Registration Dossier

Administrative data

Endpoint:
distribution modelling
Type of information:
(Q)SAR
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: modelled from a validated (Q)SAR model.
Justification for type of information:
QSAR prediction: migrated from IUCLID 5.6

Data source

Reference
Reference Type:
other:
Title:
Unnamed
Year:
2004

Materials and methods

Model:
calculation according to Mackay, Level III
Calculation programme:
Equilibrium Calculation (EQC), version 2.02
Release year:
2 003
Media:
air - biota - sediment(s) - soil - water

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
modeled as 100% pure

Results and discussion

Percent distribution in media

Air (%):
91.31
Water (%):
7.97
Soil (%):
0.71
Sediment (%):
0.01

Any other information on results incl. tables

The results show that cyanide discharged into surface water will remain mainly in the water compartment at compartmental transfer equilibrium and the partition equilibrium will never be achieved. Likewise, cyanide discharged into air will stay in air.

In a 1994 HazChem model (ECETOC, 1994), a more realistic global model was used, in which water accounts for 70% and soil accounts for 30% (earth's surface area), the air compartment was scaled up to 5000 m and depth of water to 200 m, while advection of water and air was set to zero. These dimensions showed an overall residence time in air of 2,310 hours (3.3 months). The release rate of HCN required to achieve a steady-state level in air of 0.2639 microgram/m3 (243 ppt) of HCN in this real world required an annual input of 3.1 Mtonnes HCN.

Applicant's summary and conclusion

Conclusions:
Cyanide in air will remain in air (91.31%); cyanide in water will remain in water (92%). A small amount of cyanide will adsorb to soil and will preferentially (10-fold) move to the air compartment over water. The small amount of cyanide which will adsorb to sediment will preferentially (10-fold) move to the water compartment over air. The half life in air is predicted to 357 day; in water, 15 days; in sediment, 60 days. A more relevant model predicts a half life in air of 3.3 months.
Executive summary:

A Mackay Level III model was applied to hydrogen cyanide to predict distribution in air/water/soil/sediment compartments. Cyanide in surface water is predicted to remain mainly in the water compartment at compartmental transfer equilibrium, while the cyanide in air will remain in air. The partition equilibrium will never be achieved. The half-life in air is predicted to be approximately a year (357 days); in water and soil: 15 days; and in sediment: 60 days. A more global model predicts a residence time of 3.3 months in air.. The release rate of HCN required to achieve a steady state level in air of 0.2639 micrograms/m3 (243 ppt) of HCN in this model required an annual input of 3.1 metric tonnes of HCN.