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Hank discusses the chemistry of sarin, the nerve agent that killed more than 1400 people in a chemical weapons attack in Syria.

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Chemistry can be pretty great. It can also be really, really, really terrible. I believe that science is like a hammer; it can be used to build or to destroy. I have that it is sometimes used to destroy, but humanity is a difficult force to control. Today on SciShow News, we discuss Sarin Gas, the nerve agent that was used in the recent attacks in Syria. 

Okay, so we tend to think of our muscles as being actively on, and inactively off. But in fact, both the on and off stages require an active step. When you tell your muscles to flex, acetylcholine, a neurotransmitter, floods around your muscle cells, telling them to contract. When your brain tells the muscles to stop contracting, the acetylcholine has to be removed. This is done with acetylcholinesterase, an enzyme that breaks down the acetylcholine into its constituent parts, allowing your muscles to relax. These steps occur every time you flex and relax any muscle in your body. Every blink of your eye, every time you click a mouse, every beat of your heart. 

Last weekend, the UN confirmed that the Syrian government used the nerve agent Sarin on civilians in Damascus last month. Sarin kills by bonding with acetylcholinesterase, completely changing its physical structure. With the enzyme non-functioninal, acetylcholine is thus never removed, it never breaks down, so instead of muscles flexing and relaxing, they can only flex, and flex more, and flex more. Everything from your pupils to your fingers cramp, completely rigid. The muscles burn with exhaustion but cannot relax. The pain is terrible. If enough of the agent enters the bloodstream, usually through lungs or skin, it will cause cramping of the diaphragm, which locks the lungs in place, and the victim will asphyxiate.

Sarin was created in Germany, just as World War II was breaking out, by scientists attempting to create pesticides for use in agriculture. But, with the war, it turned out to be something of a dream agent for killing. It's odorless and colorless, very volatile, meaning that it evaporates quickly so it can enter the lungs. It kills quickly, and unlike traditional warfare, it doesn't damage infrastructure. This has led to Sarin Gas being called "The Poor Man's Neutron Bomb." Great at killing every living thing, and leaving everything like power lines and buildings and water pipes left for the invading army to use.

The one good thing about Sarin, when compared to other chemical weapons, people who survive attacks tend to fully recover. Other classes of chemical weapons, like choking agents which can permanently scar lung tissue, and blister agents which, yes, are as bad as they sound, can leave people permanently and painfully disabled. 

Sarin also degrades quickly after use. In fact, its shelf life is so short that its often created from precursor chemicals on the ground as its used. Soon after being used, Sarin breaks down into harmless chemicals, and weeks after an attack it is impossible to determine whether the gas was ever present. In this case, though, UN investigators were able to detect Sarin-using gas chromatographs and mass spectrometers.

We know enough about our nervous system now that we have developed antidotes that can block Sarin from interfering with enzymes, but they're only effective when taken immediately after exposure, which is generally extremely impractical. Sarin's effectiveness in killing and the fact that it kills indiscriminately and in a very painful way is why it has been classified as a weapon of mass destruction and banned from use in warfare. 

We at SciShow, and also, I assume, all other sane people agree that banning chemical weapons makes sense. I feel personally offended every time chemistry is used to kill someone, but I don't get to choose the moment in time in which humanity stops being terrible. I just get to keep hoping for it, I guess. Thank you for watching this episode of SciShow News. I guarantee you that science, right now, is being used to do great and amazing things and not to kill people. We'll talk more about that next week. 

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