Mustards

Sulfur mustard has been used as a chemical weapon since World War I. Nitrogen mustard, a derivative of sulfur mustard, was one of the first chemotherapy agents but never has been used in warfare. These agents cause blistering of exposed surfaces. Both mustard agents rapidly penetrate cells and generate a highly toxic reaction that disrupts cell function and causes cell death. The chemical reaction is both temperature dependent and aided by the presence of water, which explains why warm, moist tissues are affected more severely. Actively reproducing cells, such as skin and blood cells, are most at risk.

• Physical properties: Mustards are oily liquids with odors of mustard, onion, garlic, or horseradish. Highly soluble in oils, fats, and organic solvents, mustards quickly penetrate skin and most materials, including rubber and most textiles. Sulfur mustard is considered a persistent agent with low volatility at cool temperatures but becomes a major vapor hazard at high temperatures. Exposure to mustard vapor, not mustard liquid, is the primary medical concern. More than 80% of mustard casualties in World War I were caused by exposure to mustard vapor. Mustard vapor is 3 times more toxic than a similar concentration of cyanide gas; however, mustard liquid is also quite toxic. Skin exposure to as little as 1-1.5 teaspoons of liquid (7 g) is lethal to half of those exposed.
  
  
• Signs and symptoms: Mustards injure the skin, eyes, respiratory tract, GI tissues, and blood system. The pattern of toxicity depends partly on whether the person is exposed to liquid or vapor. Liquid exposure primarily damages the skin, producing an initial rash followed by blistering similar to a partial-thickness burn. Vapor exposure damages the upper respiratory tract (skin usually is not affected). Mustards penetrate cells in less than 2 minutes, yet signs and symptoms usually are delayed 4-6 hours (the range can be from 1-24 hours). The time it takes to show symptoms is shorter with high-concentration exposures, such as those occurring at increased room temperature and humidity.
  
  
  • Skin: Chemical burns caused by mustard often appear deceptively superficial at first. Earliest symptoms are itching, burning, and stinging pain over exposed areas. Moist, thinner skin is affected more severely. Affected areas appear red and swollen. If contamination is more extensive, superficial blisters occur within 24 hours of exposure. Most burns are partial thickness, but full-thickness burns with deep blisters may result from exposure to higher concentrations. Blister fluid does not contain active mustard and is not toxic.
    
    
  • Eyes: Eyes are especially sensitive to the effects of mustard. Symptoms begin 4-8 hours after exposure. Earliest symptoms include burning pain, a feeling that something is in the eye, sensitivity to light, tearing, and blurred vision. Permanent corneal scarring and blindness may occur with severe exposures, but is rare.
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  • Respiratory tract: Mustards primarily damage tissues in the upper airway through a direct inflammatory effect. Following a period of 2-24 hours after exposure, symptoms may appear. Early symptoms include sinus congestion, a sore throat, and hoarseness. Later, cough, shortness of breath, and trouble breathing may develop. People with severe and extensive contact with mustard gas may develop respiratory complications up to several days after exposure.
    
    
  • Gastrointestinal tract: Rarely, mustard damages rapidly growing cells of the intestinal tract. GI involvement results in abdominal pain, nausea, vomiting, diarrhea, and weight loss.
    
    
  • Blood system: Rarely, mustards cause unpredictable loss in the production of bone narrow. Certain specialized cells begin dying 3-5 days after exposure reaching its worst point in 3-14 days, depending on the severity of exposure.
  
  
• Diagnosis: Diagnosis of mustard exposure is based on what the doctor observes from the person’s signs and symptoms. No laboratory tests are useful.
  
  
• Personal protective equipment: Liquid mustard contamination poses a risk for emergency care personnel. Ideally, they will be wearing appropriate personal protective gear.
  
  
• Decontamination: Immediate decontamination within 2 minutes of exposure is the most important intervention for people who have skin exposure to mustard, because it rapidly becomes fixed to tissues, and its effects are irreversible. Even if an exposure takes place and a person shows no obvious sign and symptoms, decontamination is still urgent.
  
  
  • Remove clothing immediately and wash the skin with soap and water.
    
    
  • Eye exposure requires immediate washing out with a large amount of saline or water.
    
    
  • Decontamination after the first few minutes of exposure does not prevent further damage later but at least prevents spread of the chemical to other parts of the body and protects emergency care personnel from further contact exposure.
  
  
• Treatment: Treatment of mustard exposure is based on symptoms. Because the effects of mustards typically are delayed, people with complaints immediately after exposure may have an additional injury.
  
  
  • For those with signs of upper airway obstruction, doctors may treat by using a tube in the person's throat or perform surgery to open the airway.
    
    
  • Mustard-induced burns are especially painful. Doctors will use strong pain relievers. Adequate burn care is essential, because skin lesions heal slowly and are prone to infection. Severe burns may require removal of dead tissue, irrigation, and placement of antibiotics, such as silver sulfadiazine, directly on the burned area. The victim may need a tetanus shot.
    
    
  • Severe eye burns may be treated with daily irrigation, topical antibiotic solutions, topical corticosteroids, and drugs that dilate the pupil. Petroleum jelly may be applied to prevent eyelids from sticking together. More severe corneal injuries may take as long as 2-3 months to heal. Permanent visual problems are rare.
    
    
  • Although no antidotes currently are available to treat mustard toxicity, several agents are under investigation.
    
    
  • Victims with bone marrow suppression following mustard exposure may be treated with medication to stimulate the bone marrow, such as granulocyte colony-stimulating factor.
  
  
• Prognosis: Victims with significant respiratory tract burns usually require admission to the hospital’s intensive care unit. Also, victims with several skin burns will be admitted to the burn unit for burn care, pain relief, and supportive care. Blood cell counts will be monitored for 2 weeks following significant exposures. Most people recover completely. Only a small fraction have long-term eye or lung damage. About 2% of those exposed to sulfur mustard in World War I died, mostly due to burns, respiratory tract damage, and bone marrow suppression. Sulfur mustard is known to cause cancer, yet a single exposure causes only a small risk.