Chemical Weapons - Introduction
Source: American Federation of Scientists Chemical weapons use the toxic properties of chemical
substances rather than their explosive properties to produce physical
or physiological effects on an enemy.
Although instances of what might be styled as chemical
weapons date to antiquity, much of the lore of chemical weapons as
viewed today has its origins in World War I. During that conflict
"gas" (actually an aerosol or vapor) was used effectively on numerous
occasions by both sides to alter the outcome of battles. A significant
number of battlefield casualties were sustained. The Geneva Protocol,
prohibiting use of chemical weapons in warfare, was signed in 1925.
Several nations, the United States included, signed with a reservation
forswearing only the first use of the weapons and reserved the right
to retaliate in kind if chemical weapons were used against them (the
United States did not ratify the Protocol until 1975). Chemical
weapons were employed in the intervening period by Italy (in Ethiopia)
and Japan (in Manchuria and China). Both nations were signatories to
the Geneva Convention. Chemical weapons were never deliberately
employed by the Allies or the Axis during World War II, despite the
accumulation of enormous stockpiles by both sides. Instances of
employment of chemical weapons in the local wars since then are
arguable, although they were definitely used in the Iran-Iraq conflict
of 1982-87.
Development of chemical weapons in World War I was
predominantly the adaptation of a chemical "fill" to a standard
munition. The chemicals were commercial chemicals or variants. Their
properties were, for the most part, well known. The Germans simply
opened canisters of chlorine and let the prevailing winds do the
dissemination. Shortly thereafter the French put phosgene in a
projectile and this method became the principal means of delivery. In
July 1917, the Germans employed mustard shells for the first time and
simultaneously attempted to use a solid particulate emetic, diphenyl
chloroarsine, as a mask breaker. Mustard, an insidious material,
penetrates leather and fabrics and inflicts painful burns on the skin.
These two themes, along with significant increases in
toxicity, represent a large segment of the research and development of
chemical weapons that nations have pursued over the years. There is
first the concept of agents that attack the body through the skin,
preferably also through clothing, and more preferably through
protective clothing. Along with that concept is the idea of
penetrating or "breaking" the protective mask so that it no longer
offers protection for the respiratory system. Increasing the toxicity
of the chemical agent used would theoretically lower the amounts
required to produce a battlefield effect. Unless this increase is
significant, however, it can be masked by the inefficiencies of
disseminating the agent. Consequently, later development has focused
on the methods for delivering the agent efficiently to the target.
The chemicals employed before World War II can be styled
as the "classic" chemical weapons. They are relatively simple
substances, most of which were either common industrial chemicals or
their derivatives. An example is phosgene, a choking agent (irritates
the eyes and respiratory tract). Phosgene is important in industry as
a chlorinating material. A second example is hydrogen cyanide, a
so-called blood agent (prevents transfer of oxygen to the tissues),
now used worldwide in the manufacture of acrylic polymers. The classic
chemical agents would be only marginally useful in modern warfare and
generally only against an unsophisticated opponent. Moreover, large
quantities would be required to produce militarily significant
effects, thus complicating logistics.
Blister agents or vesicants are an exception to the limited utility of
classic agents. Although these materials have a relatively low
lethality, they are effective casualty agents that inflict painful
burns and blisters requiring medical attention even at low doses. The
classic mustard is the most popular among proliferant nations since it
is relatively easy to make. Mustard is generally referred to as the
"king" of agents because of its ease of production, low cost,
predictable properties, persistence, and ability to cause
resource-devouring casualties rather than fatalities. Its insidious
nature is both an advantage and a disadvantage. Mustard on the skin
causes no immediate sensation and symptoms normally do not appear
until several hours after exposure. At incapacitating levels this may
be as long as 12 hours. (Contrary to the normal expectation, horrible
fatalities occurred in the Iran-Iraq War because Iranian soldiers,
feeling no effects, continued to wear mustard soaked clothing and
inhale its fumes.)
To produce immediate effects, an arsenical vesicant
known as lewisite was developed in the United States. Much of the
former Soviet Union vesicant stocks were mixtures of lewisite and
sulfur mustard. Between the world wars the development of chemical
weapons included adaptation to aircraft delivery (bombs) and
exploitation of lewisite, since the more potent mustard was, from a
battlefield perspective, slow in producing casualties. Independent
experiments in several countries led them to consider/adopt mixtures
of mustard and lewisite as fills for chemical munitions.
The Italians, Hungarians, Japanese, French, English,
Russians, and Americans, as well as the Germans, all perfected
mustard, phosgene, and similar agents during World War II. Although
never used in the conflict, these nations amassed such huge quantities
of chemical munitions that their disposal presented a practical
problem, one that would be virtually insurmountable in today's more
environmentally conscious world. In those more naive times, however,
the munitions simply found their way to the bottoms of almost all the
world's oceans in the holds of expendable ships.
Nerve gases are liquids, not gases, which block an
enzyme (acetylcholinesterase) that is necessary for functions of the
central nervous system. Nerve agents are generally divided rather
arbitrarily into G- and V-agents, although there are numerous
structural variants that are potent cholinesterase inhibitors. Nerve
agents known to date to have been produced for chemical warfare
purposes are all organo-phosphorus compounds and are liquids at room
temperature. Similar in action to many pesticides, they are lethal in
much lower quantities than classic agents. The nerve gases are
effective when inhaled or when absorbed by the skin (percutaneous), or
both, although there are differences in effectiveness. In general, the
lower the material's volatility (and hence its inhalation threat) the
greater its percutaneous toxicity.
Nerve gases, or anticholinesterase agents, were
discovered by the Germans in the 1930's and developed during World War
II. In 1936 during studies of possible pesticides, the German chemist
Gerhard Schrader discovered what he called "tabun" or GA. Two years
later Schrader discovered the even more toxic "sarin" or GB. These
compounds are orders of magnitude more toxic than those used in World
War I and thus represent the significant toxicity increase that
changed the concept of employment. Fortunately for the Allies, the
Germans never exploited their technological advantage, although they
did produce a large number of tabun-filled munitions.
After World War II the victors took an interest in
exploiting the potential of the remarkably potent "nerve" agents. The
British, in particular, had captured small stocks of sarin (GB) and
set about investigating its potential. The Soviets removed the Germans
' GB production plant to the Soviet Union. GB turned out to be perhaps
the best of the respiratory agents, being volatile as well as
exceedingly toxic. The United States designed a cluster bomb to
exploit the characteristics of GB and followed this with a litany of
adaptations of munitions. Artillery rockets were produced as were
bombs, projectiles, and spray tanks. Many of these used the basic
design of high-explosive weapons and simply changed the fill to GB. In
the instance of the spray tank, it was necessary to use a polymeric
thickening material so that the liquid would form large droplets and
not evaporate before it reached the ground.
The French, British, and Canadians all built small-scale
facilities to produce the GB for testing. The United States, however,
entered into full-scale production of GB, as did the Russians just a
little later. The Russians also produced soman (GD), an agent the U.S.
developers had decided to forswear because of its properties of being
refractory to treatment above a single lethal dose.
In the late 1950's, UK scientists discovered another
category of nerve agents, the V-agents. These were particularly
interesting in that most of them were very effective percutaneously
and represented an effective way to circumvent the ubiquitous gas
mask. The United States and the UK pursued a form of V-agent called
VX, although they produced it by entirely different processes. The
Russians exploited another structural analog that proved more
adaptable to their industrial processes.
The 1960's saw continued development in nonlethal
agents, or riot control agents, first used in World War I. These
materials, most notably CS, are strong irritants of the mucous
membranes with very high safety ratios. The letters "CS" are code
letters for a solid powder classified as a riot-control agent
(O-chlorobenzylmalonitrile). This compound is a highly effective
irritant of the mucous membranes with an exceedingly high safety ratio
(~63,000). The purpose of CS and similar materials is temporary
incapacitation without permanent harm. CS was developed and first used
by the UK. It was quickly adopted and used extensively by the United
States and since has been produced and employed by many nations. CS is
a solid at room temperature and presents a problem for effective
dissemination in useful particle sizes. Particulate CS, like most
solids, tends to develop an electrostatic charge which causes the
particles to agglomerate into larger particles. Much development
effort during the 1960's was spent on finding effective dissemination
techniques.
The work on particulate CS could be extrapolated to
another type of chemical agent that was of extreme interest in the
1960's: incapacitating agents. These were initially seen by some as a
panacea to make warfare safe and humane. Thousands of potential
compounds were screened, obtained from government sources in the
United States and from commercial pharmaceutical companies around the
world. Although there were several promising materials, primarily
mental incapacitants, only BZ was ever standardized. The problem of
incapacitants, or incapacitating agents, is complex. The use of
incapacitants in warfare is considered to be prohibited by the
Chemical Weapons Convention even though only a single agent, BZ
(3-Quinuclidinyl benzilate), and its immediate precursors are included
as listed compounds (Schedule 2) in that Treaty. In retrospect, while
BZ was the only incapacitating agent formally accepted (i.e., type
classified) by the United States, it was a poor choice and is now
obsolete. It remained in U.S. stocks for only a short period of time.
The substance is a mental rather than a physical incapacitant with
long-onset time and unpredictable symptoms. The victim becomes
confused and is likely to be incapable of acting decisively. The
confusion, however, may not be readily apparent. The duration of
action is long, about 48 hours, making prisoner management difficult.
There are, moreover, hundreds of compounds more potent, faster acting,
and with shorter duration of effect.
Mental incapacitants are predominantly glycolates,
whereas some of the more potent candidates for physical incapacitants
have come from research on improved anesthetics. Indeed, almost all
potential incapacitants are byproducts of the pharmaceutical industry
and have legitimate pharmaceutical uses. The defining technologies for
such incapacitating weapons, then, are the production of a
physiologically effective compound in greater than practical
pharmaceutical quantities and incorporation of the material in
weapons. It is probable that the physical state of an incapacitant
will be a particulate solid and that the practical route for effective
use is by inhalation.
Binary chemical weapons use toxic chemicals produced by
mixing two com-pounds immediately before or during use. Binary weapons
do not necessarily employ new toxic chemicals. In U.S. parlance,
relatively innocuous precursors were stored separately and reacted to
form the toxic chemical agent en route to the target. In principle,
the binary concept could also be used to produce highly lethal but
unstable compounds or mixtures of compounds unsuitable for long-term
storage. The U.S. type classified and produced a GB (sarin) binary
nerve agent weapon, the M687 projectile (a 155-mm artillery shell),
and was in the late stages of development of two other binary weapons
when its offensive CW program was terminated. The Russians have been
publicly accused by dissidents within their own agencies of developing
new binary agents, and the Iraqis are known to have constructed binary
bombs and missile warheads, albeit with crude manual mixing of the
reactants.
Other possibilities for chemical agents include toxins
and allergens which also have been, at times, considered biological
agents. Although not living organisms them-selves, these materials are
usually products of living organisms with complex molecu-lar
structures. A wide variety of toxins with an equally broad spectrum of
chemical, physical, and physiological properties exists.
Until the recent attempts at terrorism by the Japanese
cult Aum Shinrikyo, virtually all uses of chemical weapons have been
as tactical weapons by nations. These have ranged from attempts to
break the stalemate in World War I to the recent use by Iraq to blunt
Iranian human wave attacks in the Iran-Iraq War (1982-87). Chemical
weapons were not employed by the major protagonists in World War II.
Between World Wars I and II, two signatories of the Geneva Protocol
(Italy and Japan) employed chemical weapons. Typically, nations have
employed them against unprotected targets and not against an equally
well-armed nation; chemical weapons are therefore arguably an example
of mutual deterrence. Although there have been charges of chemical
weapon use in virtually every conflict in recent decades, most have
not been substantiated by clinical or physical evidence.
Sources and Methods:
Adapted from - Chemical Weapons Technology Militarily
Critical Technologies List (MCTL) Part II: Weapons of Mass Destruction
Technologies.
http://www.fas.org/nuke/intro/cw/intro.htm