Modes of Release of Chemical and Biological Warfare Agents

Chemical Agent Release

Military Release

In warfare, the release of CBW agents is a deliberate action achieved by the use of shells or missiles or through spraying ( Table 64-3 ). Aerosol release is the essential technique that allows attack through the respiratory route, but for more persistent agents that are designed to deny terrain, the use of spray devices is more common. By the end of World War I, chemical warfare agents were almost exclusively delivered by means of explosive shells, and by the end of the war, 40% of the fills were chemical, indicating the effectiveness of chemical warfare agents on the battlefield. The rise of aerial bombardment before World War II brought great fears that cities would be wiped out by gas attacks, but these fears were never substantiated, and it is now realized that dissemination of chemical warfare agents over a wide area (rather than a limited tactical area) by explosion is not easy. During the Cold War, the Russians developed considerable expertise in the use of BM21/24 multiple rocket launchers (Stalin Organs), which could deliver a high concentration of nonpersistent agents such as hydrogen cyanide during a short period and then allow dispersal and the entry of unprotected troops. Missiles such as the Scud were developed for chemical weapon release at this time, and it was feared that they had been developed for use by Iraq before the Gulf War of 1991.

In the military context, release of toxic agents may be revealed or concealed. Attack by whatever means is usually predicted and detectable with the considerable resources that the military can bring to bear in this area for chemical and biological agents. Tuned detection systems are

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Release on a Civilian Population

Toxic agent release on a civilian population is usually accidental and is usually revealed by the circumstances of the accident. Road and other transportation accidents, particularly when vehicles carrying HAZMAT plates are involved, gives an immediate warning about the nature of the problem.^[19] Despite this, accidental releases, particularly in nations with poor emergency response resources, can be catastrophic, as in the case of the mass release of methyl isocyanate in the Indian city of Bhopal in 1984, which caused more than 5000 deaths and 50,000 casualties.^[26] Civilian populations, unlike their military counterparts, are usually untrained and unprotected against toxic agents release. The panic induced by the fear of the actions of

TABLE 64-4 -- Detection and monitoring

Detection of a chemical or biological warfare agent means identifying its presence in a contaminated environment.

Monitoring is a process by which contamination on an exposed patient is detected.

Detection Techniques

Agent-specific chemistry

Generic chemical detection techniques

Mass spectrography

Ion current devices

Bioluminescence

Microbial techniques

Chemical-pathologic studies of an affected patient after the attack

Internal versus external detection

CBW agents compounds the flexibility of the emergency medical response.

Biological Warfare Agent Release

The deliberate release of classic biologic warfare agents such as bacteria or viruses may not be as easy as the media have led the public to believe. Effective mass release implies aerosol release, and very few biological warfare agents are capable of withstanding the environmental stresses involved. Some, such as anthrax spores, have long been recognized as being sufficiently robust and have therefore attracted the most research attention. The only other bacteria that have probably been used as biological warfare agents are Tularemia, spread through infected fodder, and Yersinia (plague), which was said to have been used by the Japanese during World War II in their campaign against China and where the vector used was the traditional one of the rat-borne flea.^[13] Considerable research work was carried out by the Soviet Union during the Cold War to try to find new ways of delivering biological agents and for their modification using genetic engineering.^[15] This work also developed agents of biologic origin that lie in the middle of the CBW spectrum and that produce subtle pathophysiologic effects and are difficult to detect postmortem in the body. In military terms, biological warfare has always been seen as a debilitating weapon, self-promulgating and of long latency, which could be used to degrade the capability of static enemy formations or key formations operating behind front lines, such as airfields. In the civilian context, the potential use by terrorists has yet to be established, but the current rationale is to cause "terror" in populations in developed countries, where mass epidemics are usually rare.