(1) The cutaneous syndrome is divided into four phases: latent, erythema, vesication, and necrosis. Vesicants can penetrate the skin by contact with either liquid or vapor. The latent period is characteristic of the agent. For mustards it is usually several hours, for L it is short, and for CX it is negligible. The latent period is also affected by the dose, temperature, and humidity. The symptoms of the erythema phase are red, painful itching followed by painful necrosis that heals slowly.
(2) In the eyes, vesicants produce intense pain and photophobia. Blistering of the eyelids and mucous membranes can result in temporary blindness. Even after recovery, scars on the cornea can reduce visual acuity.
(3) In the respiratory tract, these agents attack the mucous membranes irritating them. They can paralyze vocal chords and can lead to chemical pneumonitis, or possibly death.
(4) Although blister agents can affect other organs and produce deleterious effects, the skin, eyes, and respiratory tract are the principle organs effected.
c. Chemical agents that attack lung tissue (choking agents) and cause pulmonary edema are classed as lung damaging agents. Choking agents consist of CG and DP, CL, and PS. Phosgene is typical of the lung-damaging agents; it is used as the example here.
(1) Phosgene is a colorless gas that has an odor resembling new mown hay. Although effects are primarily confined to the lungs, phosgene may also cause mild irritation of the eyes and upper respiratory tract. Phosgene causes a shift in the membrane potential of the alveoli allowing the passage of fluid into the alveoli, resulting in massive pulmonary edema and severely impairing the exchange of oxygen (O2) and carbon dioxide (CO2) between the capillary blood and the alveolar air.
(2) Initially hypoxemia occurs and is followed shortly by hyperventilation when the frothy edema fluid fills the bronchioli and CO2 expiration stops.
(3) Signs and symptoms during and immediately following exposure are coughing, tightness of chest, nausea, occasionally vomiting, headache, and lacrimation (tearing).
d. Blood agents consist of AC and CK; both are readily absorbed by the mucous membranes and the intact skin. The odor of AC resembles bitter almonds, but many people cannot detect it. Detecting the odor of CK is difficult because of its irritating and lacrimatory effects. It is also poorly absorbed by the metallic salt-impregnated charcoal filters in the protective mask. These agents inhibit certain enzymes (particularly cytochrome oxidase) that are important for oxidation-reduction in the cells; therefore, cell respiration is inhibited and oxygen carried by the hemoglobin is not consumed causing the venous blood to remain bright red. Initial symptoms are characterized by violent convulsions, increased deep respiratory movements, followed by cessation of respiration within one minute, slowing of heart rate to death. High concentrations exert their effects rapidly; however, if the patient is still alive after the cloud has passed, he will probably recover spontaneously.
e. Incapacitating agents are chemicals that produce a temporary disabling condition that persists for hours to days after exposure to the agent has ceased (unlike that produced by riot control agents). While not required, medical treatment produces a more rapid recovery. Characteristics of these agents are that they—