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Chemical terrorism

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Revision as of 06:01, 18 March 2007 by T. Mark Ellis (Talk | contribs) (The selection of chemical weapons)

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Chemical terrorism is the form of terrorism that uses the toxic effects of chemicals to kill, injure, or otherwise adversely affect the interests of its targets.


While there may be controversy about the definition of the politically-charged word "terrorism," the tactics and technology of chemical terrorism are clearly distinguished from those of other forms of chemical warfare. Chemical terrorism is asymmetric warfare as practiced by non-uniformed forces using light and/or improvised weapons against non-combatant targets. It is therefore unlike the symmetric warfare of the First World War, in which dug-in troops fired poison-filled artillery shells at each other across a wire-bounded no-man's-land. It is also distinct from the asymmetric "terror from above" that uses uniformed military personnel and such military delivery systems as bombs, missiles, and artillery shells to terrorize civilian populations.

Chemical terrorism is also qualitatively different from biological terrorism involving infectious diseases, but quite similar to the covert employment of biologically-produced toxins, which differ from synthetic poisons mainly in their extreme potency and the means by which they are produced.

There have been few documented acts of chemical terrorism, and none of those has caused casualties justifying the treatment of chemical weapons as "Weapons of Mass Destruction." However, there has been much discussion and some serious study of the possibility of chemical terrorism. One of the stated concerns leading to the 2003 invasion of Iraq was the possibility that chemical weapons technology developed and used by Iraq could be transferred to terrorist organizations.


The main issue in chemical warfare, for high-tech state-funded military users as well as for non-traditional forces, is distributing the material efficiently in the target area. In most chemical warfare scenarios, much or most of the toxic agent will be destroyed by explosive dispersal devices, delivered in massive overkill quantities to a few victims, and/or broadcast into areas where no potential victims exist. Toxic agents that do not find victims immediately on delivery may degrade spontaneously, or be deactivated or sequestered by decontamination teams.

It is rarely reasonable to think of chemical weapons as weapons of mass destruction in the sense of even the Hiroshima and Nagasaki bombs. Realistic chemical attacks will be on a smaller scale, but a campaign of such attacks could be extremely disruptive. On the other hand, chemical weapons can be weapons of mass terror, because people in a target area - or simply in what they perceive to be a target area or potential target area - will not know whether or not they've been poisoned.

Methods used by terrorists or hypothesized by analysts include:

  • Contamination of reservoirs and urban water supply systems.
  • Contamination of food, beverages, drugs, or cosmetics in manufacturing or distribution processes.
  • Contamination of food or beverages near the point of consumption.
  • Miscellaneous product contaminations: stamps/envelopes, IV fluids, etc.
  • Release of gases or aerosols into building HVAC systems.
  • Release of gases or aerosols from aircraft.
  • Dispersal in bombs or projectiles.
  • Miscellaneous direct methods: hand sprayers, water guns, parcels.
  • Release of industrial/agricultural chemicals via attacks on production or storage facilities.
  • Release of industrial/agricultural chemicals via attacks on truck, rail, or barge shipping.
  • Miscellaneous releases of industrial/agricultural chemicals, especially anhydrous ammonia, fumigants and pesticides, and disinfectant gases (e.g., chlorine, chlorine dioxide, ethylene oxide).

The selection of chemical weapons

Military "nerve gases" are selected for their extreme toxicity, and are produced in quantity only for use as weapons. The LD50s of these compounds (lethal dose for 50% of exposed humans) are expressed in micrograms of poison per kilogram of victim body weight, making them more toxic by orders of magnitude than even the most dangerous industrial materials. The compounds Tabun and Sarin were developed - but never used - by Nazi Germany, and have since been manufactured and stockpiled by the United States, the Soviet Union, and numerous other countries. More potent compounds, most notably VX and the other V-series compounds, have been developed and weaponized more recently.

The choice of toxic agents for use in the improvised weapons of asymmetric warfare is constrained by the availability of usable poisons. This is obviously true in the selection of sabotage targets from which existing stocks of hazardous materials can be released, but it is also true in general: without a state sponsor, or the ability to steal from military arsenals, or the sort of heroic efforts made by the Aum Shinrikyo cult to synthesize its own Sarin, military-style supertoxic weapons must be considered unavailable to non-state organizations.

The most common toxic hazardous materials are chlorine and anhydrous ammonia. While chlorine is normally stored and shipped in very large containers, the use of ammonia in agriculture requires it to be distributed to many more sites in smaller containers. These gases create possibilities for highly disruptive large-scale releases, but will cause few or no fatalities unless victims are trapped in areas where concentrations are high. Recent suicide bombings in Iraq have combined conventional explosives with chlorine tanks; while this technique hasn't produced exceptionally high death tolls, it causes increased chaos and can be expected to drive all unprotected survivors away from the scene of an attack.

Some pesticides share characteristics with military chemical agents. Tabun was originally developed in a German search for new pesticides, and Amiton, the earliest V-series agent, was actually brought to market as a pesticide by a British company. Manufacturing technology and raw materials that can be used to make pesticides may also be used to make chemical warfare agents. The most dangerous pesticides have been largely or completely replaced by more selective alternatives that kill pests effectively with less danger to humans. Several highly-toxic "restricted-use" pesticides are still produced and used in very large quantities, and could be hijacked by the truckload. This includes parathion, methyl parathion, and other organophosphorus compounds with LD50s on the order of 10 mg/kg. As alternatives to highly-toxic pesticides become available, the older and more dangerous substances are de-certified for commercial use, and are either dropped entirely or made only for export by the chemical industry. However, some of these are relatively simple compounds that could be made in clandestine labs. For example, TEPP, the first and most dangerous organophosphorus pesticide, though significantly less toxic than Tabun, Sarin, and VX, is nevertheless fast-acting and deadly enough for use in direct attacks on soft targets, and its relatively simple synthesis is described in old patents.

It is to be expected that certain rodenticides would be extremely effective as contaminants, since their normal application requires them to be stable, odorless, and tasteless while possessing high mammalian toxicity. Modern rat and mouse killers meet these criteria without creating extreme hazards for humans. Arsenic, on the other hand, is the classic example of a rat poison that is equally applicable to homicide. Inorganic thallium, barium, and phosphorus compounds might also be used, although some of these will require high concentrations for reliable lethality.

Much more potent than arsenic are two widely-banned rodenticides: sodium fluoroacetate, also known as Compound 1080, and tetramethylenedisulfotetramine, sometimes called TETS or "tetramine." The human LD50 for these substances is on the order of 1 mg/kg, with TETS being perhaps 3-10 times stronger than 1080. No antidote is known for either agent. TETS has been widely discussed as a potential terrorist weapon, having been used in several multi-fatality crimes of private revenge in China, where there exists a black market for illegal TETS-based rat poisons made in secret factories. Very small amounts of Compound 1080 are used legally for predator control in the United States, but several tons per year are made for export by Tull Chemical in Alabama. Because the use of 1080 to kill predators has been very controversial, environmental organizations have stressed its potential as a terrorist weapon in their attempts to have it outlawed completetely.

The Aum Shinrikyo scenario

The Bhopal scenario

Terrorists might seek to engineer something like the 1984 disaster in Bhopal, India, in which thousands of people were killed by a release of about thirty tons of methyl isocyanate. However, this is an extreme worst-case scenario that would be very difficult to recreate in more developed countries. A substance as dangerous as methyl isocyanate should normally be produced as needed rather than stored in the large quantities that remained at the Bhopal plant after the process in which it was used had been shut down. Safety systems had fallen into disrepair, and population density around the plant was very high. A concentration of three parts per million of methyl isocyanate in the air is considered "immediately dangerous to life or health," and a simulation of the Bhopal release suggested that concentrations would have ranged from 10 ppm 5500 meters downwind from the release up to 3000 ppm at 270 meters. Another factor is that methyl isocyanate kills rather slowly and produces long-lasting injuries (which still plague thousands of Bhopal survivors).

Although the possibilities for large-scale chemical accidents obviously creates a need for public information about hazards concealed within privately owned facilities, this information is frequently suppressed, either because the proprietors of dangerous facilities prefer to avoid public notice, or because authorities hope to keep that information out of the hands of terrorists. However, any serious attempt at this kind of terrorism would involve a detailed study of potential targets by people with a good understanding of chemical engineering, making the removal of hazard information from the public domain naive at best.

The Nanjing snack shop scenario

In September 2002, hundreds of people were made ill and several dozen died after eating breakfast at a snack shop in Nanjing, China. The owner of a competing restaurant had poisoned the shop's products with a TETS-based rat poison, apparently because of jealousy of his rival's success.