Nerve agents are now divided into three series:
- The G-series is named because German scientists first
synthesized them. G series agents are known as non-persistent, while
the V series are persistent. The first nerve agent synthesised was GA
(Tabun) in 1936. GB (Sarin) was discovered next in 1939, followed by
GD (Soman) in 1944 and finally the more obscure GF (Cyclosarin) in
1949.
- The V-series were developed in the 1950s. Workers at ICI in
the UK were looking for new organophosphorous pesticides. In 1954, ICI
put one of them on the market under the trade name Amiton. It was
subsequently withdrawn, as it was too toxic for safe use. The toxicity
did not go unnoticed and some of the more toxic materials had in fact
been sent to the Chemical Defence Establishment at Porton Down for
evaluation. After the evaluation was complete, several members of this
class of compounds became a new group of nerve agents, the V agents
(depending on the source, the V stands for Victory, Venomous, or
Viscous). The best known of these is probably VX, with the Russian
V-gas coming a close second (Amiton is largely forgotten as VG). This
class of compounds is also sometimes known as Tammelin's esters, after
Lars-Erik
Tammelin of the Swedish Institute of Defense Research who first
synthesised a number of the agents.
- The Novichok (Russian for "newcomer") agents are a
series of organophosphorous compounds that were developed in the
Soviet Union from the mid-1960s to the 1990s. The goal of this program
was to develop and manufacture highly deadly chemical weapons that
were unknown to the West. These new agents were designed to be
undetectable using standard 1970s and 80s NATO chemical detection
equipment; to defeat NATO chemical protective gear; to be safer to
handle; and to circumvent the Chemical Weapons Convention list of
controlled precursors, classes of chemical and physical form. In
addition to the newly developed "third generation" weapons, binary
versions of several Soviet agents were developed and were also
designated as "Novichok" agents. In the USA binary weapons were also
developed. Binary agents are made up of two parts, individually they
are relatively non-toxic, but when combined following discharge from a
weapon, they form the active agent. Novichok
agents are of such importance that on this site they warrant their
own page.
A colourless liquid, odorless to fruity odour, possibly of peach.
Cyclosarin is readily absorbed through skin, eyes, and respiratory tract
with inhalation and dermal routes of exposure posing significant
threats.Toxic manifestations of exposure to cyclosarin vapor or aerosols
occur within seconds to minutes of inhalation, while signs and symptoms of
percutaneous exposure to liquid cyclosarin may take a minute to hours.
In the pure form a colourless, odourless liquid. Exposure is lethal even
at very low concentrations, where death can occur within one-to-ten
minutes after direct inhalation of a lethal dose, due to suffocation from
lung muscle paralysis, unless antidotes are quickly administered. People
who absorb a non-lethal dose, but do not receive immediate medical
treatment, may suffer permanent neurological damage.
A structural isomer of VX. It is an organic thiophosphate that is an ester
of S-[2-(diethylamino)ethyl] O hydrogen methylphosphonothioate. A toxic
nerve agent developed by the Peoples' Republic of China. It has a role as
a neurotoxin and an acetylcholinesterase inhibitor. It is an organic
thiophosphate and a tertiary amino compound.
A clear, colourless to brownish, and tasteless liquid with a faint fruity
odor. The symptoms of exposure include: nervousness/restlessness, miosis ,
rhinorrhea, excessive salivation, dyspnea, sweating, bradycardia, loss of
consciousness, convulsions, flaccid paralysis, loss of bladder and bowel
control, apnea and lung blisters. The exact symptoms of overexposure are
similar to those created by all nerve agents. Tabun is toxic even in
minute doses. The number and severity of symptoms which appear vary
according to the amount of the agent absorbed and rate of entry of it into
the body. Very small skin dosages sometimes cause local sweating and
tremors accompanied with characteristically constricted pupils with few
other effects. Tabun is about half as toxic as sarin by inhalation, but in
very low concentrations it is more irritating to the eyes than sarin. The
effects of tabun appear slowly when tabun is absorbed through the skin
rather than inhaled. A victim may absorb a lethal dose quickly, although
death may be delayed for one to two hours. A person's clothing can release
the toxic chemical for up to 30 minutes after exposure. Inhaled lethal
dosages kill in one to ten minutes, and liquid absorbed through the eyes
kills almost as quickly. However, people who experience mild to moderate
exposure to tabun can recover completely, if treated almost as soon as
exposure occurs.
A clear, amber-colored odorless, oily liquid. People exposed to a
low or moderate dose of VX by inhalation, ingestion (swallowing), or skin
absorption may experience some or all of the following symptoms within
seconds to hours of exposure: abnormally low or high blood pressure,
blurred vision, chest tightness, confusion, cough, diarrhea, drooling,
excessive sweating, drowsiness, eye pain, headache, increased urination,
nausea, vomiting, abdominal pain, tachypnea, rhinitis, bradycardia,
tachycardia, miosis, lachrymation, weakness. Even a tiny drop of nerve
agent on the skin can cause sweating and muscle twitching where the agent
touched the skin.
Exposure to a large dose of VX by any route may result in these additional
health effects: convulsions, loss of consciousness, paralysis, respiratory
failure possibly leading to death.
VR has similar lethal dose levels to VX. Acute exposure to a lethal
dose of VR has been shown to cause cholinergic hyperfunction,
incapacitation, seizures, convulsions, cardiorespiratory depression and
death.
A volatile, corrosive, and colorless liquid with a faint odor like that of
mothballs or rotten fruit. In the impure form it has a yellow to brown
colour and has a strong odour described as similar to camphor. It is
both more lethal and more persistent than sarin or tabun, but less so than
cyclosarin.
VG has a toxicity of about 1/10 that of VX, i.e. similar to that of sarin.
Probably too unstable to be weaponise.
Odourless and colourless to yellow-brown liquid. The effect of exposure to
Ethyl sarin depends on the amount of the agent, route and duration of the
exposure. The symptoms will appear within a few seconds after inhalation
exposure to the vapour form and from a few minutes to 18 hours after
exposure to the liquid form. Ethyl sarin may be absorbed quickly and
easily. When dispersed as a vapour or aerosol, or absorbed on dust, it is
readily absorbed through the respiratory tract and conjunctivae.
Absorption is most rapid and complete through the respiratory tract.
Aerosols and liquids are also absorbed through skin. Vapours may be
absorbed through skin if at very high concentrations. Liquid
droplets or even vapor may persist in a victim's clothes after minutes to
hours of exposure which may lead to cross-contamination of others.
Following local exposure, symptoms may include: rhinorrhoea and hyperaemia
of nasal mucosal membranes, miosis - sometimes unequal, hyperaemia
of conjunctivae, excessive sweating at site of exposure, frontal headache,
eye pain on focusing, slight dimness of vision, occasional nausea and
vomiting, tightness of chest, sometimes with prolonged wheezing,
expiration suggestive of bronchoconstriction or increased secretion and
cough. Fasciculations (muscle twitching) at site of exposure to liquid.
Following systemic absorption: tightness in chest with prolonged wheezing
expiration suggestive of bronchoconstriction or increased secretion,
dyspnoea, slight pain in chest, increased bronchial secretion,
cough, pulmonary oedema, cyanosis, anorexia, nausea, vomiting,
abdominal cramps, epigastric and substernal tightness with heartburn and
eructation, diarrhoea, tenesmus; involuntary defaecation,
increased/excessive sweating, increased/excessive salivation,
increased/excessive lacrimation, bradycardia, slight miosis occasionally
unequal, blurring of vision, involuntary urination, easy fatigue, mild
weakness, muscular twitching, fasciculations, cramps, generalized
weakness, including muscles of respiration, with dyspnoea and cyanosis
Similar lethal dose levels to VX (between 10 and 50 mg) and have similar
symptoms and method of action to other nerve agents.
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