Tabun (Forensic Science)
Tabun, which was discovered in Germany in the 1930’s during a search for new insecticides, is the earliest and most easily manufactured of the so-called nerve gases. Although it has been superseded as a chemical weapon by agents such as VX, its relative ease of manufacture makes it attractive to some nations that might consider using it as a weapon.
Tabun was manufactured and stored in multiton quantities in Nazi Germany during World War II, but it was never used in combat. During the Iran-Iraq War (1980-1988), however, Iraq used the agent against Iranian troops. In 1984, a team sent to Iran by the United Nations found tabun in a dud bomb that Iraq had dropped inside Iran’s borders. The team also visited a field hospital where several patients were recovering; they exhibited symptoms consistent with poisoning by tabun, although no detailed tests were done.
Like other organophosphorus nerve agents, tabun is an inhibitor of the vital enzyme acetylcholinesterase (AChE). When tabun is absorbed through the skin or the vapor or aerosol of the agent is inhaled, the chemical binds to AChE. The normal function of AChE is to catalyze a reaction that removes acetylcholine from the nerve endings, where it activates muscle contraction. Inhibition of the enzyme allows accumulation of acetylcholine, which causes sweating, runny nose, incontinence, visual impairment (including pain and contraction of the pupils, or meiosis), respiratory failure,...
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Further Reading (Forensic Science)
Croddy, Eric A., and James J. Wirtz, eds. Weapons of Mass Destruction: An Encyclopedia of Worldwide Policy, Technology, and History. Santa Barbara, Calif.: ABC-CLIO, 2005.
Hoenig, Steven L. Handbook of Chemical Warfare and Terrorism. Westport, Conn.: Greenwood Press, 2002.
Somani, Satu M., and James A. Romano, Jr., eds. Chemical Warfare Agents: Toxicity at Low Levels. Boca Raton, Fla.: CRC Press, 2001.
Suzuki, Osamu, and Kanako Watanabe, eds. Drugs and Poisons in Humans: A Handbook of Practical Analysis. New York: Springer, 2005.
Tucker, Jonathan B. War of Nerves: Chemical Warfare from World War I to al-Qaeda. New York: Pantheon Books, 2006.
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Tabun (World of Forensic Science)
Tabun (or "GA") is one of a group of synthetic chemicals that were developed in Germany during the 1930s and 1940s. (Tabun was developed in 1936.) The original intent of these compounds, including tabun, was to control insects. These pesticides were similar to organophosphates (pesticides that contain phosphorus and act as nerve poisons on most animals) in their action on the nervous system. However, tabun and the other human-made nerve agents proved to be much more potent than the organophosphates, and so quickly became attractive as chemical weapons.
Tabun is one of the G-type nerve agents, along with sarin and soman. They are all clear, colorless, and tasteless. As a result, tabun mixes readily with water, and so can be used as a water-poisoning agent. Food can also be contaminated. The fluid form of tabun can also be absorbed through the skin.
When in water, tabun loses its potency relatively quickly, compared to airborne vapors, which can remain potent for a few days. The vapors can even bind to clothing, where they will subsequently be released for 30 minutes or so. People close to the contaminated person can themselves be affected by the vapor. Tabun vapors tend to be denser than air and so settle into low-lying depressions or valleys. People in such regions are especially susceptible.
Like the other members of the G series, tabun is a nerve agent. Specifically, it inhibits an enzyme called cholinesterase. This enzyme breaks apart a compound that acts as a communication bridge between adjacent nerve cells. Normally, the transient formation and destruction of the bridge allows a control over the transmission of nerve impulses. But, the permanent presence of the bridging compound means that nerves "fire" constantly, which causes muscles to tire and eventually stop functioning. In the case of the lungs, this can be fatal.
Symptoms of tabun poisoning, which can begin within minutes of exposure, include runny nose, watery and painful eyes, drooling, excessive sweating, rapid breathing, heart beat abnormalities, and, in severe cases, convulsions, paralysis, and even fatal respiratory failure.
Treatment for the inhalation of tabun consists of three timed injections of a nerve agent antidote such as atropine. Since this may or may not be successful, prevention remains the most prudent strategy. Protective clothing including a gas mask is a wise precaution for forensic investigators who are in an environment where the deployment of tabun is suspected.
SEE ALSO Chemical warfare; Sarin gas.