Chemical warfare agents - A Typology

According to what chemists know, the material world consists of more than 40 million of different substances of which 80,000 are also produced artificially. A proportion of these substances has harmful effects on humans or nature. These hazardous substances can be divided into toxic industrial chemicals (tics) or chemical warfare agents (CWA). The first chemical warfare agents in World War I were simply known toxins from chemical industry (mostly chlorine and phosgene) that were filled in containers and used against the enemy on the front lines. Later on, chemists developed warfare agents specifically for the use by the military. Usually, these chemical agents are divided according to their pharmacological-toxic effects as follows:

Choking agents

Choking or pulmonary agents inhibit the intake of oxygen in the lungs. They destroy the mucous membrane of the lung so that blood enters into the alveoli and cause oedema. The first chemical weapons were such choking agents. An enemy soldier then was still able to recognize the smell of such agents during an attack with chemical weapons and put on his gas mask. Chlorine is used to disinfect the water in swimming pools; this is why its characteristic smell is well-known. The even more toxic phosgene smells of freshly cut grass.

Blood agents

Blood agents attack the red blood pigment haemoglobin, which transports oxygen around the body. When this happens, the oxygen uptake in the organs is inhibited. Well-known blood agents are arsine, hydrogen cyanide and cyanogen chloride.

Blister agents

The skin, as is well-known, is a person’s largest organ. Various substances have been developed to damage the cells of the skin: Mustard gas (sulphur mustard and nitrogen mustard), a colourless gas with the smell of mustard or garlic is one of them. Other blister agents (or vesicants) are Lewisite and phosgene oxime. Mustard agents and lewisite are the best-known blister agents. Blister agents are heavier than air and are readily absorbed through the eyes, lungs, and skin. On the skin, they cause large, water-filled, blisters that resemble severe burns. These blisters can cause the skin of the affected areas to die (necrosis). Those who survived a mustard gas attack suffer from a higher risk of cancer; their children may suffer from deformities.

Nerve agents

Nerve agents are much more toxic than the other chemical agents, and they can neither be seen nor smelled. All nerve agents belong chemically to the group of organophosphorus compounds. The first of these agents was developed by Nazi Germany: In December 1936, Gerhard Schrader, a chemist at the company IG Farben in Leverkusen, who was given the task to develop a pesticide, developed tabun; three years later sarin (an isopropyl methyl phosphorofluoridate). In 1944, Nobel Prize Laureate Richard Kuhn and his colleague Konrad Henke developed the nerve gas soman.

The most toxic nerve agent was discovered in the mid-1950s by a Swedish researcher: O-ethyl O-2-diisopropylaminoethyl methylphosphonothioate, or in short VX (as it is known by the military). Nerve agents affect the transmission of nerve impulses in the nervous system: Impulses from the brain to the muscles are transmitted by the messenger substance acetylcholine. Once the movement has been carried out, this substance has to be broken down by a corresponding enzyme—the acetylcholinesterase. The nerve agent blocks this enzyme so that the body is swamped by acetylcholine in just a few minutes. Results are vomiting, diarrhoea, hallucinations, muscle convulsions, coma and muscular paralysis that also affects the respiratory muscles, which can finally lead to a long and painful death.

Due to the extremely rapid effects of nerve gas poisoning, soldiers are equipped with an auto-injector, a special syringe, they can use themselves to inject the antidote atropine into their thigh muscle. As the atropine cannot stop any respiratory paralysis, a victim will have to be kept alive by mouth to mouth resuscitation.

Tear gas (riot control agents)

Tear gas does not play a leading role amongst the chemical weapons, as it hardly ever leads to the death of affected people. This is why it is grouped as a ‘non-lethal weapon’. Today, these chemical agents are no longer used by the military but rather by the police for law enforcement purposes to disperse crowds, for instance, during large-scale rallies. These agents are generally lacrimators (tear / CS gas).

In World War I, during the trench warfare on the Western Front, the German military was the first also to use sneeze gases or vomiting agents (adamsite and diphenylchlorarsine-DA, Clark I, diphenylcyanoarsine-CDA, Clark II). Adamsite is a yellowish substance that causes violent coughing, nausea, headaches, convulsions and chest pains. These symptoms can last for a few days. These agents were often used as ‘mask breakers’ (Maskenbrecher) by the German armed forces (see below). It was later used by the British in the Spanish Civil War. All warfare agents that do not kill are also called incapacitating agents.

Toxins used for sabotage

Toxins used for sabotage are a special category amongst the chemical weapons. They are not utilized by the armed forces but by intelligence services. The aim is not to kill as many people as possible but to targetedly kill certain individuals. Toxins are chosen that at best cannot be traced, i.e. highly toxic biotoxins. Botulinum, for instance, is a neurotoxic protein produced by the bacteria clostridium botulinum that lives in the soil. With a lethal dosage (LD50) of 2.1 ng, botulinum is one of the most acutely lethal toxins known. Ricin is a highly toxic, naturally occurring lectin produced in the seeds of the castor oil plant. Polonium-210 is a highly toxic, radioactive isotope. In November 2006, the Russian dissident Alexander Litwinenko was murdered in London, being the first known victim of lethal polonium 210-induced acute radiation syndrome. On his way from Moscow to London, the potential assassin, Russian businessman and former member of the KGB Andrey Lugovoy, passed through Hamburg, where later the slightest traces of the radioactive material could be found. The secret special unit of the German Federal Criminal Police (BKA), the Central Federal Support Group, took part in this investigation.

Psychopharmacological agents

Just like the toxins used for sabotage, psychopharmacological agents are a special category of chemical weapons. It is indeed not very clear to what degree they have been used in warfare, but it has become known that intelligence services have experimented with these drugs. The US-American CIA, for instance, conducted the programmes ARTICHOKE and MKULTRA during which they used LSD-25 and 3-quinuclidinylbenzilate (BZ). They tested these substances in the context of mind control (‘brainwashing’) and the development of a truth serum for interrogations. Some test subjects died or committed ‘suicide’. Cats that were administered BZ were afraid of mice. A military deployment of psychopharmacological agents, however, is considered to be counterproductive. Just imagine, soldiers equipped with nuclear weapons would suddenly develop paranoia.

‘Mask breakers’

While ‘mask breakers’ are not toxic agents, they are still important for chemical warfare. As many agents can be filtered out by the ABC mask filters, special irritants are used that pass through the filter. They cause nausea or heavy sneezing and thus force the soldiers to take off their masks, leaving them unprotected against the simultaneously used toxic agents.

Environmental toxins

Besides warfare agents that have a detrimental effect on people, environmental toxins, primarily herbicides, are also utilized by the military. These herbicides are sometimes propagated to be ‘plant protection agents’. They defoliate forests or destroy harvests. The victims do not die of that toxin but starve to death. Agent Orange, used by the US army in the jungle warfare in Vietnam, is the most well-known environmental toxin. Besides the physiological effect of chemical weapons, they can be categorized into lethal and non-lethal or sedentary or volatile agents. All kinds of smoke grenades are also counted among chemical weapons by the military.

Sources and further information:

• Franke, Siegfried (Hrsg.) (1976): Lehrbuch der Militärchemie, Band 1 Entwicklung der chemischen Kampfstoffe, Chemie der Kampfstoffe, Berlin(-Ost), Militärverlag der DDR. (German)
• Hunger, Iris, Meier, Oliver und Arend Wellmann (1996): Das Kleine ABC der Massenvernichtung; in: antimilitarismus information, Nr. 3/1996, Berlin, S. 13-28. (German)
• Schulz-Kirchrath, Stefan (2006): Kompendium Chemische Kampfstoffe, OWR AG (Hrsg.), Elztal-Rittersbach. (German)
• Stöhr, Ralf (Hrsg.)(1977): Chemische Kampfstoffe und Schutz vor chemischen Kampfstoffen, Berlin(-Ost), Militärverlag der DDR. (German)
• Organisation for the Prohibition of Chemical Weapons. “Chemical Weapons”.