Sodium Chloride (table salt) is found in seawater and natural deposits, Sodium Chloride constitutes approximately 2% of the earth’s surface. Chlorine gas is generated by the electrolysis of aqueous sodium chloride. Chlorine gas is a noncombustible pale yellow-green, gas with a pungent, irritating odor. Chlorine is one of the ten most produced chemicals in the United States by weight. Chlorine gas is heavier than air and is categorized as a “choking agent”. Chlorine is a strong oxidizing agent and can react explosively or form explosive compounds with many other common materials. Chlorine is slightly soluble in water, but increases chlorine’s oxidizing and corrosive effects through the formation hypochlorous acid (HClO) and hydrochloric acid (HCl).
Chlorine has many applications: disinfectant (drinking water treatment facilities, wastewater purification systems, and swimming pools,); bleaching agents (paper and cloth); construction materials (polyvinyl chloride, or PVCs), computer silicon chips; pharmaceutical compounds (Singulair, Plavix, and Norvasc). Chlorine’s used widely as a chemical reagent in the synthesis and manufacture of metallic chlorides, chlorinated solvents, pesticides, polymers, synthetic rubbers, and refrigerants.
Use of Chlorine as a weapon was considered during the U.S. Civil War. The first documented use is April 22, 1915 during First World War, wherein Chlorine had a psychological shock effect, but proved to have limited military effectiveness due to changes in wind patterns available PPE for soldiers. Consequently, the use of Chlorine was abandoned in preference to other more effective chemicals (e.g. phosgene and mustard gas)
. The international legal community moved to outlaw the use of chemical weapons.
On January 28, 2007 Iraqi insurgent suicide bombers killed 16 people by detonating a truckload of explosives and a chlorine tank in the town of Ramadi in the al-Anbar province. Since then, insurgents have used vehicle borne IEDs containing chlorine on multiple occasions. Iraqi tactic changes demonstrate their flexibility and ability to adopt tactics that are successful. While these attacks have caused deaths, it is the explosion and not the chlorine that has proved to be lethal. Regardless, the efficacy of these attacks has increased as dispersion methods are improved.
Terrorist Advantages of Using Chemical Agents as WMDs
• They are relatively inexpensive to produce.
• The components are often cheap and easily accessible.
• They are easy to use.
• There are multiple means of delivery.
• The fear factor. They can have a psychological as well as physical impact, causing pain for the victims and panic for the survivors.
• Chlorine does not need to be chemically synthesized (given its abundance), and as a gas does not require active aerosolization for efficient dispersal.
• A large release of chlorine may inflict mass casualties on unprepared civilians.
Terrorist Disadvantages of Using Chemical Agents as WMDs
• There can be unpredictable consequences.
• A terrorist group might not be able to effectively use them without causing harm to themselves.
• There are often unpredictable effects.
• Environmental conditions may cause the chemical agent to dissipate making it difficult to deliver a lethal dose.
• chlorine is not nearly as potent a toxin as other chemical weapons used in terrorist attacks,
• Relatively biological weapons require substantial finances, advanced equipment, appropriate chemical precursors, and personnel with specialized training in synthetic organic chemistry to prepare.
Meanwhile the US is examining its chemical infrastructure for vulnerabilities. It is believed that a deliberate release of 60,000 gallons of liquefied Chlorine in a highly populated area might result in between 10,000 and 17,500 deaths. The EPA estimates that there are approximately 15,000 facilities and 2,000 water systems in the US that which store more than the threshold quantities of hazardous chemicals necessary to trigger EPA regulation.
Chlorine, like all commodities, must be transported to market. It is estimated that approximately 12 million tons of is manufacture annually in the United States. Of which 90 ton pressurized railroad tankers move 3 million tons. Rail tankers are cost effective for large shipments. Railroad infrastructure (including trains, tracks, and stations) includes 171,000 miles of track. This provides a large window of vulnerability as there is no reasonable way to secure the entire US rail system.
Rubber or plastic PPE is effective dermal protection against Chlorine. APRs or PAPRs with appropriate cartridges or preferably SCBA or should be used by rescuers.
Risk for dermal absorption and ingestion is not high because Chlorine converts to a gas at room temperature. However, solutions such as sodium hypochlorite that can generate chlorine are corrosive and will damage skin and GI tract. Chlorine can also be converted to hypochlorous acid, which penetrates cells and reacts with cytoplasmic proteins which result in the destruction of cellular structures. Symptoms may be immediate or delayed. Victims should first be removed from the hot zone and then decontaminated by first removing all clothing, followed by flushing all skin, hair and eyes for 15 minutes or more and then washed with soap and water.
Because the pediatric population is closer to the ground (Chlorine is heavier than air), their airways are smaller (more surface area per ml of air), their increased minute ventilation is higher, and greater lung surface area to body weight ratio, in addition to their relative inability to self evacuate or self decontaminate they are more at risk than adults.
Because chlorine is water soluble, exposure to the gas irritates the mucous membranes and eyes at concentrations of less than 3 ppm. Moderate irritation of the upper respiratory tract occurs at 5-15 ppm, followed by chest pain, vomiting, and dyspnea at 30 ppm. Above 50 ppm, lung inflammation causes pulmonary edema followed by organ damage, and death secondary to cardiovascular collapse from lack of oxygen. Insufficient tissue oxygenation can produce acidosis. Chlorine is deadly at concentrations of several hundred ppm or higher. The IDLH for chlorine is 10 ppm. A 30 minute exposure at 430 ppm is lethal. Concentrations of 1000 ppm can be fatal within minutes.
There is no treatment for Chlorine exposures. Like many hazardous chemicals treatment is directed at supporting the ABCs.
The vulnerability of the transportation system and the potential effects that even a small release would have on the physical and psychological aspects of individuals and society suggest that education of the public should be done. This education should be directed at increasing awareness regarding appropriate courses of action (e.g. shelter in place) in the case of a chlorine release should be organized.
Chemical Terrorism Fact Sheet: Chlorine Chemical Overview; September 2002; Saint Louis University School of Public Health; https://erplan.net/WMD/ChemFiles/Links/ChemicalAgents/FactSheets/ChlorineFS.pdf
Richard Weitz; CHLORINE AS A TERRORIST WEAPON IN IRAQ; Hudson Institute, Ibrahim Al-Marashi – Koc University, and Khalid Hilal – Monterey Institute Center for Nonproliferation Studies; http://www.wmdinsights.com/I15/I15_ME1_Chlorine.htm
Benjamin H. Brodsky; Industrial Chemicals as Weapons: Chlorine; The James Martin Center for Nonproliferation Studies; July 31, 2007; http://www.nti.org/e_research/e3_89.html
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