According to a June 22, 2021 court filing, Syngenta, Chevron Phillips Chemical Company, and Chevron USA had hundreds of cases pending against them in state and federal courts across the country. The lawsuits claim that their paraquat-based herbicides cause Parkinson’s disease. All named defendants have denied liability. 

Paraquat dichloride is a highly toxic chemical commonly used as an herbicide. It can be found in commercial herbicides like Gramoxone, a powerful weed and grass killer frequently used as a defoliant or harvest aid desiccant for crops like cotton. Given its toxicity, it is a restricted use pesticide, meaning only licensed applicators may purchase it. Applicators must take an EPA-approved training program every three years to maintain their certification. 

Since its introduction in the 1960s, paraquat has become one of the most popular commercial herbicides in the United States. The chemical is used to treat weeds resistant to glyphosate, better known by its brand name, Roundup. Because of the increased prevalence of glyphosate-resistant weeds in the food system and several high-profile cases involving the herbicide, paraquat usage is expected to trend upward unless pending litigation results in its removal from the U.S. market. 

In response to emerging risks associated with paraquat, the EPA recently adopted policies to protect people who work with the herbicide, requiring those who use it to undergo further training and limiting its use to certified individuals. 

Paraquat is banned in at least 32 countries, including the entire European Union and China. In 2020, the Chinese Ministry of Agriculture and Rural Affairs strengthened regulations against paraquat use, stating that only manufacturers with a pesticide registration for exported sales may continue to produce paraquat. According to the CDC, paraquat is highly poisonous. A blue dye, strong odor, and vomit-inducing agent have been added to the U.S.-marketed product as safety measures. Paraquat from outside the U.S. may lack these safeguards. 

Scientists believe that Parkinson’s is likely caused by a combination of genetic and environmental factors, paraquat being one of the most pervasive. Paraquat and rotenone (a separate herbicide) are routinely used in Parkinson’s research to induce and study Parkinson’s in animal models. The Parkinson’s Foundation joined forces with the Unified Parkinson’s Advocacy Council to sign a letter to the EPA encouraging them to cancel the registration of paraquat based on scientific research linking the herbicide to Parkinson’s Disease. 

Despite a thorough literature review conducted in 2019, the EPA found no clear link between paraquat exposure, when used according to its label, and adverse health outcomes. The EPA took no remedial action against paraquat and subsequently reapproved it for labeled use in the United States. 

Notably, the EPA does caution that paraquat is a highly toxic chemical with no antidote. Just one sip can be fatal. These findings led the EPA to implement risk mitigation strategies regulating how paraquat is packaged. 

Pesticides and Parkinson’s Disease

Parkinson’s is a progressive nervous system disease. Symptoms usually start slowly and can take years or even decades to fully manifest. Most people are aware of the tremors that often accompany Parkinson’s, but the symptoms that are not visible are often the hardest for those living with the disease.  Common symptoms include:

• Stiff muscles
• Slowness of movement
• Balance and coordination issues
• Depression and mental health problems 
• Hallucinations or delusions
• Problems with chewing and swallowing
• Loss of smell 

As the disease progresses, individuals may experience talking, sleeping, and memory issues that continue to worsen. Behavioral changes are also common in the later stages of the disease. Parkinson’s often results in the inability for self-care and patients often need assistance with basic tasks. Pain, fatigue, and apathy are also common in the later stages of Parkinson’s disease. 

The family members of those with Parkinson’s carry a heavy burden as well. Changes in behavior, depression, and apathy make it increasingly difficult to care for a Parkinson’s patient at home. It is clear that the disease impacts balance, coordination, and movement, resulting in a need for care that exceeds what a loved one can provide at home. 

The neurotransmitter norepinephrine is a critical chemical needed for the sympathetic nervous system to function properly. Parkinson’s interferes with this process, resulting in problems with autonomic functions such as regulating heart rate, blood pressure, digestion, and breathing. 

The exact cause of Parkinson’s disease is unknown, but research strongly links pesticides with the disease’s development. According to a study published in the Journal of American Medical Association, working with pesticides increases the risk of Parkinson’s disease by almost 80 percent. An investigation of eight pesticides, including paraquat, found a causal association between pesticide use and Parkinsonism. 

Researchers found that prolonged exposure to paraquat and permethrin, an insect repellent, increased Parkinson’s disease risk three-fold. Paraquat toxicity is a serious concern, a claim the Michael J. Fox Foundation asked the EPA to examine. According to the organization, acute toxicity and organ failure affecting the liver, eyes, lungs, kidneys, and the endocrine system should result in the immediate removal of paraquat from American agriculture.  

What Will Differ from the Roundup Lawsuits?

Paraquat litigation is likely to follow a similar path to the still-unfolding Roundup MDLs. When compared to Roundup, which contains glyphosate, the primary difference is availability. Roundup is sold at easily accessible stores such as Walmart, Costco, and Home Depot. Paraquat-based herbicides are only available to commercially licensed applicators. 

Given that a paraquat purchase requires a license, it may limit the number of individuals eligible to file a lawsuit. This difference notwithstanding, the litigation will likely be equally grueling and lengthy. 

The primary claim in the Roundup legal battle is that the product causes non-Hodgkin lymphoma (NHL). According to the American Cancer Society, approximately 81,560 Americans will be diagnosed with NHL in 2021. In contrast, The Parkinson’s Foundation estimates that roughly 60,000 Americans will be diagnosed with Parkinson’s this year. Given the combined prevalence of Roundup use and the higher incidences of NHL, it follows that paraquat litigation may not reach the massive scale of the ongoing Roundup litigation. 

Bayer AG, which inherited Roundup in its acquisition of Monsanto in 2018, has failed to reach a settlement covering future claims brought by those diagnosed with NHL in relation to Roundup. Bayer AG recently increased the settlement reserve fund by $4.5 billion for future claims. 

Considering the license requirements for using paraquat, plaintiffs may be asked to provide more proof that they were exposed to the chemical. Evidence of contact was less of an issue in the Roundup litigation, given the product’s public accessibility. Paraquat litigation has just begun, and there are no settlements or resolutions to guide predictions. 

Sudden Rise in Paraquat Litigation Cases

The first case linking paraquat to Parkinson’s disease was filed in Missouri in 2017. Since then, lawsuits surged against Syngenta and Chevron, the two most common defendants, leading to a consolidation of lawsuits into an MDL on June 8, 2021. The cases all allege that paraquat exposure played a role in developing Parkinson’s disease. 

Many attorneys involved in Roundup lawsuits are taking on other dangerous herbicides such as paraquat. Although many Roundup lawsuits have settled, there are still pending appeals, and a judge recently rejected a settlement agreement for future claimants for the consolidated case. 

In May 2021, Syngenta filed suit in a Delaware state court, asking that 130 insurers be on the hook for litigation expenses related to paraquat allegations. 

The Paraquat Problem

The causal link between Parkinson’s disease and paraquat will be the subject of extensive debate in the case. Several scientific studies, including a 2011 study of U.S. farmers conducted by multiple government agencies, found that “exposure to agricultural pesticides may increase a person’s risk of developing Parkinson’s disease.” 

Several agricultural groups and farmers are campaigning for the continued use of paraquat. Although concerns about environmental impact have been raised, the companies endeavor to keep the product on the market to protect profits. The EPA indicated its intent to ban aerial spraying of paraquat, but industry lobbying efforts succeeded, and the agency agreed to allow aerial spraying with some restrictions. The decision to allow continued use of paraquat for aerial spraying was based on information provided by the manufacturers of farm chemicals, leaving skeptics to doubt its veracity.