Hydrogen cyanide (HCN)

HCN, Cyanväte (Vätecyanid)

 Hydrogen cyanide is a colourless gas or liquid (boiling point of 26°C) with an odour of bitter almond.

Uses

Hydrogen cyanide is produced synthetically but is also a by-product of certain combustion processes (for example in coke ovens).

The substance is used in production of synthetic fibres, plastics, pesticides and dyes as well as in chemical synthesis¹. Hydrogen cyanide is also used as a pesticide for insects, arthropods and smaller vertebrates and in rat poisoning².

Hydrogen cyanide is a reaction product of cyanogenic glycosides – a group of toxins that for example exist in certain plants of which some are foods, e.g. cassava, apricot kernels and flax seeds³.

Sources and transportation pathways

Hydrogen cyanide is formed during combustion of materials containing nitrogen, for example nylon, wool, rubber and polyurethane⁴. The substance also exists in tobacco smoke.

The most important transportation pathway is by air and larger point sources of hydrogen cyanide are for example emissions from metal industry and from different combustion processes.

Effects on environment and health

Hydrogen cyanide is highly poisonous to aquatic organisms and may result in both acute and long-term effects⁵.

Hydrogen cyanide is also highly poisonous to humans. Ingestion, skin contact or inhalation may be lethal or result in severe poisoning⁶. Hydrogen cyanide poisoning may cause cramps, unconsciousness, difficulty in breathing and have effects on the heart⁷.

International agreements and regulations

Hydrogen cyanide is regulated by the EU Water Framework Directive (2000/60/EC). The UN Protocol on PRTRs and the EU E-PRTR regulation regulate how data on hydrogen cyanide emissions is made available.



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¹ https://www.atsdr.cdc.gov/substances/toxsubstance.asp?toxid=249
² https://rib.msb.se/Portal/template/pages/Kemi/Substance.aspx?id=2422
³ https://www.livsmedelsverket.se/livsmedel-och-innehall/oonskade-amnen/vaxtgifter/cyanogena-glykosider-och-vatecyanid
⁴ https://www.msb.se/RibData/Filer/pdf/17521.pdf
⁵ https://echa.europa.eu/information-on-chemicals/cl-inventory-database/-/discli/details/131393
⁶ https://echa.europa.eu/information-on-chemicals/cl-inventory-database/-/discli/details/131393
⁷ https://rib.msb.se/Portal/Template/Pages/Kemi/Substance.aspx?id=2422&q=cyanv%c3%a4te&p=1