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How deadly nerve gas sarin kills

Sarin gas -- which U.S. officials believe Syria has used to help quell a rebellion -- is one of the deadliest poisons made by people.

It’s a colorless, odorless nerve agent, best known as the weapon used by the Aum Shinrikyo sect in an attack on the Tokyo subway in 1995 that killed 13 people, and one the year before in Matsumoto that killed eight people.

Iraq also used sarin in an attack on the Kurdish city of Halabja in 1988. Iraq killed 5,000 people in that attack, in which other poisons such as cyanide were also used.

The gas, originally developed by German scientists as a pesticide, can be inhaled or absorbed through the skin. It dissipates quickly in open air – a good thing – but can linger on clothing and surfaces. People don’t know right away they’ve been exposed because it doesn’t smell or burn them. It can also be used to poison water.

“Symptoms will appear within a few seconds after exposure to the vapor form of sarin and within a few minutes up to 18 hours after exposure to the liquid form,” the Centers for Disease Control and Prevention says on its website about sarin.

“All the nerve agents cause their toxic effects by preventing the proper operation of the chemical that acts as the body’s ‘off switch’ for glands and muscles. Without an ‘off switch,’ the glands and muscles are constantly being stimulated. They may tire and no longer be able to sustain breathing function.”

The first symptoms include a runny nose and watery eyes. People may drool and cough, their heart rate goes up and they become confused.

“Even a small drop of sarin on the skin can cause sweating and muscle twitching where sarin touched the skin,” the CDC says “If people think they may have been exposed, they should remove their clothing, rapidly wash their entire body with soap and water, and get medical care as quickly as possible.”

Sarin interferes with an important enzyme called acetylcholinesterase, which in turn controls nerve signals to the muscles. There are some antidotes, which include atropine and pralidoxime.

Iraq is accused of having used sarin against Iran in the 1980 Iran-Iraq war, and U.S. soldiers found a shell containing sarin in 2004.

Syria’s accused of using other chemical agents, too, including tabun, a nerve agent very similar to sarin in its effects, cyanide, and a heavy, greasy chemical called VX that also acts as a nerve agent. Syria’s also accused of having mustard gas, an older World War II chemical weapon named for its distinctive burning odor. Mustard gas not only burns on contact but it can cause cancer years later in people who survive an attack.

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