MILNET: Chemical Weapons Detail
The Organisation for the Prohibition of Chemical Weapons (OPCW) website at http://www.opcw.nl/ptshome.htm using material taken from the publication http://www.opcw.nl/ptshome.htm explains the differences between a total of eight types of chemical agents:
| Type | Description |
| Nerve Agents | Among lethal CW agents, the nerve agents have had an entirely dominant role since the
Second World War. Nerve agents acquired their name because they affect the
transmission of nerve impulses in the nervous system. All nerve agents belong chemically to
the group of organo-phosphorus compounds. They are stable and easily dispersed, highly
toxic and have rapid effects both when absorbed through the skin and via respiration.
Nerve agents can be manufactured by means of fairly simple chemical techniques. The raw
materials are inexpensive and generally readily available.
It was not until the early 1930's that German chemists observed that organo-phosphorus compounds could be poisonous. In 1934, Dr Gerhard Schrader, a chemist at IG Farben, was given the task of developing a pesticide. Two years later a phosphorus compound with extremely high toxicity was produced for the first time. According to contemporary regulations, discoveries with military implications had to be reported to the military authorities, which was also done with Schrader's discovery. This phosphorus compound, given the name tabun, was the first of the substances later referred to as nerve agents. The most important nerve agents included in modern CW arsenals are:
When exposed to a low dose of nerve agent, causing minor poisoning, characteristic symptoms are increased production of saliva, a running nose and a feeling of pressure on the chest. The pupil of the eye becomes contracted (miosis) which impairs night-vision. The accommodation capacity of the eye is also reduced so that short-range vision deteriorates and the victim feels pain when he tries to focus on an object nearby. This is accompanied by headache. More unspecific symptoms are tiredness, slurred speech, hallucinations and nausea. Exposure to a higher dose leads to a more dramatic development and symptoms are more pronounced. Bronchoconstriction and secretion of mucous in the respiratory system leads to difficulty in breathing and to coughing. Discomfort in the gastrointestinal tract may develop into cramp and vomiting. Involuntary discharge of urine and defecation may also form part of the picture. The discharge of saliva is powerful and the victim may experience running eyes and swetting. Symptoms from the skeletal muscles are very typical. If the poisoning is moderate, this may express itself as muscular weakness, local tremors or convulsions. When exposed to a high dose of nerve agent, the muscular symptoms are more pronounced. The victim may suffer convulsions and lose consciousness. To some extent, the poisoning process may be so rapid that earlier mentioned symptoms may never have time to develop. Muscular paralysis caused by nerve agents also affects the respiratory muscles. Nerve agents also affect the respiratory centre of the central nervous system. The combination of these two effects is the direct cause of death. Consequently, death caused by nerve agents is a kind of death by suffocation. [MILNET: Treatment varies and usually if not administered within seconds of exposure, is useless. Of course this depends on the levels of exposure and panic certainly adds to the shock induced by exposure. Treatment descriptions are lengthy and we refer you to the actual page at OPCW for further information. Note that nerve gases may pool in droplets, and therefore precautions should be taken to prevent secondary exposure to response teams. To prevent death from exposure many military and CW response teams have "rapid antidote delivery systems" which consist of quickly deployed syringes that are use to administer atropine and/or other broad spectrum antidotes for a variety of nerve gas exposures. While these are a stop-gap measure, the effects can be dehabilating to say the least and may cause great harm if improperly used or injected to a person allergic to their components.] |
| 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 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. Towards the end of the Second World War a large number of soldiers and sailors were injured during a German attack on the Italian port of Bari. A cargoship loaded with mustard agent ammunition was hit and large amounts of mustard agent became mixed with the water. The victims swam around in the contaminated water but it was not realized until too late that a large number of people had been injured by mustard agent. The Bari Incident served as a macabre illustration of the delayed effect of mustard agent. During the war between Iran and Iraq in 1979-88, Iraq used large quantities of chemical agents. About 5 000 Iranian soldiers have been reported killed, 10-20 per cent by mustard agent. In addition, there were 40 000 to 50 000 injured. A typical result of warfare with mustard agent is that the medical system is loaded with numerous injured who require long and demanding care. In its pure state, mustard agent is colourless and almost odourless. 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. At room temperature, mustard agent is a liquid with low volatility and is very stable during storage. The melting-point for pure mustard agent is 14.4 oC. In order to be able to effectively use mustard agent at lower temperatures, it has been mixed with lewisite in some types of ammunition in a ratio of 2:3. This mixture has a freezing-point of -26 oC. During the Second World War, a form of mustard agent with high viscosity was manufactured by means of the addition of a polymer. This is the first known example of a thickened CW agent. Gas or liquid, mustard agent attacks the skin, eyes, lungs and gastro-intestinal tract. Internal organs may also be injured, mainly blood-generating organs, as a result of mustard agent being taken up through the skin or lungs and transported into the body. The delayed effect is a characteristic of mustard agent. Mustard agent gives no immediate symptoms upon contact and consequently a delay of between two and twenty-four hours may occur before pain is felt and the victim becomes aware of what has happened. By then cell damage has already been caused. 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. There is no treatment or antidote which can affect the basic cause of mustard agent injury. Instead, efforts must be made to treat the symptoms. By far the most important measure is to rapidly and thoroughly decontaminate the patient and thereby prevent further exposure. This decontamination will also decrease the risk of exposure to staff. Clothes are removed, the skin is decontaminated with a suitable decontaminant and washed with soap and water. If hair is suspected to be contaminated then it must be shaved off. Eyes are rinsed with water or a physiological salt solution for at least five minutes. [MILNET: As stated, treatment consists of ensuring the effects of the agent do not result in infection and reducing as much as possible damage to tissue. Therefore prompt and proper treatment is essential. The treatments shown above must be carefully carried out as written. Untrained personnel can be more damaging in their efforts, therefore it is essential to get victims to qualified CW care givers immediately. As these agents are extremely efficient upon contact with the skin or inhaled, precautions must be taken to protect the response teams form secondary exposure.] |
| Hydrogen Cyanide | 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.
owever, 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 chambers.
At room temperature, hydrogen cyanide is a colourless liquid which boils at 26 oC. The most important route of poisoning is through inhalation. Both gaseous and liquid hydrogen cyanide, as well as cyanide salts in solution, can also be taken up through the skin. Its high volatility probably makes hydrogen cyanide difficult to use in warfare since there are problems in achieving sufficiently high concentrations outdoors. On the other hand, the concentration of hydrogen cyanide may rapidly reach lethal levels if it is released in confined spaces. The most important toxic effect of hydrogen cyanide is by inhibiting the metal-containing enzymes. One such enzyme is cytochromoxidase, containing iron. This enzyme system is responsible for the energy-providing processes in the cell where oxygen is utilized, i.e., cell respiration. When cell respiration ceases, it is no longer possible to maintain normal cell functions, which may lead to cell mortality. 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 failure and unconsciousness. If the poisoning occurs rapidly, e.g., as a result of extremely high concentrations in the air, there is no time for symptoms to develop and exposed persons may then suddenly collapse and die. |
| Tear Gases | Tear gases is the common name for substances which, in low concentrations, cause pain in the eyes,
of tears and difficulty in keeping the eyes open. Tear gases are used mainly in military exercises
in riot control, etc., but have also been used as a method of warfare. Irritating gases have been
in war since ancient times but it was not until after the Second World War that a more systematic
ch for effective substances was started.
Among a long series of substances, three have become of greater importance than the others. They are effective and imply low risks when used. These substances are chloroacetophenone (codename CN), orto-chlorobenzylidene-malononitrile (codename CS) and dibenz (b,f)-1,4-oxazepine (codename CR). CN was formerly the most widely used tear gas. Today, CS has largely replaced CN and is probably the most widely used tear gas internationally. At room temperature, these tear gases are white solid substances. They are stable when heated and have low vapour pressure. Consequently, they are generally dispersed as aerosols. All of them have low solubility in water but can be dissolved in several organic solvents. Hydrolysis of CN is very slow in water solution, also when alkali is added. CS is rapidly hydrolyzed in water solution (half-life at pH 7 is about 15 min. at room temperature) and extremely rapid when alkali is added (half-life at pH 9 is about 1 min.). CR is hydrolyzed only to a negligible extent in water solution. CN and CR are, thus, difficult to decompose under practical conditions, whereas CS can easily be inactivated by means of a water solution. Skin is suitably decontaminated by thorough washing with soap and water. CS is then decomposed whereas CN and CR are only removed. Decontamination of material after contamination with CS can be done with a 5-10 % soda solution or 2 % alkaline solution. If this type of decontamination cannot be accomplished (e.g., contaminated rooms and furniture), then the only other means is by intensive air exchange - preferably with hot air. |
| Arsines | 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. Other arsenic-containing substances have also been of interest as CW agents. One example is adamsite, 10-chloro-5,10-dihydrophenarsazine, which is a nasal and throat-irritating powder. |
| Psychotomimetic Agents | This group of agents usually includes substances which, when administered in low doses
(<10 mg) cause conditions similar to psychotic disorders or other symptoms emanating
from the central nervous system (loss of feeling, paralysis, rigidity, etc.). The effects are
transitory and cause inability to make decisions and incapacitation. Several such substances
may be used to achieve these objectives and only a few examples are given here.
During the 1950's, studies were made of substances such as glycolic acid esters (glycolates). Particular interest was paid to 3-quinuclidinylbenzilate, BZ. The effects of this group of substances are similar to those caused by atropine. BZ causes poisoning at doses of 0.5-5 mg. Peripheral symptoms such as distended pupils, deteriorated short-distance vision, dry mouth and palpitations occur after about 30 minutes. A serious effect of poisoning with BZ, as also with other atropine-like substances, is an increased body temperature. Deterioration in the level of consciousness, hallucinations and coma occur subsequently. Incapacitating after-effects may remain 1-3 weeks after the poisoning. Since the effect of glycolates was found to be difficult to predict, interest in continued research into this type of substance gradually decreased. Phencyclidine is a substance with analgetic and anaesthetic properties. Symptoms such as disturbed body-awareness, disorientation and vivid dreams occur. These symptoms occur after some hours at doses of 5-20 mg. At very high doses (>100 mg) there is a major risk for, e.g., respiratory depression and death. Phencyclidine is widely used by drug addicts who drench tobacco in this substance and then inhale it when smoking. Phencyclidine is easy to produce. LSD is probably one of the most active of all known substances having psychotomimetic effects. However, its chemical stability is very low and it is probably of little use as a CW agent. Nonetheless, there are other chemical substances with effects similar to LSD. These substances are chemically similar to amphetamine and are also stable. Theoretically, this type of substance could be used as a CW agent in special circumstances and dispersed as an aerosol. |
| Toxins | Toxins are effective and specific poisons produced by living organisms. They usually
consist of an amino acid chain which can vary in molecular weight between a couple of
hundred (peptides) and one hundred thousand (proteins). They may also be low-molecular
organic compounds. Toxins are produced by numerous organisms, e.g., bacteria, fungi,
algae and plants. Many of them are extremely poisonous, with a toxicity that is several
orders of magnitude greater than the nerve agents.
Toxins started to attract military interest already during the first half of the present century. At that time, it was difficult to manufacture sufficiently large amounts of toxin which caused interest to decrease. Many of the toxins discussed at that time were sensitive to heat and light which made them unstable and unpractical to use. In the late 1970's, there was a rapid development of gene technology together with biotechnology. This led to the threat from toxins as CW agents again arising. Now it became possible to produce greater amounts of many toxins more easily, in some cases even synthetically. Gene technology can be used to modify the toxin genes so that the end product obtains new properties and, for example, may become less sensitive to sunlight. Together with increased research into toxins, the bioregulators have also been studied and synthesized. Bioregulators are naturally-occurring substances, usually peptides, which participate in the physiological and neurological activities of the body. These substances can also be modified synthetically, whereupon they may obtain new properties. Toxins are still considered to be less suitable for dispersal on a large scale. Nonetheless, they could be used for sabotage or in especially designed inputs, e.g., against key persons. Since toxins have low volatility, they are dispersed as aerosols and then taken up foremost through inhalation. The new microencapsulation technology, which is easy to use, makes it possible to protect unstable toxins when dispersed. Most toxins are unstable in alkaline water solutions and are thus easily destroyed by means of normal decontamination methods. [MILNET: While toxins may be easily eradicated by normal sterilization techniques, and in some cases difficult to administer to large masses at once, it is clear that their deadliness is unique. A botulism attack, however manifested, would be extremely deadly to whatever number were exposed, and therefore the realitively small numbers of those exposed will result in far higher fatalities than perhaps any other form of chemical or biological attack. Treatment must be swift and unerring, which poses a further problem in defending against this type of attack. Especially since treatment may appear to be working only to have patients suddenly lapse into coma and die.] |
| Potential CW Agents | The borderline between BW and CW agents has started to lose importance as a result of
the rapid development in biotechnology. This mainly depends on the emergence of a
category of agents based on biotechnology. Biotechnology has enabled the largescale
production of new types of substances. Toxic compounds of natural origin which were
earlier difficult to produce, e.g., toxins and bioregulators, can now be produced in large
quantities. Many of these substances exceed the toxicity of nerve agents by several orders
of magnitude.
Biotechnology has also offered opportunities to produce bacteria, viruses, etc., in modified
form. The gene material of microorganisms can be modified so that new bacteria or viruses
are created, against which man has no immune defence. In addition, the bacteria can be
changed so that they themselves can produce toxins while they multiply in the body. In
comparison with pure toxin, only a very small dose of bacteria is then needed to achieve
full effect.
There are large opportunities to further develop weapons based on biotechnology. After
studies of structure-activity relationships for certain toxins and substances produced within
the body, it is possible to develop modified and even more active substances. Improved
knowledge of receptors on the cell surface, for example as a result of cancer research, ill
make it possible to target toxic substances to selected organs.
Weapons based on biotechnology today are probably still within the research or
developmental stages. In the long-term, they may become a serious threat. Factors
supporting this are that such substances:
Factors suggesting that their use may not arise are:
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