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The use of chemical warfare agents (CWAs) in modern warfare dates back to World War I (WWI). Sulfur mustard and nerve agents were used by Iraq against the Iranian military and Kurdish civilians. Most recently the nerve agent Sarin, GB, was used by the Syrian military against their civilian population. Since the Japanese sarin attacks in 1994–1995 and the terrorist strikes of September 11, 2001, the all-too-real possibility of chemical or biological terrorism against civilian populations anywhere in the world has attracted increased attention.

Military planners consider the WWI blistering agent sulfur mustard and the organophosphorus nerve agents as the most likely agents to be used on the battlefield. In a civilian or terrorist scenario, the choice widens considerably. For example, many of the CWAs of WWI, including chlorine, phosgene, and cyanide, are used today in large amounts in industry. They are produced in chemical plants, are stockpiled in large tanks, and travel up and down highways and railways in large tanker cars. The rupture of any of these stores by accident or on purpose could cause many injuries and deaths. In three attacks in February 2007, for example, insurgents in Iraq used chlorine gas released from tankers after explosions as a crude form of chemical weaponry; these attacks killed 12 people and intoxicated more than 140 others. Countless hazardous materials (HAZMATs) that are not used on the battlefield can be used as terrorist weapons. Some of them, including insecticides and ammonia, could wreak as much damage and injury as the weaponized chemical agents.

Many mistakenly believe that chemical attacks will always be so severe that little can be done except to bury the dead. History proves the opposite. Even in WWI, when IV fluids, endotracheal tubes, and antibiotics were unavailable, the mortality rate among U.S. forces on the battlefield from CWAs—chiefly sulfur mustard and the pulmonary intoxicants—was only 1.9%. That figure was far lower than the 7% mortality rate from conventional wounds. In the 1995 Tokyo subway sarin incident, among the 5500 patients who sought medical attention at hospitals, 80% were not actually symptomatic and only 12 died. Recent events should prompt not a fatalistic attitude but a realistic wish to understand the pathophysiology of the syndromes these agents cause, with a view to treating expeditiously all patients who present for care and an expectation of saving the vast majority. As we prepare to defend our civilian population from the effects of chemical terrorism, we also must consider the fact that terrorism itself can produce sequelae such as physiologic or neurologic effects that may resemble the effects of nonlethal exposures to CWAs. These effects are due to a general fear of chemicals, fear of decontamination, fear of protective ensembles, or other phobic reactions. The increased difficulty in differentiating between stress reactions and nerve agent–induced organic brain syndromes has been pointed out. Knowledge of the behavioral effects of CWAs and their medical countermeasures is imperative to ...

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