Nerve agent Guide, Meaning , Facts, Information and Description
Nerve agents (also known as nerve gases, though these chemicals are liquid at room temperature) are a class of phosphorus-containing organic chemicals (organophosphates) that inhibit the acetylcholinesterase enzyme in animals. As a chemical weapons, they are classified as weapons of mass destruction by the United Nations according to UN Resolution 687, and their production and stockpiling was outlawed by the Chemical Weapons Convention of 1993; the Chemical Weapons Convention officially which took effect in 1997.Poisoning by a nerve agent leads to contraction of pupils, profuse salivation, convulsions, involuntary urination and defecation, and eventual death by asphyxiation as control is lost over respiratory muscles. Nerve agents can be absorbed through the skin, requiring that those likely to be subjected to such agents wear a full body suit in addition to a gas mask.
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2 Different nerve agents 3 History 4 References |
As their name suggests, nerve agents attack the nervous system of the human body. All such agents function the same way: by interrupting the breakdown of the neurotransmitters that signal muscles to contract, preventing them from relaxing.
Initial symptoms following exposure to sarin (and other nerve agents) are a runny nose, tightness in the chest and dilation of the pupils. Soon after, the victim will then have difficulty breathing, and will experience nausea and drooling. As the victim continues to lose control of his or her bodily functions, he or she will involuntary vomit, defecate and urinate. This phase is followed by twitching and jerking, and ultimately the victim will become comatose and suffocate as a consequence of convulsive spasms.
The effects of nerve agents are very long lasting and cumulative (increased successive exposures), and survivors of nerve agent poisioning almost invariably suffer chronic neurological damage.
When a normally funtioning motor nerve is stimulated it releases the neurotransmitter acetylcholine, which transmits the impulse to a muscle or organ. Once the impulse is sent, the enzyme acetylcholine esterase immediately breaks down the acetylcholine in order to allow the muscle or organ to relax.
Nerve agents disrupt the nervous system by inhibiting the enzyme acetylcholine esterase by forming a covalent bond with the site of the enzyme where acetylcholine normally undergoes hydrolysis (breaks down). The results is that acetylcholine builds up and continue to act so that any nerve impulses is continually transmitted, and muscle contractions do not stop.
This same action also occurs at the gland and organ levels, causing uncontrolled resulting in drooling, tearing of the eyes (lacrimation), and excess production of mucous from the nose (rhinorreah).
Atropine and related anticholinergic drugs act as antidotes to nerve agent poisoning because they block acetylcholine receptors, but they are poisonous in their own right. While they will save the life of a person affected with nerve agents, that person may be incapacitated briefly, or for an extended period of time, depending on the amount of exposure. Atropine for field use by military personnel is often loaded in an autoinjector, for ease of use in stressful conditions.
Pralidoxime chloride, also known as 2-Pam chloride, is also used as an antidote. Rather than counteracting the initial effects of the nerve agent on the nervous system like atropine, while pralidoxime chloride actually neutralizes the nerve agent in the bloodstream. Though safer to use, it takes a longer time to have an effect.
This series is the first and oldest family of nerve agents. The first nerve agent ever synthesised was was GA (tabun) in 1936. GB (Sarin) was discovered next in 1938, followed by GD (soman) in 1944 and finally the more obscure GF (cyclosarin) in 1949.
All of the V-agents are persistent agents, meaning that these agents do not degrade or wash away easily, and can therefore remain on clothes and other surfaces for long periods. The consistency of these agents is similar to oil; as a reults, the contact hazard for V-agents is primarily - but not exclusively - dermal.
After World War II, the Allies recovered German artillery shells containing the three German nerve agents of the day, prompting further research into nerve agents by the former Allies. In 1952, researchers in Porton Down, England invented the VX nerve agent, but soon abandoned the project. In 1958 the British government traded their VX technology with the United States of America in exchange for information on thermonuclear weapons; by 1961 the US was producing large amounts of VX, and performing its own nerve agent research. This research produced three more agents; the four agents (VE, VG, VM, VX) are collectively known as the "V-Series" class of nerve agents.
During that time, German intelligence believed that the Allies also knew of these compounds, assuming that because these compounds were not discussed in the Allies' scientific journals information about them was being suppressed. Though sarin, tabun and soman were incorporated into artillery shells, Germany ultimately decided not to use nerve agents against Allied targets, fearing a potentially devastating Allied retaliatory nerve agent deployment (in actuality, the Allies didn't learn about these agents until shells filled with them were captured near the end of the war.) This is detailed in Joseph Borkin's book The Crime and Punishment of IG Farben:
One of the most widely publicised uses of nerve agents was the 1995 terrorist attack in which operatives of the group Aum Shinrikyo released sarin into the Tokyo subway system (see Sarin gas attack on the Tokyo subway).
This is an Article on Nerve agent. Page Contains Information, Facts Details or Explanation Guide About Nerve agent Biological Effects
Mechanism of action
Antidotes
Different nerve agents
There are two main classes of nerve agents. The members of the two classes share similar properties, are are given both a common name (such as sarin), and a two character NATO identifier (such GB).G-Series
The G-series, thus named because German scientists first synthesized them. All of the compounds in this class were discovered and synthesized during or soon after World War II, led by Dr. Gerhard Schrader.V-Series
The V-series is the second family of nerve agents, and also contains four members: VE, VG, VM, VX. The most studied agent in this family, VX, was invented in the 1950s at Porton Down in England. The other agents in this series have not been studied extensively, and information about them is limited. It is known, however, that the V-series agents are about 10 times more toxic than the G-agent sarin (GB).Insecticides
A number of insecticides, such as dichlorvos, malathion and parathion are nerve agents. The metabolism of insects is sufficiently different from mammals that these compounds are considered innocuous for humans and their food animals; but there is considerable concern about the effects of long-term exposure to these chemicals by farm workers and animals alike.History
The Discovery of Nerve Agents
This first class of nerve agents, the so-called "G-Series", was accidentally discovered in Germany the late 1930s by a research team headed by Gerhard Schrader attempting to develop an improved insecticide. Almost immediately, the Nazi government classified all reasearch related to these compounds, and continued their development in secret throughout World War II. three of the most widely known agents, sarin (GB), soman (GD), and tabun (GA) were developed at that time for use as chemical warfare agents, but were not used in combat. Cyclosarin (GF) was developed somwhat later, in 1949, by the same team.Nerve Agents in Nazi Germany
In mid-1939, the formula for the agent was passed to the Chemical Warfare section of the German Army Weapons Office, which ordered that it be brought into mass production for wartime use. A number of pilot plants were built, and a high-production facility was under construction (but was not finished) by the end of World War II. Estimates for total sarin production by Nazi Germany range from 500 kg to 10 tons. Since World War II
To date, nerve agents have not been used in warfare on a large scale. Iraq briefly used chemical weapons, including nerve agents, during the Iran-Iraq war of 1981-1988; the Kurdish village of Halabja was exposed to nerve agents, and controversy still rages as to whether this was a deliberate or accidental act. Nerve agents were not used by Iraq in the Gulf War, despite widespread fears to the contrary. However, the widespread use of anticholinergic drugs as a prophylaxis against nerve gas attack has been proposed as a possible cause of Gulf war syndrome.References