Causes and Risks:

Paraquat is a weed killer used by the ATF (department of Alcohol, Tobacco and Firearms) and other law-enforcement agencies in the U.S. and abroad for the large-scale destruction of marijuana plants.  Often, Paraquat- tainted marijuana is harvested and sold.  While lighting the marijuana to smoke it should inactivate the Paraquat, it is possible to inhale some Paraquat by smoking tainted marijuana.  

Paraquat may cause lung damage by inhalation, it may cause esophageal erosions or ulcers from ingestion and absorption through the gut, or it can cause skin breakdown through contact with intact skin.

Severe ingestion of Paraquat can rapidly cause death from respiratory failure due to a form of proliferative alveolitis, or inflammation of the air spaces in your lungs, which impairs oxygen transport to the blood. This may lead to acute respiratory distress syndrome (ARDS).  Administering oxygen to improve the blood oxygen level may actually increase the damage to the lung. With chronic exposure to Paraquat, it is possible to develop pulmonary fibrosis, or a stiffening of the lung tissue.

Paraquat may also damage the kidneys, liver, mouth, and esophagus. Death may occur from perforation of the esophagus, or from acute inflammation of the mediastinum.

Prevention: For people involved in the application of Paraquat as a weed killer, strict adherence to the label instructions and the use of protective clothing and masks will prevent Paraquat lung. Marijuana-users must be aware that Paraquat-tainted marijuana is on the market and that there is little they can do to distinguish tainted from non-tainted plants.

Symptoms:

• shortness of breath
• difficulty breathing
• breathing requires increasing effort
• sore throat
• vomiting or GI distress

Signs and Tests:

• history of exposure to Paraquat
• history of marijuana smoking

Tests:

• arterial blood gasses (abnormal results)
• X-ray of the chest
• electrolytes (see chem-20)
• urinalysis
• BUN
• creatinine
• pulmonary function tests

Treatment: Treatment is supportive as there is no specific treatment for Paraquat poisoning.

Prognosis: The outcome depends on the severity of exposure. The affected person may develop mild respiratory symptoms with full recovery, permanent pulmonary changes, or, if the exposure was large and acute (as in ingestion), death may occur.

Complications:

• ARDS
• Pulmonary fibrosis
• Esophageal perforation
• Mediastinitis

If you believe you have been exposed to Paraquat, you should seek medical care immediately.