On January 23, the Environmental Protection Agency moved to withdraw its 2021 interim decision allowing the use of the herbicide paraquat, following the filing of a petition spotlighting the links between the weedkiller and Parkinson’s Disease. Despite stating last year that it would spend 2024 analyzing new information about paraquat with the aim of issuing a final document on its use by mid-January 2025, the EPA opted to delay, stating it needed more time to examine the potential health effects of the chemical.
“Instead of facing us in court, EPA is cowering behind the tired old industry tactic of delay, delay, delay.”
Nathan Donley, environmental health science director at the Center for Biological Diversity
The recent petition, which was filed jointly by the Michael J. Fox Foundation for Parkinson’s Research and several other health advocacy organizations, shone a light on the evidence linking the herbicide to the disease1. The petition challenged the EPA’s 2021 conclusion that there was “insufficient” evidence of this connection. The evidence, characterized as “incredibly overwhelming” by Jonathan Kalmuss-Katz, a senior attorney with Earthjustice and the suit’s lead plaintiff, has in fact been building up for decades.
For industry experts, the move to withdraw is a disappointing maneuver. “Instead of facing us in court, EPA is cowering behind the tired old industry tactic of delay, delay, delay,” said Nathan Donley, environmental health science director at the Center for Biological Diversity. “It’s already been more than three years since this litigation started, we cannot wait another four years just to start back at square one. Too many lives are at stake.”
What Is Paraquat Used For?
Paraquat is one of the most widely-used weed-killing chemicals in the U.S. It was first introduced to the market in 1962 by Imperial Chemical Industries (a predecessor of Syngenta) under the brand name Gramoxone. Paraquat is typically used to control weeds in fields growing grapes, almonds, soy beans, and cotton, most often in California’s Central Valley, Iowa, and the Mississippi River Valley. It has also historically been used to kill fields of illegally-grown marijuana.
Paraquat is a restricted substance in the U.S. due to its propensity for human harm — according to the EPA, just one sip of paraquat is fatal. Because of this, it’s only available for use by licensed users, and the chemical is typically dyed blue to avoid accidental ingestion.
Paraquat also stands out from other similar chemicals given its potential to volatilize, or to change from a liquid to a vapor. When you’re dealing with a toxic and potentially deadly substance, you can understand why this would be concerning — paraquat evaporation could increase the risk of inhalation by bystanders.
Paraquat vs. Glyphosate
Paraquat is far more potent than fellow common herbicide glyphosate, which itself has been categorized as a probable human carcinogen by the World Health Organization. Farm businesses often resort to paraquat on crops exhibiting resistance to glyphosate, a widespread problem dating back to the mid-90s2.
Glyphosate is sold under the brand name Roundup by Bayer (formerly Monsanto, before it was acquired in 2018), and widespread overuse meant that some weeds were able to adapt and develop a resistance to the chemical. Following this, the Guardian reported that paraquat use in the U.S. tripled between 2008 and 2018 — which suggests its presence on American farms will only increase if the EPA continues to delay3.
What Are the Proven Health Risks of Paraquat?
The scientific evidence linking Parkinson’s and paraquat has been piling up for years. Animal studies published in 2004 in Cell and Tissue Research4 and in 2005 in Neurobiology of Disease5 showed that rats exposed to the weedkiller developed the disease. Even more concerning, human studies confirmed these findings in 2011. A National Institutes of Health study found that workers who have used paraquat are 2.5 times as likely to develop Parkinson’s6.
A 2024 study in the International Journal of Epidemiology found that even those who simply lived or worked near agricultural facilities using the herbicide had a greater risk of contracting Parkinson’s Disease7. The strongest odds were observed for those diagnosed at less than 60 years of age.
A Dangerous Secret
It gets worse. According to documents released in 2022 by The New Lede, Syngenta has been aware of the potential links between paraquat and Parkinson’s for decades, identifying — and hiding — potential effects on the central nervous system as early as 19588.
A 1976 autopsy of a farmworker analyzed by Syngenta (then ICI) showed “degenerative changes” in the cells of the substantia nigra of the brain, which the outlet characterizes as “a hallmark for Parkinson’s.” And in 1985, an internal memorandum circulated to officials at Chevron (the former chief distributor of the chemical) showed awareness of a Canadian study finding “an extraordinarily high correlation” between Parkinson’s and the use of paraquat.
What Is Parkinson’s Disease?
Parkinson’s Disease is a disorder of the nervous system caused by a breakdown of dopamine-producing neurons in the brain, which can lead to irregular brain activity, movement problems, emotional changes, sleep disorders, pain, and early death9. Nearly 1 million people in the U.S. are living with the disease10.
As of January, more than 5,000 farmers with Parkinson’s disease have filed federal lawsuits against Syngenta and Chevron. These paraquat lawsuits assert that the companies were aware of the risks and hid them from the public for over 50 years11.
It’s Not Just Parkinson’s: The Other Risks of Paraquat
In addition to the links to Parkinson’s Disease, the recent petition also explored other potential health ramifications of paraquat use, including respiratory and dermal ailments.
According to the CDC, paraquat poisoning by way of ingestion, skin exposure, or inhalation can cause toxic chemical reactions around the body, but specifically in the lungs, liver, and kidneys12. The ingestion of small volumes of the herbicide causes delayed but fatal lung fibrosis13. As of this year, treatment options for paraquat-induced lung fibrosis remain limited, according to a study in EJNMMI Research14.
The Environmental Risks of Paraquat
Paraquat also has dire environmental consequences. A 2021 study in Ecotoxicology and Environmental Safety showed that it could cause “serious harm” to the environment15, and a 2023 study in Ecotoxicology showed that aquatic plants are particularly vulnerable to the herbicide16. It has also shown a remarkable ability to persist in soil and water long after its application, which means the long-term effects will likely carry on for years to come.
In October, more than 50 U.S. lawmakers sent letters to the EPA calling for a ban on the herbicide, citing harm to farmworkers and rural communities, as well as “grave impacts on the environment.” Roughly 70 countries have already banned paraquat, including the European Union, Switzerland, and the UK. It was banned in China in 2012, and in Vietnam, where paraquat was killing 1,000 people every year, the chemical was banned in 201717. It seems high time the U.S. did the same.
Sources:
- https://www.epa.gov/system/files/documents/2021-10/21-71287_docketentry_09-23-2021_1.pdf
- https://crops.extension.iastate.edu/encyclopedia/status-and-concerns-glyphosate-resistance
- https://www.theguardian.com/environment/2024/feb/11/epa-reapprove-paraquat-herbicide-parkinsons
- https://pubmed.ncbi.nlm.nih.gov/15258850/
- https://pubmed.ncbi.nlm.nih.gov/16242641/
- https://www.nih.gov/news-events/news-releases/nih-study-finds-two-pesticides-associated-parkinsons-disease
- https://pubmed.ncbi.nlm.nih.gov/38309714/
- https://www.thenewlede.org/2022/10/secret-paraquat-papers-reveal-corporate-tactics-to-protect-weed-killer-linked-to-parkinsons-disease/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC8900653/
- https://www.parkinson.org/understanding-parkinsons/statistics
- https://www.torhoermanlaw.com/paraquat-lawsuit/
- https://www.cdc.gov/chemical-emergencies/chemical-fact-sheets/paraquat.html
- https://pmc.ncbi.nlm.nih.gov/articles/PMC1948029/
- https://ejnmmires.springeropen.com/articles/10.1186/s13550-024-01118-1
- https://www.sciencedirect.com/science/article/pii/S014765132100823X
- https://pubmed.ncbi.nlm.nih.gov/37973658/
- https://vietnamnews.vn/society/351267/paraquat-poisoning-kills-1000-every-year.html
