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What are chemical
weapons?
The Chemical Weapons Convention considers chemical weapons
to include both the toxic chemicals that are used in warfare, and the
munitions and equipment used to disperse them. Toxic chemicals are defined as
"any chemical which through its chemical action on life processes can
cause death, temporary incapacitation or permanent harm to humans or animals.
This includes all such chemicals, regardless of their origin or of their
method of production and regardless of whether they are produced in
facilities, in munitions or elsewhere."
Today, thousands of poisonous substances are known but
only a few are considered suitable for chemical warfare. About 70 different
chemicals have been used or stockpiled as CW agents during the 20th century.
Today, only a few of these are considered of interest because:
 A presumptive agent must not only be highly
toxic but also "suitably highly toxic" so that it is not too
difficult to handle.
The substance must be capable of being stored
for long periods without degradation and without corroding the packaging
material.
It must be relatively resistant to atmospheric
water and oxygen so that it does not lose effect when dispersed.
It must also withstand the heat developed when
dispersed by explosion.
The World Health
Organization has listed 17 chemical weapons which are grouped as:
NERVE AGENTS, for example tabun, sarin and
soman.
VESICANTS (blister gases), for example
"mustard gas" and other.
CHOKING AGENTS (lung irritants), for example
phosgene and chloropicrin
BLOOD GASES, for example hydrogen
TEAR GASES and other disabling chemicals
cyanide
War gases" are
seldom gases
The CW agents used today are only exceptionally gases.
Normally they are liquids or solids, often dispersed in the air in so-called
aerosols. An aerosol can penetrate the body through the respiratory organs in
the same way as a gas. In order to achieve good ground coverage when
dispersed from a high altitude with persistent CW agents the dispersed
droplets must be sufficiently large to ensure that they fall within the
target area. This can be achieved by dissolving polymers (e.g., polystyrene
or rubber products) in the CW agent to make the product highly-viscous or
thickened. The result will be that the persistence time and adhesive ability
increase which thus complicates decontamination.
ROUTES OF EXPOSURE
SKIN: Systemic
poisoning may result from inhalation, dermal exposure and ingestion. Some CW
agents can penetrate the skin. This mainly concerns liquids but in some cases
also gases and aerosols. Solid substances penetrate the skin slowly unless
they happen to be mixed with a suitable solvent. Local damage to the skin may
promote absorption.
INHALATION: Chemical
agents may be inhaled, or ingested (e.g. through contaminated food or water).
The respiratory system is affected by inhalation.
EYES: The eyes
are particularly sensitive to chemical agents and may cause the development
of symptoms very quickly.
Psychological
stress may itself mimic some of the effects of chemical weapons.
Fact Sheets on
Chemical Warfare Agents, SDE/SEARO, World Health Organization, New
Delhi, India`
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