Registration Dossier

Administrative data

Endpoint:
distribution modelling
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: modeled from a validated (Q)SAR model.

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

Other distribution results:
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.

Any other information on results incl. tables

Table: Input of HCN to air and water at 25°C following EQC level III modelling (ten Berge,

2004a)

Compartment

Input to air (%)

Input to water (%)

Air

91.31

 

7.77

 

Water

7.97

 

92.0

 

Soil

0.707

 

6.01 x 10-2

 

Sediment

1.33 x 10-2

 

 

0.154

 

Half-life in air

8,556 h (356.5 d)

 

Half-life in water, soil

360 h (15 d)

 

Half-life in sediment

1,440 h (60 d)

 

 

 

Potassium cyanide and sodium cyanide can be considered as a chemical category, along with hydrogen cyanide (HCN) and acetone cyanohydrin (ACH, also known as 2-hydroxy-2-methylpropanenitrile), based on structural similarity, similar physico-chemical properties and common breakdown/metabolic products in physical and biological systems. Particular attention is paid to the dissociation constant of HCN. In the vast majority of environmental and physiologic conditions, the cyanide salts will dissolve in water to form hydrogen cyanide. The physico-chemical hazards and toxicity result from the activity of this common proximal toxicant, HCN.An ECETOC Task Force, in the 2007 ECETOC Joint Assessment of Commodity Chemicals ( JACC ) Report No. 53, “Cyanides of Hydrogen, Sodium and Potassium, and Acetone Cyanohydrin (CAS No. 74-90-8, 143-33-9, 151-50-8 and 75-86-5)” supports the development of this chemical category. Hydrogen cyanide (Index No.006-006-00-X) and salts of hydrogen cyanides (Index No.006-007-00-5) are both listed in Annex VI,Table 3.1 of Regulation (EC) No. 1272/2008, entry 006-007-00-5, and are restricted in comparable ways taking into account physical characteristics. Thus, the assignment of potassium cyanide and sodium cyanide to a chemical category does not result in a less protective regulatory status.

Applicant's summary and conclusion

Conclusions:
Cyanide released to air will remain mainly in the air compartment (91.31%); cyanide released to water will remain mainly in the water compartment (92%). A small amount of cyanide will adsorb to soil and will preferentially (10-fold) move to the air compartment over the water compartment. The small amount of cyanide which will adsorb to sediment will preferentially (10-fold) move to the water compartment over the air compartment. 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. Hydrogen cyanide (Index No.006-006-00-X) and salts of hydrogen cyanides (Index No.006-007-00-5) are both listed in Annex VI, Table 3.1 of Regulation (EC) No. 1272/2008, entry 006-007-00-5, and are restricted in comparable ways taking into account physical characteristics. Thus, the assignment of potassium cyanide and sodium cyanide to a chemical category does not result in a less protective regulatory status.
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.