Paraquat was first produced in 1961 and is one of the most commonly used herbicides worldwide. Due to its toxicity, paraquat is available in the U.S. under “restricted use” only to commercially licensed users.
Commonly sold under the brand name Gramoxone by Syngenta, paraquat is also marketed by other companies as Para-SHOT, Helmquat, Parazone, Firestorm, Ortho-Paraquat, Quick-Quat, Devour, and Blanco. Licensed applicators of paraquat are the people most at risk for exposure.
Only a small dose of paraquat, about a spoonful, is needed to cause severe bodily damage and even death. According to the U.S. Centers for Disease Control and Prevention, the extent of paraquat poisoning depends on the amount, route, and duration of exposure, as well as the person’s health at the time.
Once ingested, paraquat quickly spreads throughout the body where it can cause toxic chemical reactions and direct damage when coming into contact with the lining of the mouth, stomach, intestines, lungs, liver, and kidneys. After a person ingests even a small amount of paraquat, pain and swelling of the mouth and throat and gastrointestinal symptoms occur, like nausea, vomiting, abdominal pain, and diarrhea (which can be bloody).
In general, ingestion of paraquat can lead to the following signs/symptoms within a few hours to a few days:
- acute kidney failure
- fast heart rate
- injury to the heart
- liver failure
- lung scarring
- muscle weakness
- pulmonary edema (fluid in the lungs)
- respiratory (breathing) failure, possibly leading to death
The American Association of Poison Control Centers cites 50 deaths from paraquat, with at least 12 being from accidental ingestion of paraquat from a beverage container. Documented cases of deaths from paraquat mostly show that people, sometimes children, mistakenly ingested the chemical from beverage containers after it was improperly stored and labeled. Thousands of deaths from paraquat have been reported worldwide, including Sri Lanka, the United Kingdom, South Korea, China, Brazil, and South Africa.
Paraquat can easily be mixed with food, water, or other beverages, making paraquat-contaminated food and drink highly poisonous. Without safeguard additives, such as dye, odor, and vomiting agents, people might not know that the food, water, or other beverages are contaminated.
Paraquat poisoning is also possible after skin exposure, mainly if the exposure lasts for a long time, involves a concentrated version of paraquat, or occurs through skin that is not intact, such as sores, cuts, or a severe rash. Two cases of paraquat poisoning by skin absorption published in the Journal of Experimental and Therapeutic Medicine show that skin damage developed in two contractors who sprayed paraquat in an orchard for approximately three hours.
Paraquat can cause lung damage when inhaled.
Studies + Science
Some evidence suggests that paraquat is linked to Parkinson’s disease, a neurological disorder that occurs when nerve cells in the area of the brain that controls movement become impaired and die. Common Parkinson’s symptoms – shaking, stiffness, difficulty walking and talking, balance, and coordination – usually worsen over time. Other potential symptoms include depression, memory loss, sleep issues and fatigue.
A 2009 study of paraquat exposure in California’s Central Valley estimated risk of Parkinson’s disease from 1978-1999. Researchers found that exposure to a combination of maneb, a fungicide, and paraquat, within 500 meters of the home increased the risk of Parkinson’s by 75%, with risk even higher for people aged 60 years or younger.
Another 2009 study of various occupations found that the risk of Parkinson’s disease increased by nearly 200% from using pesticides, including paraquat. The study authors note that evidence suggests certain pesticides, like paraquat, may cause degeneration of the neurological system.
A 2010 review of more than 40 epidemiological studies from the U.S. and other countries evaluated studies on paraquat exposure and Parkinson’s disease and found the evidence inconclusive. The authors noted that “experimental studies that might inform us do not reflect human exposure.”
The 2011 Farming and Movement Evaluation (FAME) study found that individuals with Parkinson’s disease were 2.5 times more likely to have been exposed to paraquat or rotenone than those without Parkinson’s disease.
“Paraquat increases the 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,” Freya Kamel, study author, said in a news release.
A 2015 FAME study found that consistent use of protective gear and hygiene habits modified the risk of developing Parkinson’s disease after paraquat exposure.
Since 2007, more than 32 countries have banned paraquat, including all member nations of the European Union, according to The New York Times.
As mentioned earlier, in the United States all paraquat products are Restricted Use Pesticides that may only be used by trained licensed applicators.
The EPA investigated reported cases of fatal and high-severity paraquat incidents following deaths from the chemical being mistakenly ingested because they were in drink containers, according to an EPA ingestion risk message, “Paraquat Dichloride: One Sip Can Kill.”
In a 2014 report, the EPA identified 27 reports of death from paraquat through 2014 in its Incident Data System. The IDS database contains all submissions of adverse health effects from pesticide products, as mandated by the Federal Insecticide, Fungicide and Rodenticide Act. More than 80% of all identified paraquat deaths reported to IDS were due to ingestion of paraquat.
A 2016 EPA memorandum on the human health risks of paraquat and implementation of mitigation efforts cited a large body of epidemiological evidence (reviewed above), noting that paraquat is a “great concern to the EPA” and that it is clear paraquat is a highly toxic substance through ingestion, inhalation, and contact with the skin and eyes.
In 2016, to minimize accidental paraquat ingestions and to reduce exposure to workers who mix, load, and apply paraquat, the EPA started requiring:
- Changes to the paraquat product label and distribution of supplemental warning materials to highlight the toxicity and risks of paraquat products.
- Restricting the use of paraquat to licensed or certified pesticide applicators only. Unlicensed individuals working under the supervision of a certified applicator are prohibited from using paraquat.
- Specialized training for certified applicators who use paraquat emphasizing that paraquat should not be transferred into or stored in improper containers.
- New packaging that prevents spills and other incidents that could lead to paraquat exposure.
Based on a 2019 review of scientific literature on paraquat exposure and health outcomes, including Parkinson’s disease, cancer, lung function and respiratory effects, the EPA concluded that there is insufficient evidence to link registered paraquat products to the health outcomes investigated, including Parkinson’s disease, when paraquat is used properly.
The Unified Parkinson's Advocacy Council is a group of state, regional and national organizations that prioritizes and advocates for people living with Parkinson's disease. The group is calling for the EPA to ban paraquat, including this petition. UPAC is linked to the Michael J. Fox Foundation, which is dedicated to advancing a cure for Parkinson’s disease.
Beyond Pesticides is a nonprofit organization that partners with local groups to lead action against pesticide use and promote safe alternatives, working to create an environment that is free from toxic pesticides. They have a quarterly publication Pesticides and You and their Beyond Pesticides National Pesticide Forum which convenes activists and scientists.