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Thanks to Michael J. Fox, just about everyone has heard of Parkinson’s disease by now. It’s a progressive disorder that affects the nervous system and the parts of the body controlled by the nerves. It often starts with a small tremor, but over time it can have a devastating effect on both movement and speech. (1) In this article, we look at the latest concerns about an EPA-approved herbicide linked to Parkinson’s disease.

According to the Parkinson’s Foundation, more than 10 million people worldwide are living with Parkinson’s disease, including nearly one million in the United States. They estimate the total costs at nearly $52 billion per year in the U.S. alone, where 90,000 new cases are diagnosed each year. (2) What you may not realize, however, is just how widespread this disease is.

Growing Concerns about Parkinson’s Disease and Herbicide Use

The New Lede, a journalism organization specializing in environmental issues, reports that the death rate from Parkinson’s has increased more than 60% in the US over the past 20 years. They say that as its spread has accelerated concerns about possible links between Parkinson’s and paraquat, a herbicide often used as a replacement for Roundup, has grown.

Paraquat is sold by Syngenta, a Swiss chemical company that is now owned by ChemChina. Ironically, neither Switzerland nor China allow farmers to use paraquat, due to the health risks.

In fact, it’s been banned in 60 countries. The EPA (the Environmental Protection Agency in the U.S.) allows it on farms – but not on golf courses.


Thousands of people are suing Syngenta (along with Chevron USA, who previously distributed paraquat), claiming they suffer long-term chronic effects as a result of exposure to the weedkiller.

Syngenta has repeatedly stated that research fails to prove a connection between paraquat and Parkinson’s, claiming that it “does not readily cross the blood-brain barrier” and does not cause Parkinson’s.

Lawsuits like these, as well as the work of journalists, have made internal company documents available, some of which go all the way back to the 1950s. Journalists from both The New Lede and the Guardian have reviewed hundreds of pages of these documents; they concluded that scientists with both Syngenta and their predecessor knew there were problems.

EPA’s Approach

Although it was developed as a herbicide, paraquat is categorized as a Restricted Use Pesticide. This means it’s not available to the public and training is required before use. That sounds like a good strategy… when people follow the rules. An article published by the EPA (the Environmental Protection Agency in the United States) shares what happens when people fail to do so (3):

In 2008, an 8-year-old boy drank paraquat that had been put in a Dr. Pepper bottle, which he found on a window sill in the garage. He died in the hospital 16 days later. His older brother had used the product on weeds around the house and put it in the bottle in the garage. The older brother obtained the product from a family friend who is a certified Restricted Use Pesticide applicator. (3)

The chemical has also been used in suicides. In the same article, the EPA puts the danger in simple terms: One sip can kill.

So far, their solution has been to insist that everyone who has access to paraquat must follow all instructions to the letter. That means always wearing protective gear, never giving it to anyone who’s not certified to use it, and no placement of the product into other containers, especially food and beverage containers. But even if that level of compliance were possible, would it be enough?

Evidence of Potential Harm

According to the New Lede, the answer to that question is a resounding “No!”. They say that Imperial Chemical Industries (ICI), who sold paraquat to Syngenta, and Chevron, who distributed it for ICI, “were aware in the 1960s and 70s of mounting evidence showing paraquat could accumulate in the human brain”.

Here are a few of the journalists’ discoveries:

  • Notes from a February 1974 meeting at Chevron referred to the “paraquat toxicological problem in the USA” and “increasing numbers of reports of toxicological effects of paraquat to applicators in the field.” Notes from a follow-up meeting a month later quoted a Chevron lawyer as saying, “to a lawyer there is evidence now that paraquat could cause industrial injury and it should be recognized that Chevron could face suits totaling millions of dollars.”
  • In a July 1975 letter to ICI, a Chevron toxicologist noted “problems of nosebleed and sore throat in our own plant workers,” as well as studies indicating the potential for central nervous system effects from the  paraquat.
  • Notes from an October 1975 meeting between Chevron and ICI recorded concerns about paraquat’s effect on the central nervous system.
  • A 1976 autopsy of a farmworker analyzed by ICI showed “degenerative changes” in the “cells of the substantia nigra” of the brain, a hallmark for Parkinson’s.
  • An internal Chevron memo dated October of 1985 noted that paraquat was “chemically very similar” to the byproduct of a synthetic heroin called MTPT, “which produces almost instant Parkinson’s, by killing dopaminergic neurons in the brain.” They stopped selling it in 1986.

The response

The New Lede also reported that Syngenta’s internal research revealed that paraquat had adverse effects on brain tissue. They say the company’s scientists were also aware of evidence that it could trigger tremors and other Parkinson-like symptoms in animals. They stated on their website that the chemical did not reach the specific area of the brain necessary to produce Parkinson’s symptoms.

Syngenta disagrees. They refer to a recent US Agricultural Health Study update to support their position that, “There is no properly designed epidemiological study that shows a link between paraquat and Parkinson’s disease.

Who’s at risk of disease?

Farmers, farmworkers, and the people who live near farms using paraquat are at the highest risk.

According to The New Lede, studies submitted by Michael J. Fox Foundation for Parkinson’s Research make the connection between paraquat and Parkinson’s clear. One study found that people who sprayed the chemical were more than twice as likely to develop Parkinson’s as those who applied other pesticides.

A 2019 analysis of 13 studies reported that exposure to paraquat increased the chances of developing Parkinson’s by 64 percent. They also state that a recent study concluded that living or working within 500 meters (about a third of a mile) of a farm using paraquat increased the likelihood of developing Parkinson’s disease by 75 to 100 percent.

More than 10 million pounds of paraquat were used in the U.S. in 2018. In California, its use (in 2021) was concentrated to a few counties, including some major agricultural areas. There it’s used on almonds, pistachios, grapes (including wine grapes), and other crops.

There’s less research on the effects of eating food treated with paraquat. That might be because it was developed as a weedkiller. Unfortunately, farmers are also spraying the chemical on crops to dry them out before harvest, which dramatically increases the amount you can take in.

What does this mean to me?

Unless you’re exposed to paraquat (or other pesticides and herbicides) in the surrounding air, your greatest risk is the consumption of conventionally grown food that’s been sprayed with it. Though that risk hasn’t been quantified, the simplest way to minimize it is through a healthy lifestyle.

Eat food free from pesticides and herbicides as often as possible. Exercise regularly. Be sure to get enough sleep, and do some detoxing on a regular basis. Our world is full of things our bodies weren’t designed to handle. Fortunately, they can be pretty resilient when they get the support they need.


Read more about Michael J. Fox’s lifetime commitment to raising awareness about Parkinson’s Disease.

Michael J. Fox 30 Years Living with Parkinson’s disease


Steph Sterner

Steph Sterner

Steph Sterner is a holistic practitioner and the author of No Guilt, No Games, No Drama and other self-help books. She writes about personal development, why we think and feel the way we do, and the nature of consciousness. You can find her on Medium (@Steph.Sterner) or at


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