The toxicity of lung agents is due to their effect on lung tissues; they cause extensive damage to alveolar tissue, resulting in severe pulmonary edema. This group includes phosgene (CG) and chlorine (Cl) as well as chloropicrin and diphosgene. However, CG is most likely to be encountered and its toxic action is representative of the group.
Phosgene is a colorless gas with a distinctive odor similar to that of new-mown hay or freshly cut grass; unfortunately, the minimal concentration in air that can cause damage to the eyes and throat is below the threshold of olfactory perception. Generally speaking, CG does not represent a hazard of long duration, so that if an individual were to be exposed to a casualty-producing amount, he or she should be able to smell it.
There may be watering of the eyes, coughing, and a feeling of tightness in the chest. More often, however, there will be no symptoms for 2 to 6 hours after exposure. Latent symptoms are rapid, shallow, and labored breathing; painful cough; cyanosis; frothy sputum; leadened, clammy skin; rapid, feeble pulse; and low blood pressure. Shock may develop, followed by death.
Once symptoms appear, complete bed rest is mandatory. Keep victims with lung edema only moderately warm, and treat the resulting anoxia with oxygen. Because no specific treatment for CG poisoning is known, treatment has to be symptomatic.
Psychochemical agents, often referred to as incapacitating agents, temporarily prevent an individual from carrying out assigned actions. These agents may be administered covertly by contaminating food or water, or they maybe released as aerosols. The characteristics of the incapacitants include:
The first symptoms appear in 30 minutes to several hours and may persist for several days. Abnormal, inappropriate behavior may be the only sign of intoxication. Those affected may make irrational statements and have delusions or hallucinations. In some instances, the victim may complain of dizziness, muscular incoordination, dry mouth, and difficulty in swallowing.
The standard incapacitant in the United States is 3-quinuclidinyl benzilate (BZ), a cholinergic blocking agent, which is effective in producing delirium that may last several days. In small doses it will cause an increase in heart rate, pupil size, and skin temperature, as well as drowsiness, dry skin, and a decrease in alertness. As the dose is increased to higher levels, there is a progressive deterioration of mental capability, ending in stupor.
The principal requirement for first aid is to prevent victims from injuring themselves and others during the toxic psychosis. Generally, there is no specific therapy for intoxication. However, with BZ and other agents in the class of compounds known as glycolates, physostigmine is the treatment of choice. It is not effective during the first 4 hours following exposure; after that, it is very effective as long as treatment is continued. However, treatment does not shorten the duration of BZ intoxication, and premature discontinuation of therapy will result in relapse,
Riot control agents is the collective term used to describe a divergent collection of chemical compounds, all having similar characteristics. They are relatively nontoxic compounds, which produce an immediate but temporary effect in very low concentrations. Generally, no therapy is required; removal from their environment is sufficient to effect recovery in a short time.