Paraquat

Paraquat is a popular herbicide because it’s highly effective at killing unwanted weeds and grasses, especially those resistant to Roundup (glyphosate). It’s sold in concentrated form and is mixed with water and sprayed on crops.

About 377 companies manufacture paraquat products worldwide. Gramoxone, manufactured by Syngenta, is one of the most well-known brands in the United States.

Paraquat is highly toxic and can cause short-term and long-term health effects, some of which may be fatal.

Research also links long-term paraquat exposure to Parkinson’s disease, an incurable nervous system disorder that affects movement and communication.

Commercial farmers and other agricultural workers in the United States have been using paraquat to control invasive weeds and grasses since 1964. Applicators spray it on commercial crops such as corn, soy and cotton.

Because of its toxicity, the EPA limits the herbicide’s use to licensed applicators for commercial use. There are no paraquat products licensed for use by homeowners.

People who are licensed paraquat applicators are at the greatest risk for exposure, but anyone who works in places where paraquat is used may be exposed.

This includes groundskeepers, farmers, growers, pickers and other agricultural workers.

Paraquat is highly poisonous, and the U.S. Environmental Protection Agency says just “one sip can kill.”

All brands of paraquat marketed in the United States contain dyes, sharp odors and chemicals that help prevent people from accidentally drinking the weed killer — including an agent that induces vomiting.

Paraquat Poisoning

Acute paraquat poisoning occurs through ingestion, inhalation or skin exposure. Most cases of poisoning occur because of accidental ingestion. Poisoning is usually fatal and there is no antidote.

Small to medium amounts can damage the mouth, stomach, lungs or intestines. Swallowing large amounts can damage multiple organs and lead to death within hours.

Symptoms of paraquat exposure vary depending on the amount of exposure and how someone was exposed. For example, ingesting a large amount of paraquat causes acute poisoning and symptoms appear quickly.

Licensed applicators and other agricultural workers exposed to smaller amounts of the chemical over a long period may not manifest symptoms for years.

Short-Term Side Effects

The first symptoms of acute poisoning through ingestion are immediate and start with pain and swelling in the mouth and throat. When the chemical enters the stomach, it causes gastrointestinal problems such as diarrhea, vomiting and nausea.

Short-term symptoms and side effects can occur within hours to several weeks after exposure and can be fatal.

Long-Term Side Effects

People that survive acute paraquat poisoning typically have long-term health problems that affect various organs.

Licensed applicators, farmers and agricultural workers that have been exposed to paraquat for years may not suffer acute symptoms of poisoning. But they can still have long-term side effects from exposure such as an increased risk for developing Parkinson’s disease.

Parkinson’s disease is an incurable brain disorder. Researchers theorize it’s caused by the loss of neurons that produce dopamine.

Several studies link long-term paraquat exposure to developing Parkinson’s disease. These studies propose that paraquat increases Parkinson’s disease risk by creating oxidative stress that damages and kills neurons that produce dopamine.

The scientific link to Parkinson’s disease has led several people to file paraquat lawsuits against herbicide manufacturers, including Syngenta.

Lawsuits claim paraquat is defective and led farmers to develop Parkinson’s disease. Plaintiffs say that manufacturers failed to warn the public about the risk.

Sampling of Studies

The Agricultural Health Study conducted in part by the National Institutes of Health, National Institute for Occupational Safety and Health and the EPA examined the health of U.S. farmers over several years. Researchers found that paraquat use increased the risk of developing Parkinson’s disease.

People exposed during their teen or young adult years had an increased Parkinson’s disease risk of 200 to 600 percent, according to studies quoted by The Unified Parkinson’s Advocacy Council.

Many epidemiological studies found a two- to five-fold or greater increase in the risk of Parkinson’s disease in people exposed to paraquat on the job, according to the lawsuit filed by Dale Smith on April 27, 2021.

The EPA’s Position

The EPA reviewed studies connecting paraquat to Parkinson’s. In 2019 the agency released a memorandum saying the evidence was insufficient to determine a link between paraquat and Parkinson’s disease.

“After comprehensive review of the relevant studies, the Agency concluded that the weight of evidence was insufficient to link paraquat exposure from pesticidal use of US registered products to PD [Parkinson’s disease] in humans,” the agency said.

However, in September 2022, the EPA cancelled the registrations for several products containing paraquat at the request of manufacturers. Among the registrations cancelled include Gramoxone SL 2.0, and Parazone 3SL Herbicide produced by Syngenta Corp. and Amvac Chemical Corporation.

There is no antidote for paraquat poisoning and it’s usually deadly. People who ingested paraquat should seek emergency care.

Hospital treatment consists of removing paraquat from the body by using Fuller’s earth or activated charcoal, according to the Centers for Disease Control and Prevention. If the patient arrives at the hospital within an hour of ingesting paraquat, nasogastric suction may be used.

People who may have gotten paraquat on their skin should wash themselves with soap and water. Flush eyes with plain water for 10 to 15 minutes. Seek medical care immediately.

Roundup — also known as glyphosate — and paraquat are both herbicides, but they contain different chemicals.

Paraquat is more poisonous than glyphosate and is 28 times more acutely toxic, according to a report by the Pesticide Action Network. Because of its toxicity, paraquat is banned in several countries and is a restricted use herbicide in the United States.

Unlike paraquat, Roundup has no restrictions on use and anyone can purchase and use it, including homeowners. EPA considers glyphosate’s toxicity to humans to be low.

Several people have sued the makers of Roundup because of its link to cancer, specifically non-Hodgkin lymphoma.

Despite being banned or phased out in the European Union, Brazil and China, paraquat is more popular than ever in the United States.

Paraquat use in the United States has increased and continues to rise, according to the National Water-Quality Assessment (NAWQA) Project. From 2006 to 2017, the estimated amount used jumped from about 3 million pounds to 11 million pounds.

Every 15 years, the EPA reevaluates the use of certain pesticides. In October 2020, the EPA reapproved paraquat for restricted U.S. The agency proposed more strict safety measures to protect human and environmental health.