Characteristics of Mustard (Blister) Agents

Mustard blister agent, purified sulfur mustard or distilled mustard, has a 5 percent sulfur impurity, less odor and greater blistering power than the original mustard agent used in World War I. Mustard agent is also known as H, HD or HT. Agent H contains about 20-30 percent impurities and HD is a nearly pure substance. HT is a mixture of 60 percent HD and 40 percent of another substance called T. In its pure liquid state, mustard agent is colorless. However, when exposed to impurities, it becomes a pale yellow to brown oily substance. Mustard agent freezes at 58 F, is liquid at any temperature above 58 F, boils becomes a vapor with a garlic-like odor at 419 F and can remain active in the soil for at least three years. Exposure to mustard agent causes inflammation of the eyes, nose, throat, trachea, bronchi and lung tissue and blisters the skin. In amounts approaching the lethal dose, injury to bone marrow, lymph nodes and spleen may occur. Mustard agent is toxic and the International Agency for Research on Cancer has deemed it a carcinogen cancer-causing agent. Lewisite, also a blister agent, is a colorless liquid with an odor similar to Geraniums. Exposure causes irritation to eyes, skin, respiratory tract and circulatory system and the effects are immediate, within seconds.