The 'sulfur mustards', of which 'mustard gas' is a member, are a class of related
cytotoxic,
vesicant chemical warfare agents with the ability to form large
blisters on exposed skin. In their pure form most sulfur mustards are colorless, odorless, viscous liquids at room temperature. When used as warfare agents they are usually yellow-brown in color and have an odor resembling
mustard plants,
garlic or
horseradish.
Sulfur mustards are variations of "mustard gas" (
bis(2-chloroethyl) sulfide). Mustard gas is referred to by numerous other names, including ''HD'', ''senfgas'', ''sulfur mustard'', ''
blister gas'', ''s-lost'', ''lost'', ''Kampfstoff LOST'', ''
yellow cross liquid'', and ''yperite''. The abbreviation LOST comes from the names Lommel and
Steinkopf, who developed a process for
mass producing the gas for war use at the
German company
Bayer AG. This involved reacting
thiodiglycol with
hydrochloric acid.
Mustard agents, including sulfur mustard, are regulated under the 1993
Chemical Weapons Convention (CWC). Three classes of chemicals are monitored under this Convention, with sulfur and nitrogen mustard grouped in the highest risk class, "
schedule 1".
In its history, several varieties and mixtures of sulfur mustard have been employed. Some of those varieties are listed below:
★ 'H' – Also known as 'HS' ("Hun Stuff") or ''Levinstein mustard''. Manufactured by reacting dry
ethylene with
sulfur monochloride under controlled conditions. Undistilled sulfur mustard contains 20–30% impurities, for which reason it does not store as well as 'HD'. Also, as it decomposes, it increases in vapor pressure, making the munition it is contained in likely to split, especially along a seam, thus releasing the agent to the atmosphere
[1]
★ 'HD' – Codenamed 'Pyro' by the British, and 'Distilled Mustard' by the US
[1].
Distilled sulfur mustard (bis(2-chloroethyl) sulfide); approximately 96% pure. The term "mustard gas" usually refers to this variety of sulfur mustard.
★ 'HT' – Codenamed 'Runcol' by the British, and 'Mustard T- mixture' by the US
[1]. A mixture of 60% sulfur mustard (HD) and 40% T (, a related vesicant with lower
freezing point lower
volatility and similar vesicant characteristics)
★ 'HL' – A blend of distilled mustard (HD) and
lewisite (L)
★ 'HQ' – A blend of distilled mustard (HD) and sesquimustard (Q) (Gates and Moore 1946)
Chemistry
Chemically, it is a β-chloro
thioether with the formula
C4H8Cl2S. Its structure can be described as 2,2′-dichlorodiethyl sulfide (ClCH
2CH
2)
2S, or bis(2-chloroethyl) sulfide. Mustard gas can be synthesized by reacting sulfur dichloride (SCl
2) with two
equivalents of ethene (C
2H
4).
Although the compound is commonly known as "mustard gas", it is a viscous liquid at normal temperatures. The pure compound has a melting point of 14°C (57°F) and decomposes before boiling at 218°C (423°F).
The compound readily eliminates
chloride ion by intramolecular
nucleophilic substitution to form a cyclic
sulfonium ion. This very reactive intermediate is particularly detrimental to cellular health as it has a strong tendency to bond to the
guanine nucleotide in
DNA strands. This leads to either immediate
cellular death or, as recent research has found,
cancer. Mustard gas is not very soluble in water but is very soluble in fat, contributing to its rapid absorption into the skin.
In the wider sense, compounds with the structural element BCH
2CH
2X, where ''X'' is any
leaving group and ''B'' is a
Lewis base are known as ''mustards''. Such compounds can form cyclic onium ions (
sulfonium,
ammoniums, etc.) that readily react with
nucleophiles. Examples are bis(2-chloroethyl) ether or the (2-haloethyl) amines.
A variant form of mustard gas is Sesquimustard, with the molecular formula C
6H
12Cl
2S
2.
Sulfur mustard produces a sulfonium ion, which attacks DNA in cells.
Physiological effects
A soldier with mustard gas burns sustained during
World War I.
Mustard gas is a strong
vesicant (
blister-causing agent). Those exposed usually suffer no immediate symptoms. Within 4 to 24 hours the exposure develops into deep, itching or burning blisters wherever the mustard contacted the skin; the eyes (if exposed) become sore and the eyelids swollen, possibly leading to
conjunctivitis and blindness. According to the Medical Management of Chemical Casualties handbook, there have been experimental cases in humans where the patient has suffered
miosis, or pinpointing of pupils, as a result of the cholinomimetic activity of mustard. At very high concentrations, if inhaled, it causes bleeding and blistering within the
respiratory system, damaging the
mucous membrane and causing
pulmonary edema. Blister agent exposure over more than 50% body surface area is usually fatal.
Skin damage can be reduced if
povidone iodine in a base of
glycofurol is rapidly applied, but since mustard initially has no symptoms, the exposure is usually not identified until the blisters rise. The vesicant property can be neutralised by
oxidation or
chlorination; household bleach (
sodium hypochlorite) or decontamination solution "DS2" (2% NaOH, 70%
diethylenetriamine, 28%
ethylene glycol monomethyl ether) can be used. Mustard gas is also
carcinogenic (cancer causing) and
mutagenic (causing damage to
DNA of exposed cells).
History
Mustard gas was possibly developed as early as 1822 by M. Depretz (1798–1863). Depretz described the reaction of
sulfur dichloride and
ethene but never made mention of any irritating properties of the reaction product which makes the claim doubtful. In 1854, another French chemist Alfred Riche (1829–1908) repeated the procedure but again did not describe any adverse physiological properties. In 1886, chemist
Albert Niemann, known as a pioneer in
cocaine chemistry, repeated the reaction but this time blister forming properties were recorded. In 1860,
Frederick Guthrie synthesised and characterized the compound, and he also noted its irritating properties especially in tasting. In 1886,
Viktor Meyer published a paper describing a synthesis which produced good yields. He reacted
2-chloroethanol with
aqueous potassium sulfide and treated the resulting thiodiglycol with
phosphorus trichloride. The purity of this compound was much higher and the adverse health effects on exposure consequently much more severe. These presented themselves in an assistant, and in order to rule out that the assistant was suffering from a mental illness (faking the symptoms) Meyer had the compound tested on rabbits, which consequently died. In 1913, English chemist
Hans T. Clarke (of
Eschweiler-Clarke fame) replaced phosphorus trichloride by
hydrochloric acid in Meyers recipe while working with
Emil Fischer in
Berlin. Clarke was hospitalized for 2 months for burns after a flask broke, and according to him Fisher's subsequent report on this incident to the
German Chemical Society set Germany on the chemical weapons track
[5].
Germany in
World War I relied on the Meyer-Clarke method with a
2-chloroethanol infrastructure already in place in the dye industry of that time.
After a failed attempt on the
Eastern Front, mustard gas was first
used effectively in World War I by the German army against
Canadian soldiers in 1915 and later also against the
French — the name ''Yperite'' comes from its usage by the German army near the city of
Ypres. It took the British over a year to develop their own mustard gas weapon (their only option was the Despretz–Niemann–Guthrie process), first using it in September 1918 during the breaking of the
Hindenburg Line.
Mustard gas was dispersed as an
aerosol in a mixture with other chemicals, giving it a yellow-brown color and a distinctive odor. Mustard gas has also been dispersed in such munitions as aerial bombs, land mines, mortar rounds, howitzer rounds, and rockets
[1]. Mustard gas was lethal in only about 1% of cases. Its effectiveness was as an incapacitating agent. The countermeasures against the gas were quite ineffective, since a soldier wearing a
gas mask was not protected against absorbing it through the skin.
Furthermore, mustard gas was a persistent agent which would remain in the environment for days and continue to cause sickness. If mustard gas contaminated a soldier's clothing and equipment, then other soldiers he came into contact with would also be poisoned. Towards the end of the war it was even used in high concentrations as an
area-denial weapon, which often forced soldiers to abandon heavily contaminated positions.
Since then, mustard gas has also been reportedly used in several wars, often where the side it is used against cannot retaliate:
[7]
★
United Kingdom against the
Red Army in 1919;
[8]
★
Spain against
Rif insurgents in
Morocco in 1921-1927;
[7][10]
★
Italy in
Libya in
1930;
[7]
★
Soviet Union in
Xinjiang,
China in
1934 and 1936-1937;
[8][10]
★
Italy in Abyssinia (now
Ethiopia) in 1935-1940;
[7]
★
Poland against
Germany in
1939 during an isolated incident, British product;
[7]
★ Germany against Poland and the Soviet Union in a few erroneous uses during the
Second World War;
[7]
★
Japan against
China in 1937-1945;
[8]
★
Egypt against
North Yemen in 1963-1967;
[7]
★
Iraq against
Iran in 1981 and 1983-1988;
[7]
★ Iran against Iraq in 1987-1988, possibly using captured Iraqi munitions;
[7]
★ Iraq against
Kurds in 1988;
[7]
★ Possibly
Sudan against insurgents in the civil war, in 1995 and 1997
[7]
In 1943, a
U.S. stockpile was bombed in
Bari,
Italy, accidentally exposing thousands of civilians and 628 Allied troops. It was noted by medical workers that the white cell counts of exposed soldiers were decreased, and mustard gas was investigated as a therapy for
Hodgkin's lymphoma, a form of cancer. Study of the use of similar chemicals as agents for the treatment of cancers led to the discovery of
mustine, and the birth of anticancer
chemotherapy.
The use of poison gas, including mustard gas, during warfare, a practice known as
chemical warfare, was prohibited by the
Geneva Protocol of 1925 and the subsequent
Chemical Weapons Convention of 1993, which also prohibits the development, production and stockpiling of such weapons.
Disposal
Most of the mustard gas found in Germany after World War II was dumped into the
Baltic Sea. Between 1966 and 2002, fishermen have found around 700 chemical weapons outside
Bornholm, most of which were mustard gas bombs. When mustard gas is exposed to seawater, it forms a tar-like
gel and maintains its lethality for at least five years. It is possible to mistake a piece of
polymerised mustard gas for
ambergris, which can lead to severe health problems.
Shells containing mustard gas and other toxic ammunition from World War I (as well as conventional explosives) can still occasionally be found in
France and
Belgium; they used to be disposed of by explosion at sea, but current environmental regulations prohibit this and so the French government is building an automated factory to dispose of the backlog of shells.
In 1972, the
United States Congress banned the practice of disposing chemical weapons into the ocean. However, 64 million pounds of nerve and mustard agents had already been dumped into the ocean waters off the United States by the
U.S. Army. According to a 1998 report created by William Brankowitz, a deputy project manager in the U.S. Army Chemical Materials Agency, the Army created at least 26 chemical weapons dump sites in the ocean off at least 11 states on both the west and east coasts. Additionally because of poor records, they currently only know the rough whereabouts of half of them.
A significant portion of the
stockpile of mustard agent in the United States was stored at the Edgewood Area of
Aberdeen Proving Ground in
Maryland. Approximately 1,621 tons of mustard agent was stored in one-ton (900 kg) containers on the base under heavy guard. A disposal plant built on site neutralized the last of this stockpile in February 2005. This stockpile had priority because of the potential for quick reduction of risk to the community. The closest schools were fitted with overpressurization units to protect the students and staff in the event of a catastrophic explosion and fire at the site. These projects, as well as planning, equipment, and training assistance, were provided to the surrounding community as a part of the Chemical Stockpile Emergency Preparedness Program (CSEPP), a joint US Army and Federal Emergency Management Agency program
[1]. Unexploded shells containing mustard agent and other chemical agents are still present in several test ranges in proximity to Edgewood area schools, but the smaller amounts (4–14 pounds; 2–6 kg) present considerably less risk. They are being systematically detected and excavated for disposal. There are several other sites in the United States where the remaining U.S. stockpiles of chemical agents are awaiting destruction in compliance with international chemical weapons treaties; the largest mustard agent stockpile, approximately 6,196 tons, is stored at the Deseret Chemical Depot in
Utah. Destruction of this stockpile began in 2006. U.S. mustard agent and other chemical agent storage is managed by the US Army's Chemical Materials Agency
[2]. The Chemical Materials Agency (CMA) manages disposal operations at five of the remaining seven stockpile sites, located in
Alabama,
Arkansas,
Indiana, Utah, and
Oregon; disposal projects at the other two sites, located in
Kentucky and
Colorado, are managed by the Program Manager Assembled Chemical Weapons Alternatives (ACWA)
[3].
See also
★
Blister agent
★
Nitrogen mustard
★
Chemical warfare
External links
★
Textbook of Military Medicine - Intensive overview of mustard gas Includes many references to scientific literature
★
An overview of the sulfur and nitrogen mustard agents (Caution: contains graphic images)
★
Questions and Answers for Mustard Gas
★
UMDNJ-Rutgers University CounterACT Research Center of Excellence A research center studying sulfur mustard
References
1. 'FM 3-8 Chemical Reference handbook'; US Army; 1967
2. 'FM 3-8 Chemical Reference handbook'; US Army; 1967
3. 'FM 3-8 Chemical Reference handbook'; US Army; 1967
4. 'FM 3-8 Chemical Reference handbook'; US Army; 1967
5. ''Mustard Gas: Its Pre-World War I History'' Duchovic, Ronald J.; Vilensky, Joel A. J. Chem. Educ. '2007', 84, 944. Link
6. 'FM 3-8 Chemical Reference handbook'; US Army; 1967
7. Blister Agent: Sulfur Mustard (H, HD, HS), CBWinfo.com
8. Uses of CW since the First World War, Federation of American Scientists
9. Blister Agent: Sulfur Mustard (H, HD, HS), CBWinfo.com
10. Global Civil Society Yearbook 2003, Daniel Feakes, , , Oxford University Press, 2003,
11. Blister Agent: Sulfur Mustard (H, HD, HS), CBWinfo.com
12. Uses of CW since the First World War, Federation of American Scientists
13. Global Civil Society Yearbook 2003, Daniel Feakes, , , Oxford University Press, 2003,
14. Blister Agent: Sulfur Mustard (H, HD, HS), CBWinfo.com
15. Blister Agent: Sulfur Mustard (H, HD, HS), CBWinfo.com
16. Blister Agent: Sulfur Mustard (H, HD, HS), CBWinfo.com
17. Uses of CW since the First World War, Federation of American Scientists
18. Blister Agent: Sulfur Mustard (H, HD, HS), CBWinfo.com
19. Blister Agent: Sulfur Mustard (H, HD, HS), CBWinfo.com
20. Blister Agent: Sulfur Mustard (H, HD, HS), CBWinfo.com
21. Blister Agent: Sulfur Mustard (H, HD, HS), CBWinfo.com
22. Blister Agent: Sulfur Mustard (H, HD, HS), CBWinfo.com
العربية
ä¸å›½
Français
Deutsch
Ελληνική
हिनà¥à¤¦à¥€
Italiano
日本語
Português
РуÑÑкий
Español
