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Chemical Name: Hydrogen Cyanide
Common Names: Prussic acid, Formonitrile
CAS Number: 74-90-8
Appearance: Colorless or pale blue liquid or gas, bitter almond odor
Uses: Industrial precursor for chemicals, fumigation, mining, plastics production, pest control
Hazard Class: Acute toxicity, high flammability
Main Hazards: Inhalation leads to rapid poisoning; systemic toxicity affects the central nervous system, heart, respiration
Hazard Statements: Short exposure causes headaches, dizziness, rapid breathing; heavier exposure leads to seizures, loss of consciousness, death
Signal Words: Danger
Label Pictograms: Skull and crossbones, flame
Substances: Pure hydrogen cyanide
Chemical Formula: HCN
Concentration: Over 99% in pure products used for industrial processing
Inhalation: Remove victim to fresh air without delay; provide oxygen support if trained; immediate medical attention is life-saving
Skin Contact: Strip off contaminated clothing; wash skin vigorously with soap and water
Eye Contact: Flush eyes with water, keep eyelids wide; seek emergency care
Ingestion: Do not induce vomiting; wash out mouth if patient is conscious; move quickly to advanced care
Important Note: Immediate use of antidotes such as hydroxocobalamin or amyl nitrite supports recovery and can drastically cut down fatal outcomes
Suitable Extinguishing Agents: Carbon dioxide, dry chemical powder, water spray
Specific Hazards: Vapors form explosive mixtures with air; combustion releases highly toxic fumes, including nitrogen oxides
Protective Equipment: Self-contained breathing apparatus and full protective gear
Firefighting Tactics: Approach from upwind, isolate area, keep out unnecessary personnel, and avoid direct contact with substance
Personal Precautions: Evacuate area, ensure immediate ventilation, wear chemical-resistant clothing and respirators
Environmental Measures: Prevent run-off from reaching sewers, soil, or surface water; HCN vaporizes quickly and can threaten nearby communities
Containment and Cleanup: Use absorbents designed for strong acid neutralization, collect with spark-proof equipment; safe disposal in sealed containers under strict supervision limits further risk
Handling: Always use in well-ventilated settings, preferably fume hoods; avoid ignition sources, static discharge, and unnecessary handling
Storage: Keep containers tightly closed and secured in cool, dry places; use corrosion-resistant materials; store away from acids, alkalis, oxidizers
Additional Notes: Promptly lock or restrict access areas due to extreme hazard
Occupational Exposure Limit: OSHA ceiling value sits at 10 ppm; NIOSH recommends lower limits for short exposure
Engineering Controls: Closed systems, exhaust hoods, gas monitoring detectors
Personal Protection: Full-face respirators with suitable cartridges, chemical-resistant gloves, flame-resistant protective clothing, safety goggles, and emergency eye wash and showers
Hygiene Measures: No eating, drinking, or smoking in work area; wash up thoroughly before breaks or leaving
Physical State: Liquid below 26°C (78°F), gas above
Melting Point: -13.4°C
Boiling Point: 25.6°C
Solubility: Miscible with water, alcohol, ether
Vapor Pressure: High, increases accident risk
Odor Threshold: Variable, depends on genetic factors—some individuals lack ability to detect odor altogether
Flammability: Extremely high, easily ignited by heat, sparks, or open flames
Chemical Stability: Decomposes on exposure to light, heat, humidity; stabilizers like phosphoric acid sometimes added in commercial uses
Hazardous Reactions: Rapid polymerization with alkaline substances; forms explosive compounds with some metals and acids
Incompatible Materials: Alkalis, acids, bases, oxidizers, ammonia, chlorides
Decomposition Products: Nitrogen oxides, carbon monoxide, carbon dioxide, amid other toxic gases
Acute Effects: Rapid onset of headache, nausea, convulsions, coma, cardiac arrest
Target Organs: Central nervous system, respiratory system, heart
Lethal Dose: 50 mg by ingestion or 270 ppm exposure for 5 min proves fatal for humans
Carcinogenicity: Not classified as carcinogenic by IARC, but repeated low-level exposure damages health slowly
Other Symptoms: Bluish skin from oxygen deprivation, anxiety, abnormal heart rhythm, sudden collapse
Environmental Fate: Hydrogen cyanide disperses in air and water, evaporates or degrades with sunlight and microbes
Acute Toxicity: High risk for aquatic life even at low concentrations, kills fish and invertebrates rapidly
Mobility: High; enters streams and groundwater easily from accidental spills or industrial discharges
Persistence: Short-lived under sunlight, but enough to harm biota before breakdown
Methods: Incineration using specialized high-temp equipment under licensed supervision
Precautions: Never pour down the drain; must not be mixed with general waste; double containment prevents leaks during storage and transport
Legal Requirements: Disposal follows federal and state hazardous waste laws to minimize population and ecosystem risks
Shipping UN Number: UN 1051
Hazard Class: 6.1 – Poison, 3 – Flammable liquid
Packing Group: I (highest hazard)
Transport Conditions: Sealed, protected from shock, stored upright, container integrity routinely verified
Mode Restrictions: Transport workers need intensive training; use dedicated vehicles and constant monitoring to prevent leaks en route
Workplace Regulations: OSHA, EPA, and EU classify hydrogen cyanide as an immediate threat to health; strict exposure limits control every step
Manufacture and Use: Facilities must prove strong evidence of protection plans, emergency procedures, real-time monitoring
Community Right-to-Know: Federal Emergency Planning laws mandate that inventories and spill response systems are filed and checked regularly
