What is Sarin Gas, the Chemical Weapon That Has Killed Over 70 in Syria?

U.N. chemical weapons expert
A U.N. chemical weapons expert, wearing a gas mask, holds a plastic bag containing samples from one of the sites of an alleged chemical weapons attack in the Ain Tarma neighborhood of Damascus, August 29, 2013. Mohamed Abdullah/Reuters

The U.S. government and the Syrian opposition have accused the regime of Syrian President Bashar al-Assad of releasing sarin, a deadly nerve agent in the town of Khan Sheikhoun this week, in the worst use of chemical weapons in the Syrian civil war since 2013.

The government in Damascus has strenuously denied the accusations, just as it has in the past dismissed all reports of chemical weapons' use throughout Syria's six-year-long conflict, and despite evidence to the contrary.

Russia, a principal backer of the Assad regime, claimed the toxic gas was dispersed when a Syrian air strike accidentally hit a "terrorist warehouse."

Read more: Russia says Syria strike hit rebel "toxic" weapons depot

This week's incident isn't the first time the Syrian government has been accused of deploying the chemical agent sarin. In 2013, the United Nations confirmed that 1,300 people were killed in rebel-held Ghouta, a suburb of Damascus. Following the attack, a UN team supervised the surrender of Syria's sarin, a project completed in 2014 although suspicions persisted that a portion of the stockpile was never surrendered, the Guardian reported.

Syria chemical attack
A civil defense member breathes through an oxygen mask, after a suspected gas attack in the town of Khan Sheikhoun in rebel-held Idlib, Syria April 4. Ammar Abdullah/ REUTER

What is Sarin Gas and what does it do?

The symptoms caused by the nerve agent vary by the length of exposure, the Centre for Disease Control (CDC) and Prevention says. Small pinpoint pupils are a tell-tale sign of the nerve agent. The CDC describes the most harmful effects include loss of consciousness, painful convulsions, paralysis and respiratory failure, possibly leading to death. Victims of the toxin can also lose bodily functions and begin drooling, defecating, urinating, and vomiting under the effects of the agent.

The CDC classifies sarin as a human-made chemical warfare agent. Nerve agents are the most toxic and rapidly acting type of chemical weapon. Sarin comes in liquid form but can also be weaponized as a gas to spread throughout an environment.

Sarin is described as the most volatile of the nerve agents. It can easily and quickly evaporate from a liquid into a vapor. Because it evaporates so quickly, sarin presents an immediate threat.

How and Why governments Might use Sarin

Karl Dewey at IHS Jane's intelligence tells Newsweek there are many ways of weaponizing sarin, as there are other chemical weapons. There's also a psychological impact, he added. "There are other social effects such as fear and terror," Dewey says, adding that "anecdotal evidence suggests CW use causes much higher levels of population flight than conventional explosives."

Gas Attack In Tokyo Subway
Gas attack in Tokyo subway in March 1995 Kurita Kaku/Getty

The History of Sarin

Sarin originally was developed in Germany in 1938 as a pesticide, and while the U.S. and the Soviet Union weaponized the deadly gas it was never used by either of the Cold War superpowers.

The largest military use of the nerve agent was by Iraqi dictator Saddam Hussein who dropped the gas in bombs on the Kurdish village of Halabja in 1988. The payload included mustard gas and the nerve agent tabum, according to media reports at the time. Estimates of the civilians killed range from 3,200 to 5,000.

Between 1994 and 1995 the Aum Shinrikyo, a Japanese doomsday cult, carried out two sarin attacks, killing 12 and injuring thousands after it released the toxin in the Tokyo subway. In an attack seen as a precursor to the subway bombing, eight people were killed and 200 injured in a sarin gas incident in 1994 in the residential neighborhood of Matsumoto in Nagano Prefecture.

The Aum Shinrikyo attacks were the last to use chemical weapons before the Syrian war erupted. In 1993, 162 countries signed the Chemical Weapons Convention, which outlawed the manufacture and stockpiling of chemical weapons.

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