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Chemical nerve agents: A "very toxic and horrible way to die"

An alleged poison gas attack in Syria last week left hundreds of people dead and thousands sickened, and has the U.S. considering military action against President Bashar Assad's government. While U.N. investigators are on the scene near Damascus searching for evidence of a chemical attack, many observers suspect a chemical nerve agent like Sarin gas may be involved.

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"The reported symptoms of the patients, in addition to the epidemiological pattern of the events -- characterized by the massive influx of patients in a short period of time, the origin of the patients, and the contamination of medical and first aid workers -- strongly indicate mass exposure to a neurotoxic agent," Dr. Bart Janssens, director of operations at the international medical humanitarian organization, Doctors Without Borders Medecins Sans Frontieres, said in an Aug. 24 statement. "This would constitute a violation of international humanitarian law, which absolutely prohibits the use of chemical and biological weapons."

Hamish de Bretton-Gordon, a British consultant in chemical and biological weapons, added to last Wednesday that, based on the reported death tolls and some yet-to-be authenticated video reports, he suspects a weapon of mass destruction like Sarin gas may have been involved. He has not been directly involved in the investigation of this outbreak.

Sarin is a type of nerve gas that was developed by the Germans in 1938 prior to World War II, originally for use as a pesticide.

Chemical nerve agents like Sarin use concentrated amounts of pesticides called organophosphates. Sarin might be more than 1,000 times more toxic than organophosphate pesticides, which were recently linked to fatal poisonings in India. De Bretton-Gordon said last month that exposure to a nerve agent is a "very toxic and a horrible way to die."

Sarin is classified as a nerve agent because of its poisonous effects on the body's central and peripheral nervous systems, explained biological weapons expert Dr. Kenneth Spaeth, director of the Occupational and Environmental Medicine Center at North Shore University Hospital in Manhasset, N.Y, in an interview with

From a medical standpoint, Sarin is similar to other nerve agents like VX, Soman and Tabun in how they poison the body, said Spaeth, co-author of "The Bioterrorism Sourcebook."

Nerve gases like Sarin poison the acetylcholinesterase enzyme that's found throughout our nervous systems. Enzymes are proteins that break down substances in the body. Typically this enzyme serves as an "off switch" for a neurotransmitter called acetylcholine, a chemical messenger that sends signals to nerves that control muscle movements, breathing and other bodily functions. Neurotransmitters are released from one nerve to the next in a continuous signaling system, and the enzyme typically turns this cycle off, which allows the acetylcholine to get recycled and reused later in the body.

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"What the Sarin gas does, is it basically renders the enzyme ineffectual," said Spaeth. That causes acetylcholine to build up and keep jumping from one nerve to the next in a constant, unending signal. Depending on which nerves were affected and how much gas exposure there was, devastating symptoms may quickly follow.

For someone inhaling the gas, nausea, diarrhea, vomiting, seizures, muscle spasms, excessive secretions (like mucus production) and breathing problems can occur within minutes.

"You're talking about many different organ systems being affected, not just one," he said.

In the event of an attack, the gas can also absorb through the skin or eyes and remain on clothing, the latter posing a risk to emergency responders rushing to treat the wounded.

Doctors Without Borders said Saturday that three hospitals in the Damascus region received 3,600 patients displaying neurotoxic symptoms in less than three hours on Aug. 21, the day of the alleged attacks. 355 of them reportedly died. Symptoms included convulsions, excess saliva, pinpoint pupils, blurred vision and breathing difficulties.

The organization has released more than 7,000 vials of a treatment called atropine to facilities in the area.

Atropine is one of three drugs -- along with diazepam and pralidoxime -- used to treat people affected by Sarin gas. But Spaeth warns they have to be given quickly or their benefits are greatly diminished. This can be difficult in a war-torn area, he said, because it's often not readily apparent which nerve agent was used, which is critical to deciding the proper course of treatment.

"If you don't know what the agent was, it makes a difficult situation even worse," said Spaeth.

He pointed out in the U.S., many hospitals and first responders have been well-prepared for the possibility of chemical nerve agent attacks since 9/11, and have protocols put in place.

Even with treatment, there may still be long-term effects for survivors of a nerve gas attack. Some of the thousands injured in a 1995 Sarin gas attack on the Tokyo subway still experience respiratory and neurological effects that linger to this day, according to Spaeth.

"If you're having significant exposure like breathing, it will travel through the body and have multiple effects," he said. "And that's often the case when you have these large-scale attacks."

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