Paraquat is a highly toxic herbicide used to control weeds and grass. The compound was first synthesized in 1882, and its plant-killing properties were discovered in 1955 by what was then Imperial Chemical Industries (ICI), a British chemical company.
Paraquat is now manufactured by many companies, including:
Paraquat has been used in the United States since the early 1960s. It is sold under dozens of trade names, alone or in combination products with other herbicides. Popular trade names for paraquat include:
Gramoxone, now manufactured by Swiss-based Syngenta, was the first commercial paraquat product (sold since 1962) and is the most common trade name for paraquat. Syngenta is owned by China National Chemical Company.
Paraquat is used as an herbicide, to kill unwanted weeds and grasses; a desiccant (drying agent); a defoliant, to cause the leaves to fall off unwanted plants; and a plant growth regulator. It has been used to control broadleaf weeds and grasses in the cultivation of more than 100 different crops worldwide, including:
Paraquat has also been used as a pre-harvest defoliant or desiccant on crops such as beans, hops, pineapple, and sugar cane, and as a post-harvest desiccant to speed removal of spent plants, such as tomatoes. It is used in no-till agriculture to kill grasses and weeds and, by doing so, minimizes plowing and help prevent soil erosion. Despite its strength as an herbicide, paraquat breaks down quickly once it enters the soil.
Paraquat is extremely poisonous—highly toxic to all mammals including humans. Paraquat most commonly enters the body by swallowing or through damaged skin but can also be inhaled when it is being sprayed or shortly afterwards. Paraquat is corrosive to skin. One farmer died after spending 3 and a half hours spraying diluted paraquat from a leaking knapsack, and others have died after spilling it on their skin.
Swallowing even a small amount of paraquat is lethal; there is no antidote. Paraquat kills by causing respiratory failure, which can take days or as long as a month after the fatal exposure. Paraquat poisoning also damages the:
Paraquat causes multiple-organ failure and damages the skin and eyes.
Common symptoms of paraquat exposure include:
Studies have also linked paraquat exposure to Parkinson’s disease.
To prevent accidental exposure and to respond if accidental exposure occurs, the U.S. Centers for Disease Control and Prevention (CDC) advises:
There is not accurate or complete data about how many people have died from swallowing paraquat since its 1962 debut, but at least one source estimates there have been tens of thousands of paraquat deaths. Some of those deaths have been accidents while others have been suicides. In the mid-1980s, Japan had more than 1,000 paraquat deaths a year. China, South Korea, Sri Lanka, and Taiwan have recorded hundreds of paraquat-related deaths in some years.
Syngenta exports thousands of tons of paraquat annually and has publicly maintained that its product is safe when used as directed. Syngenta also cites the fact that it has added “safening” agents to Gramoxone (its paraquat brand-name) since the 1970s—a dye to prevent the liquid from being confused with beverages, a sharp odor to make it undesirable, and an emetic drug to induce vomiting if paraquat is ingested. However, internal company documents unearthed in a U.S. lawsuit reveal that Syngenta and its predecessors have known for decades that the emetic in Gramoxone doesn’t prevent poisoning. Simply put, paraquat is so toxic that it poisons the body before the body can throw it back up.
Paraquat is still widely used throughout the world, but it has now been banned in more than 50 countries, including throughout the European Union.
Many international organizations have voluntarily banned paraquat use in their production systems, including the Rainforest Alliance, Fairtrade, the Forest Stewardship Council, and Dole, the well-known multinational agricultural corporation.
In the United States, paraquat use is restricted and those who apply the herbicide must be specially trained and certified.
Per the United States Environmental Protection Agency (EPA), quoted here:
Who is required to take [paraquat] training?
Any person who intends to use paraquat must be a certified applicator and is required to take the training. ‘Use’ includes pre-application activities involving mixing and loading the pesticide; applying the pesticide; and other pesticide-related activities, including, but not limited to, transporting or storing opened pesticide containers, cleaning equipment, and disposing of excess pesticides, spray mix, equipment wash waters, pesticide containers, and other paraquat-containing materials.
Who is permitted to use paraquat?
The use of paraquat, which is a restricted use pesticide, is restricted to certified pesticide applicators only; noncertified persons working under the supervision of a certified applicator are prohibited from using paraquat, including mixing, loading, applying the pesticide, and other pesticide-related activities.
Because paraquat it is not available to individual consumers in the United States, those most at risk for paraquat exposure in the U.S. work on farms where paraquat is used, and include:
Bertram, A. et al. (2013). Tissue concentration of paraquat on day 32 after intoxication and failed bridge to transplantation by extracorporeal membrane oxygenation therapy. Retrieved from https://link.springer.com/article/10.1186/2050-6511-14-45
Boose, K. (2021, April 2). The Hidden Health Risks of Paraquat. Retrieved from https://www.legalexaminer.com/environment/the-hidden-health-risks-of-paraquat/
Brody, J.E. (2020, July 20). The Link Between Parkinson’s Disease and Toxic Chemicals. Retrieved from https://www.nytimes.com/2020/07/20/well/live/parkinsons-disease-toxic-chemicals.html
Centers for Disease Control and Prevention. (2018, April 4). Facts About Paraquat. Retrieved from https://emergency.cdc.gov/agent/paraquat/basics/facts.asp
Dowler, C., and L. Gaberell. (2021, March 24). The Paraquat Papers: How Syngenta’s bad science helped keep the world’s deadliest weedkiller on the market. Retrieved from https://unearthed.greenpeace.org/2021/03/24/paraquat-papers-syngenta-toxic-pesticide-gramoxone/
Gatto, N., et al. (2009, July 31). Well-Water Consumption and Parkinson’s Disease in Rural California. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2799466/
Gillam, C. (2021, March 24). ‘A sip can kill’: did a chemical company misrepresent data to avoid making a safer product? Retrieved from https://www.theguardian.com/environment/2021/mar/24/syngenta-paraquat-deadly-john-heylings
Gotter, Ana. (2018, September 16). Paraquat Poisoning. Retrieved from https://www.healthline.com/health/paraquat-poisoning
Hakim, D. (2016, December 20). Fact-Checking a Claim About a Weed Killer. Retrieved from https://www.nytimes.com/2016/12/20/business/fact-check-paraquat-weed-killer-parkinsons.html
Hakim, D. (2016, December 20). This Pesticide Is Prohibited in Britain. Why Is It Still Being Exported? Retrieved from https://www.nytimes.com/2016/12/20/business/paraquat-weed-killer-pesticide.html
Leyva, M. (2021, April 1). EPA Decides Not to Ban a Pesticide Despite Strong Links to Parkinson’s Disease. Retrieved from https://www.legalreader.com/epa-decides-not-to-ban-a-pesticide-despite-strong-links-to-parkinsons-disease/
Meyer, B. (2019, July 29). New Legislation Seeks to Ban Pesticide Linked to Parkinson’s. Retrieved from https://www.michaeljfox.org/news/new-legislation-aims-ban-herbicide-linked-parkinsons
Meyer, B. (2020, October 26). Update from D.C.: EPA Allows Usage of Hazardous Pesticide Paraquat to Continue in the U.S. Retrieved from https://www.michaeljfox.org/news/update-dc-epa-allows-usage-hazardous-pesticide-paraquat-continue-us
Michael J. Fox Foundation for Parkinson’s Research. (2019, February 6). New Legislation Aims to Ban Herbicide Linked to Parkinson’s. Retrieved from https://www.michaeljfox.org/news/new-legislation-aims-ban-herbicide-linked-parkinsons
Ohio State University. (2020, April 12). New Restrictions on Widely Used Herbicide: Paraquat Dichloride. Retrieved from https://u.osu.edu/psep/2020/04/14/new-restrictions-on-widely-used-herbicide-paraquat-dichloride/
Prada, P. (2015, April 2). Paraquat: A controversial chemical’s second act. Retrieved from https://www.reuters.com/article/brazil-pesticide-paraquat/paraquat-a-controversial-chemicals-second-act-idUSL2N0WY2V720150402
Syngenta Global. (n.d.). Paraquat. Retrieved from https://www.syngenta.com/en/protecting-crops/paraquat
Thostenson, A. (2020, July 23). Paraquat, an Older Herbicide, Making a Comeback in the Age of Resistant Weeds. Retrieved from https://www.ag.ndsu.edu/cpr/weeds/paraquat-an-older-herbicide-making-a-comeback-in-the-age-of-resistant-weeds-07-23-20
U.S. Environmental Protection Agency. (n.d.). Paraquat Dichloride: One Sip Can Kill. Retrieved from https://www.epa.gov/pesticide-worker-safety/paraquat-dichloride-one-sip-can-kill
U.S. Environmental Protection Agency. (n.d.). Paraquat Dichloride Training for Certified Applicators. Retrieved from https://www.epa.gov/pesticide-worker-safety/paraquat-dichloride-training-certified-applicators