How Sarin Nerve Gas Works (And What to Do If Exposed)

Sarin is an organophosphate nerve agent. It most commonly is considered a nerve gas, but it mixes with water, so ingestion of contaminated food/water or liquid skin contact also are possible. Exposure to even a small amount of Sarin may be fatal, yet treatments are available that may prevent permanent neurological damage and death. Here's a look at how it works and how exposure to Sarin is treated.

What Is Sarin?

Sarin is a man-made chemical with the formula [(CH₃)₂CHO]CH₃P(O)F. It was developed in 1938 by German researchers at IG Farben for use as a pesticide. Sarin gets its name from its discoverers: Schrader, Ambros, Rüdiger, and Van der Linde. As a weapon of mass destruction and chemical weapon, sarin is identified by NATO designation GB. The production and stockpiling of sarin was forbidden by the Chemical Weapons Convention of 1993.

Pure Sarin is colorless, odorless, and has no flavor. It is heavier than air, so Sarin vapor sinks into low-lying areas or toward the bottom of a room. The chemical evaporates in air and mixes readily with water. Clothing absorbs Sarin and its mixtures, which can spread exposure if contaminated clothing is not contained.

It's important to understand you can survive a low concentration of Sarin exposure as long as you don't panic and do seek medical attention. If you survive initial exposure, you may have several minutes to several hours to reverse the effects. At the same time, don't assume you are in the clear just because you survived initial exposure. Because effects may be delayed, it's important to get medical attention.

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How Sarin Works

Sarin is a nerve agent, which means it interferes with the normal signaling between nerve cells. It acts in much the same way as organophosphate insecticides, block nerve endings from allowing muscles to stop contracting. Death may occur when the muscles controlling breathing become ineffective, causing asphyxiation.

Sarin acts by inhibiting the enzyme acetylcholinesterase. Ordinarily, this protein degrades acetylcholine released at the synaptic cleft. The acetylcholine activates nerve fibers that cause muscles to contract. If the neurotransmitter is not removed, the muscles don't relax. Sarin forms a covalent bond with the serine residue at the active site on the cholinesterase molecule, making it unable to bind to acetylcholine.

Symptoms of Sarin Exposure

Symptoms depend on the route and intensity of exposure. The lethal dose is incrementally higher than the dose producing minor symptoms. For example, inhaling an extremely low concentration of Sarin may produce a runny nose, yet a very slightly higher dose may cause incapacitation and death. The onset of symptoms depends on dose, usually within minutes to hours after exposure. Symptoms include:

• Dilated pupils
• Headache
• Sense of pressure
• Salivation
• Runny nose or congestion
• Nausea
• Vomiting
• Tightness in chest
• Anxiety
• Mental confusion
• Nightmares
• Weakness
• Tremors or twitches
• Involuntary defecation or urination
• Abdominal cramps
• Diarrhea

If an antidote is not given, symptoms may proceed to convulsions, respiratory failure, and death.

Treating Sarin Victims

Although Sarin can kill and cause permanent damage, individuals who suffer mild exposure usually recover completely if given immediate treatment. The first and most important action is removing Sarin from the body. Antidotes to Sarin include atropine, Biperiden, and pralidoxime. Treatment is most effective if given immediately, but still helps if some times passes (minutes to hours) between exposure and treatment. Once the chemical agent is neutralized, supportive medical care is helpful.

What to Do If You Are Exposed To Sarin

Do not administer mouth-to-mouth resuscitation to a person exposed to Sarin, since the rescuer can be poisoned. If you think you have been exposed to Sarin gas or Sarin-contaminated food, water, or clothing, it's important to seek professional medical attention. Flush exposed eyes with water. Clean exposed skin with soap and water. If you have access to a protective respiratory mask, hold your breath until you can secure the mask. Emergency injections typically are used only if symptoms of severe exposure occur or if the Sarin is injected. If you have access to injectables, be sure to understand when to use/not-use them, since the chemicals used to treat Sarin come with their own risks.

References

• CDC Sarin Fact Sheet
• Sarin Material Safety Data Sheet, 103d Congress, 2d Session. United States Senate. May 25, 1994.
• Millard CB, Kryger G, Ordentlich A, et al. (June 1999). "Crystal structures of aged phosphonylated acetylcholinesterase: nerve agent reaction products at the atomic level". Biochemistry 38 (22): 7032–9.
• Hörnberg, Andreas; Tunemalm, Anna-Karin; Ekström, Fredrik (2007). "Crystal Structures of Acetylcholinesterase in Complex with Organophosphorus Compounds Suggest that the Acyl Pocket Modulates the Aging Reaction by Precluding the Formation of the Trigonal Bipyramidal Transition State". Biochemistry 46 (16): 4815–4825.