HYDROGEN CYANIDE, ANHYDROUS, STABILIZED

Diamond	Hazard	Value	Description
4 4 1	Health	4	Can be lethal.
	Flammability	4	Burns readily. Rapidly or completely vaporizes at atmospheric pressure and normal ambient temperature.
	Instability	1	Normally stable but can become unstable at elevated temperatures and pressures.
	Special

A deadly human poison by all routes. Very volatile.

Colorless or pale-blue liquid or gas (above 78°F) with a bitter, almond-like odor. Often used as a 96% solution in water. (NIOSH, 2022)

• Highly Flammable
• Polymerizable

Highly flammable. Flame may easily travel back to source of leak. Vapors forms explosive mixtures with air. Soluble in water.

Unstabilized hydrocyanic acid may polymerize spontaneously with explosive violence. Flashback along vapor trail may occur. The explosion hazard is severe when this material is exposed to heat, flame, or oxidizers. It forms explosive mixtures with air, and will react with water, steam, acid, or acid fumes to produce highly toxic fumes of cyanides. It may decompose explosively upon contact with alkaline material. Avoid acetylaldehyde, alkaline materials, oxidizers, water, steam, acid, and acid fumes. Hydrocyanic acid solution is sensitive to light. It may become unstable and subject to explosion if stored for an extended time or exposed to high temperature and pressure. Avoid heat, flame or oxidizers. Hazardous polymerization may occur. Unstabilized hydrocyanic acid may polymerize spontaneously with explosive violence. Can polymerize at 122-140F or when catalyzed with traces of alkali. (EPA, 1998)

It is super toxic. Breathing in a small amount of the gas or swallowing a very small amount may be fatal. Average fatal dose is 50-60 mg. A few minutes of exposure to 300 ppm may result in death. Exposure to 150 ppm for 1/2 to 1 hour may endanger life. (EPA, 1998)

HYDROGEN CYANIDE, ANHYDROUS presents a severe explosion hazard when exposed to oxidizing agents. The vapors form explosive mixtures with air. May polymerize explosively at elevated temperature (50-60°C) or in the presence of traces of alkali [Wohler, L. et al., Chem. Ztg., 1926, 50, p. 761, 781]. In the absence of a stabilizer (such as phosphoric acid), may undergo explosively rapid spontaneous (autocatalytic) polymerization leading to a fire. The reaction is autocatalytic because of ammonia formation. [Bond, J., Loss Prev. Bull., 1991, 101, p.3]. Dissolves in water to give weakly acidic solutions. Reacts violently with acetaldehyde. During the preparation of imidoester hydrochlorides, hydrogen chloride was rapidly passed over alcoholic hydrogen cyanide. An explosion ensued, even with cooling of the process [J. Org. Chem., 1955, 20, 1573].

• Cyanides, Inorganic
• Acids, Weak
• Polymerizable Compounds

Use caution: Liquids with this reactive group classification have been known to react with the absorbents listed below.

• Mineral-Based & Clay-Based Absorbents
• Dirt/Earth

Excerpt from 117 [Gases - Toxic - Flammable (Extreme Hazard); polymerization hazard]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area for at least 100 meters (330 feet) in all directions.

SPILL: See ERG Table 1 - Initial Isolation and Protective Action Distances on the UN/NA 1051 datasheet.

FIRE: If tank, rail car or tank truck is involved in a fire, ISOLATE for 1600 meters (1 mile) in all directions; also, consider initial evacuation for 1600 meters (1 mile) in all directions. (ERG, 2020)

Firefighting should be done from a safe distance. A few whiffs of gas, or liquid penetrating firefighter's protective clothing, could be fatal. Only special protective clothing should be worn. Water spray should be used to keep containers cool. Keep unnecessary people away; isolate hazard area and deny entry. Stay upwind; keep out of low areas. Ventilate closed spaces before entering them. Wear positive pressure breathing apparatus and special protective clothing. Evacuate area endangered by gas. Isolate for 1/2 mile in all directions if tank car or truck is involved in fire.

Use dry chemicals, alcohol foam, or carbon dioxide. Small fires: let burn unless leak can be stopped immediately. Large fires: water spray, fog or foam. Move container from fire area if you can do it without risk. Stay away from ends of tanks. Withdraw immediately in case of rising sound from venting safety device or any discoloration of tank due to fire. Cool container with water using unmanned device until well after fire is out. Isolate area until gas has dispersed. (EPA, 1998)

Excerpt from 117 [Gases - Toxic - Flammable (Extreme Hazard); polymerization hazard]:

ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area. All equipment used when handling the product must be grounded. Do not touch or walk through spilled material. Stop leak if you can do it without risk. Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled material. Do not direct water at spill or source of leak. If possible, turn leaking containers so that gas escapes rather than liquid. Prevent entry into waterways, sewers, basements or confined areas. Isolate area until gas has dispersed. Consider igniting spill or leak to eliminate toxic gas concerns. (ERG, 2020)

Excerpt from NIOSH Pocket Guide for Hydrogen cyanide:

Skin: PREVENT SKIN CONTACT - Wear appropriate personal protective clothing to prevent skin contact.

Eyes: PREVENT EYE CONTACT - Wear appropriate eye protection to prevent eye contact.

Wash skin: WHEN CONTAMINATED - The worker should immediately wash the skin when it becomes contaminated.

Remove: WHEN WET (FLAMMABLE) - Work clothing that becomes wet should be immediately removed due to its flammability hazard (i.e., for liquids with a flash point <100°F).

Change: No recommendation is made specifying the need for the worker to change clothing after the workshift.

Provide:
• EYEWASH - Eyewash fountains should be provided in areas where there is any possibility that workers could be exposed to the substances; this is irrespective of the recommendation involving the wearing of eye protection.
• QUICK DRENCH - Facilities for quickly drenching the body should be provided within the immediate work area for emergency use where there is a possibility of exposure. [Note: It is intended that these facilities provide a sufficient quantity or flow of water to quickly remove the substance from any body areas likely to be exposed. The actual determination of what constitutes an adequate quick drench facility depends on the specific circumstances. In certain instances, a deluge shower should be readily available, whereas in others, the availability of water from a sink or hose could be considered adequate.] (NIOSH, 2023)

Normalized Breakthrough Times (in Minutes)

Chemical	CAS Number	State	QS	QC	SL	C3	TF	TP	RC	TK	RF
Hydrogen cyanide (21°C, liquid)	74-90-8	Liquid							135	>480	135
Hydrogen cyanide (27°C, gaseous)	74-90-8	Vapor				30			>480	>480	>480

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Warning: Hydrocyanic acid may be fatal if inhaled, swallowed, or absorbed through skin or mucous membranes. Caution is advised.

Signs and Symptoms of Acute Hydrocyanic Acid Exposure: Signs and symptoms of acute exposure to hydrocyanic acid may include hypertension (high blood pressure) and tachycardia (rapid heart rate), followed by hypotension (low blood pressure) and bradycardia (slow heart rate). Cherry red mucous membranes and blood may be noted. Cardiac arrhythmias and other cardiac abnormalities are common. Cyanosis (blue tint to the skin and mucous membranes) may be observed. Weakness, headache, vertigo (dizziness), agitation, giddiness, salivation, nausea, and vomiting, may be followed by combative behavior, convulsions, paralysis, protruding eyeballs, dilated and unreactive pupils, and coma. Tachypnea (rapid, shallow respirations) or hyperpnea (rapid, deep respirations) may be followed by respiratory depression. Lung hemorrhage and pulmonary edema may also occur. Hydrocyanic acid is may be irritating to the skin, eyes, and mucous membranes. Lacrimation (tearing) and a burning sensation of the mouth and throat are common.

Emergency Life-Support Procedures: Acute exposure to hydrocyanic acid may require decontamination and life support for the victims. All exposed persons should be transported to a health care facility as quickly as possible. Emergency personnel should wear protective clothing appropriate to the type and degree of contamination. Air-purifying or supplied-air respiratory equipment should also be worn, as necessary. Rescue vehicles should carry supplies such as plastic sheeting and disposable plastic bags to assist in preventing spread of contamination.

Inhalation Exposure:
1. Move victims to fresh air. Emergency personnel should avoid self-exposure to hydrocyanic acid.
2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. IMMEDIATELY begin administering 100% oxygen to all victims. Monitor victims for respiratory distress.Warning: To prevent self-poisoning, avoid mouth-to-mouth breathing; use a forced-oxygen mask. Direct oral contact with hydrocyanic acid- contaminated persons or their gastric contents can result in self- poisoning.
3. RUSH to a health care facility!
4. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.

Dermal/Eye Exposure:
1. Remove victims from exposure. Emergency personnel should avoid self- exposure to hydrocyanic acid.
2. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. IMMEDIATELY begin administering 100% oxygen to all victims. Monitor victims for respiratory distress.Warning: To prevent self-poisoning, avoid mouth-to-mouth breathing; use a forced-oxygen mask. Direct oral contact with hydrocyanic acid- contaminated persons or their gastric contents can result in self- poisoning.
3. RUSH to a health care facility!
4. Remove contaminated clothing as soon as possible.
5. If eye exposure has occurred, eyes must be flushed with lukewarm water for at least 15 minutes.
6. Wash exposed skin areas twice with soap and water.
7. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.

Ingestion Exposure:
1. Evaluate vital signs including pulse and respiratory rate, and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. IMMEDIATELY begin administering 100% oxygen to all victims. Monitor victims for respiratory distress.Warning: To prevent self-poisoning, avoid mouth-to-mouth breathing; use a forced-oxygen mask. Direct oral contact with hydrocyanic acid- contaminated persons or their gastric contents can result in self- poisoning.
2. RUSH to a health care facility!
3. DO NOT induce vomiting or attempt to neutralize!
4. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.
5. Activated charcoal may be administered if victims are conscious and alert. Use 15 to 30 g (1/2 to 1 oz) for children, 50 to 100 g (1-3/4 to 3-1/2 oz) for adults, with 125 to 250 mL (1/2 to 1 cup) of water.
6. Promote excretion by administering a saline cathartic or sorbitol to conscious and alert victims. Children require 15 to 30 g (1/2 to 1 oz) of cathartic; 50 to 100 g (1-3/4 to 3-1/2 oz) is recommended for adults. (EPA, 1998)

• AC (CHEMICAL WARFARE AGENT)
• AERO LIQUID HCN
• CARBON HYDRIDE NITRIDE (CHN)
• CYCLON
• CYCLONE B
• EVERCYN
• FORMIC ANAMMONIDE
• FORMONITRILE
• HYDROCYANIC ACID
• HYDROGEN CYANIDE
• HYDROGEN CYANIDE (HYDROCYANIC ACID)
• HYDROGEN CYANIDE, ANHYDROUS, STABILIZED
• HYDROGEN CYANIDE, STABILIZED
• HYDROGEN CYANIDE, [ANHYDROUS, STABILIZED]
• PRUSSIC ACID
• ZACLONDISCOIDS