Mustard gas

• 1. Introduction

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  Mustard gas is a chemical weapon whose victims could not be touched. A British nurse who treated soldiers burned by it in World War I described the ward in stark terms. In her words, "They cannot be bandaged or touched. We cover them with a tent of propped-up sheets." She noticed that men with terrible wounds of other kinds usually did not complain. The gas cases, by contrast, were beyond endurance and could not stop crying out. Why did a poison named after a condiment cause suffering like this? How did a laboratory curiosity of the 1800s become a weapon of war? Why do fishermen and archaeologists still stumble on it today? And how did the same substance end up pointing doctors toward the first drug for cancer?

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• 2. A Misleading Name

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  Three sensory clues gave mustard gas its name: a yellow color, a smell like mustard, and a burning sensation in the eyes. The term first appeared in 1917, when German forces used the poison in combat. Even so, the label is technically wrong. Once dispersed, the agent is often a fine mist of liquid droplets rather than a true gas.

  Pure sulfur mustard is colorless and, at room temperature, a viscous liquid. The impure batches made for war were usually yellow-brown. The odor resembles mustard plants, garlic or horseradish. Chemists know the main compound as bis(2-chloroethyl) sulfide.

  The French called it Yperite, because the compound was first used at Ypres. German scientists first labeled it LOST, after Wilhelm Lommel and Wilhelm Steinkopf. In 1916 the two men developed a method of large-scale production for the Imperial German Army.

  Many blends followed. Levinstein mustard, coded H or HS for "Hun Stuff", was named for the inventor of a quick but dirty manufacturing process. Undistilled, it carried 20 to 30 percent impurities, so it stored badly. As it decomposed its vapor pressure rose, and a shell holding it could split along a seam and leak.

  Distilled mustard, coded HD, is 95 percent pure or better. This is the variety people usually mean by the term mustard gas. The British codenamed it Pyro, and the Americans called it Distilled Mustard.

  HT mixed 60 percent HD with 40 percent O-mustard, a relative with a lower freezing point. HL combined HD with lewisite, whose job was to act as antifreeze in winter. HQ blended HD with sesquimustard. The name Yellow Cross covered several blends, after the yellow cross painted on artillery shells. That marking warned of a weapon whose chemistry works deep inside living cells.

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• 3. What It Does to the Body

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  Within 24 hours of exposure, victims of mustard gas feel intense itching and skin irritation. The delay is part of the danger. Mustard agents often cause no immediate symptoms, so a contaminated area can look perfectly normal.

  Without treatment, blisters filled with pus form wherever the agent touched the skin. These are chemical burns, and they are severely debilitating. Depending on the level of contamination, they range from first and second degree to as bad as third degree burns. The skin can also change color through a process called melanogenesis. Of the sulfur mustard that lands on skin, about 80 percent evaporates, 10 percent stays in the skin and 10 percent enters the blood.

  Exposed eyes grow sore and develop conjunctivitis. The eyelids then swell, and temporary blindness follows. In severe but infrequent cases, the cornea ulcerates and scars, and a corneal transplant has been used as treatment. Long-term eye trouble includes burning, tearing, itching, pain and sensitivity to light.

  Inhaled in high concentrations, the agent causes bleeding and blistering in the airways. It damages mucous membranes and fills the lungs with fluid.

  At the cellular level, a sulfur mustard molecule easily sheds chloride ions and forms a reactive ring-shaped ion. That ion permanently attaches to the building blocks of DNA. Cells with damaged DNA may be unable to divide, and they die by programmed cell death. If they survive, the damage can lead to cancer, which is why mustard gas is classed as a carcinogen. Oxidative stress adds to the harm.

  The long shadow shows up in genetics. In a study of patients 25 years after wartime exposure, 122 genes were significantly mutated in their lungs and airways.

  No preventive agent and no antidote exist. Protection depends entirely on covering the skin and airways. Treatment follows a rinse-wipe-rinse sequence, using liquid soap and water or an absorbent powder, with saline or clean water for the eyes. Larger blisters are irrigated repeatedly, then dressed with an antibiotic and petroleum gauze.

  The burns heal slowly and risk sepsis from bacteria such as Staphylococcus aureus and Pseudomonas aeruginosa. In laboratory tests at low concentrations, the compound N-acetyl-L-cysteine reduced cell death. The same tests suggested that actin filaments play a large role in the severity of the burns. Ironically, the effect on dividing cells and blood cells would soon attract the attention of doctors as well as generals.

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• 4. Chemists and Flasks

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  The French chemist César-Mansuète Despretz, who lived from 1798 to 1863, may have made the compound as early as 1822. He reacted sulfur dichloride with ethylene but never mentioned any irritating effect. In 1854 another French chemist, Alfred Riche, repeated the procedure and was equally silent about adverse effects.

  The British scientist Frederick Guthrie synthesized and characterized the compound in 1860. He noted its irritating properties, especially when tasting it. In the same year Albert Niemann, a pioneer in cocaine chemistry, repeated the reaction. Niemann recorded that the product raised blisters.

  In 1886 Viktor Meyer published a synthesis that gave good yields. He combined 2-chloroethanol with aqueous potassium sulfide, then treated the resulting thiodiglycol with phosphorus trichloride. The product was much purer, and its effects were much more severe. Symptoms appeared in his assistant. Meyer wanted to rule out a psychosomatic cause, so he tested the compound on laboratory rabbits. Most of them died.

  In 1913 the English chemist Hans Thacher Clarke was working with Emil Fischer in Berlin. Clarke is known for the Eschweiler-Clarke reaction. He replaced the phosphorus trichloride in Meyer's recipe with hydrochloric acid. One of his flasks broke, and burns kept him in hospital for two months.

  Meyer later claimed that Fischer's report on the accident to the German Chemical Society sent the German Empire on the road to chemical weapons. During World War I, Germany relied on the Meyer-Clarke method. The reason was practical. The German dye industry of the time supplied 2-chloroethanol in abundance.

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• 5. From Ypres to Halabja

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  On the 12th of July 1917, the German army used mustard gas against British and Canadian soldiers near Ypres, Belgium. It was later turned on the French Second Army as well. The Allies first used it in November 1917 at Cambrai, France, after capturing a stockpile of German mustard shells.

  The British took more than a year to make their own. Production centred on Avonmouth Docks, because the only route open to them was the Despretz-Niemann-Guthrie process.

  The weapon rarely killed. Exposure was lethal in about 1 percent of cases, and its strength lay in disabling troops. Early defenses failed, since a gas mask could not stop the agent from blistering a soldier's skin. A common remedy was a mask or facecloth soaked in urine. Soldiers described it in documentaries such as They Shall Not Grow Old in 2018, and in interviews recorded by the BBC between 1947 and 1981. Whether it worked is unclear.

  Contamination lingered. Mustard gas can stay in the ground for weeks. Clothing soaked while cold could poison men sharing an enclosed space once it warmed, a danger in the underground berthing areas built in Belgium and France. Near the war's end, heavy concentrations were used to force troops out of whole areas.

  The agent was delivered in aerial bombs, land mines, mortar rounds, artillery shells and rockets, and sprayed from aircraft. After 1918 it was used again and again, usually against people who could not answer in kind. The United Kingdom used it against the Red Army in 1919. Spain used it against the Rifian resistance in Morocco during the Rif War of 1921-27. Italy used it in Libya in 1930 and against Abyssinia in 1935-36. The Empire of Japan used it against China from 1937 to 1945. Egypt used it in North Yemen in 1963-67.

  In 1988 Iraq used it against Kurds in the town of Halabja. During the Iran-Iraq War, mustard gas caused more than 100,000 casualties. In the Iraq War, abandoned shells were destroyed in the open air, and some turned up in roadside bombs. In August 2015, ISIS forces used it against Kurdish forces in Iraq.

  The Geneva Protocol of 1925 prohibited chemical warfare. The Chemical Weapons Convention of 1993 went further. It banned development, production, stockpiling and sale, and it placed sulfur and nitrogen mustards in Schedule 1.

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• 6. From Poison to Medicine

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  By 1919 researchers knew that mustard agent suppressed the formation of blood cells. Autopsies on 75 soldiers killed by it in World War I, done by researchers at the University of Pennsylvania, showed reduced white blood cell counts.

  During World War II, the American Office of Scientific Research and Development paid the biology and chemistry departments at Yale University to study chemical warfare. The Yale group investigated nitrogen mustard as a treatment for Hodgkin's lymphoma and other lymphomas and leukemia. The compound was tried on its first human patient in December 1942. The results stayed secret until they were declassified and published in 1946.

  A second thread began on the 2nd of December 1943. An air raid on Bari destroyed an Allied stockpile of mustard gas aboard the SS John Harvey. The attack killed 83 people and put 628 in hospital. US Army doctors noticed that their patients' white blood cell counts had fallen.

  Some years after the war, the Bari incident and the Yale work came together and set off a search for similar compounds. The nitrogen mustard called HN2 had already featured in earlier studies. It became the first cancer chemotherapy drug, known as chlormethine, mechlorethamine or mustine.

  Mustard molecules are still used against cancer today. Safer drugs such as cisplatin and carboplatin have largely replaced them.

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• 7. Secret Experiments

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  In tropical Queensland, Australian service volunteers were exposed to mustard agent in 1943-44. Royal Australian Engineers, the British Army and American experimenters ran the trials, and some men were severely injured. One site, Brook Islands National Park, was chosen to imitate Pacific islands held by the Imperial Japanese Army. The documentary Keen as Mustard tells the story.

  The United States tested sulfur mustards, nitrogen mustards, lewisite and other agents on up to 60,000 servicemen during and after World War II. On the 3rd of June 1945, Naval recruits at the Great Lakes Naval Base were tested in a laboratory.

  Race shaped some of the trials. African American servicemen were tested alongside white men in separate trials, to see whether darker skin gave some immunity. Nisei servicemen, some of whom had joined after leaving Japanese American internment camps, were tested to learn how Japanese troops might react. Puerto Rican subjects were included too.

  Rollin Edwards, one of the men tested, described the experience this way: "It felt like you were on fire, guys started screaming and hollering and trying to break out." He also said: "It took all the skin off your hands. Your hands just rotted."

  The experiments were classified secret. Claims for medical care and compensation were routinely denied, even after the tests were declassified in 1993. The Department of Veterans Affairs said it would contact 4,000 surviving test subjects. It reached only 600. Skin cancer, severe eczema, leukemia and chronic breathing problems afflicted the men, some of whom had been as young as 19 at the time.

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• 8. Dumped and Found

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  In 1946-10,000 drums holding 2,800 tonnes of mustard gas left the Stormont Chemicals plant in Cornwall, Ontario. They traveled 900 miles in 187 boxcars. A 400-foot barge then carried them 40 miles south of Sable Island, where they were buried at sea in 600 fathoms of water.

  In Germany, most of the mustard gas found after World War II went into the Baltic Sea. Between 1966 and 2002, fishermen near Bornholm found about 700 chemical weapons, most of them containing mustard gas. A frequent type was the Sprühbüchse 37, or Spray Can 37, fielded by the German Army in 1937. Its mustard gas was mixed with a thickener and had a tar-like consistency.

  When such a lump meets water, only its outer layer breaks down. The inside stays as dangerous as the day it was dumped, and the residue looks like amber. Washed-up lumps have been mistaken for the gemstone, with severe consequences for those who handled them.

  In South Africa, military personnel under William Bleloch dumped stockpiled mustard gas off Port Elizabeth. Local trawler crews suffered burns. In 1972 the US Congress banned ocean disposal of chemical weapons, but the US Army had already dumped 29,000 tons of nerve and mustard agents. A 1998 report by William Brankowitz counted at least 26 ocean dumping sites off at least 11 states. Poor recordkeeping means that about half of them have only rough locations.

  On land, finds keep coming. A mining survey near Chinchilla, Queensland, uncovered 144 howitzer shells in 2009, some containing "Mustard H". In 2014, around 200 bombs near the Flemish villages of Passendale and Moorslede, mostly filled with mustard agents, formed the largest collection of chemical weapons ever found in Belgium. A neighborhood in Washington, D.C. needed a cleanup, finished in 2021. In 2010, a clamming boat south of Long Island, New York, hauled up old shells, and several fishermen needed hospital care.

  Destruction has been slow but real. When the Chemical Weapons Convention took effect in 1997, countries declared 17,440 tonnes of mustard gas worldwide. By December 2015-86 percent had been destroyed. India declared 1044 tonnes in June 1997 and told the United Nations in May 2009 that its stock was gone. It was the third country to finish, after South Korea and Albania.

  In the United States, the Deseret Chemical Depot in Utah held the largest stockpile, about 6,200 short tons. Incineration began in 2006. The last mustard agents there were burned in May 2011, and the last mustard shells in January 2012. The last declared American mustard stockpile was destroyed in Pueblo, Colorado, on the 22nd of June 2023.

  Researchers are now developing portable tests that can detect mustard gas and its breakdown products in small quantities. Such tests could protect civilians near old dumping sites without waiting for slow laboratory analysis.

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