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Overview of Chemical-Warfare Agents

By

James Madsen

, MD, MPH, Uniformed Services University of the Health Sciences

Last full review/revision May 2019| Content last modified May 2019
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Chemical-warfare (CW) agents are chemical mass-casualty weapons (MCWs) developed by governments for wartime use and include

  • Toxic agents (intended to cause serious injury or death)

  • Incapacitating agents (intended to cause only temporary, non–life-threatening effects)

Although incapacitating agents are sometimes mistakenly referred to as nonlethal, in high doses, these agents can cause serious injury or death.

Toxic industrial chemicals are chemicals produced for industrial uses that are capable of causing mass casualties. Some chemicals (eg, chlorine, phosgene, cyanide compounds) have both industrial and CW uses and are called dual-use agents.

A useful online and downloadable resource for incidents involving chemical agents is Chemical Hazards Emergency Medical Management (CHEMM).

Classification

Toxic chemical warfare agents are divided into 4 major classes:

Nerve agents inhibit the enzyme acetylcholinesterase, causing excess cholinergic stimulation and cholinergic crisis (eg, diarrhea, urination, miosis, bronchorrhea, bronchoconstriction, emesis, lacrimation, salivation).

Because pulmonary agents include substances that also affect primarily the upper respiratory tract rather than lung parenchyma, some experts prefer to call this class “agents with acute local effects on the respiratory tract.” Because most toxic industrial chemicals capable of generating mass casualties affect the respiratory tract, they are discussed with pulmonary CW agents.

Systemic asphyxiants, specifically cyanide compounds and hydrogen sulfide, interfere with mitochondrial energy transport, blocking cellular respiration. They are distributed in the blood (and are thus termed blood agents in military references) and thus affect most tissues.

Vesicants damage the dermoepidermal junction, causing pain and typically blistering. Many can affect the lungs if inhaled.

Incapacitating agents can be divided into

  • Riot-control agents (often incorrectly called tear gas) are dispersed as solid aerosols or as solutions (Note: The US military does not consider riot-control agents to be chemical warfare agents.)

  • Opioids, especially potent fentanyl derivatives

Opioids, such as the potent fentanyl derivatives reputedly used by Russia against Chechnyan terrorists in 2002, can be considered incapacitating in that their use is not typically intended to cause serious injury or death. However, when they are used as mass-casualty weapons they can far too easily cause death via respiratory depression. (See Opioid Toxicity and Withdrawal.) In mass-casualty situations, the route of exposure will most likely be inhalation of aerosolized agent; larger than usual doses of naloxone may be needed for fentanyl derivatives.

In addition to their chemical designations, most CW agents also have a 1- to 3-letter North Atlantic Treaty Organization (NATO) code.

Incendiary agents, designed to create light and flame, may also cause thermal burns in large numbers of casualties. Hydrogen fluoride (HF) may likewise cause chemical burns. Some of these burns require specific management apart from the typical management of thermal burns.

The views expressed in this article are those of the author and do not reflect the official policy of the Department of Army, Department of Defense, or the US Government.

Drugs Mentioned In This Article

Drug Name Select Trade
EVZIO
ACTIQ, DURAGESIC, SUBLIMAZE
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