Chemical Warfare (cont.)
Jeffrey L Arnold, MD, FACEP
Francisco Talavera, PharmD, PhD
Raymond J Roberge, MD, MPH, FAAEM, FACMT
Types of Chemical Weapon Agents
- Chemical weapon agents are hazardous substances. Major categories of CWAs include the following:
- Nerve agents (such as sarin, soman, cyclohexylsarin, tabun, VX)
- Vesicating or blistering agents (such as mustards, lewisite)
- Choking agents or lung toxicants (such as chlorine, phosgene, diphosgene)
- Incapacitating agents (such as anticholinergic compounds)
- Lacrimating or riot control agents (such as pepper gas, chloroacetophenone, CS)
- Vomiting agents (such as adamsite)
- Physical properties: CWAs generally are stored and transported as liquids and deployed as either liquid aerosols or vapors. Victims usually are exposed to agents via 1 or more of 3 routes: skin (liquid and high vapor concentrations), eyes (liquid or vapor), and respiratory tract (vapor inhalation). In general, some liquids may be harmful whether inhaled into the lungs or absorbed into the skin. Vapors can be affected by winds. Even a slight breeze can blow a nerve agent vapor away from its intended target. The effects of vapor are enhanced when used within an enclosed space.
- Clinical effects: Depending on the agent and the type and amount (concentration) of exposure, CWA effects may be immediate or delayed. Large inhalation exposures to nerve agents or mustards are likely to kill people immediately. Small exposures on the skin to nerve agents and mustards are more dangerous than they seem at first. People exposed to such agents need to be carefully observed for slowly developing or delayed effects. A chart of signs and symptoms is available from the North Carolina Statewide Program for Infection Control and Epidemiology.
- Medical management: Ideally, emergency personnel will wear personal protective equipment, decontaminate the victims immediately, provide medical support to the victims and provide specific antidotes to counteract the harmful effects.
- Personal protective equipment: First responders to a chemical attack are at serious risk themselves from the chemically contaminated environment (known as the hot zone). They can come in direct contact with the CWA or inhale the vapor. They are also at risk if they handle skin and clothing of victims if a liquid chemical agent was used. Vapors pose little added risk for anyone outside the hot zone.
- Decontamination: Decontamination is the physical process of removing the remaining chemicals from people, equipment, and the environment. Residual hazardous chemicals on those who have been exposed directly are a source of ongoing exposure to others and pose a risk of secondary exposure to first responders and emergency care personnel. Immediate decontamination is a major treatment priority for those with CWA exposure.
- Initial decontamination involves removing all contaminated clothes and jewelry from the affected person and then washing the body thoroughly with warm water and soap.
- Hot water and vigorous scrubbing may actually worsen the effects by increasing chemical absorption into the skin.
- Vapor exposure alone may not require decontamination. But if it is not known whether the exposure was to a vapor or liquid, or if exposed people have symptoms, they should undergo decontamination.
- Ideally, decontamination will take place as close as possible to the site of exposure to minimize duration of exposure and prevent further spread. Hospitals receiving contaminated people may establish an area outside the Emergency Department in which to perform initial decontamination before people and equipment are allowed entry. Portable decontamination equipment with showers and run-off water collection systems are commercially available. All hospitals should have the capacity to safely decontaminate at least 1 person.
- Supportive and specific therapy: Doctors will first make sure exposed victims are able to breathe. For many chemical warfare agents, doctors can only treat the symptoms they produce. But specific, well-established antidotes are available for nerve agent and cyanide exposures. Lab tests are not widely available in hospitals to rapidly confirm exposure to chemical agents.
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