Hydrogen cyanide

Other names

HCN, prussic acid, carbon hydride nitride, formic acid nitrile, hydrocyanic acid, formonitrile, cyclon

CAS Number



  • highly flammable, water-soluble liquid
  • smells like bitter almonds
  • cyanides convert to hydrogen cyanide in human stomachs, in reaction to stomach acid

Main sources

  • industrial processes: metal mining, plastics manufacturing (combustion of polymers that contain nitrogen)
  • waste management: waste water, exhaust air
  • agriculture: pest control
  • tobacco smoke

Thresholds for the reporting requirement of facilities in accordance with Annex 2 PRTRO

(Ordinance on the Register relating to Pollutant Release and the Transfer of Waste and of Pollutants in Waste Water)

  • Air                200 kg/year
  • Water           -
  • Soil               -


  • very toxic, to aquatic organisms as well

Further information

Last modification 04.07.2018

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