CHAPTER 4


BLISTER AGENTS (VESICANTS)

SECTION I - INTRODUCTION

4-1. General

a.    Blister agents (vesicants) are likely to be used to produce casualties and to force opposing troops to wear full protective equipment. Blister agents are used to degrade fighting efficiency rather than to kill, although exposure to such agents can be fatal. Thickened blister agents will contaminate terrain, ships, aircraft, vehicles, or equipment and present a persistent hazard. ; Vesicants include sulphur mustard (H and HD), nitrogen mustards (HN), lewisite (L) (this may be used in mixture with HD), and halogenated oximes (example, phosgene oxime (CX)). Halogenated oximes properties and effects are very different from those of the other vesicants.

b.    Vesicants burn and blister the skin or any other part of the body they contact. They may act on the eyes, mucous membranes, lungs, and skin; mustards may act on blood-forming organs. They damage the respiratory tract when inhaled and cause vomiting and diarrhea when ingested.

c.    Some vesicants have a faint odor; others are odorless. They often have more serious effects than is immediately apparent. Both L and CX cause immediate pain on contact. The mustards are insidious in action, with little or no pain at the time of exposure. In some cases, signs of injury may not appear for several hours.

d.   Vesicants poison food and water and make other supplies dangerous to handle.

e.    Vesicants can be disseminated by artillery shell, mortar shell, rocket, aircraft spray, and bomb.

f.    The severity of a blister agent burn is directly related to the concentration of the agent and the duration of contact with the skin.

4-2. Self-Aid

a.    Assume MOPP 4 whenever liquid or vaporized agents are known to be present. b.    Liquid vesicants in the eyes or on the skin require immediate decontamination procedures as outlined in appendix d.

4-3. Precautions in Receiving Casualties

a.    Casualties contaminated with vesicants endanger unprotected attendants. Individuals in contact with these casualties must be at MOPP 4, plus wear a butyl rubber apron.

b.    Special precautions must be taken in receiving contaminated casualties to prevent injury to others. Contaminated casualties are decontaminated outside the field MTF to prevent vapor accumulation indoors. They are kept separated from clean (uncontaminated) casualties until decontamination is completed. Contaminated litters, blankets, and equipment must be left outdoors. Decontamination is necessary for equipment, vehicles, watercraft, and aircraft that have been used to transport contaminated casualties. Appendix B contains further information on decontamination.

c.    Unhydrolyzed mustard on patients� skin surface can present a hazard to individuals receiving or treating these patients even after several hours. As mustard reacts with skin and subcutaneous tissue, it is hydrolyzed; however, the destroyed tissue becomes a barrier for complete hydrolyzation of excess mustard on the surface.

4-4. Protective Devices

a.    The protective mask protects only the face, eyes, and respiratory tract. The mask protects against both liquid and vapor forms of vesicants.

b.    Chemical protective overgarments help prevent the vesicant from reaching the skin.

4-5. Disposition of Casualties

See section V for disposition of casualties with blister agent burns.

SECTION II. MUSTARDS

4-6. Mustard (H and HD)

a.    Physical Properties. Mustard is an oily liquid ranging from colorless, when pure (neat), to dark brown when plant-run (unpurified form when first produced). Mustard is heavier than water, but small droplets float on water surfaces and present a special hazard in contaminated areas. It smells like garlic or horseradish. Distilled HD, the most common form of mustard, freezes at 57�F (14�C) and boils at 442�F (228�C). It is only slightly soluble in water, which gradually destroys it, but undissolved mustard may persist in water for long periods. It is most soluble in fats and oils. It is freely soluble in acetone, carbon tetrachloride, alcohol and liquid fuels (gasoline, kerosene, and diesel); however, these solvents do not destroy mustard. Mustard disappears from contaminated ground or materials through evaporation or through hydrolysis. It is rapidly destroyed by decontaminating chemicals or by boiling in water. The primary use of mustard is to cause delayed casualties by the liquid and vapor effects on the skin and the eyes and by the vapor effects through the respiratory system.

b.    Persistence. The persistence of hazard from mustard vapor or liquid depends on the degree of contamination by the liquid, type of mustard, nature of the terrain and soil, type of munition used, and weather conditions. Mustard may persist much longer in wooded areas than in the open. Mustard persists two to five times longer in winter than in summer. The hazard from the vapor is many times greater under hot conditions than under cool conditions. Standard chemical agent detector kits should be used to detect the presence of HD vapor in the field.

c.    Cumulative Effect. Even very small repeated exposures to mustard are cumulative in effect. For example, repeated exposures to vapors from spilled mustard can kill or produce 100 percent disability by irritating the lungs and causing a chronic cough and pain in the chest.

Figure 4-1. Casualty with mustard burn of the face and eyes.

[DATA UNAVAILABLE - FORTHCOMING]

4-7. Effects of HD on the Eyes

a.    Pathology, Symptoms, and Prognosis. In a single exposure, the eyes are more susceptible to mustard than either the respiratory tract or the skin. Figures 4-1 through 4-4 show effects of mustard on the eyes. Conjunctivitis follows an exposure time of about 1 hour to a concentration barely perceptible by odor. This exposure does not affect the respiratory tract or the skin significantly. A latent period of 4 to 12 hours follows mild exposure, after which there is lacrimation and a sensation of grit in the eyes. The conjunctivae and the lids become red and edematous. Heavy exposure irritates the eyes after 1 to 3 hours and produces some severe lesions. Although temporary blindness may occur, permanent blindness is very rare. Casualties should therefore be reassured and a positive attitude taken. Care must be exercised to avoid transferring liquid agent from the hands to the eyes. Mustard burns of the eyes may be divided as follows:

(1)    Mild conjunctivitis (75 percent of cases in World War I). Recovery takes 1 to 2 weeks.

(2)    Severe conjunctivitis with minimal corneal involvement (15 percent of the cases in World War I). Blepharospasm, edema of the lids, and conjunctivae occur, as may orange-peel roughening of the cornea. Recovery takes 2 to 5 weeks.

(3)    Mild corneal involvement (10 percent of the cases in World War I). Areas of corneal erosion stain green with fluorescein. Superficial corneal scarring and vascularization occurs as does iritis. Temporary relapses occur and convalescence may take 2 to 3 months. Hospital care is indicated for casualties of this type.

(4)    Severe corneal involvement (about 0.1 percent of mustard casualties in World War I). Ischemic necrosis of conjunctivae may be seen. Dense corneal opacification with deep ulceration and vascularization occurs. Convalescence may take several months. Patients may be predisposed to late relapses.

b.    Treatment.

(1)    Self-aid.

(a)    The risk of leaving liquid vesicant in the eyes is much greater than the risk from exposure of the eyes to vesicant vapors during the short period of decontamination. Decontamination must, therefore, be done despite the presence of vapor.

(b)   Speed in decontaminating the eyes is absolutely essential. This self-aid procedure is very effective for mustard within the first few seconds after exposure but is of less value after 2 minutes. Decontamination is done the same as for other vesicants (app D). (2)    Treatment of mustard conjunctivitis.

(a)   Mild lesions require little treatment. Although the lesions may become infected, a steroid antibiotic eye ointment, such as dexamethasone sodium phosphate-neomycin ophthalmic ointment, can be applied. Ophthalmic ointments, such as 5 percent boric acid ointment, will provide lubrication and minimal antibacterial effects. The application of sterile petroleum jelly between the eyelids will provide addi- tional lubrication and prevent sealing of the eyelids.

(b) More severe injuries will cause enough edema of the lids, photophobia, and blepharospasm to obstruct vision. This obstruction of vision alarms patients. To allay their fears, the lids may be gently forced open to assure them that they are not blind.

(c)   The pain is controlled best by systemic narcotic analgesics. Patients with severe photophobia and blepharospasm should have one drop of atropine sulfate solution (1 percent) instilled in the eye three times a day. To prevent infection, a few drops of 15 percent solution of sodium sulfacetamide should be instilled every 4 hours. Other antibacterial ophthalmic preparations may be substituted for sodium sulfacetamide.

(d)   The eye must not be bandaged or the lids allowed to stick together. Sealing of the lids may be prevented as described in a above. The accumulation of secretions in the conjunctival sac or pressure on the eye predisposes to corneal ulceration. To prevent complications, the patient should be treated by an ophthalmologist as soon as possible. When possible, the patient should be kept in a darkened room, given dark sunglasses, or given an eyeshade to help his photophobia.

Figure 4-1. Casualty with mustard burn of the face and eyes.

[DATA UNAVAILABLE - FORTHCOMING]

Figure 4-3. Casualty showing eye effects of mustard vapor.

Figure 4-4. Casualty showing effects of mustard conjunctivitis.

(3)    Treatment of infected mustard burns of the eye. Secondary infection is a serious complication and increases the amount of permanent scarring of the cornea. If infection develops, initial treatment should be carried out with several drops of a 15 percent solution of sodium sulfacetamide every 2 hours. After appropriate cultures, specific antibacterial preparations may be applied. Irrigation should be gentle and employed only to remove accumulated exudate. Pain is controlled as described in (2) (c) above. Patients with secondary infection or other complications should be referred to an ophthalmologist. Local anesthetics should not be used.

c.    Classification of Eye Lesions. See paragraph 4-29b.

4-8. Effects of HD on the Skin

a.    Pathology. The severity of the lesions and the rapidity with which they develop are greatly influenced by weather conditions as well as by the degree of exposure. Hot, humid weather strikingly increases the action of mustard. Even under temperate conditions, the warm, moist skin of the perineum, external genitalia, axillae, antecubital fossae, and neck are particularly susceptible.

(1)    Latent period. Exposure is followed by a latent period which varies with the degree of exposure. It may be as short as an hour after liquid contamination, when the weather is hot and humid, or as long as several days after mild vapor exposures. With most vapor exposures in temperate weather, the latent period is usually 6 to 12 hours.

(2)    Erythema. Erythema gradually appears (2 to 48 hours postexposure) and becomes brighter, resembling sunburn (figs 4-5 and 4-6). Slight edema of the skin may occur. In severe burns, the edema may limit motion of the limb. Itching is common and may be intense. As the erythema fades, areas of increased pigmentation are left (this sequence is reminiscent of that seen in sunburn).

(3)    Vesication. Except with mild vapor burns, erythema is followed by vesication (figs 4-7, 4-8, 4-9, and 4-10). This is caused by progressive development of liquefaction necrosis of the cells in the lower layers of the epidermis. Exudation of tissue fluid into the spaces so formed results in an intraepidermal vesicle. Clinically, multiple pinpoint lesions may arise within the erythematous skin; these enlarge and coalesce to form the typical blister (which is unusually large, domed, thin-walled, yellowish, and may be surrounded by erythema). The blister is filled with a clear or slightly yellow liquid that tends to coagulate. The blister fluid does not contain mustard and is not a vesicant. Liquid contamination of the skin usually results in a ring of vesicles surrounding a gray-white area of skin which, although necrotic, does not vesicate. As noted in paragraph 4-3c above, unhydrolyzed vesicant on contaminated patients may pose a hazard to other individuals coming in contact with them.

Figure 4-5. Noncasualty with erythema.

(4)    Resorption. If the blister does not rupture, resorption takes place in about a week. The roof forms a crust beneath which reepidermization takes place. However, because of their thinness and tenseness, the blisters are fragile and usually break. If the roof becomes ragged, the burn may be considered an open wound. Once the blister has broken, it is best to remove its ragged roof to decrease the possibility of secondary infection.

(5)   Healing. Since the damage to the corium is relatively superficial, healing occurs with little scar tissue formation, except in more extensive or infected burns where scarring is more severe.

(6)   Pigmentation. Mustard burns usually are followed by a persistent brown pigmentation except at the site of actual vesication, where there may be a temporary depigmentation due to exfoliation of the pigmented layers of the skin (figs 4-11 and 4-12).

(7)   Hypersensitivity. Repeated burns may lead to hypersensitivity of the skin to mustard.

b.    Symptoms and Prognosis.

(1)    An outstanding characteristic of the action of mustard is its insidiousness. Exposures to mustard are not accompanied by immediate symptoms, nor do any local manifestations occur until erythema develops. At this time there may be itching and mild burning. This pruritus may last several days and persist after healing. The blisters may be painful.

Figure 4-6. Casualty with generalized erythema and systemic intoxication.

Figure 4-7. Casualty with severe vestication. 

(2)    Mustard erythema heals at about the same rate as sunburn of like severity. Areas of multiple pinpoint vesication usually heal, with desquamation, in 1 to 2 weeks. Healing times for mustard blisters vary widely with both severity and anatomical location. In general, blisters of the face heal in 1 to 2 weeks. Blisters located in other areas may take slightly longer to heal; but if protected from infection, they will heal in 2 to 4 weeks. If cutaneous injury results in full-thickness coagulation necrosis, skin grafting may ultimately be necessary. However, a mustard burn of the skin is usually limited to the epidermis and does not require grafting (fig 4-13).

(3)    Moderate contamination of mustard skin lesions with saprophytic bacteria, which causes no appreciable inflammatory reaction, does not seem to delay the healing of mustard burns. Active infection, with inflammation and purulent exudation, may increase the severity of the lesions and delay healing greatly (fig 4-14).

c.    Diagnosis of Skin Lesions Due to Mustard. Similar skin burns are produced by mustard and the nitrogen mustards. Mustard burns are also similar in appearance to those caused by arsenical vesicants. Differentiation of mustard lesions from those produced by arsenicals is based upon:

(1)    History of exposure to mustard.

(2)    Absence of pain or discomfort at time of contamination (L is irritating and immediately painful).

(3)    A zone of erythema surrounding blisters (not predominant with arsenicals). It should be remembered that vesicular lesions, much like mild mustard burns, may be produced in sensitive individuals by a variety of substances, notably plant poisons such as poison ivy or poison oak. However, the skin lesions of plant contact are on exposed skin and linear in configuration. The earliest affected areas of skin from mustard are the skin folds, groin, and inner aspects of the extremities.

d.    Decontamination of Casualties. Casualties who have experienced liquid mustard contamination of the skin or clothing will seldom be received by the medical service in time to prevent subsequent blistering. Nevertheless, if erythema has not appeared, known or likely contaminated skin areas should be decontaminated as described in appendix d. Cut away and discard hair contaminated with liquid mustard. Decontaminate the exposed scalp with the M291 Skin Decontaminating Kit. If short of these substances, use 0.5 percent aqueous chlorine solution for decontamination of skin and hair. Wash off the decontaminating solutions promptly (within 3 or 4 minutes) to prevent additional skin injury, taking care that none of the solutions wash into the eyes. If erythema of the skin has appeared, soap and water is the best decontaminant. Contaminated clothing should be removed promptly from casualties outside the treatment facility to prevent more severe burns and to lessen the vapor hazard to patients and attendants.

e.    Treatment of Mustard Erythema. Mustard erythema in mild cases requires no treatment. If an annoying itch is present, considerable relief may be obtained with topical steroid creams or sprays. Severe erythema around the genitalia may become quite painful and associated weeping and maceration may ensue. Often, treatment with exposure of the area is desirable and care must be taken so that secondary infection of tissue does not occur.

 

| First Page | Prev Page | Next Page | Back to Text |