Lewisite

Chemical warfare agent

Lewisite is a chemical compound that was developed as a chemical warfare agent. It is classified as a blister agent or vesicant, similar to mustard gas. Lewisite is an organoarsenic compound and is known for its ability to cause severe skin, eye, and respiratory tract irritation.

History

Lewisite was first synthesized in 1904 by the American chemist Julius Arthur Nieuwland, but its potential as a chemical weapon was not recognized until later. During World War I, the United States developed Lewisite as a chemical warfare agent, although it was not used in combat during that conflict. The compound was named after Winford Lee Lewis, who was involved in its development.

Chemical Properties

Lewisite is an organoarsenic compound with the chemical formula C₂H₂AsCl₃. It is a colorless or yellowish liquid with a distinctive odor similar to geraniums.

Chemical structure of Lewisite

The compound is highly reactive and can easily penetrate the skin, causing severe blistering. It is also a potent lachrymator, causing tearing and irritation of the eyes.

Mechanism of Action

Lewisite acts by inhibiting the function of sulfhydryl groups in enzymes and other proteins, disrupting cellular metabolism. This leads to cell death and tissue damage, particularly in the skin, eyes, and respiratory tract.

Effects on Health

Exposure to Lewisite can cause a range of symptoms, depending on the route and level of exposure. Skin contact results in immediate pain and irritation, followed by blistering. Eye exposure can lead to severe irritation, pain, and potential blindness. Inhalation of Lewisite vapors can cause respiratory distress, coughing, and pulmonary edema.

Decontamination and Treatment

Immediate decontamination is crucial to minimize the effects of Lewisite exposure. This can be achieved by removing contaminated clothing and washing the affected area with soap and water. Medical treatment may include the use of British anti-Lewisite (BAL), a chelating agent that can bind to arsenic and help remove it from the body.

Lewisite sample with geranium odor

Environmental Impact

Lewisite is a persistent environmental contaminant due to its stability and resistance to degradation. It poses a long-term hazard in areas where it has been released or disposed of improperly.

Related Pages

• Chemical warfare
• Blister agent
• Mustard gas
• British anti-Lewisite