Breaking News

Error rendering macro 'rss' : java.io.IOException: Failed to recover from an exception: http://environmentalhealthnews.org/archives_rss.jsp?sm=&tn=1title%2Clede%2Cdescription%2Ctext%2Csubject%2Cpublishername%2Ccoverage%2Creporter&tv=toxicology&ss=1

Nerve Agents


Topic editor

Overview


Nerve Agents were developed just prior to World War II initially as Insecticides but later used as Chemical Warfare agents and were advanced throughout the 20th century. There are three classes, G-Agents, V-Agents, and Novichok agents, that all inhibit the production of cholinesterase which results in a surplus of Acetylcholine. This surplus produces negative effects on the nervous system at first, and later negatively affects the skeletal system as well.

Health Effects


Nerve agent or organophophate poisoning results in a wide range of exposure because it affects a large number of organs and physical processes. Below is a list retrieved from the CDC site on nerve agent exposure.

Health Effects

  • Miosis (unilateral or bilateral)
  • Headache
  • Restlessness
  • Convulsions
  • Loss of consciousness
  • Coma
  • Rhinorrhea (perfuse watery runny nose)
  • Bronchorrhea (excessive bronchial secretions)
  • Dyspnea - (shortness of breath)
  • Chest tightness
  • Hyperpnea - (increased respiratory rate/depth) - early (increased respiratory rate/depth)
  • Bradypnea - (decreased respiratory rate) - late (decreased respiratory rate)
  • Tachycardia - (increased heart rate) - early (increased heart rate)
  • Hypertension - (high blood pressure) - early (high blood pressure)
  • Bradycardia - (decreased heart rate) - late (decreased heart rate)
  • Hypotension - (low blood pressure) - late (low blood pressure)
  • Arrhythmias Dysrhythmias (prolonged QT on EKG, ventricular tachycardia) Abdominal pain
  • Nausea and vomiting
  • Diarrhea
  • Wheezing
  • Urinary incontinence, frequency
  • Profuse sweating (local or generalized)
  • Lacrimation (tear formation)
  • Conjunctival injection
  • Weakness (may progress to paralysis)
  • Fasciculations (local or generalized)

 

Modes of Action


Nerve agents inhibit the enzyme cholinesterase which is released when a nerve is stimulated. Inhibiting the molecule leads to a surplus amount of Acetylcholine which then overstimulates the muscatinic or nicotinic cell receptors of organs (#Tucker, 2006).

From #Tucker, 2006:
"The smooth muscles surrounding the bronchial tubes tighten, reducing the flow of air and causing an asthma-like shortness of breath; the muscles of the gastrointestinal tract go into spasm, resulting in abdominal cramps, nausea, vomiting, and diarrhea; and the ciliary muscles in the eye constrict, reducing the iris to pinpoint dimensions with a concomitant dimming and blurring of vision. Too much acetylchline also causes several glands to become overactive and secrete excessive amounts of nasal mucus, saliva, and sweat" (#Tucker, 2006).

At high doses of exposure, nerve agents cause skeletal muscles to contract resulting in violent convulsions. They also affect the brain causing seizures and a loss of consciousness (#Tucker, 2006).

Classifications


G-Class Agents
The G-Class Agents are GA (Tabun), GB (Sarin), and GD (Soman). The G-Agents were discovered by German chemist Gerhard Schrader while doing research on organophosphate pesticides while working at IG Farben. The first agent synthesized was Tabun in the mid-1930s which was put into commercial production and eventually stockpiled by numerous countries throughout the world. Later, German chemists synthesized Sarin and Soman which also were traded and stockpiled throughout the world (#Tucker, 2006). The "G" refers to the fact that they were synthesized in Germany.

V-Class Agents
The only V-Class Agent significantly developed was VX. VX, the "v" being short for "venomous", are much more potent than the G-Class Agents. They were initially developed by Ranajit Ghosh while working at Britain's Imperial Chemical Industries in 1952. It was marketed as Amiton for a short while until its pernicious side effects forced them to remove it from the market. Porton Down, Britain's chemical weapons agency, developed it as a chemical weapon and it remains one of the potent chemical warfare agents (#Tucker, 2006).

Novichok Agents
The Novichok Agents or foliant agents were developed after the Soviet Union received the chemical formula for VX in the late 1950s. These agents are much more toxic than both the V-Agents and g-agents. They developed the Novichok agents throughout the 1980s and up until the mid-1990s until a scientist, frustrated with the health conditions surrounding the secret plant, exposed the plant to the media. This was signifigant because the Russian government pledged to declare all stocks of chemical weapons, but withheld information on this highly toxic substance (#Tucker, 2006).

Regulation


See Chemical Weapons Convention.

External Links



Emedicine.com. Retreived Jan. 5, 2004.

References



Tucker, Johnathon B. War of Nerves: Chemical Warfare from World War I to Al-Qaeda. Pantheon Books, 2006.

  • No labels