Chemical weapon

A chemical weapon is a chemical, with a delivery system that can deliver the agent in militarily significant concentrations, the primary effect of which is to injure or kill through poisoning: molecular interaction between the chemical agent and the metabolism of the victim. While explosives and incendiaries are indeed chemical compounds, and may even be poisonous if ingested, because their major military effect is through blast or heat, they are not considered chemical weapons.

Use of chemical (and biological) warfare is banned by the 1925 Geneva Protocol The production and proliferation of chemical weapons is internationally banned by the Chemical Weapons Convention (CWC); the CWC deals with the complexity that some chemical weapons, or precursors needed to prepare them, are dual-use. Dual use chemicals such as chlorine have widespread peaceful uses in water purification and in industrial chemistry, but have also used as weapons of war.

Historically, the most extensive use of lethal chemical weapons was in the First World War, although they were used sporadically in counterinsurgency, or in the Second World War Japanese campaign against China. The gassing of the Kurdish people by Saddam Hussein is another well known example.

History

While there were proposals, for example, for the use of chemical weapons in the American Civil War, the first large-scale use was in World War I.

World War I

See World War I, poison gas

Interwar

After years of agitation by women's groups in Europe and the U.S. (led by Jane Addams). the 1925 Geneva protocol banned poison gas as an illegal weapon of mass destruction.

1925 Ban

After years of agitation by women's groups in Europe and the U.S. (led by Jane Addams). the 1925 Geneva protocol banned poison gas as an illegal weapon of mass destruction.

Nevertheless in the pacifistic decade of the 1920s, dire predictions struck fear worldwide that the next war would see long-range bombers gassing millions of civilians in the large cities. Technologically that was quite impossible (it would take hundreds of thousands of bomber sorties to gas New York City or London), but the fears presaged the nightmares in the 1960s about nuclear weapons that were all too true. Apart from chemists who insisted that gas was far more humane than high explosives, the military did not want chemical warfare. It therefore acquiesced in the international consensus reached in the 1920s that poison gas was an illegal and immoral weapon of mass destruction. Nations pledged never to use it first--but they nevertheless prepared masks and their own stocks of poison in case they needed to retaliate. Since 1918 gas has occasionally been used in remote areas against civilians or soldiers with no protection. (

Nevertheless, in the culture 1920s, there was popular fear that the next war would see long-range bombers gassing millions of civilians in the large cities. Technologically that was quite impossible (it would take hundreds of thousands of bomber sorties to gas New York City or London), but the fears presaged the nightmares in the 1960s about nuclear weapons that were all too true.

Apart from chemists who insisted that gas was far more humane than high explosives, the military did not want chemical warfare. Certainly with the agents available in the 1920s, most had no particular tactical advantage over weapons that killed through more traditional means of injury. An international consenuss reached in the 1920s that poison gas was an illegal and immoral weapon of mass destruction. In the 1925 Geneval protocol, nations pledged never to use it first--but they nevertheless prepared masks and their own stocks of poison in case they needed to retaliate.

Since 1918 gas has occasionally been used in remote areas against civilians or soldiers with no protection. Since 1918, no nation has used poison gas against a foe that had masks or gas of its own.

World War II

The greatest number of deaths by chemical weapons, in World War II was principally genocidal, against defenseless civilian prisoners in the Holocaust and against Soviet prisoners, rather than against soldiers capable of fighting back. The closest the Germans came to using chemical weapons against armed people was some limited use of toxic smokes against resistance bunkers, as in the Warsaw Ghetto. While their early gas chambers used carbon monoxide, for large scale use, they used a preparation of hydrogen cyanide, adsorbed onto inert material forming a pesticide product called Zyklon B. Commercial Zyklon had an added sent to warn of exposure, but the operators of the gas chamber order a version without it. When one local Polish unit used mustard gas against the Nazi invaders in 1939, the Germans did not retaliate.

Japanese forces used chemical and biological weapons in China, and Italy used chemical weapons against Ethiopia. Britain deliberately ignored Japanese use of gas against China and Italian use against Ethiopia.

Winston Churchill's history of WWII shows he intended to use mustard gas against the beaches if the Germans invaded. The United States Joint Chiefs of Staff recommended that chemical weapons be used against the Japanese garrison of Iwo Jima before the invasion, but President Franklin D. Roosevelt personally denied the request.

Outside China, the worst exposure, in a military context, was an accident. The U.S. had sent mustard gas bombs to Europe, to be used only in retaliation for a German attack. They were still on the ammunition ship SS John Harvey, moored in the harbor of Bari, Italy. On December 2, 1944, German bombers made a night attack on what Germany simply regarded as a concentration of Allied supplies and shipping. Medical personnel were unaware that the smoke and surface oil slick contained mustard; they not only did not treat for mustard poisoning, but, concerned about hypothermia, wrapped victims, still contaminated in oil, with blankets, increasing the exposure. There were at least 59 military deaths, and almost certainly some in civilian areas affected by the smoke.

When one local Polish unit used mustard gas against the Nazi invaders in 1939, the Germans did not retaliate. Britain deliberately ignored Japanese use of gas against China and Italian use against Ethiopia.

Vietnam

The U.S. made fairly routine use of the "riot control agent" CS in clearing enemy tunnels and bunkers. While CS is considered a nonlethal agent, the safety in a confined space is not fully understood.

There was widespread use of a defoliant mixture called Agent Orange. While the actual defoliants were in regular agricultural use and not especially toxic, a number of batches contained a then-undetectable quantity of extremely toxic dioxn.

Types

Chemical agents fall into three broad categories:

• Incapacitating, with minimal long-term morbidity or mortality
• Casualty-producing, with significant morbidity and some mortality; meant more to strain resources by creating large numbers of patients
• Lethal, intended to cause quick death

While the choking agents, such as chlorine and phosgene, can kill, they are regarded primarily as casualty-producing, and of minimal use in warfare due to their low toxicity for their weight. Chlorine, and to a lesser extent, phosgene, are in widespread industrial use; the concern is their improvised use. In Iraq, there have already been incidents of improvised explosive devices attached to tanks of chlorine; the chemical addition added injuries and increased the psychological effects, but did not significantly increase the number of casualties.

Blood gases, such as hydrogen cyanide and cyanogen chloride are quite lethal in confined spaces; hydrogen cyanide was the principal lethal agent used in Nazi genocide. It is quite difficult to achieve a lethal concentration in open air, and they dissipate quickly. They should be considered potential lethal agents that would be usable only in niche situations, such as introducing them into a relatively small enclosed space.

Vesicants

• Sulfur mustard
• Nitrogen mustard

Nerve agents

Nerve agents, which are inhibitors of the enzyme cholerinesterase, are orders of magnitude more toxic per unit of weight than any previous class. Cholinesterase destroys the neurotransmitter acetylcholine, which causes muscles to contract; the nerve agents essentially cause all muscles to contract and never relax, which includes the breathing muscles in the diaphragm.

As an accidental discovery in pesticide research, German scientists discovered the family of "G-agents", which are nonpersistent cholinesterase inhibitors. In actuality, the Allies had not synthesized these especially toxic molecules, but the Germans, apparently aware of Allied research with diisopropyl fluorophosphate (DFP), assumed that the Allies had nerve agents and could retaliate with them. DFP has applications in ophthalmology and in neuroscience research.

Nerve agents, unless highly purified, have limited shelf life. "Binary" munitions are safer to handle, but also more stable, because the act of firing a binary artillery shell shatters a membrane between two relatively stable mixtures; the spin of the shell in flight causes the true nerve agent to form.

Weaponized G-agents include Tabun (GA), Sarin (GB), cyclosarin, and Soman (GD). Another class of cholinesterase, designated V-agents, are both more toxic and more persistent than G-agents; VX is the known weaponized form. Russia has produced another class, comparable to the V-agents, called Novichuk agents. All can penetrate unbroken skin.

Immediate treatment involves the injection of large doses of atropine.

Incapacitating

Tear gas

• CN
• CS
• Capsaicin

Vomiting gas

Agents that cause nausea, which are generally arsenic-based, were used for different reasons. In the First World War, they were mixed with lethal agents, with the intention of forcing troops masked against the other agent to remove the mask or risk drowning.

They have also been used as an extreme riot control agent. Adamsite (coded DM) was marked, in U.S. Army documentation, to be used only in situations when some fatalities were acceptable. DM was used when troops were called in to control a prolonged riot at the Alcatraz prison.

Other agents of the class, developed by Germany in WWI, include diphenylchlorarsine (DA, Clark I, Blaukreuz) and diphenylcyanarsine (DC, Clark II, Cyan Cross)

Delivery systems

Chemical weapons are not extremely efficient for their weight, even with the nerve agents. Less toxic agents have little logistic practicality, with mustard perhaps used more for psychological effect.

In the U.S. arsenal, the 4.2" mortar was called "chemical", but the primary artillery delivery methods for the nerve agents would be 155mm howitzers or 115mm purpose-built multiple rocket launchers.

Air delivery used large bombs of 1000 pounds or larger. Spray tanks for aircraft existed, but were implausible to use against an enemy with any air defense. Chemical warheads were also available for large battlefield rockets such as the Soviet FROG series or U.S. MGR-1 Honest John.

Chemical warheads for ballistic missiles were built, but were unlikely to be effective unless the chemical was released in spray submunitions. Nerve agents, especially VX, could burn, and a warhead burster very well might destroy them.

Significance in terrorism

While the extremely well funded cult, Aum Shinryo, did synthesize impure GB and released it, inefficiently, in the Tokyo subway system, many analysts regard the logistics of true chemical weapons to be impractical for terrorism. This report, however, was criticized as overestimating terrorist capabilities by Milton Leitenberg of the University of Maryland.

A more likely scenario would be a deliberate release of an industrial or agricultural chemical such as chlorine or anhydrous ammonia. The U.S. Department of Homeland Security, has been active in work to improve the safety of industrial materials.

Some pesticides, such as parathion, are cholinesterase inhibitors, and, while not as potent as the G-agents, could be a significant hazard if dispersed. If for no other reason than industrial safety, their use, and thus availability, is being reduced.

al-Qaeda threats of the use of hydrogen cyanide in the New York subways, with minimal calculation, show that so much precursor chemical would be needed that it is implausible that adequate supplies could be brought in without being observed. An al-Qaeda video, showing the unpleasant death of some dogs, was claimed to be a nerve agent, but the appearance of the chemical fumes, and the reactions of the victims, would be more consistent with a cyanide than a cholinesterase inhibitor.

Defense and emergency management

Most defensive measures are military.

They begin with a gas mask and protective clothing. Antidotes for nerve agents carried by individual soldiers include atropine, 2-PAM, and diazepam.