laid out in the records. The Paraquat documents exclusively analyzed by Public Eye together with Unearthed, Greenpeace U.K.’s investigative journalism unit, show that the agrochemical giant and its predecessor corporate entities rejected or resisted many different options for changes to the formulations of Gramoxone on cost grounds and due to a desire to protect profits.

On March 24, 2021, Jon Heylings, formerly the head of research and investigative toxicology at Syngenta, claimed that the company did not want to change the formulation of Gramoxone to make it less dangerous. That same day, Syngenta denied Heylings’s claims.

Due to its toxicity, Paraquat sold in the U.S. is dyed blue to keep it from being mistaken for beverages and other liquid consumables; its sharp odor serves as a warning, and it includes a substance that induces vomiting when ingested. At the heart of the matter is a chemical compound codenamed PP796, an emetic that reduces the product’s toxicity by triggering rapid vomiting in people who ingest it. If the vomiting happens fast enough, the theory goes, it possibly could rid people’s bodies of the poison before a fatal dose can be absorbed into the bloodstream.

Heylings told the company more of the additive was needed in order to obtain the intended emetic effect, but his concerns were rejected, and a product that could have made Paraquat less deadly was shelved, according to the Paraquat documents. After raising the issue within the company for the first time in 1990, Heylings recently renewed his push for the pesticide giant to acknowledge his concerns.

After studying the emetic effects of PP796 on experimental animals, the company eventually settled on a dose of 5mg per 10ml of Gramoxone, and research supporting that dose was submitted to regulators. However, data based on more reliable laboratory testing would show that the amount of emetic in Gramoxone was too low to prevent fatal poisonings. Heylings accuses his former employer and Syngenta’s predecessor companies of relying on data generated in the 1970s that misrepresented the amount of the emetic additive that could potentially make Gramoxone less deadly.

Today, the most common causes of Paraquat exposure come from swallowing the chemical, prolonged contact with the skin or inhalation. Victims may be exposed to the toxic effects of the herbicide if the chemical directly enters the body through a cut, scrape, sore or rash.

A wide variety of studies have linked Paraquat exposure and Parkinson’s disease, including epidemiological reviews that have looked at human disease patterns, studies involving experiments on rats and research examining toxicity on a cellular level. Symptoms of the disease, such as tremors and slowed movement, stem from a loss of nerve cells in a part of the brain.

Ethan W.* began fieldwork picking cotton on the West Coast 10 years ago when he was 28. Now at age 38, he has developed adverse health effects, which have been caused by his prolonged exposure to pesticides. “The majority of the damage was to my brain and central nervous system; my cognitive functions began to deteriorate, along with my eyesight, balance, and a host of other related symptoms. I was told I am now at high risk to acquire Parkinson’s, Alzheimer’s, multiple sclerosis, or other neurological disorder,” Ethan said. “Doctors assumed that I would never drive again, go back to work or even be able to care for myself, let alone take care of my then 8-year-old daughter.” Although cotton pickers are not involved in pesticide spraying, they are exposed to residual effects of pesticides applied on the cotton crop.

The emotional burden of Parkinson’s disease is oftentimes overshadowed by the financial burden sustained by the patient and the family, and that is one reason why, currently, farmworkers who have developed this degenerative disorder as a result of Paraquat exposure are filing claims for compensation. In addition to helping victims’ efforts to recover the money to which they are entitled, specialized attorneys can hold the negligent manufacturing, distributing and marketing entities liable for their actions, and send a message that poisoning people cannot be tolerated.

In the United States, Paraquat use is growing exponentially, so that concern is sensible. To prevent future problems, the EPA should be concerned about this exposure and work to strengthen the current rules; we owe it to these workers to have the best standards for pesticides. Yet, the federal agency is still weighing whether to continue allowing the chemical to be sprayed on U.S. cropland. Delaying and derailing regulations leave the health of an estimated 3 million farmworkers in the United States at risk.

*Due to client confidentiality purposes, Ethan’s full name cannot be provided.

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