Medical management of incidents with chemical warfare agents
Introduction
After the terrorist attacks of Matsumoto (1994), Tokyo (1995) and of September 11th, 2001 with the subsequent anthrax letters there is an increased awareness that terrorists might use chemical warfare agents or other very toxic materials in future homicidal attempts. Though prevention and mitigation are in the focus of planning activities, the medical toxicologist must be ready to treat poisoned victims in the case of a chemical incident according to the state of the art.
Some of the diagnostic and therapeutic experiences with chemical warfare agents are based on the outcome of their former use. The devastating effect of chemical warfare agents such as chlorine and mustard gas which even surprised the first users is well-known from World War I (Koch, 1921, Muntsch, 1939). The nerve agents were developed just before the second World War in search of insecticides by Schrader (Schrader, 1950). When they were used by the Iraq Forces during the Iraq–Iran War (1983–1988) nobody had much experience with their effects on humans. Also sulphur mustard claimed many deaths and 100,000 injured (Balali Mood, 1988) in the Iran–Iraq War. In 1995, Japanese terrorists used the nerve agent sarin in two terrorist assaults. The first one happened in Matsumoto (Okudera et al., 1997). The second attack was launched in the subway of Tokyo. More than 5000 persons needed medical care and 12 died (Nozaki et al., 1995, Ohbu et al., 1997).
The mechanism of action of selected chemical warfare agents will be briefly discussed in this paper. Diagnostic and therapeutic options in case of mass poisoning will be considered from the viewpoint of a clinical toxicologist in an emergency poison center.
Section snippets
Management principles of incidents with chemical warfare agents
Management of chemical incidents requires specific knowledge of the toxicants and their biological effects as well as clinical experiences in the diagnosis and treatment of intoxications. Compared to common medical emergencies, the management of chemical incidents is aggravated by requirements of decontamination and personal protection. Stockpiled antidotes and protective equipment must be immediately available (Table 1).
In the initial phase of a chemical mass casualty, the identity of the
Groups of chemical warfare agents
Chemical warfare agents include nerve agents, blister agents, blood agents and lung agents. Blister agents include sulphur mustard and nitrogen mustard. Nerve agents include tabun (GA), sarin (GB), soman (GD) and VX. Blood agents are hydrogen cyanide (AC) and cyanogen chloride (CK). Lung agents include phosgene and diphosgene (Helm and Weger, 1980).
General
The term blister agents seems to be very euphemistic and describes only one of the visible symptoms of a potentially systemic poisoning. Many other organs are damaged not just the skin. Organs with proliferating epithelia like eyes, lungs and the bone marrow may be severely damaged. Death ensues either due to bronchial obstruction, bronchopneumonia or bone marrow aplasia (Zilker and Felgenhauer, 2002). The blistering agent sulphur mustard has the highest military significance in the group. It
General
Nerve agents belong to the group of phosphororganic (OP) cholinesterase inhibitors, with some prominent of these compounds first synthesized by German chemists in the 1930s (Baselt, 2002). Their basic chemical structure which they all have in common, is described by the Schrader formula (Abou-Donia, 1995).
The structural diversity of OPs is due to different substituents at the phosphorus atom. R1 and R2 are alkyl-, alkoxy-, alkylthio- or amino-groups and X is a labile acyl residue (halide-,
General
The devastating action of cyanide gas has been dug into the memory of mankind by the inhuman use of it for the genocide of the Jewish people by the Nazis. As a matter of fact cyanide was used during WW I under the name of Vincennite as warfare agent (Paulet, 1962). Hydrogen cyanide gas has a high vapour pressure and low molecular weight which means that deadly concentrations in the open air are difficult to achieve. Nevertheless, a terrorist attack inside buildings cannot be excluded and could
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