Chemical terrorism is typically described as a “high probability” event. This classification reflects the fact that chemicals potentially useful in an attack are readily available in quantity, and that the world’s population includes significant numbers of individuals with chemical training. A Monterey Institute study of international terrorist incidents involving chemical, biological, radiological or nuclear agents over a 20 year period confirms this classification; more than half of the incidents or attempts involved chemical agents.
Chemical terrorists have a large and diverse group of agents to choose from. Toxic industrial chemicals represent one class of agents usable in a terrorist attack. More than 6,000,000 distinct chemicals have been described in the scientific literature; about 90,000 are available for sale or are in use, and about 3,000 have been made in quantities exceeding 1,000,000 pounds.
The U.S. Department of Transportation classifies 3,000 chemicals as hazardous, and the U.S. Occupational Safety and Hygiene Administration enforces workplace exposure limits on about 600 chemicals. A terrorist could launch an effective attack using literally thousands of toxic industrial chemicals shipped freely by highway or railway, or stored in quantity at chemical and manufacturing plants.
There is some overlap between these two categories. During WWI, industrial chemicals such as chlorine and phosgene were used effectively in the battlefield. However, beginning with the WWII era, these chemicals were supplanted for military purposes by typically much more potent chemicals whose properties were optimized to kill or disable. It is believed that nations selected only a dozen or so chemical warfare agents for mass production. However, a knowledgeable chemist could easily “design” structural analogs of the mass produced agents that would have similar properties and toxicity. This makes illicit preparation of chemical warfare agent–like compounds more difficult to prevent, and complicates the analytical laboratory’s efforts to identify the agent used in an attack.
Though this is a debatable question, most observers believe use of a toxic industrial chemical is the more probable scenario. These chemicals are readily available in quantity – perhaps by hijacking a tanker truck, by detonating a railway car in a populated area, or by releasing a chemical from a storage tank at a plant located near a city. Conversely, chemical warfare agents (or even their immediate precursors) are very difficult to obtain and are hazardous for the terrorist to work with. Their main advantage may be that an effective attack might be launched with a much smaller amount of material (e.g., for an indoor attack, a thermos bottle instead of a tank car). This lends itself to a surreptitious attack (allowing the perpetrator to escape, and potentially allowing long-term exposure to unwitting victims if the agent is slow acting) and to a targeted attack. It may also be true that such an attack would produce greater “terror” in the civilian population than use of a more familiar chemical.
If the discussion is confined to politically motivated terrorist attacks, actual events using chemicals are rare. The impact of an accidental release of the chemical intermediate methyl isocyanate in Bhopal, India in 1984 provides an instructive example. The events leading up to the chemical release remain controversial; one plausible hypothesis is that a disgruntled worker ran a water hose from a nearby tap into a 40,000 gallon tank containing the chemical. The resulting reaction produced sufficient heat to vaporize the toxic chemical, resulting in exposure of about 500,000 individuals, long–term disability of about 11,000 and death of 3,800.
The Aum Shinrikyo cult launched several more-or-less successful attacks using the home-made nerve agent sarin. The best known event was the 1995 “Tokyo Subway Incident” in which three teams each placed a plastic bag containing low purity sarin on the floors of subway cars, then punctured them with an umbrella. The attack was moderately successful, resulting in 12 deaths and about 5,000 panicked visitors to hospital emergency rooms (mostly the “worried well”). The casualty count was limited by the purity of the sarin and the ineffective plan to vaporize it. Sarin, a liquid, was only slowly vaporized from the subway floor.
The laboratory will be called upon to test environmental samples (air, water, wipes, powders, etc.). Environmental samples will be used to identify the agent, to define the contamination zone, to test whether decontamination of individuals and areas is being effectively performed, and to verify that conditions are safe for re-entry.
The laboratory also will process human specimens (e.g., blood, urine). Identification of the agent or its metabolite in the human specimen will confirm any environmental data. Additionally, since many agents dissipate rapidly or are highly reactive, and sample collection may not be a high priority immediately after an attack, these specimens may provide the only identification of the agent.
Since the clinical specimens can give a direct measurement of an individual’s exposure, these specimens may assist in medical treatment. However, the time delays associated with specimen collection, transport, and testing mean that the data only will become available days after the incident. These data will also assist in separating the exposed from the “worried well”, who may unnecessarily consume scarce medical resources. Finally, since the human data will be relatable to individuals, it will strongly support epidemiologic studies to establish the long-term health effects of these exposures.
Wadsworth currently has an extensive program requiring testing of air, soil, water, etc. for toxic industrial chemicals potentially impacting the health of New York citizens, and is therefore well-prepared to respond to an incident involving industrial chemicals. Since international treaties essentially preclude work with chemical warfare agents, Wadsworth, and virtually all non-federal laboratories are less well prepared to test for these chemicals in environmental samples. Wadsworth is, however, able to analyze human specimens for metabolites of chemical warfare agents. Wadsworth is one of five state public health laboratories competitively chosen by the Centers for Disease Control and Prevention to develop this capacity in order to meet in-state response needs and to serve as surge capacity in case of an incident that overwhelms CDC’s Atlanta laboratory, or an incident which disables their facility.
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