What is the Proof Linking Paraquat and Parkinson’s Disease?

What is the Proof Linking Paraquat and Parkinson’s Disease?
What is the Proof Linking Paraquat and Parkinson’s Disease?

For decades, the scientific community has examined whether a wide range of environmental, occupational, lifestyle and genetic factors increase a person's risk for Parkinson's disease, a progressive neurodegenerative disorder. However, the one factor that continues to compel researchers is the possible link between paraquat and Parkinson’s disease.

In this post, we’ll delve into the risk factors for Parkinson’s disease, the research into the possible link, and how establishing this link can bolster paraquat claims against the manufacturers of this toxic herbicide.

What is Paraquat?

Paraquat, sold under the brand name Gramoxone, is an industrial herbicide used in the U.S. primarily for weed and grass control. Syngenta, Chevron Chemical Company, and other chemical companies manufacture it. Paraquat exposure by skin contact, ingestion, or inhalation can have immediate, often deadly, effects, as well as long-term effects.

Because it is so dangerous, 32 countries have banned the herbicide. The U.S. Environmental Protection Agency (EPA) has restricted paraquat use in the U.S. to industrial use only, and those who mix, load, and apply it are required to wear protective gear to reduce their risk of exposure.

Who is at Risk of Paraquat Exposure?

Paraquat is not available for household use. So, those most at risk are people who apply, mix or load the weedkiller, including:

  • Farmers and farm workers
  • Agriculture workers
  • Herbicide applicators
  • Crop dusters
  • Tank fillers
  • Chemical mixers

The EPA also cautioned that people living near land treated with paraquat can also be exposed. According to an American Journal of Epidemiology study, people who live within about 1,600 feet of land where paraquat was used had a 75% increased risk of developing Parkinson’s disease.

What is Parkinson’s and Who is at Risk?

Parkinson's disease is a complex neurodegenerative disorder. While the exact cause is not fully understood, scientific research suggests that a combination of genetic susceptibility and exposure to certain environmental factors may contribute to its development. Some risk factors include:

  • Advanced age
  • Gene mutations
  • Family history
  • Being male
  • Head trauma
  • Certain medical conditions, such as REM sleep behavior disorder (RBD)

The American Parkinson Disease Association also identifies early-age exposure to a rural environment with an increased risk of Parkinson’s later in life. Those with an increased risk of developing the disease include individuals who:

  • Farm as an occupation
  • Live on a farm
  • Live in a rural area
  • Are exposed to farm animals
  • Drink well water

How Does Paraquat Cause Parkinson’s?

The exact mechanism by which paraquat causes Parkinson's disease is not fully understood, but it is thought to be due to its ability to damage cells in the brain, particularly those in the substantia nigra, a region that is responsible for producing dopamine. This neurotransmitter plays an important role in movement, and its loss is thought to be a major factor in the development of Parkinson's disease.

Some evidence suggests that paraquat may also damage mitochondria, which are the cell's power plants. Mitochondria are essential for cellular energy production. Damage to mitochondria can lead to a variety of problems, including cell death.

Paraquat may also increase the risk of Parkinson's disease by promoting inflammation. Inflammation is a natural immune response to injury or infection, but it can also be harmful if it is chronic. Chronic inflammation has been linked to a number of diseases, including Parkinson's.

A Closer Look at the Scientific Evidence Linking Paraquat to Parkinson’s

In 2011, the National Institute of Health (NIH) published a study finding that people who used either paraquat or another rotenone (a broad-spectrum pesticide/insecticide) developed Parkinson’s about 2.5 times more often than those who didn’t use the pesticides. The study was a collaborative effort between the NIH’s National Institute of Environmental Health Sciences (NIEHS) and the Parkinson’s Institute and Clinical Center in Sunnyvale, California.

"Paraquat increases production of certain oxygen derivatives that may harm cellular structures. People who used these pesticides or others with a similar mechanism of action were more likely to develop Parkinson's disease,” wrote Freya Kamel, PhD, an NIEHS researcher and co-author of the paper.

The study matched 110 people diagnosed with Parkinson’s disease with 358 controls from the Farming and Movement Evaluation (FAME) Study to assess their exposure to pesticides and other agents known to be toxic to nervous tissue. FAME is part of the larger Agriculture Health Study investigating farming and health in 90,000 licensed pesticide applicators and their spouses.

In 2019, a systematic review and meta-analysis of observational studies investigating the link between Parkinson’s and paraquat found that individuals exposed to paraquat had a 25% greater occurrence of Parkinson’s. A subgroup analysis also found that those who were exposed to the herbicide for an extended period of time were even more likely to be diagnosed with the disease.  

Coincidentally, the paraquat molecule is structurally similar to a chemical called N-methyl-4-1,2,3,6-tetrahydropyridine, or MPTP, used to induce Parkinson’s in laboratory animals.

Despite the scientific research, paraquat makers maintain that the herbicide poses “no risk to human safety,” is “not a neurotoxicity hazard,” and “does not cause Parkinson’s disease.”

However, more than 4,000 paraquat lawsuits pending in multi-district litigation (MDL) against paraquat makers claim otherwise, and they’re fighting to hold the companies accountable for their actions.

Contact an Experienced Lawyer for your Paraquat Lawsuit

Parkinson’s disease is a progressive disease that requires ongoing medical care. If you or someone you love was exposed to paraquat and developed Parkinson’s, you may be eligible to recover compensation for your medical bills and other expenses. A dedicated mass tort lawyer from Lawsuit Legal News can help.

Our law firm is not afraid to hold these big chemical companies accountable for the harm they cause. We will fight for justice. Call us today at 866-467-0943 or complete our online contact form for a free consultation.


Matthew Dolman

Personal Injury Lawyer

This article was written and reviewed by Matthew Dolman. Matt has been a practicing civil trial, personal injury, products liability, and mass tort lawyer since 2004. He has represented over 11,000 injury victims and has served as lead counsel in over 1000 lawsuits. Matt is a lifetime member of the Million Dollar Advocates Forum and Multi-Million Dollar Advocates Forum for resolving individual cases in excess of $1 million and $2 million, respectively. He has also been selected by his colleagues as a Florida Superlawyer and as a member of Florida’s Legal Elite on multiple occasions. Further, Matt has been quoted in the media numerous times and is a sought-after speaker on a variety of legal issues and topics.

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