By Jocelyn Kaiser
August 28, 2013
The United States is weighing a military strike against Syria after concluding that Syrian President Bashar al-Assad is responsible for an “undeniable” chemical attack that killed hundreds of people. This week, U.N. investigators are interviewing survivors and collecting samples in the area near Damascus where the 21 August attack allegedly occurred. The team includes experts from the World Health Organization and the Organisation for the Prohibition of Chemical Weapons (OPCW). Judging from videos and other accounts of the attack, chemical weapons specialists say that the investigators are likely to focus on suspicions that the attack involved the nerve agent sarin. It is an inhibitor of the enzyme acetylcholinesterase, which controls the body’s levels of the neurotransmitter acetylcholine. More background:
Q: Why do experts suspect that sarin was used, not another nerve agent or different chemical weapon such as mustard gas?
A: The fact that victims apparently had symptoms such as paralysis and convulsions, but didn’t suffer from skin blistering, points toward a nerve agent, not mustard gas, says Amesh Adalja, an expert on disaster medicine at the University of Pittsburgh Medical Center’s Center for Health Security in Baltimore, Maryland. Sarin is more likely than the deadlier nerve agent VX because that chemical is much less volatile and would leave contamination on equipment that could harm soldiers, according to chemist Carlos Fraga of Pacific Northwest National Laboratory in Richland, Washington. Some news accounts have also speculated that the attack involved a mixture of chemicals, which could complicate the analysis.
Q: What evidence will the U.N. investigators in Syria collect?
A: One thing to look for is debris left from the bombing, says Philip Coyle, a weapons expert and former White House national security official in the Obama administration who is now at the Center for Arms Control and Non-Proliferation in Washington, D.C. Sarin might be delivered in bomblets like those in this Wikipedia image, he says. Although each country may have its own way of packaging the agent, “people in the [Department of Defense] have a pretty good idea what Syrian weapons look like,” Coyle says.
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