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Types of Chemical Weapons

© Linda Mamassian

A month ago, when I wrote an article about the background and history of chemical and biological weapons, most experts thought that an attack with such weapons was highly unlikely. Since then, we've all learned more than we ever wanted to know about anthrax, and many are worried about smallpox.

So much has been said and written recently about biowarfare that there is little need for me to dwell on the topic, especially since I'm supposed to be writing about chemistry. However, relatively little has been said about chemical weapons. A variety of chemical weapons are known. Their effectiveness depends on a number of factors, including purity, age, weather conditions, wind speed and direction, method of dissemination, etc. The technology to produce such chemical weapons is widely available. In the aftermath of the September 11 attacks, we cannot ignore the threat of chemical weapons.

Sarin and Other "Nerve Gases"

Sarin was the chemical weapon used by the Arum Shinrikyo terrorists in their 1995 attack on three Tokyo subway lines, which left twelve people dead and over 5,000 wounded. It was also stockpiled by Iraq during its war with Iran and during the Gulf War. Iraq used chemical weapons against Iran's forces and against its own people, although there is no evidence of chemical weapon use in the Gulf War.

This "nerve gas" was originally developed in Germany in 1938 as an insecticide. Like other nerve agents, Sarin kills people by attacking a substance called acetylcholinesterase, the body's "off switch." Without this substance, glands and voluntary muscles are continually stimulated ("switched on"). When the muscles are exhausted the victim can no longer breath. Small amounts of Sarin are lethal. It can be inhaled and can also be absorbed through the eyes or skin, which limits the protection you can get from a gas mask. Symptoms include runny nose, watery eyes, drooling, sweating, difficulty breathing, nausea, headache, twitching, and staggering. Sarin is not "persistent" -- it evaporates about as fast as water. If you are exposed, call for emergency help, remove contaminated clothing and wash exposed skin with soap and water or 5% household bleach. Atropine is used in medical treatment of victims.

Other nerve agents -- Tabun, Soman, and VX -- are more toxic and last longer in the environment than Sarin. Compared to biological weapons, nerve agents are more expensive to produce, but they are easier to use effectively.

Other Agents

Cyanides

Hydrogen cyanide is used in many plastic and chemical products. It is a colorless vapor at normal temperatures with a smell similar to bitter almonds. It is highly toxic, and high concentrations can rapidly lead to death.

Sarin Molecular Structure

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