1-5

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1-5. BLISTER AGENTS (VESICANTS)

Blister agents are vesicants (chemicals which causes blisters). They attack the eyes, lungs, skin, mucous membranes, and blood-forming organs. Blister agents can be deadly when inhaled in sufficient quantities due to their destructive effect on lung tissue. Some blister agents do not produce immediate signs and symptoms. A soldier may be exposed to these agents for several hours before he realizes the danger. Blister agents can poison food and water and contaminate supplies, making them dangerous to handle.

a. Types of Blister Agents. The principle blister agents are mustard (HD), nitrogen mustard (HN), lewisite (L), and phosgene oxime (CX).

b. Methods of Dissemination. Blister agents can be delivered by artillery shell, mortar shell, rocket, aircraft bomb, and spray. The blister agents can be disseminated in either vapor or liquid form. The vapor is really tiny droplets rather than a true vapor.

c. Characteristics of Blister Agents. Mustard is an oily liquid ranging from dark brown (unpurified form) to colorless (purified form). Mustard smells like garlic or horseradish. Nitrogen mustard agents are oily liquids ranging from colorless to pale yellow. Some HN agents have a slightly fishy odor while others are odorless. Lewisite and related vesicants containing arsenic range from brown to colorless and have fruity to geranium-like odors. Phosgene oxime is colorless. It may be used as a liquid or in the form of a crystalline solid. Phosgene oxime has a disagreeable, penetrating odor. Blister agents are persistent, but HD is more persistent than others, especially in cold or wooded areas.

d. Absorption of Blister Agents. Blister agents are absorbed through the respiratory system, the eyes, and the skin. Although usually not fatal, exposure is cumulative in effect. Small, repeated doses of HD can cause lung damage severe enough to result in death. Mustard remaining on the casualty's skin can be a hazard to other personnel for up to 48 hours.

e. Physiological Effects.

(1) Mustard and HN are readily absorbed through the respiratory system and through exposed skin. When they come into contact with skin, they produce redness at the point of contact that is usually followed by blistering and ulceration. When inhaled, these agents produce inflammation of the lungs and the rest of the respiratory system. Death is rare and usually results from bacterial infection of the lungs. The effects on the skin and respiratory system may not be noticeable at the time of exposure and may be delayed for up to 12 hours. The eyes are affected even if exposed to an extremely low dosage. There may be no pain or signs at the time of exposure with redness and inflammation developing in about 20 minutes (HN) to an hour (HD) later.

 

(2) Lewisite is much more dangerous in its liquid form than in its vapor form. Liquid will cause severe burns of the eye and skin. Exposure can cause an immediate, searing sensation in the eyes. Severe exposure of the eyes to lewisite can result in permanent injury or blindness. Inhalation of vapor usually results in mild to moderate irritation of the upper respiratory tract.

Lewisite contains arsenic, a poison that attacks the capillaries of the circulatory system, the liver, and the intestines. Acute poisoning can result in hypovolemic shock and death.

 

(3) Phosgene oxime is a powerful irritant that produces immediate irritation or pain upon contact. When the agent comes into contact with skin, the sensation ranges from a mild, prickling sensation to a pain resembling that of a severe insect sting. When the agent comes into contact with the mucous membranes of the eyes or nose, an immediate and painful irritation is felt.

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