CHEMICAL DATA NOTEBOOK SERIES #38 SODIUM CYANIDE
HAZARDOUS MATERIALS
SODIUM CYANIDE, chemical formula NaCN, is a toxic, reactive, corrosive, deliquescent, nonflammable white solid (as granules, flakes, or lumps) with a faint odor of almonds. It is used in the electroplating of materials, metal treatment processes, gold and silver extraction, and in the manufacture of dyes, pigments, insecticides, fumigants, and various other chemicals.
PROPERTIES
Sodium cyanide will not burn, but it can he decomposed in a fire and will produce carbon monoxide and a family of gases called the nitrogen oxides. It has a specific gravity of 1.6 and a molecular weight of 49. It melts at 1,040°F, boils at 2,725°F, and is very soluble in water.
HAZARDS
The major hazard of sodium cyanide is its toxicity in its own right. An additional hazard is the reaction into which it enters that produces the deadly gas hydrogen cyanide (HCN).
Sodium cyanide has a TLV-TWA (Threshold Limit Value—Time Weighted Average) of 5 mg/m3 (milligrams per cubic meter of air) as cyanide, its IDLH (Immediately Dangerous to Life and Health) value is 50 mg/m3. It is toxic by all routes of entry, and its LD50 is less than 50 mg/kg (milligrams per kilogram of body weight). Hydrogen cyanide has a TLV-TWA of 10 ppm (parts per million parts of air).
Sodium cyanide can be absorbed through the skin in amounts that can produce fatal results. Contact with the skin can result in itching, discoloration, dermatitis, and caustic burns.
Contact with the eyes can produce severe injury.
Inhalation of the dust in sufficient quantities will cause death in much the same manner of ingestion. Small amounts can cause irritation in the upper respiratory tract.
Very small amounts of sodium cyanide. if ingested, can cause death. There may or may not be prior symptoms of poisoning, depending on whether the victim has any other food in his stomach. Those symptoms include weakness, dizziness, headaches, vomiting, convulsions, and coma.
Although sodium cyanide is a stable chemical and dissolves rather rapidly in water, it will, if exposed to moisture or small amounts of water, liberate small amounts of hydrogen cyanide gas. If the water is at all acidic—even slightly — hydrogen cyanide will be liberated in large quantities.
It is well known (or should be) that hydrogen cyanide is deadly. As a matter of fact, the original gas chambers used to execute persons convicted of capital crimes were permeated with sodium cyanide and an acid, usually sulfuric. One pellet (perhaps half the size of a small hen’s egg) of sodium cyanide was placed in each of two tubes that led to a glass container partially filled with sulfuric acid. When a lever was moved, the sodium cyanide pellets rolled down the tubes to the container of acid, and the reaction was immediate. Hydrogen cyanide was generated immediately and the chamber (an enclosed room) rapidly filled with the deadly gas. Only a few short “whiffs” of hydrogen cyanide are required to begin the convulsions, and death is fairly rapid. Even if the condemned peson could hold his breath (or wore a self-contained breathing apparatus), the hydrogen cyanide would he absorbed through the skin and death would still occur within 10 minutes.
SODIUM CYANIDE
Sodium cyanide will react violently (explosively) with any strong oxidizing agent. Other reactions will occur with other chemicals, and they may produce potentially poisonous substances. During transportation and storage, sodium cyanide should be kept cool and dry, and contact with the material must be avoided. Contamination with oxidizers such as inorganic nitrates, nitrites, perchlorates, chlorates, chlorites, hypochlorites, and permanganates must be avoided, in addition to nitric acid, chromic acid, perchloric acid, the halogens (fluorine, chlorine, bromine, and iodine), and any peroxide, organic or inorganic.
GLOSSARY
TLV-TWA—The amount of material, usually expressed in ppm or mg/m3, to which a person may be exposed for 40 hours per week with no adverse effects.
IDLH—The amount of a material, usually expressed as ppm or mg/m’, that will pose an immediate life or health-threatening situation to the exposed person.
LD50—The amount of material, usually expressed as nig/kg, that will cause death in half the test animals to which the material was administered (usually fed) during the test period, usually 14 days.
MSDS—Material Safety Data Sheet. A variable form that must contain certain information about a substance. It must be provided by all manufacturers, distributors, and importers of hazardous chemicals (as defined by the OSHA Hazard Communication Standard) to all nonretail users of the substance.
SARA—Superfund Amendments and Reauthorization Act of 1986.
Title HI—A section of SARA known as the Emergency Planning and Community Right-to-Know Act.
NONFIRE SPILL
Any spill of sodium cyanide will result in a powder, pellet, or granulated material being released. In all spills and accidental releases, the proper environmental authorities must be notified while action is being taken to protect the populaton.
If the sodium cyanide is dusty, evacuation downwind must be considered immediately. However, if the product is in a size that would not be blown around, there is no danger of the spread of contamination. No action should be taken other than securing the area of the spill and keeping all personnel away from the material. The seller, the shipper, and the consignee (the company to whom the material is being shipped) must be notified immediately of the spill so they can begin salvage and cleanup activities.
At no time should it be necessary for emergency response personnel to get involved in the cleanup. If for some reason it does become necessary for firefighters and/or other emergency response personnel to actually handle the product, they must remember that they are dealing with a deadly poison and protect themselves accordingly.
(It has been pointed out many times in this series that cleanup and/or salvage should be done by professionals who are properly educated, trained, and equipped. However, as a reader has recently pointed out, some of these “professionals” are not always as properly educated, trained, and equipped as they should be. This is probably true, but it still is not the job of the fire service to involve themselves in the cleanup, unless it is deemed necessary to protect human life. If the environment is involved, the federal or state ERA will see to it that the spill is properly cleaned up if the first cleanup crew’ is not effective. But the point has been made: The “pros” of salvage and cleanup may be worse than the amateurs. This is not an indictment of professional salvage firms, but it is important that the fire service get to know those firms before an incident occurs and they are needed. To make sure the point of this “aside” is not lost: The fire department should not involve itself in cleanup or salvage operations after the conclusion of a hazardous-materials incident. They may be asked to “stand by” to ensure that if the incident reoccurs due to cleanup or salvage procedures, they may again mitigate the incident, but that should be the extent of their activities.)
Since sodium cyanide is sensitive to moisture, it may be necessary to cover the spill with a material that is impervious to water, such as plastic or rubber sheeting. In any event, the approach to the spilled product must be made with extreme caution and always from upwind. If dust is being blown about, a water spray or fog will dissolve it from the air. However, attention must now be paid to confining the runoff water which has sodium cyanide dissolved in it.
If moisture does reach the spilled product, evacuation downwind must be considered due to the danger of hydrogen cyanide evolution. The hydrogen cyanide gas is just slightly lighter than air (the vapor density of hydrogen cyanide is 0.931), and should dissipate slowly, but chances cannot be taken with such a toxic material.
Entry of sodium cyanide into waterways and/or sewer systems must be avoided. Entrances to sewers should be diked; if the product or runoff containing the product does enter a sewer, the sewage treatment facility must be altered immediately. If the product or runoff enters a waterway, all downstream users must be notified.
The hazards of such contaminated water should be obvious to users but may not be. Untreated water will be poisonous to anyone who drinks it, but industrial users may not realize the danger. If water with dissolved sodium nitrate were to enter an industrial (or other) operation where it became acidic, large volumes of hydrogen cyanide gas would be generated from the contaminated water.
If the product enters a waterway, it will sink to the bottom and dissolve rapidly. The only way to prevent the contamination from moving downstream is to dam the stream or divert the water to a low-lying impoundment area. Manufacturers and/or users of the sodium cyanide can then recommend action to neutralize the threat.
For a released product in solution form, or where water was used to dissolve the released product, containment ponds or pits can be constructed to hold the liquid. Contamination is greater when the dissolved product is involved.
Once a waterway has been dammed or diverted, or the dissolved product has been contained in a pond or pit, the liquid may be siphoned or pumped from the building area into secure containers for disposal. If the solid material or a solution of it has been salvaged and is to be disposed of, it must be done in accordance with federal, state, and local regulations.
The dry product may be salvaged simply by shoveling or scooping from the ground and transferred to secure containers. In any case, any personnel involved must be protected from contact with the product.
FIRE SITUATION
Although sodium cyanide is not flammable, it can be decomposed by high heat such as that produced by a fire. Whenever the material is exposed to fire, carbon monoxide and the nitrogen oxides will be formed. Carbon monoxide is flammable, and the amount generated from decomposing sodium cyanide may not pose a hazard too much greater than the CO from the fire.
However, the nitrogen oxides are another matter. With the exception of nitrous oxide, the other nitrogen oxides (nitric oxide, nitrogen dioxide, nitrogen trioxide, nitrogen peroxide, dinitrogen pcntoxide, and trinitrogen tetroxide) are quite toxic and do not burn. The effect of nitrogen oxide poisoning is often delayed eight to 48 hours and may result in death. Naturally, the amount of nitrogen oxides generated will he determined by the amount of the material exposed to high heat, but the toxic hazards of sodium cyanide are so great that all emergency responders must protect themselves from the material at all times, whether it is threatened by fire or not.
IDENTIFICATION NUMBERS AND RATINGS
CAS
(Chemical Abstract Services)
143-33-9
RTECS
(Registry of Toxic Effects of Chemical Substances)
VZ7525000
STCC
(Standard Transportation Commodity Code)
4923228 (solid), 4923227 (water solution)
UN/NA
(United Nations/North America)
1689
CHRIS
(Chemical Hazard Response Information System)
SCN
RCRA
(Resource Conservation and Recovery Act)
P106
DOT
(U.S. Department of Transportation)
Poison B
IMO
(International Maritime Organization)
6.1, poisonous
SODIUM CYANIDE
Care must be used in extinguishing a fire near sodium cyanide, particularly if the extinguishing agent and/or the way it is discharged might cause the material to spread.
When water is used, you must remember that sodium cyanide is sensitive to small amounts of moisture, and it will dissolve in large amounts. If any of the solid material begins to release hydrogen cyanide, all emergency measures needed to prevent exposure to humans must be taken. If large amounts of the gas are generated, an imminent explosion hazard must be added to the toxicity hazard.
If enough water is used in fighting the fire to dissolve some or all of the sodium cyanide, the runoff will become a hazard and must be contained in containment ponds or pits. The amount of sodium cyanide present and the amount that may be dissolved should be considered when a choice of fire extinguishing agents is available. Foams, because they are water-based, may provide just enough moisture to cause gas evolution from the solid product but not enough water to dissolve it. On the other hand, the use of a large amount of foam may blanket the sodium cyanide and effectively reduce the release of gas to the atmosphere.
Carbon dioxide, when discharged, might have enough force to spread the solid material around, especially if it is in powder form.
If the release or spill of sodium cyanide occurs in a mixed load, or if it occurs at a warehouse location, the other chemicals present must be considered as adding to the danger. If any contact occurs with the oxidizer, decomposition of sodium nitrate will accelerate. And if any acid (even if diluted with water) comes in contact with the material, the evolution of hydrogen cyanide will be very rapid.
It must be understood that a release or spill of sodium cyanide is not necessarv for the above-mentioned problems to occur. If sodium cyanide is present in a mixed transport load or in a warehouse, it can become involved in an incident simply by the nature of the incident. In a warehouse fire, all sorts of chemicals may be released and come into contact with sodium cyanide, even if it is in its original container. This is only one reason why emergency responders must pay attention to the MSDS or lists of chemicals provided under SARA Title III. It is also important to preplan chemical warehouses so the possibility of the presence of each hazardous chemical is known. By studying all the MSDSs or chemical lists provided by industry, a pattern will develop that will allow each fire department to preplan even transportation accidents involving hazardous chemicals. This is possible because the presence of these chemicals usually indicates shipment into or out of the site where they are found (assuming they are not intermediate chemicals produced on site for use on site).
SYNONYMS
cyanide of sodium
cyanobrik
cyanogran
cymag
cyanoids
hydrocyanic acid
sodium salt
sodium cyanide solution (when shipped as the water solution)
Sodium cyanide presents such a major hazard that its presence within a fire department’s protection jurisdiction must be known long before it becomes involved in an incident.
PROTECTIVE EQUIPMENT AND CLOTHING
Protective equipment and protective clothing chosen must prevent all contact with the product, including eye, mouth, and skin contact. Face shields and chemical splash-proof goggles must be used to protect the face and eyes, and rubber aprons, gloves, and boots may protect other parts of the body. Any clothing impervious to water and dust should protect a responder from contact with either the solid or dissolved material. Since sodium cyanide itself is relatively nonreactive (with some exceptions), any good chemical encapsulating suit that is air-tight and water-tight should protect the wearer. SCBA must be used in all incidents involving this material.
FIRST AID
For skin contact, all contaminated clothing must be removed, and any skin that has come in contact with the product must be thoroughly flushed with water, followed by thorough washing with large amounts of soap and water. Medical attention is needed immediately.
In case of eye contact, flush the eyes with water for at least fifteen minutes, occasionally lifting the eyelids. Get immediate medical attention.
For ingestion, the victim must be kept quiet and warm. Cyanide kits will provide sodium thiosulfate, and the victim (if conscious) must be made to drink a pint of 1% solution of sodium thiosulfate, which must be repeated in 15 minutes. Never try to make an unconscious person drink anything. Immediate medical attention is imperative.
If the victim has inhaled the dust or hydrogen cyanide gas, he must be removed to fresh air and kept quiet and warm. Immediate medical attention must be sought. If the victim is unconscious, artificial respiration should be administered, but care must be exercised to protect the first-aid giver from the toxic effects of material in the victims lungs and/or vomit. If a cyanide kit is available, amyl nitrate should be administered per instructions (usually having the victim breathe the vapors of a crushed ampule or pearl of amyl nitrate for five cycles of breathingamyl nitrate for 15 seconds and air for 15 seconds). Oxygen must be administered once the victim is conscious or has trouble breathing.
