Emergency Response Card

 NIOSH CDC
HYDROGEN CYANIDE (AC) :: Systemic Agent  
CAS #:74-90-8
RTECS #:MW6825000
UN #:1051 (Guide 117)
Common Names:
  • Formonitrile
  • Hydrocyanic acid
  • Prussic acid
Agent Characteristics 
  • APPEARANCE: Colorless or pale blue liquid below 78°F (25.6°C), colorless gas above 78°F (25.6°C).
  • DESCRIPTION: Hydrogen cyanide (AC) is a systemic chemical asphyxiant. It interferes with the normal use of oxygen by nearly every organ of the body. Exposure to hydrogen cyanide (AC) can be rapidly fatal. It has whole-body (systemic) effects, particularly affecting those organ systems most sensitive to low oxygen levels: the central nervous system (brain), the cardiovascular system (heart and blood vessels), and the pulmonary system (lungs). Hydrogen cyanide (AC) is a chemical warfare agent (military designation, AC). It is used commercially for fumigation, electroplating, mining, chemical synthesis, and the production of synthetic fibers, plastics, dyes, and pesticides. Hydrogen cyanide (AC) gas has a distinctive bitter almond odor (others describe a musty "old sneakers smell"), but a large proportion of people cannot detect it; the odor does not provide adequate warning of hazardous concentrations. It also has a bitter burning taste and is often used as a solution in water.
  • METHODS OF DISSEMINATION:
    • Indoor Air: Hydrogen cyanide (AC) can be released into indoor air as a liquid spray (aerosol) or as a gas.
    • Water: Hydrogen cyanide (AC) can be used to contaminate water.
    • Food: Hydrogen cyanide (AC) can be used to contaminate food.
    • Outdoor Air: Hydrogen cyanide (AC) can be released into outdoor air as a liquid spray (aerosol) or as a gas.
    • Agricultural: If hydrogen cyanide (AC) is released into the air as a liquid spray (aerosol), it has the potential to contaminate agricultural products. If hydrogen cyanide (AC) is released as a gas, it is highly unlikely to contaminate agricultural products.
  • ROUTES OF EXPOSURE: Hydrogen cyanide (AC) can affect the body by ingestion, inhalation, skin contact, or eye contact.
Personal Protective Equipment 
  • GENERAL INFORMATION: First Responders should use a NIOSH-certified Chemical, Biological, Radiological, Nuclear (CBRN) Self Contained Breathing Apparatus (SCBA) with a Level A protective suit when entering an area with an unknown contaminant or when entering an area where the concentration of the contaminant is unknown. Level A protection should be used until monitoring results confirm the contaminant and the concentration of the contaminant.
    NOTE: Safe use of protective clothing and equipment requires specific skills developed through training and experience.
  • LEVEL A: (RED ZONE): Select when the greatest level of skin, respiratory, and eye protection is required. This is the maximum protection for workers in danger of exposure to unknown chemical hazards or levels above the IDLH or greater than the AEGL-2.
    • A NIOSH-certified CBRN full-face-piece SCBA operated in a pressure-demand mode or a pressure-demand supplied air hose respirator with an auxiliary escape bottle.
    • A Totally-Encapsulating Chemical Protective (TECP) suit that provides protection against CBRN agents.
    • Chemical-resistant gloves (outer).
    • Chemical-resistant gloves (inner).
    • Chemical-resistant boots with a steel toe and shank.
    • Coveralls, long underwear, and a hard hat worn under the TECP suit are optional items.
  • LEVEL B: (RED ZONE): Select when the highest level of respiratory protection is necessary but a lesser level of skin protection is required. This is the minimum protection for workers in danger of exposure to unknown chemical hazards or levels above the IDLH or greater than AEGL-2. It differs from Level A in that it incorporates a non-encapsulating, splash-protective, chemical-resistant splash suit that provides Level A protection against liquids but is not airtight.
    • A NIOSH-certified CBRN full-face-piece SCBA operated in a pressure-demand mode or a pressure-demand supplied air hose respirator with an auxiliary escape bottle.
    • A hooded chemical-resistant suit that provides protection against CBRN agents.
    • Chemical-resistant gloves (outer).
    • Chemical-resistant gloves (inner).
    • Chemical-resistant boots with a steel toe and shank.
    • Coveralls, long underwear, a hard hat worn under the chemical-resistant suit, and chemical-resistant disposable boot-covers worn over the chemical-resistant suit are optional items.
  • LEVEL C: (YELLOW ZONE): Select when the contaminant and concentration of the contaminant are known and the respiratory protection criteria factors for using Air Purifying Respirators (APR) or Powered Air Purifying Respirators (PAPR) are met. This level is appropriate when decontaminating patient/victims.
    • A NIOSH-certified CBRN tight-fitting APR with a canister-type gas mask or CBRN PAPR for air levels greater than AEGL-2.
    • A NIOSH-certified CBRN PAPR with a loose-fitting face-piece, hood, or helmet and a filter or a combination organic vapor, acid gas, and particulate cartridge/filter combination or a continuous flow respirator for air levels greater than AEGL-1.
    • A hooded chemical-resistant suit that provides protection against CBRN agents.
    • Chemical-resistant gloves (outer).
    • Chemical-resistant gloves (inner).
    • Chemical-resistant boots with a steel toe and shank.
    • Escape mask, face shield, coveralls, long underwear, a hard hat worn under the chemical-resistant suit, and chemical-resistant disposable boot-covers worn over the chemical-resistant suit are optional items.
  • LEVEL D: (GREEN ZONE): Select when the contaminant and concentration of the contaminant are known and the concentration is below the appropriate occupational exposure limit or less than AEGL-1 for the stated duration times.
    • Limited to coveralls or other work clothes, boots, and gloves.
Emergency Response 
  • CHEMICAL DANGERS:
    • Hydrogen cyanide (AC) is unstable with heat, alkaline materials, and water.
    • Hydrogen cyanide (AC) reacts with amines, oxidants, acids, sodium hydroxide, calcium hydroxide, sodium carbonate, caustic substances, and ammonia.
    • Hydrogen cyanide (AC) may polymerize at 122°F to 140°F (50°C to 60°C); polymerization can occur violently in the presence of heat, alkaline materials, or moisture.
  • EXPLOSION HAZARDS:
    • Hydrogen cyanide (AC) gas mixes well with air, and explosive mixtures are easily formed.
    • Confined polymerization can cause container failure and a violent explosion.
    • Hydrogen cyanide (AC) can decompose explosively on contact with alkaline materials.
    • Explosive potential is severe when hydrogen cyanide (AC) is exposed to heat or flame or to alkaline agents.
    • Lower explosive (flammable) limit in air (LEL), 5.6%; upper explosive (flammable) limit in air (UEL), 40%.
    • The agent or its vapors present a vapor explosion and poison (toxic) hazard indoors, outdoors, or in sewers.
    • Run-off to sewers may create an explosion hazard.
    • Containers may explode when heated.
    • Ruptured cylinders may rocket.
  • FIRE FIGHTING INFORMATION:
    • Fire will produce irritating, corrosive, and/or toxic gases.
    • UN 1051, hydrogen cyanide (AC), >20% solution or anhydrous, is extremely flammable.
    • UN 1051 may be ignited by heat, sparks, or flames.
    • UN 1614, hydrogen cyanide (AC), stabilized and UN 3294, hydrogen cyanide (AC) solution in alcohol, are highly flammable.
    • UN 1614 and UN 3294 will be easily ignited by heat, sparks, or flames.
    • Caution: UN 1614 and UN 3294 have very low flash points. Use of water spray when fighting fires may be inefficient.
    • UN 1613, hydrogen cyanide (AC), not more than 20% solution, is non-combustible.
    • UN 1613 itself does not burn, but it may decompose upon heating to produce corrosive and/or toxic fumes.
    • UN 1613 may be an oxidant, and it may ignite combustibles (wood, paper, oil, clothing, etc.).
    • Vapors of UN 1051, UN 1614, or UN 3294 may travel to the source of ignition and flash back.
    • Run-off of UN 1051, UN 1614, or UN 3294 may create a fire hazard.
    • Do not extinguish a leaking gas fire of UN 1051 unless the leak can be stopped.
    • For small fires, use dry chemical, carbon dioxide, or water spray. Regular foam may also be used on small fires involving UN 1051. Alcohol-resistant foam may also be used on small fires involving UN 1614 or UN 3294.
    • For large fires involving UN 1051, use water spray, fog, or regular foam. For UN 1614 or UN 3294, use water spray, fog, or alcohol-resistant foam. For UN 1613, use dry chemical, carbon dioxide, alcohol-resistant foam, or water spray. Move containers from the fire area if it is possible to do so without risk to personnel. Dike fire control water for later disposal; do not scatter the agent. Use water spray or fog; do not use straight streams. Damaged cylinders of UN 1051 should be handled only by specialists.
    • For fire involving tanks or car/trailer loads, fight the fire from maximum distance or use unmanned hose holders or monitor nozzles. Do not get water inside containers of UN 1613. Cool containers with flooding quantities of water until well after the fire is out. Do not direct water at the source of the leak of UN 1051 or at safety devices; icing may occur. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tanks. Always stay away from tanks engulfed in fire.
    • For massive fire involving UN 1614 or UN 3294, use unmanned hose holders or monitor nozzles; if this is impossible, withdraw from the area and let the fire burn.
    • Run-off from fire control or dilution water may be corrosive and/or toxic, and it may cause pollution.
    • If the situation allows, control and properly dispose of run-off (effluent).
  • INITIAL ISOLATION AND PROTECTIVE ACTION DISTANCES:
    • If a tank, rail car, or tank truck is involved in a fire, isolate it for 1 mi (1600 m) in all directions; also consider initial evacuation for 1 mi (1600 m) in all directions.
    • Small spills (when used as a weapon):
      • First isolate in all directions: 200 ft (60 m).
      • Then protect persons downwind during the day: 0.1 mi (0.2 km).
      • Then protect persons downwind during the night: 0.3 mi (0.5 km).
    • Large spills (when used as a weapon):
      • First isolate in all directions: 1500 ft (500 m).
      • Then protect persons downwind during the day: 1.0 mi (1.7 km).
      • Then protect persons downwind during the night: 2.4 mi (3.9 km).
      • Small spills:
      • First isolate in all directions: 100 ft (30 m).
      • Then protect persons downwind during the day: 0.1 mi (0.1 km).
      • Then protect persons downwind during the night: 0.3 mi (0.4 km).
      • Large spills:
      • First isolate in all directions: 500 ft (150 m).
      • Then protect persons downwind during the day: 0.8 mi (1.3 km).
      • Then protect persons downwind during the night: 2.3 mi (3.7 km).
  • PHYSICAL DANGERS:
    • Hazardous concentrations may develop quickly in enclosed or poorly-ventilated areas.
    • Hydrogen cyanide (AC) gas mixes well with air; explosive mixtures are easily formed.
  • NFPA 704 Signal:
    • Health: 4
    • Flammability: 4
    • Reactivity: 2
    • Special:
Health: 4, Flammability: 4, Reactivity: 2, Special:
  • SAMPLING AND ANALYSIS:
    • OSHA: Not established/determined
    • NIOSH: 6010, 6017
  • ADDITIONAL SAMPLING AND ANALYSIS INFORMATION:
    References are provided for the convenience of the reader and do not imply endorsement by NIOSH.

    • AIR MATRIX
      Agrawal V, Cherian L, Gupta VK [1991]. Extractive spectrophotometric method for the determination of hydrogen cyanide in environmental samples using 4-aminosalicylic acid. Int J Environ Anal Chem 45(4):235-244.

      Amlathe S, Gupta VK [1990]. Spectrophotometric determination of hydrogen cyanide in air using phloroglucinol. Fresenius' J Anal Chem 338(5):615-617.

      Asano Y, Ito S [1990]. Development of a potentiometric continuous monitoring system for cyanide ion in aqueous solution utilizing a hydrogen cyanide gas sensor. Bunseki Kagaku 39(11):693-698.

      Bentley AE, Alder JF [1989]. Optical fibre sensor for detection of hydrogen cyanide in air: Part 1. Reagent characterization and impregnated bead detector performance. Anal Chim Acta 222(1):63-73.

      de Gouw J, Warneke C, Karl T, Eerdekens G, van der Veen C, Fall R [2003]. Sensitivity and specificity of atmospheric trace gas detection by proton-transfer-reaction mass spectrometry. Int J Mass Spectrom 223(1-3):365-382.

      Foerg W [1995]. Method for the removal of hydrogen cyanide from gases and a catalyst for hydrogen cyanide decomposition. Fuel Energy Abst 36(5):373.

      Hachiya H [2003]. Study on the downsizing of electrochemical gas sensors.Bunseki Kagaku 52(1):83-84.

      Jawad SM, Alder JF [1991]. Optical-fibre sensor for the detection of hydrogen cyanide in air. II. Theory and design of an automatic detection system. Anal Chim Acta 246(2):259-266.

      Kim E, Little JC, Chiu N, Chiu A [2001]. Inhalation exposure to volatile chemicals in drinking water. J Environ Sci Health Part C-Environ Carcinog Ecotoxicol Rev 19(2):387-413.

      Kluchinsky TA, Savage PB, Fitz R, Smith PA [2002]. Liberation of hydrogen cyanide and hydrogen chloride during high-temperature dispersion of CS riot control agent. AIHAJ 63(4):493-496.

      Kuban V, Dasgupta PK [1992]. Selective determination of gases by two-stage membrane-differentiated flow-injection analysis. Determination of trace hydrogen cyanide in the presence of large concentrations of hydrogen sulfide. Anal Chem 64(10): 1106-1112.

      Langmaier J, Janata J [1992]. Sensitive layer for electrochemical detection of hydrogen cyanide. Anal Chem 64(5):523-527.

      Li J, Petelenz D, Janata J [1993]. Suspended gate field-effect transistor sensitive to gaseous hydrogen cyanide. Electroanalysis 5(9-10):791-794.

      Marion P, Rouillier MC, Blet V, Pons MN [1990]. Online monitoring of cyanide concentration via a gas membrane system in extractive metallurgical processes. Anal Chim Acta 238(1):117-127.

      Nagy A, Nagy G [1993]. Amperometric air gap cell for the measurement of free cyanide. Anal Chimica Acta 283(2):795-802.

      Nakano N, Yamamoto A, Kobayashi Y, Nagashima K [1999]. An automatic measurement of hydrogen cyanide in air by a monitoring tape method. Anal Chimica Acta 398(2-3):305-310.

      NIOSH [1994]. NMAM Method 6010: Hydrogen cyanide. In: NIOSH manual of analytical methods. 4th ed. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 94-113.

      NIOSH [1994]. NMAM Method 7904: Cyanides, aerosol and gas. In: NIOSH manual of analytical methods. 4th ed. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 94-113.

      Olson DC, Bysouth SR, Dasgupta PK, Kuban V [1994]. New flow-injection analyser for monitoring trace hydrogen cyanide in process gas streams. Proc Contr Qual 5(4):259-265.

      Rao VK, Suresh S, Bhattacharya A, Rao NBSN [1999]. A potentiometric detector for hydrogen cyanide gas using silver dicyano complex. Talanta 49(2):367-371.

      Seto Y [2002]. False cyanide detection. Anal Chem 74(5):134A-141A.

      Sicilia D, Rubio S, Perez-Bendito D, Maniasso N, Zagatto EA [1999]. An impregnated filter sampling approach for determination of hydrogen cyanide in air by a kinetic-flourimetric micellar method. Analyst 124(4):615-620.

      Smith PA, Sheely MV, Kluchinsky TA [2002]. Solid phase microextraction with analysis by gas chromatography to determine short term hydrogen cyanide concentrations in a field setting. J Separation Sci 25(14) 917-921.

      Sweileh JA [1996]. Study of equilibria in cyanide systems by gas-diffusion measurement of hydrogen cyanide. Anal Chimica Acta 336(1-3):131-140.


    • OTHER
      No references were identified for this sampling matrix for this agent.


    • SOIL MATRIX
      EPA [1992]. SW-846 Method 9013: Cyanide extraction procedure for solids and oils. Washington, DC: U.S. Environmental Protection Agency.


    • SURFACES
      Botschwina P, Horn M, Matuschewski M, Schick E, Sebald P [1997]. Hydrogen cyanide: theory and experiment. J Mol Structure: THEOCHEM 400:119-137.


    • WATER
      Brimer L, Rosling H [1993]. Microdiffusion method with solid state detection of cyanogenic glycosides from cassava in human urine. Food Chem Toxicol 31(8):599-603.

      Calafat AM, Stanfill SB [2002]. Rapid quantitation of cyanide in whole blood by automated headspace gas chromatography. J Chromatogr B: Anal Technol Biomed Life Sci 772(1):131-137.

      Cardeal ZL, Pradeau D, Hamon M [1993]. Determination of hydrogen cyanide by headspace gas chromatography using an improved method of standardization. Chromatographia 37(11-12):613-617.

      Carr SA, Baird RB, Lin BT [1997]. Wastewater derived interferences in cyanide analysis. Water Res 31(7):1543-1548.

      Cruz-Landeira A, Lopez-Rivadulla M, Concheiro-Carro L, Fernandez-Gomez P, Tabernero-Duque MJ [2000]. A new spectrophotometric method for the toxicological diagnosis of cyanide poisoning. J Anal Toxicol 24(4):266-270.

      do Nascimento PC, Bohrer D, de Carvalho LM [1998]. Cyanide determination in biological fluids using a microdiffusion method with a flow system and polarographic detection. Analyst 123(5):1151-1154.

      EPA [1996]. SW-846 Method 9010B: Total and amenable cyanide: distillation. Washington, DC: U.S. Environmental Protection Agency.

      EPA [1996]. SW-846 Method 9012A: Total and amenable cyanide (automated colorimetric, with off-line distillation. Washington, DC: U.S. Environmental Protection Agency.

      EPA [1996]. SW-846 Method 9014: Titrimetric and manual spectrophotometric determinative methods for cyanide. Washington, DC: U.S. Environmental Protection Agency.

      Franson MAH, ed. [1985]. Cyanide. Standard methods for the examination of water and wastewater. 16th ed. Washington, DC: American Public Health Association, p. 327.

      Fushinuki Y, Nanamegi K, Hachiya H, Ito S, Asano Y, Taniguchi I [1997]. Preparation of a simple system for the analysis of cyanide using a hydrogen cyanide gas sensor and application to the analysis of blood samples. Bunseki Kagaku 46(12):971-977.

      Gerrits PJ, Zumbragel F, Marcus J [2001]. Analyzing the hydrocyanation reaction: chiral HPLC and the synthesis of racemic cyanohydrins. Tetrahedron 57(41):8691-8698.

      Hachiya H, Ito S, Fushinuki Y, Masadome T, Asano Y, Imato T [1999]. Continuous monitoring for cyanide in waste water with a galvanic hydrogen cyanide sensor using a purge system. Talanta 48(5):997-1004.

      Ma HC, Liu JF, Feng JZ, Gao Y [1994]. Simultaneous determination of cyanide and sulfide by reversed flow injection analysis. J Flow Inject Anal 11(1):58-67.

      Marin MAB, Ganzarollli EM, Lehmkuhl A, de Souza IG, de Queiroz RRU [1999]. Sequential determination of free and total cyanide by flow injection. J Automated Meth Mgmt Chem 21(1):23-26.

      Maseda C, Matsubara K, Shiono H [1989]. Improved gas chromatography with electron-capture detection using a reaction pre-column for the determination of blood cyanide: A higher content in the left ventricle of fire victims. J Chromatogr B: Biomed Sci Appl 490:319-327.

      Miralles E, Prat D, Compano R, Granados M [1998]. Online gas-diffusion separation and fluorimetric detection for the determination of acid dissociable cyanide. Analyst 123(2):217-220.

      Nakamura E, Kuniyasu M, Namiki H [1992]. Determination of cyanide (in water) in the presence of formaldehyde cyanohydrin. Bunseki Kagaku 41(10):T131-T134.

      Pihlar B, Kosta L. [1980]. Determination of cyanides by continuous distillation and flow analysis with cylindrical amperometric electrodes. Anal Chim Acta 114:275-281.

      Schwedt G, do Nascimento PC [1997]. Method comparisons for practical use. 5. Cyanide in waste water. CLB Chemie in Labor und Biotechnik 48(5):183-186, 191-192.

      Seto Y [2002]. False cyanide detection. Anal Chem 74(5):134A-141A.
      Seto Y, Tsunoda N, Ohta H, Shinohara T [1993]. Determination of blood cyanide by headspace gas chromatography with nitrogen-phosphorus detection and using a megabore capillary column. Anal Chim Acta 276(2):247-259.


      Tsuge K, Kataoka M, Seto Y [2001]. Rapid determination of cyanide and azide in beverages by microdiffusion spectrophotometric method. J Anal Toxicol 25(4):228-236.

      Utley D [1990]. Simultaneous determination of hydroxylamine and cyanide in formulations containing pralidoxime salts by flow injection. Analyst 115(9):1239-1242.

      Vallejo-Pecharroman B, de Castro MDL [2002]. Determination of cyanide by a pervaporation-UV photodissociation-potentiometric detection approach. Analyst 127(2):267-270.

      Vesey CJ, McAllister H, Langford RM [1999]. A simple, rapid and sensitive semimicro method for the measurement of cyanide in blood. Ann Clin Biochem 36(6):755-758.

      Wolf H [1997]. Detoxification of cyanidic wastewater. Met Finishing 95(7):68.

      Yagi K, Ikeda S, Schweiss JF, Homan SM [1990]. Measurement of blood cyanide with a micro-diffusion method and an ion-specific electrode. Anesthesiol 73(5):1028-1031.

Signs/Symptoms 
  • TIME COURSE: Effects occur extremely rapidly following exposure to hydrogen cyanide (AC). After inhalation exposure, symptoms begin within seconds to minutes; death may occur within minutes. After skin exposure, onset of symptoms may be immediate or delayed for 30 to 60 minutes. Ingestion of hydrogen cyanide (AC) solutions or cyanide salts can be rapidly fatal. The time of onset of effects depends on the concentration and duration of exposure.
  • EFFECTS OF SHORT-TERM (LESS THAN 8-HOURS) EXPOSURE: Early symptoms of cyanide poisoning include lightheadedness, giddiness, rapid breathing, nausea, vomiting (emesis), feeling of neck constriction and suffocation, confusion, restlessness, and anxiety. Accumulation of fluid in the lungs (pulmonary edema) may complicate severe intoxications. Rapid breathing is soon followed by respiratory depression/respiratory arrest (cessation of breathing). Severe cyanide poisonings progress to stupor, coma, muscle spasms (in which head, neck, and spine are arched backwards), convulsions (seizures), fixed and dilated pupils, and death. The CNS is the most sensitive target organ of cyanide poisoning. Cardiovascular effects require higher cyanide doses than those necessary for CNS effects. In serious poisonings, the skin is cold, clammy, and diaphoretic. Blue discoloration of the skin may be a late finding. Severe signs of oxygen deprivation in the absence of blue discoloration of the skin suggest cyanide poisoning.
  • EYE EXPOSURE:
    • Irritation.
    • Contact with only the eyes does not normally result in whole-body (systemic) toxicity.
    • Contact with the eyes can contribute to whole-body (systemic) toxicity. See Inhalation Exposure.
  • INGESTION EXPOSURE:
    • Burning sensation in mouth and throat, nausea, vomiting (emesis), and abdominal pain.
    • Whole-body (systemic) toxicity can occur. See Inhalation Exposure.
  • INHALATION EXPOSURE:
    • Mild to moderate: CNS effects: headache, confusion, anxiety, dizziness, weakness (malaise), and loss of consciousness. Cardiovascular effects: palpitations. Respiratory effects: respiratory tract irritation, difficulty breathing or shortness of breath (dyspnea), and transient increase in the rate and depth of breathing (hyperpnea). GI effects: nausea and vomiting (emesis).
    • Severe: CNS effects: coma, seizures, and dilated pupils (mydriasis). Cardiovascular effects: shock, abnormal or disordered heart rhythms (dysrhythmias), critically low blood pressure, and cardiac arrest. Respiratory effects: abnormally rapid, followed by abnormally slow respirations; accumulation of fluid in the lungs (pulmonary edema); and respiratory arrest. Eye effects: dilated pupils, inflammation of the surface of the eye, and temporary blindness.
  • SKIN EXPOSURE:
    • Irritation.
    • Absorption through the skin is rapid and can contribute to whole-body (systemic) toxicity. See Inhalation Exposure.
    • Absorption through the skin occurs more readily when ambient temperature and relative humidity are high.
Decontamination 
  • INTRODUCTION: The purpose of decontamination is to make an individual and/or their equipment safe by physically removing toxic substances quickly and effectively. Care should be taken during decontamination, because absorbed agent can be released from clothing and skin as a gas. Your Incident Commander will provide you with decontaminants specific for the agent released or the agent believed to have been released.
  • DECONTAMINATION CORRIDOR: The following are recommendations to protect the first responders from the release area:
    • Position the decontamination corridor upwind and uphill of the hot zone. The warm zone should include two decontamination corridors. One decontamination corridor is used to enter the warm zone and the other for exiting the warm zone into the cold zone. The decontamination zone for exiting should be upwind and uphill from the zone used to enter.
    • Decontamination area workers should wear appropriate PPE. See the PPE section of this card for detailed information.
    • A solution of detergent and water (which should have a pH value of at least 8 but should not exceed a pH value of 10.5) should be available for use in decontamination procedures. Soft brushes should be available to remove contamination from the PPE. Labeled, durable 6-mil polyethylene bags should be available for disposal of contaminated PPE.
  • INDIVIDUAL DECONTAMINATION: The following methods can be used to decontaminate an individual:
    • Decontamination of First Responder:
      • Begin washing PPE of the first responder using soap and water solution and a soft brush. Always move in a downward motion (from head to toe). Make sure to get into all areas, especially folds in the clothing. Wash and rinse (using cold or warm water) until the contaminant is thoroughly removed.
      • Remove PPE by rolling downward (from head to toe) and avoid pulling PPE off over the head. Remove the SCBA after other PPE has been removed.
      • Place all PPE in labeled durable 6-mil polyethylene bags.
    • Decontamination of Patient/Victim:
      • Remove the patient/victim from the contaminated area and into the decontamination corridor.
      • Remove all clothing (at least down to their undergarments) and place the clothing in a labeled durable 6-mil polyethylene bag.
      • Thoroughly wash and rinse (using cold or warm water) the contaminated skin of the patient/victim using a soap and water solution. Be careful not to break the patient/victim's skin during the decontamination process, and cover all open wounds.
      • Cover the patient/victim to prevent shock and loss of body heat.
      • Move the patient/victim to an area where emergency medical treatment can be provided.
First Aid 
  • GENERAL INFORMATION: Careful observation, supplemental oxygen, and supportive care may be sufficient therapy for the patient/victim who does not exhibit physical findings of cyanide toxicity. For the patient/victim exhibiting physical findings of cyanide toxicity, initial treatment consists of administration of antidotes under a physician's direction, respiratory and circulatory support (oxygen and IV fluids), correction of chemical imbalances in the blood, and seizure control. Speed is critical. Avoid mouth-to-mouth resuscitation regardless of route of exposure. Avoid contact with vomitus, which may off-gas hydrogen cyanide.
  • ANTIDOTE: Amyl nitrite, sodium nitrite, and sodium thiosulfate are antidotes for cyanide toxicity; however, amyl nitrite and sodium nitrite should not be administered to patient/victims suffering from smoke inhalation. In these cases, only administer sodium thiosulfate. The described administration of nitrites is based on a patient having normal hemoglobin levels. Below normal hemoglobin levels require titration of nitrites.
    For mild to moderate physical findings such as nausea, vomiting, palpitations, confusion, anxiety, dizziness (vertigo), and/or abnormally fast or deep respiration (hyperventilation):
    • Child (less than 55 lb (25 kg)) Observe the patient/victim and administer 0.75 mL per pound of a 25% solution (1.65 mL per kilogram of a 25% solution) of sodium thiosulfate intravenously over a period of 10 minutes.
    • Adult Observe the patient/victim and administer 12.5 g of a 25% solution (50 mL of a 25% solution) of sodium thiosulfate intravenously over a period of 10 minutes.

    For severe physical findings such as coma; cessation of breathing (apnea); seizures; slowness of the heart rate, usually to fewer than 60 beats per minute (bradycardia); abnormally low blood pressure (hypotension); bluish skin coloring due to abnormally low levels of oxygen in the blood (cyanosis); irregular heart beat (dysrhythmias); and/or accumulation of fluid in the lungs (pulmonary edema):
    • Child (less than 55 lb (25 kg)) Until sodium nitrite becomes available, break one ampule of amyl nitrite into a cloth. Out of every minute, hold the cloth containing amyl nitrite in front of the patient's mouth for 30 seconds, and then remove it for 30 seconds, until sodium nitrite can be administered. A new ampule of amyl nitrite should be broken into a cloth every 3 minutes. Discontinue use of amyl nitrite when sodium nitrite becomes available. Administration of an entire dose (10 mL of a 3% solution) of sodium nitrite to a child can produce overwhelming lethal methemoglobinemia. Therefore, children should receive 0.15 mL per pound of body weight of sodium nitrite (0.33 mL per kg body weight of 3% sodium nitrite) over a period of 5 to 20 minutes.
      • Next, administer 0.75 mL per pound body weight of 25% sodium thiosulfate (1.65 mL per kilogram body weight of 25% sodium thiosulfate) intravenously over a period of 10 minutes. If physical findings persist for 30 minutes after antidote administration, sodium nitrite and sodium thiosulfate may be readministered at half their original respective doses. However, methemoglobin levels should be monitored and not allowed to exceed 40%.
    • If a child weighs more than 55 lb (25 kg), administer antidote as described for the adult (see below).
    • Adult Until sodium nitrite becomes available, break one ampule of amyl nitrite into a cloth. Out of every minute, hold the cloth containing amyl nitrite in front of the patient's mouth for 30 seconds, and then remove it for 30 seconds, until sodium nitrite can be administered. A new ampule of amyl nitrite should be broken into a cloth every 3 minutes. Discontinue use of amyl nitrite when sodium nitrite becomes available. Administer 300 mg of a 3% solution (10 mL of a 3% solution) of sodium nitrite intravenously over a period of 5 to 20 minutes.
      • Next, administer 12.5 g (50 mL of a 25% solution) of sodium thiosulfate intravenously over a period of 10 minutes. If physical findings persist for 30 minutes after antidote administration, sodium nitrite and sodium thiosulfate may be readministered at half their original respective doses. However, methemoglobin levels should be monitored and not allowed to exceed 40%.
  • EYE:
    • Immediately remove the patient/victim from the source of exposure.
    • Immediately wash eyes with large amounts of tepid water for at least 15 minutes.
    • Monitor the patient/victim for signs of whole-body (systemic) effects.
    • If signs of whole-body (systemic) poisoning appear, see the Inhalation section for treatment recommendations.
    • Seek medical attention immediately.
  • INGESTION:
    • Immediately remove the patient/victim from the source of exposure.
    • Establish secure large-bore IV access.
    • Ensure that the patient/victim has an unobstructed airway.
    • Do not induce vomiting (emesis).
    • Immediately administer 100% oxygen.
    • Prepare a cyanide antidote kit, for use under a physician's direction, for symptomatic patient/victims. See the Antidote section for antidote administration procedures.
    • Treat seizures with benzodiazepines.
    • Seek medical attention immediately.
  • INHALATION:
    • Immediately remove the patient/victim from the source of exposure.
    • Evaluate respiratory function and pulse.
    • Ensure that the patient/victim has an unobstructed airway.
    • Immediately administer 100% oxygen.
    • Assist ventilation as required.
    • If breathing has ceased (apnea), provide artificial respiration.
    • Establish secure large-bore intravenous (IV) access.
    • Prepare a cyanide antidote kit, for use under a physician's direction, for symptomatic patient/victims. See the Antidote section for antidote administration procedures.
    • Monitor for respiratory distress.
    • Seek medical attention immediately.
  • SKIN:
    • Immediately remove the patient/victim from the source of exposure.
    • See the Decontamination section for patient/victim decontamination procedures.
    • Monitor the patient/victim for signs of whole-body (systemic) effects.
    • If signs of whole-body (systemic) poisoning appear, see the Inhalation section for treatment recommendations.
    • Seek medical attention immediately.
See ATSDR Medical Management Guidelines for Acute Chemical Exposures, Hydrogen Cyanide, http://www.atsdr.cdc.gov/MHMI/mmg8.pdf, for detailed recommendations.
Long-Term Implications 
  • MEDICAL TREATMENT: Evidence for the benefit of gastric decontamination in cases of cyanide ingestion is limited at best and should come after all other known life-saving measures have been instituted. Gastric lavage (stomach pumping) is recommended only if it can be done shortly after ingestion (generally within 1 hour), in an emergency department, and after the airway has been secured. Activated charcoal may be administered as a slurry (240 mL water/30 g charcoal). Usual dose: 25 to 100 g in adults/adolescents, 25 to 50 g in children (1 to 12 years), and 1 g/kg in infants less than 1 year old. Patient/victims who have ingested hydrogen cyanide (AC) solutions or patient/victims who have direct skin or eye contact should be observed in the Emergency Department for at least 4 to 6 hours for the development of delayed symptoms. Patient/victims with significant inhalation exposure should be monitored for the accumulation of fluid in the lungs (pulmonary edema), which may occur up to 24 to 72 hours following exposure.
  • DELAYED EFFECTS OF EXPOSURE: Usually death occurs rapidly or there is prompt recovery. Survivors of severe cyanide exposures may suffer brain damage due to a direct effect of the poison (toxin) on nerve cells, or to a lack of oxygen, or possibly due to insufficient blood circulation. Examples of long-term neurological effects caused by cyanide poisoning include personality changes, memory loss, and disturbances in movement (both voluntary and involuntary movement disorders); some damage may be permanent.
  • EFFECTS OF CHRONIC OR REPEATED EXPOSURE: Hydrogen cyanide (AC) has not been classified for cancer-causing (carcinogenic) effects, and no carcinogenic effects have been reported for hydrogen cyanide (AC). No reproductive or developmental effects of hydrogen cyanide (AC) have been reported in humans. Chronically exposed workers may complain of headache, eye irritation, easy fatigue, chest discomfort, palpitations, loss of appetite (anorexia), and nosebleeds (epistaxis). Workers such as electroplaters and picklers, who are daily exposed to cyanide solutions, may develop a "cyanide" rash, characterized by itching and by macular, papular, and vesicular eruptions. Exposure to small amounts of cyanide compounds over long periods of time is reported to cause loss of appetite, headache, weakness, nausea, dizziness, and symptoms of irritation of the upper respiratory tract and eyes.
On-Site Fatalities 
  • INCIDENT SITE:
    • Consult with the Incident Commander regarding the agent dispersed, dissemination method, level of PPE required, location, geographic complications (if any), and the approximate number of remains.
    • Coordinate responsibilities and prepare to enter the scene as part of the evaluation team along with the FBI HazMat Technician, local law enforcement evidence technician, and other relevant personnel.
    • Begin tracking remains using waterproof tags.
  • RECOVERY AND ON-SITE MORGUE:
    • Wear PPE until all remains are deemed free of contamination.
    • Establish a preliminary (holding) morgue.
    • Gather evidence, and place it in a clearly labeled impervious container. Hand any evidence over to the FBI.
    • Remove and tag personal effects.
    • Perform a thorough external evaluation and a preliminary identification check.
    • See the Decontamination section for decontamination procedures.
    • Decontaminate remains before they are removed from the incident site.
See Guidelines for Mass Fatality Management During Terrorist Incidents Involving Chemical Agents, U.S. Army Soldier and Biological Chemical Command (SBCCOM), November, 2001 for detailed recommendations.
Occupational Exposure Limits 
  • NIOSH REL:
    • STEL: 4.7 ppm (5 mg/m3) (skin)
  • OSHA PEL:
    • TWA: 10 ppm (11 mg/m3) (skin)
  • ACGIH TLV:
    • Ceiling: 4.7 ppm (5 mg/m3) (skin)
  • NIOSH IDLH: 50 ppm
  • DOE TEEL:
    • TEEL-0: 2.21 mg/m3
    • TEEL-1: 2.21 mg/m3
    • TEEL-2: 11.1 mg/m3
    • TEEL-3: 16.6 mg/m3
  • AIHA ERPG:
    • ERPG-1: Not appropriate.
    • ERPG-2: 10 ppm
    • ERPG-3: 25 ppm
Acute Exposure Guidelines 
 5 min 10 min 30 min 1 hr 4 hr 8 hr
AEGL 1
(discomfort, non-disabling) - mg/m3		 Not established/ determined 2.5 ppm 2.5 ppm 2.0 ppm 1.3 ppm 1.0 ppm
AEGL 2
(irreversible or other serious, long-lasting effects or impaired ability to escape) - mg/m3		 Not established/ determined 17 ppm 10 ppm 7.1 ppm 3.5 ppm 2.5 ppm
AEGL 3
(life-threatening effects or death) - mg/m3		 Not established/ determined 27 ppm 21 ppm 15 ppm 8.6 ppm 6.6 ppm
The conversion factor in air can be calculated using the following formulas:
  • ppm = ((mg/m3) * 24.5) / molecular mass
  • mg/m3 = (ppm * molecular mass) / 24.5

See the Acute Exposure Guideline Levels for Selected Airborne Chemicals: Volume 2, the National Academy of Sciences Press, 2003 for detailed recommendations.
Decontamination (Environment and Equipment) 
  • ENVIRONMENT/SPILLAGE DISPOSAL: The following methods can be used to decontaminate the environment/spillage disposal:
    • Do not touch or walk through the spilled agent if at all possible. However, if you must, personnel should wear the appropriate PPE during environmental decontamination. See the PPE section of this card for detailed information.
    • Keep combustibles (e.g., wood, paper, and oil) away from the spilled agent. Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact the spilled agent.
    • Do not direct water at the spill or the source of the leak.
    • Stop the leak if it is possible to do so without risk to personnel, and turn leaking containers so that gas rather than liquid escapes.
    • Prevent entry into waterways, sewers, basements, or confined areas.
    • Isolate the area until gas has dispersed.
    • Ventilate the area.
  • EQUIPMENT: Agents can seep into the crevices of equipment making it dangerous to handle. The following methods can be used to decontaminate equipment:
    • Not established/determined
Agent Properties 
Chemical FormulaHCN
  
Aqueous solubilitySoluble
Boiling Point78°F (25.6°C)
DensityLiquid: 0.687
Vapor (Gas): 0.941
FlammabilityFlammable at temperatures greater than 0°F (-18°C)
Flashpoint0°F (-18°C)
Ionization potential13.60 eV
Log Kbenzene-waterNot established/determined
Log Kow (estimated)-0.25
Melting Point7.9°F (-13.4°C)
Molecular Mass27.03
Soluble InEther, glycerine, chloroform, and benzene.
Miscible with alcohol.
Specific Gravity0.69
Vapor Pressure630 mm Hg at 68°F (20°C)
742 mm Hg at 77°F (25°C)
Volatility1,080,000 mg/m3 at 77°F (25°C)
Hazardous Materials Warning Labels/Placards 
Shipping NameHydrogen cyanide, stabilized with less than 3 percent water
Identification Number1051 (Guide 117)
Hazardous Class or Division6.1
Subsidiary Hazardous Class or Division3
LabelInhalation Hazard
Flammable Liquid
Placard Image dot_class3_flammliquid dot_class6_poisoninhalhaz
Trade Names and Other Synonyms 
  • Acide cyanhydrique (French)
  • Acido cianidrico (Italian)
  • Aero liquid HCN
  • Blausaure (German)
  • Blausaeure (German)
  • Blauwzuur (Dutch)
  • Carbon hydride nitride (CHN)
  • Cyaanwaterstof (Dutch)
  • Cyanwasserstoff (German)
  • Cyclon
  • Cyclone B
  • Cyjanowodor (Polish)
  • Evercyn
  • Formic anammonide
  • Zaclondiscoids
  • Zyklon B
Who to Contact in an Emergency 
In the event of a poison emergency, call the poison center immediately at 1-800-222-1222. If the person who is poisoned cannot wake up, has a hard time breathing, or has convulsions, call 911 emergency services.
For information on who to contact in an emergency, see the CDC website at http://www.bt.cdc.gov/emcontact/index.asp or call the CDC public response hotline at (888) 246-2675 (English), (888) 246-2857 (Español), or (866) 874-2646 (TTY).
Important Notice 
The user should verify compliance of the cards with the relevant STATE or TERRITORY legislation before use. NIOSH, CDC 2003.
Page last updated:August 22, 2008
Page last reviewed: May 12, 2011
Content Source: National Institute for Occupational Safety and Health (NIOSH) Education and Information Division