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)
Incendiary agents (intended to produce light and flame)
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 Hazard Emergency Medical Management (CHEMM).
Clinical practice guidelines for the medical management of chemical-agent exposure are available through the Department of Defense Center of Excellence for Trauma (CPG ID:69 ).
(See also Overview of Incidents Involving Mass-Casualty Weapons.)
Classification of Chemical-Warfare Agents
Toxic chemical warfare agents are divided into 4 major classes:
Systemic asphyxiants (blood agents)
Vesicants (blistering agents)
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 U.S. military does not consider riot-control agents to be chemical warfare agents.)
Opioid Toxicity and Withdrawal
In addition to their chemical designations, most CW agents also have a 1- to 3-letter North Atlantic Treaty Organization (NATO) code (eg, nerve agents GA [agents tabun], GB [sarin], GD [soman], and GF [cyclosarin]) (1).
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.
Reference
1. Chauhan S, Chauhan S, D'Cruz R, et al. Chemical warfare agents. Environ Toxicol Pharmacol. 2008;26(2):113-122. doi:10.1016/j.etap.2008.03.003
