Paraquat is a widely used herbicide known for its toxic properties and potential for causing severe harm. Classified as a "restricted use" chemical by the US Environmental Protection Agency, paraquat is primarily used for weed and grass control. It is available as a liquid in various strengths, with additional safety measures in place to prevent accidental ingestion. However, paraquat obtained from outside the United States may lack these safeguards.

Introduced for commercial purposes in 1961, paraquat remains one of the most commonly used herbicides worldwide. In the United States, its use is limited to commercially licensed applicators due to its high toxicity. Exposure to paraquat most commonly occurs through ingestion, as it can be easily mixed with food, water, or other beverages. Contamination may go unnoticed if paraquat lacks the added safeguards, posing a significant risk of poisoning.

Skin exposure to paraquat can also result in poisoning, particularly if the exposure lasts for an extended period, involves concentrated forms of the herbicide, or occurs through damaged skin. Inhalation of paraquat can lead to lung damage, and there have been instances of paraquat contamination found in marijuana in the past. Licensed applicators of paraquat face the highest risk of exposure.

Paraquat causes direct damage upon contact with the mouth, stomach, or intestines. Once inside the body, it spreads to various organs, including the lungs, liver, and kidneys. Toxic chemical reactions occur throughout these organs, leading to serious health consequences. Immediate symptoms of paraquat exposure include pain and swelling in the mouth and throat, followed by gastrointestinal symptoms such as nausea, vomiting, abdominal pain, and potentially bloody diarrhea. Severe gastrointestinal symptoms can result in dehydration, electrolyte imbalances, and low blood pressure.

Long-term effects of paraquat poisoning can be devastating. Survivors of paraquat ingestion often experience permanent lung damage in the form of scarring. Kidney failure, heart failure, and esophageal strictures (scarring of the swallowing tube) may also occur, making swallowing difficult for individuals affected.

Large ingestions of paraquat are unlikely to result in survival due to the severity of the toxic effects. Acute kidney failure, confusion, coma, fast heart rate, heart injury, liver failure, rapid lung scarring, muscle weakness, pulmonary edema (fluid in the lungs), respiratory failure, seizures, and even death can ensue within hours to days following exposure.

The highly toxic nature of paraquat underscores the need for stringent safety measures, proper handling, and restricted use of this herbicide. Awareness and adherence to guidelines can help minimize the risk of paraquat-related incidents and protect human health and the environment.