Medical Definition of Paraquat

  • Medical Author:
    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Paraquat: A toxic chemical widely used as an herbicide (plant killer), primarily for weed and grass control. Paraquat is highly poisonous. It was first produced for commercial purposes in 1961.

The most likely route of exposure to paraquat leading to poisoning is ingestion (swallowing). Paraquat can be easily mixed with food, water, or other beverages. Paraquat poisoning is also possible after skin exposure.

The extent of poisoning caused by paraquat depends on the amount, route, and duration of exposure and the person's condition of health at the time of the exposure. Paraquat causes direct damage when it comes into contact with the lining of the mouth, stomach, or intestines. After paraquat enters the body, it is distributed to all areas of the body. Toxic chemical reactions occur throughout many parts of the body, primarily the lungs, liver, and kidneys.

If a person survives the toxic effects of paraquat poisoning, long-term lung damage (scarring) is highly likely. Other long-term effects may also occur, including kidney failure, heart failure, and esophageal strictures (scarring of the swallowing tube that makes it hard for a person to swallow). People with high-dose exposure to paraquat are not likely to survive. See also: Paraquat lung.

Reviewed on 12/21/2018

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