Paraquat / Gramoxone Herbicide

Paraquat, also known by the brand name Gramoxone, is one of the most widely used herbicides in the world. Paraquat / Gramoxone is highly toxic, and a growing body of research suggests exposure to this herbicide greatly increases the risk of Parkinson’s disease.

Paraquat Background

Paraquat has been commercially available since 1961, and is marketed by Syngenta under the brand name Gramoxone.

Paraquat / Gramoxone is used on more than 100 crops and in about 100 countries across the globe, including the United States. It has proven highly effective in killing a wide range of annual grasses and broad-leaved weeds, as well as the tips of established perennial weeds. Paraquat is also very fast acting, rain-fast within minutes of application, and becomes partially inactivated upon contact with soil.

Because of these properties, Paraquat-containing herbicides were used in the development of no-till farming, a technique that allows for the growing of crops without disturbing the soil. Paraquat gained notoriety in the 1980s, when the U.S. Drug Enforcement Agency attempted to use the herbicide to kill marijuana crops in the US and Mexico.

Gramoxone and other Paraquat herbicides sold in the United States are Restricted Use Pesticides (RUPs), which means they must be applied by certified applicators who have received specialized training. The U.S. Environmental Protection Agency (EPA) has only approved Paraquat / Gramoxone for use in agricultural and commercial settings, so these products are not available for home use.

Paraquat / Gramoxone Poisoning

Paraquat is one of the most toxic herbicides in existence, and ingesting just a teaspoon-sized dose is enough to kill a human adult. In fact, the European Union and 32 other countries have banned Paraquat due to its toxic side effects and other health concerns.

According to the U.S. Centers for Disease Control, Paraquat causes direct damage when it comes into contact with the lining of the mouth, stomach, or intestines. Paraquat also cause toxic chemical reactions to occur throughout many parts of the body, primarily the lungs, liver, and kidneys.

People who ingest a small amount of Paraquat may experience severe complications within days or weeks, including:

  • Heart failure
  • Kidney failure
  • Liver failure
  • Lung scarring

Ingesting large amounts can cause the following signs or symptoms within hours or days:

  • Acute Kidney failure
  • Confusion
  • Coma
  • Fast heart rate
  • Injury to the heart
  • Liver failure
  • Lung scarring (evolves more quickly than when small to medium amounts have been ingested)
  • Muscle weakness
  • Pulmonary edema (fluid in the lungs)
  • Respiratory (breathing) failure, possibly leading to death
  • Seizures

Ingesting large amounts of Paraquat usually proves deadly. Those who do survive Paraquat poisoning are likely to suffer long-term lung damage. Other possible long-term complications include: kidney failure, heart failure, and esophageal strictures (scarring of the swallowing tube that makes it hard for a person to swallow).

Paraquat and Parkinson’s Disease

A growing body of scientific research also suggests people who are exposed to Paraquat / Gramoxone are more likely to develop Parkinson’s disease, a progressive neurological disorder that causes tremor, muscular rigidity, and slow, imprecise movement.

In February 2011, for example, findings from the National Institute of Health’s (NIH) Farming and Movement Evaluation (FAME) study found that farmers and agricultural workers exposed to Paraquat were 2 ½ times more likely to develop Parkinson’s disease. However, Syngenta rejected the NIH researchers’ conclusions, and asserted that the FAME study actually found that these workers were less likely to develop Parkinson’s.

In response, Dr. Freya Kamel, an NIH researcher, pointed out that because the data was largely self-reported, there were probably far more people with Parkinson’s who didn’t enroll. She maintained that the findings on Paraquat and Parkinson’s disease were “about as persuasive as things can get.”

The following year, a study called  Genetic Modification of the Association of Paraquat and Parkinson’s Disease suggested individuals with a specific genetic variation were 11 times more likely to develop Parkinson’s when exposed to Paraquat. Another study published that same year indicated that Paraquat exposure might increase the risk of Parkinson’s among people with traumatic brain injuries.

Most recently, a study conducted by the University of Guelph in Canada found that low-level exposure to Paraquat disrupts cells in a way that mimics the effects of mutations known to cause Parkinson’s disease. Adding the effects of the herbicide to a predisposition for Parkinson’s drastically increases the risk of disease onset.

  1. Syngenta (2019) “Gramoxone”
  2. CDC (N.D.) “Facts About Paraquat”
  3. EPA (N.D.) “Paraquat Dichloride”
  4. NIH (2011) “Farming and Movement Evaluation (FAME)”
  5. Movement Disorders (2012) “Genetic Modification of the Association of Paraquat and Parkinson’s”
  6. Neurology (2012) “Traumatic Brain Injury, Paraquat Exposure, and Their Relationship to Parkinson Disease.”
  7. Science Daily (2018) “Study Uncovers Cause of Pesticide Exposure, Parkinson’s Link”
Last Modified: August 26, 2019

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