Mustard gas (sometimes known as sulphur mustard) is a vesicant or blister agent. It causes general tissue irritation as well as affecting internal body functions. First synthesized in 1860, it was developed as a chemical warfare agent during the First World War and it has practically no other application.
At high concentrations the gas has a pungent odour variously described as being like that of horse radish, onions or garlic. Eye injuries sufficient to incapacitate will occur at doses of 100 mg-min/m3. This is the same as being exposed to a concentration of 10 mg/m3 for 10 minutes. The dose is a product of the amount to which someone is exposed and the duration of exposure. The estimated lethal dose by inhalation is 1500 mg-min/m3.
The eyes are usually the first affected, and they develop a gritty feeling and appear bloodshot. This is followed by acute pain in the eyes, which begin to water extensively. Other symptoms follow, including runny nose, sneezing, sore throat, coughing and hoarseness. Within 16-24 hours, the skin begins to itch and darken in exposed areas. Where there is moderate to severe exposure, large blisters develop, filled with a clear yellow fluid. When these break, the skin is eroded and ulcers may occur. The long term effects of exposure have become evident in Iranian victims of mustard gas exposure. There are persistent skin and eye problems and severe lung diseases such as bronchitis, asthma, and emphysema.
Mustard gas also has the ability to damage DNA and is a potential cancer causing agent. Workers involved in the manufacture of mustard gas in World War II, where they had repeated exposure to the chemical, had a high incidence of lung cancer. Their risk of contracting the disease was 30 times that of the general population. It is not clear whether a single exposure to mustard gas (as has occured in warfare) increases the risk of lung cancer developing.
Mustard gas is synthesized from thiodiglycol, a chemical used for water-based dyes in the cloth manufacturing industry, including rural industries in developing countries. Thiodiglycol is another example of a multi-use chemical, which can be beneficial when used responsibly or have devastating consequences when abused.
