On This Day: Sarin Gas Released in Tokyo Subway

On this day in 1995, the Japanese religious sect Aum Shinrikyo released sarin gas in the Tokyo subway, killing 12 people. The body count could have been much higher but they used a relatively impure form of Sarin. Sarin gas is one of the most toxic substances known. It has its origins in Germany in 1938 when two scientists came up with a formula. Initially developed as a pesticide, its profound toxic effects soon led it being used as a weapon of chemical terrorism. It was used as recently as 2004 by terrorist factions in Iraq. They attempted to make a binary weapon in which two precursor chemicals were placed in artillery shells where the chemicals would mix as the shell spun during flight, creating Sarin gas. It didn’t work very well and only a small amount of gas was released.

Sarin and its close relatives Tabun, Soman, and VX are potent neuromuscular toxins. They belong to the group known as acetylcholinesterase inhibitors. In medicine, there are several useful medications that belong to this family, but these toxic gases represent a serious terrorist threat.

Here’s how they work: Many of the things that go on inside our bodies are the result of the neurotransmitter acetylcholine. In the case of something like wiggling your finger, your brain sends an impulse down the nerves. The impulse causes the end of these nerves to release acetylcholine into a synaptic junction between the nerve and muscle. The acetylcholine then stimulates receptors on the muscle side that tell it to contract. Other chemical reactions within the muscle then causes the contraction to occur. The acetylcholine is then rapidly destroyed by an enzyme we call acetylcholinesterase. This removes the acetylcholine from the muscle receptor site and the muscle relaxes. If the acetylcholine is not destroyed in this fashion, the muscle would continue to contract and that is not a desired situation.

These toxic gases interfere with, or inhibit, the acetylcholinesterase enzymes so that indeed the acetylcholine reaction continues. This leads to widespread dysfunctions throughout the body. The muscles can contract in powerful convulsive reactions. The nose and eyes can water severely and drooling is profound. Nausea and vomiting can occur. Constriction of the pupils to pinpoints as well as loss of control of bowel and bladder can follow. Chest pain, shortness of breath, collapse, seizures, and death is the end result. It is an extremely unfortunate way to die.