Chemical warfare is the use of natural and man-made toxic substances to incapacitate
or kill an enemy. There are many different types of agents used in chemical warfare,
some of which are mustard gases, nerve gases, psychotomimetic agents, tear gases,
hydrogen cyanide, and arsines. All of which are very poisonous and lethal when
exposed to humans in large amounts. Until the 20th century such warfare was
primarily limited to starting fires, poisoning wells, distributing smallpox-infected
articles, and using smoke to confuse the enemy. Today however, it is used as lethal
Mustard Agents
Mustard agents are usually classified as "blistering agents" owing to the similarity
of the wounds caused by these substances resembling burns and blisters. However, since
mustard agents also cause severe damage to the eyes, respiratory system and internal
organs, they should preferably be described as "blistering and tissue-injuring agents".
Normal mustard agent, bis-(2-chloroethyl)sulphide, reacts with a large number of
biological molecules. The effect of mustard agent is delayed and the first symptoms do
not occur until between 2-24 hours after exposure.Mustard agent is simple to
manufacture and can therefore be a "first choice" when a country decides to build up a
capacity for chemical warfare.
Mustard agent was produced for the first time in 1822 but its harmful effects were
not discovered until 1860. Mustard agent was first used as a CW agent during the latter
part of the First World War and caused lung and eye injuries to a very large number of
soldiers. Many of them still suffered pain 30-40 years after they had been exposed,
mainly as a result of injuries to the eyes and chronic respiratory disorders.
In its pure state, mustard agent is colorless and almost odorless. The name was
given to mustard agent as a result of an earlier production method which yielded an
impure mustard-smelling product. Mustard agent is also claimed to have a characteristic
smell similar to rotten onions. However, the sense of smell is dulled after only a few
breaths so that the smell can no longer be distinguished. In addition, mustard agent can
cause injury to the respiratory system in concentrations which are so low that the human
sense of smell cannot distinguish them.
Symptoms of mustard agent poisoning extend over a wide range. Mild injuries
consist of aching eyes with abundant flow of tears, inflammation of the skin, irritation of
the mucous membrane, hoarseness, coughing and sneezing. Normally, these injuries do
not require medical treatment. Severe injuries which are incapacitating and require
medical care may involve eye injuries with loss of sight, the formation of blisters on the
skin, nausea, vomiting and diarrhoea together with severe respiration difficulty.
Acute mortality arising from exposure to mustard agent is low. The dose needed
to directly kill a person upon inhalation is, e.g., about 50 times larger than the dose giving
acute mortality upon poisoning with the nerve agent soman. People who die after
exposure to mustard agent usually do so after a few days up to one or more weeks.

Among the arsenal of chemical weapons can be found mustard agent mixed with
lewisite which is an aliphatic arsenic compound, 2-chlorovinyldichloroarsine. Pure
lewisite is a colourless liquid. Solubility in water is approximately the same as for
mustard agent but the volatility is much higher. Hydrolysis in water is faster than for
mustard agent. Injuries caused by lewisite are similar to those caused by mustard agent.
However, the mechanism of action for lewisite is different. From the diagnostic
viewpoint, an important difference is that symptoms in lewisite poisoning are not delayed
and the irritating effect occurs immediately. Skin damage is treated in the same way as
after exposure to mustard agent. A specific antidote (BAL, British Anti Lewisite,
dimercaptopropanol) gives good protection against local injuries to skin and mucous
membrane. BAL also has effect against systemic poisoning.
Hydrogen cyanide is usually included among the CW agents causing general
poisoning. There is no confirmed information on this substance being used in chemical
warfare. However, it has been reported that hydrogen cyanide was used by Iraq in the war
against Iran and against the Kurds in northern Iraq during the 1980's. Hydrogen cyanide
has high toxicity and in sufficient concentrations it rapidly leads to death. During the
Second World War, a form of hydrogen cyanide (Zyklon B) was used in the Nazi gas
Symptoms of cyanide poisoning vary and depend on, for example, route of
poisoning, total dose and the exposure time. If hydrogen cyanide has been inhaled, the
initial symptoms are restlessness and increased respiratory rate. Other early symptoms
are giddiness, headache, palpitations and respiratory difficulty. These are later followed
by vomiting, convulsions, respiratory