Registration Dossier

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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Classification & Labelling & PBT assessment

PBT assessment

Administrative data

Assessed Substance

Assessed substance:
substance itself

Results of detailed PBT / vPvB assessment


Evidence of non-P / non-vP properties
Screening criteria
Not P and not vP based on: readily biodegradable
Cyanide can be metabolised by a wide variety of organisms including bacteria, fungi, arthropods and plants using a number of different pathways. Non-toxic concentrations of cyanide can be readily biodegraded, both aerobically and anaerobically. Aerobic degradation yields CO2 and ammonia (that may be further converted to nitrate or nitrite); anaerobic biodegradation yields ammonia and methane. Degradation of cyanides in sewage treatment plants depends on the availability of adapted (micro-)organisms. Sudden high levels of cyanide in these sewage plants may lead to a loss of viability, while fully adapted sludge may tolerate and degrade concentrations up to 100 to 150 mg CN-/l with a high degree of efficiency. Vegetation is also able to remove cyanide from water or soil. Initial data indicate that cyanide-tolerant plants may be used for the remediation of cyanide-contaminated soil.
Criteria based on Annex XIII of REACH
Conclusion on P / vP properties:
not P/vP


Evidence of non-B / non-vB properties
Screening criteria
Not B and not vB based on: Log Kow ≤ 4.5
Based on its physico-chemical properties (log Kow = -0.25), HCN is not expected to bioaccumulate in aquatic organisms. HCN is either quickly metabolised or the organism dies.
Criteria based on Annex XIII of REACH
Conclusion on B / vB properties:
not B/vB


Evidence of non-T properties
Criteria based on Annex XIII of REACH
Evidence of T properties
Screening criteria: L(E)C50 < 0.01 mg/L
The acute aquatic LC50 in fish (Onchorhynchus mykiss or, for saltwater, Menidia menidia) is 57-59 micrograms of CN-/L. The acute LC50 in invertebrates in saltwater (Cancer irroratus), is 5 microgram/L. The acute aquatic EC50 in algae (Chlorococcales sp. or, in saltwater, Nitzschia closterium) is 45-57 microgram CN-/L).
The chronic LC50 for freshwater fish (Lepomis macrochirus) is estimated at 1 microgram CN-/L. The chronic LC50 for invertebrates (Gammarus pseudolimnaeus or, in saltwater, Mytilus galloprovincialis) is 3.2-3.9 microgram/L. The chronic EC50 for algae for saltwater (Champia parvula) is 3.9 microgram CN-/L.
The combined freshwater and saltwater value, based on 16 NOEC's, is 1.1 microgram CN-/L (JACC 53, 2007).
The substance is classified according to Regulation EC No. 1272/2008, for acute and chronic aquatic toxicity, Category 1, H400 and H410.
Conclusion on T properties:
HCN does not display properties of environmental persistence or bioaccumulation, although it is highly toxic to aquatic organisms. It does not meet the criteria for classification as PBT.