BY FRANK L. FIRE
Blood agents are chemical warfare agents (CWA) that interfere with the ability of the bloodstream to transport oxygen to all the body’s cells (blood asphyxiants) or that make the cells unable to use the oxygen (tissue asphyxiants). Blood asphyxiants combine with the red blood cells and make them incapable of combining with oxygen and, thereby, of carrying the oxygen to the body’s cells. After breathing, the normal process is for oxygen to form a compound in the red blood cell called oxyhemoglobin. This weak chemical compound serves as the vehicle for carrying oxygen to the cells, where it is released to the cell; the carbon dioxide released by the cell is picked up and brought back to the lungs for disposal. Anything that prevents the formation of oxyhemoglobin is a blood asphyxiant. Carbon monoxide is by far the most common blood asphyxiant.
Some blood agents work by killing the red blood cells, thus shutting off the flow of oxygen to the cells. In this manner, they differ from carbon monoxide and the other blood asphyxiants.
The red blood cells carry tissue asphyxiants to the body’s cells. The asphyxiants are given to the cells in exchange for the carbon dioxide they hold. The cells are poisoned and cannot ever again accept oxygen from the red blood cells. Unlike carbon monoxide, which attaches itself to the red blood cell so tightly that it will not let go and renders the red blood cell incapable of picking up oxygen, the tissue asphyxiant allows itself to be “dumped” to the receiving body cell just as oxygen does. The most common tissue asphyxiants are hydrogen cyanide (AC), cyanogen, and cyanogen chloride (CK).
DESCRIPTION
Cyanogen chloride is a corrosive, colorless gas (at low temperatures, it is a clear, colorless liquid) with an irritating, pungent odor, sometimes described as “biting” or “pepper-like.” It dissolves slowly in water, reacting with it to form hydrogen chloride gas. Its molecular formula is CNCl, resulting in a molecular weight of 61.47, which translates to a vapor density of 2.12. This means it will sink in air, collecting in low spots and confined areas. As a liquid, its density is 1.19, which means it will slowly sink in water as it dissolves and reacts.
It boils at 13.8°C (56.84°F) and freezes at 6.0°C (21.2°F). This indicates that the liquid is volatile and will evaporate rapidly when it contacts water in the open. Cyanogen chloride has the additional hazard of being able to polymerize, usually explosively.
Cyanogen chloride is a simple molecule, an inorganic compound that is nonflammable. The presence of cyanide in the compound is what makes it severely toxic. It causes immediate injury on contact with the eyes or respiratory organs. It is highly toxic by inhalation, ingestion, skin absorption, and entry through a wound or by injection. It will also pass through certain filters in some respiratory protection devices.
Synonyms and identification codes include the following: carbononitridic chloride, chlorine cyanide, chlorocyan, chlorocyanide, chlorocyanogen, chloroformnonitrile, cyanic chloride, cyanochloride, CK, cyanogen chloride, and UN 1589. Its CAS number is 506-77-4; its Standard Transportation Commodity Code (STCC) number is GT2275000.
Cyanogen chloride is listed in schedule 3 of the Chemical Weapons Convention: All production must be reported to the United Nations’ Organization for the Prohibition of Chemical Weapons (OPCW). It is used in several manufacturing operations to make a variety of products, including certain herbicides and as a cleaner of some metals. It is also used in mining. A deliberate use of one of its hazards is as a warning agent in fumigants, where its tendency to cause irritation at low concentrations is used to warn workers that certain hazardous materials that might be less noticeable are present. It is also used as an industrial fumigant. It is usually shipped as a liquefied gas, labeled 2.3, Toxic Gas, and 8, Corrosive Substance.
The U.S. Army tested cyanogen chloride during World War II for use as a chemical weapon. There is no record of its being used during any American combat operations. France may have used it in World War I, replacing hydrogen cyanide, which is more toxic but has a lower vapor density.
However, the U.S. Army had tested cyanogen chloride as a chemical weapon for possible use in World War II. Since cyanogen chloride could penetrate the standard-issue Japanese Army gas masks, it was seriously considered for use in the Pacific theater. Areas where the tests were carried out (San Jose Island in Panama is at least one known site) apparently still have unexploded munitions loaded with cyanogen chloride lying about. Cyanogen chloride and other chemical weapons may still be extremely dangerous if humans come in contact with old containers (or bombs or shells), which are probably leaking.
DELIVERY OF THE AGENT
A chemical warfare agent is useful only if it can be delivered to the geographic area on the battlefield where it will do the most harm. It must be able to be stored, handled, moved, and delivered without harming the user but causing maximum harm to the target. To be effective, the chemicals must have certain tactical specifications. They must be able to be stored safely for a long time and moved long distances without losing their effectiveness. Atmospheric or weather conditions or the method by which it is dispersed must not adversely affect the chemical when delivered on the battlefield. A toxic chemical must not be so toxic or so difficult to handle that it presents an unreasonable risk to those administering it. On the battlefield, it must be able to be directed toward the target and away from the user.
Cyanogen chloride fails some of these specifications, which makes it less desirable for use as a chemical weapon. Since it is a gas, a strong breeze can disperse it easily. Its vapor density is more than twice that of air but nowhere near that of tabun (5.6), a deadly nerve agent. Cyanogen chloride can be absorbed readily through the skin and may cause certain types of gas masks to fail. This means that if the wind direction changes, the users of the gas may have it redirected toward them, indicating that they will have to be heavily protected. Cyanogen chloride also may polymerize explosively, exposing the handlers to additional dangers.
However, we must remember that, with just a few exceptions, CWAs are not being used on traditional battlefields. They are the weapons of choice for terrorists who are intent on disrupting the daily lives of the target population, instilling fear and terror into everyone and coincidentally killing as many people as possible. Cyanogen chloride would be an effective chemical weapon if used in closed-in places (buildings; subways; bus, train, and airport terminals; underground shopping areas; tunnels; theaters; and other large entertainment and sporting venues)even outdoors in urban areas where the wind might be impeded by large buildings. Even if only a few contacted the deadly gas, the panic instilled in a crowd could cause many more times the casualties than the gas itself.
Cyanogen chloride may be delivered to the target area in many ways. It probably would not be delivered in the form of a bomb, because its gas would be too widely dispersed on detonation of the device (liquids would be more controllable than gases or vapors in their dispersion pattern).
Since cyanogen chloride dissolves slowly in water while reacting with it to form hydrogen chloride, it is likely that water solutions could be used to deliver the toxic gas. It could also be introduced into a community’s water supply to spread the danger much farther.
Containers of the compressed gas could be smuggled into the target area and hidden. The gas could be released manually or with a timing device. It would not be unusual to have an unprotected person release the gas manually in a crowded scenario, since most terrorists are willing to die for their “cause.” A person with a canister of the gas hidden on his person could release the gas in the most crowded situation available.
First responders must take extraordinary precautions in responding to chemical weapon attacks. With “normal” hazardous materials incidents, mitigating the particular incident at hand is the major hazard to first responders. After protection of the public, the incident commander will decide what the degree of responder involvement should be and which methods should be used and end with decontamination procedures. Although this is also true in the case of chemical weapons attacks, there is an added, perhaps even more deadly dangerthe terrorists may have a second attack planned especially for the emergency responders. The attack might be in the form of booby traps or a second direct attack with more chemical weapons.
SYMPTOMS OF CYANOGEN CHLORIDE POISONING
As in the case of exposure to any toxic material, symptoms alone are not usually specific enough to allow definitive diagnosis. And, as always, symptoms depend on the degree of intoxication produced by the concentration of the toxicant, the time of exposure, the amount that has entered the body, the method of entry into the body, and the degree of the individual’s sensitivity, plus the degree of medical attention and the time lapse between exposure and treatment or removal from the chemical.
In the case of cyanogen chloride, symptoms may include (not necessarily in this order) tearing of the eyes, a runny nose, a headache, anxiety, vertigo, excessive secretion from bronchial mucous membranes, nausea, vomiting, abnormally slow breathing, abnormally rapid breathing, a temporary cessation of breathing, a slow heart rate, cyanosis, convulsions, and cardiac arrest.
The onset of the symptoms is usually rapid. You may observe the effects on the victims of inhalation of lethal amounts in as quickly as 15 seconds. Death may occur in less than 10 minutes. Suspect cyanogen chloride in any terrorist attack involving prompt fatalities, especially when nerve agents have been ruled out.
IDENTIFICATION
It is difficult to identify the particular agent released. Certain signs that can point to members of the cyanide family (hydrogen cyanide, cyanogen chloride) as opposed to nerve agents, blister agents, and choking agents. Most responders are familiar with cyanide poisoning and can differentiate it from nerve gas poisoning. The use of blister agents and choking agents will produce a considerable difference in victims’ reactions than the poisons. Cyanosis and the odor of bitter almonds are the first signs that a cyanide compound has been used.
DETECTION
Several devices may be used to detect the presence of cyanogen chloride. They include the M-256A1 Detector Kit and the ICAD Miniature Chemical Agent Detector. There are also specialized gas chromatographs (minicams) and spectrometers that will detect the presence of cyanogen chloride. The technology for CWA detection is moving so rapidly that all responder organizations must educate themselves on the availability of devices and seek proper training in their use. Some instruments may have limitations, and detection may be possible only under ideal circumstances.
The toxicity of many CWA is so great that there may be little time to test for them. Responders responsible for the testing must wear the proper protective equipment for each agent being tested. The problem with detection of small to medium amounts of cyanogen chloride is that the initial effects of nonlethal amounts often mimic those of riot-control or tear-gas agents. Irritation of the eyes and mucous membranes, runny nose, and other similar symptoms may cause a misidentification of the cyanide compound and prevent the proper safeguards from being implemented at the proper time.
TOXICITY
Cyanogen chloride is fast acting (though not as fast as hydrogen cyanide) and very toxic by inhalation. High concentrations can kill rapidly, and the success of any rescue attempt depends on the speed at which the victim can be removed from the gas or vapor and the time between exposure and administration of oxygen and the antidotes. Exposure to low concentrations could cause delayed reactions.
Cyanogen chloride has a threshold limit value (TLV) of 0.3 parts per million (ppm). The TLV is defined as the average (weighted over time) maximum amount of gas, vapor, dust, or fumes to which a person may be exposed for eight hours a day, five days a week, without harm. This, of course, is set for workers engaged in industries that use cyanogen chloride as a raw material and is done for their protection.
At 1 ppm, the corrosive properties of cyanogen chloride appear, and it becomes very irritating to the eyes. It becomes hazardous to the eyes at 4.3 ppm; at about 20 ppm, it becomes intolerable to anyone without protection. It also has an LC50 of 430 ppm. LC50 is defined as the amount of gases, vapors, fumes, dusts, and other particulates in the air that will cause death to half the test animals exposed to the material within a specified time.
Using a different set of measurements, it has an LCt50 of 11,000 milligrams-minute per cubic meter of air. LCt50 is defined as the measure of exposure that results in the death of 50 percent of the population exposed, taking into account the concentration of the poison and the amount of time a person is exposed to it. This is simply a comparison measurement and doesn’t consider the amount required to kill the first victim, or 49 percent of the people exposed. Using this measurement, cyanogen chloride is one-third to one-fourth as poisonous as hydrogen cyanide. However, remember, it is still a deadly weapon.
Cyanogen chloride is classified as non-persistent, which means that any amount released will evaporate within a 24-hour period.
ANTIDOTES
As in the case of any exposure to toxic materials, the victim must be removed from the area of concentration of the poison and thoroughly decontaminated while a suitable antidote is prepared.
Treatment for cyanide poisoning may be effective if administered a short time after exposure. Qualified medical personnel following their training and the instructions in the cyanide antidote kit should administer it. The antidotes include amyl nitrite ampoules, sodium nitrite, and sodium thiosulfate infused intravenously; they are usually packaged in a cyanide antidote kit. The amyl nitrite ampoules are broken onto a gauze pad and held under the victim’s nose, per instructions. Oxygen should also be administered.
If the patient does not respond to the amyl nitrite and oxygen, a sodium nitrite solution is infused intravenously while monitoring the victim’s blood pressure. Then, a sodium thiosulfate solution is infused intravenously. If there is not an adequate response, the process is repeated after 30 minutes (with reduced dosage).
The purpose of the nitrite is to cause the formation of a different form of hemoglobin, which then “pulls” the cyanide from the poisoned cell so that it can return to its original state and function. The thiosulfate forms a new compound with the cyanide in the cell, thus neutralizing it and rendering it inactive.
PREVENTION
Obviously, in a terrorist attack against the public, the targeted population will not be equipped with the proper respiratory and skin protection, but the first responders must be. Wear proper SCBA to protect the respiratory system against cyanide poisoning and impervious total encapsulating suits. Ingestion is not considered a hazard, but cyanide gas or vapors are absorbed readily through the skin. Exercise care when handling victims so contamination is not spread.
FRANK L. FIRE has worked for 40 years in the plastics industry and retired as executive vice president of sales, marketing, and international from Americhem, Inc., Cuyahoga Falls, Ohio, a provider of raw materials to thermoplastics processors. He has taught “Chemistry of Hazardous Materials” to firefighters and other emergency responders for 32 years in the Fire Protection Technology program at the University of Akron (OH); Stark State College; the National Fire Academy in Emmitsburg, Maryland; and, most recently, to civil support teams of the National Guard in Missouri and Minnesota. He has a B.S. degree in chemistry and an M.B.A. degree from the University of Akron. He is the author of The Common Sense Approach to Hazardous Materials, The Common Sense Dictionary for Emergency Responders, A Study Guide to the Common Sense Approach to Hazardous Materials, Combustibility of Plastics, and Chemical Data Notebook: A User’s Manual and a co-author of SARA, Title III: Intent and Implementation of Hazardous Materials Regulations. He has written more than 120 articles on individual hazardous materials for Fire Engineering.
