What Is Paraquat?

What Paraquat Is

Paraquat is a chemical compound used as a herbicide, which is a substance designed to kill unwanted plants. Its full chemical name is paraquat dichloride, and it belongs to a class of chemicals called bipyridyliums. It works by disrupting the process plants use to make energy from sunlight, causing them to dry out and die quickly after contact.

Paraquat is fast-acting and kills a broad range of weeds and grasses, which is part of why it has been popular in commercial farming for decades. It is usually sold as a concentrated liquid that is diluted with water and sprayed. In its commercial form it is often dyed a distinctive blue or green color and given a sharp odor and an added agent that causes vomiting, all of which are safety measures intended to prevent accidental swallowing.

What Paraquat Is Used For

Paraquat is used primarily in agriculture to clear fields of weeds and grasses before planting and to manage growth around established crops. It is commonly associated with crops such as corn, soy, cotton, fruit orchards, and vineyards. Because it kills most green plant tissue on contact, it is also used to dry out or "burn down" vegetation ahead of harvest.

It is not a product sold for ordinary home or garden use. In the United States, paraquat is classified as a restricted-use pesticide, which means it can only be purchased and applied by workers who hold a pesticide applicator license. That restriction is one reason exposure questions tend to center on agricultural and occupational settings rather than consumer use.

Paraquat Products and Brand Names

Paraquat is the active ingredient in a number of herbicide products sold under different brand names. The most widely recognized is Gramoxone, but the same chemical appears in many other products and generic formulations worldwide. For the full list of products and brand names that have contained paraquat, and how to identify which one was used in a past job, see Paraquat Products and Brand Names.

Is Paraquat Banned?

Paraquat is banned or heavily restricted across much of the world. Switzerland, where Syngenta keeps its headquarters, prohibited it in 1989. The European Union banned it in 2007 and China in September 2020, and dozens of other countries have done the same, usually citing how toxic it is and how hard it is to handle safely.

There is no federal ban in the United States. It remains legal as a restricted-use pesticide, and the U.S. Environmental Protection Agency has continued to allow it with added safety requirements such as applicator training and closed-system packaging. States have begun moving on their own: Vermont passed the first state ban in 2026, and in California every manufacturer cancelled its product registrations that August, which starts a phase-out there rather than stopping use on a date. Where that leaves things is covered on Paraquat Lawsuit Updates.

The restrictions also came later than most people assume. Paraquat was registered in the United States in 1964 with no such limit attached. It was not classified as restricted-use until rules proposed in 1977 took effect in 1978, and even then it could be applied by anyone working under a certified applicator's direct supervision. Only later did the EPA narrow it to certified applicators alone. Someone who sprayed in the 1960s or 1970s may well have done so with no license and no training at all, which matters when reconstructing a work history decades later.

One point surprises almost everyone: EPA registration is not a finding that a pesticide is safe. Federal law lets the agency register a product if it concludes that using it as labeled will not generally cause unreasonable adverse effects, and the same law defines that phrase to include weighing economic and social benefits against the risk. The safety testing behind a registration is largely done by the company seeking approval, not by the EPA itself.

Is Paraquat Dangerous to Humans?

Paraquat is acutely toxic to people if it is swallowed, and even small amounts can be fatal. This acute poisoning risk, which usually involves accidental or intentional ingestion, is different from the question at the center of paraquat lawsuits. The litigation concerns long-term, lower-level exposure over years of agricultural work, and whether that kind of repeated exposure is associated with chronic disease.

Keeping those two scenarios separate matters. Acute paraquat poisoning is a medical emergency with immediate, well-documented effects on the lungs and other organs. The lawsuits, by contrast, focus on a possible association between repeated occupational exposure and the later development of Parkinson's disease, which is a slower and more complex scientific question. People researching symptoms should not assume that the two situations are the same.

For a closer look at the symptoms people sometimes research after chemical exposure, see Chemical Exposure Symptoms.

Paraquat and Parkinson's Disease

The reason paraquat is so often discussed in a legal context is the body of research examining whether long-term exposure may be associated with an increased risk of Parkinson's disease, a progressive neurological condition that affects movement. Whether that research amounts to proof is a separate question, covered in Does Paraquat Cause Parkinson's Disease? Plaintiffs in paraquat lawsuits generally allege that manufacturers knew or should have known about this potential risk and did not adequately warn the workers who handled the product.

This is the bridge between the general science of paraquat and the litigation itself. Readers who want the legal side of this topic can continue to Paraquat Parkinson's Lawsuits, which explains the claims, who tends to research them, and what records often matter. What is happening in those cases right now, including the settlement that has not yet closed, is on Paraquat Lawsuit Updates. The broader category sits alongside Neurological Conditions Linked to Lawsuits and Pesticide Exposure Lawsuits.

Who Makes Paraquat?

Paraquat came out of Imperial Chemical Industries, the British company generally known as ICI, which says it found the herbicidal properties in 1955. ICI won a US patent on paraquat formulations in 1962, and the product reached the American market in 1964 as Gramoxone. Chevron distributed it here under a license from ICI. Those two companies, through their successors, are the ones named in most paraquat lawsuits.

The trail from ICI runs through a run of mergers and spin-offs. Syngenta AG was formed in 2000 from the merger of Novartis Agribusiness and Zeneca Agrochemicals, and its US arm became Syngenta Crop Protection LLC in 2010. Syngenta AG was itself bought in 2017 by ChemChina, a Chinese state-owned company. Other manufacturers make paraquat in generic form as well, which is part of why it turns up under so many names. Which company sold the product you used, and in which years, is on Paraquat Products and Brand Names.