Registration Dossier

Administrative data

Endpoint:
distribution modelling
Type of information:
calculation (if not (Q)SAR)
Remarks:
Migrated phrase: estimated by calculation
Adequacy of study:
supporting study
Study period:
2008
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: Results were obtained using the EQC Model, as recommended by the U.S. Environmental Protection Agency. Measured and estimated data were both used for chemical-specific data required by the model.

Data source

Referenceopen allclose all

Reference Type:
other:
Title:
Fate, Distribution, and Transport of Hexamethylcyclotrisiloxane (CAS 541-05-9) in the Environment as Predicted by Multimedia modeling
Author:
SEHSC
Year:
2008
Bibliographic source:
SEHSC (2008). Revised report under review.
Reference Type:
other:
Title:
Fate, Distribution, and Transport of Dichlorodimethylsilane (CAS 75-78-5) in the Environment as Predicted by Multimedia modeling
Author:
SEHSC
Year:
2006
Bibliographic source:
SEHSC (2006). Appendix 1
Reference Type:
other:
Title:
Fate, Distribution, and Transport of Hexamethylcyclotrisiloxane (CAS 541-05-9) in the Environment as Predicted by Multimedia modeling
Author:
SEHSC
Year:
2006
Bibliographic source:
SEHSC (2006). Appendix 1
Reference Type:
other:
Title:
Estimations Programs Interface (EPI) Suite™.
Author:
USEPA
Year:
2003
Bibliographic source:
The EPI Suite™ and the individual models included within the software are owned and copyright protected by the U.S. Environmental Protection Agency

Materials and methods

Model:
calculation according to Mackay, Level III

Test material

Reference
Name:
Unnamed
Type:
Constituent

Results and discussion

Any other information on results incl. tables

D3 initially hydrolyzes to hexamethyltrisiloxanediol followed by final  hydrolysis to dimethylsilanediol (DMSD). 

Dimethylsilanediol is the final hydrolysis product of D3, but is not  usually isolated because of its tendency to condense and form higher  

molecular weight oligomers. Dimethylsilanediol can be kept in a stable  state only under special acid- and base- free conditions. Thus, most  

measured physicochemical properties of DMSD are not available; only  measured water solubility of 1x 106 mg/L at 25ºC. Furthermore, due to  

these properties, current estimation models are not capable of  calculating physicochemical or environmental fate values with any degree  of 

accuracy. Thus, modeled data are not provided for DMSD because  estimated physicochemical properties coupled with uncertainty associated  

with the modeling of this chemical class, could result in an assessment  of an unrealistic scenario.  

The adsorption of DMSD onto surfaces and its tendency to polymerize  itself are important properties of this chemical. In the environment,  DMSD 

is expected to be found in water and air and to be adsorbed by soil  and sediment, but is still subject to hydrolysis. Unbound DMSD in air,  water, 

and soil is expected to degrade photolytically to silica and  carbon dioxide. DMSD has been shown to biodegrade to methylsilanetriol,  carbon 

dioxide, and silica.


Equal Emissions Senario        Air        Water        Soil        Sed        Total
Emission rate (kg/h)        1000        1000        1000                
Distribution (%)        9.6        1.0        89.4        0.0        
Reaction losses (%)        33.4        33.3        31.5        0.0        98.2
Advective losses (%)        1.8        0.0                0.0        1.8
Overall persistence (d)        0.79
Reaction persistence (d)        0.80
Advective persistence (d)        43

Emission to Air Senario        Air        Water        Soil        Sed        Total
Emission rate (kg/h)        1000                                
Distribution (%)        99.9        0.0        0.1        0.0        
Reaction losses (%)        94.8        0.0        0.0        0.0        94.8
Advective losses (%)        5.2        0.0                0.0        5.2
Overall persistence (d)        0.22
Reaction persistence (d)        0.23
Advective persistence (d)        4.2

Emission to Water Senario        Air        Water        Soil        Sed        Total
Emission rate (kg/h)                1000                        
Distribution (%)        1.2        98.3        0.0        0.4        
Reaction losses (%)        0.1        99.8        0.0        0.0        99.9
Advective losses (%)        0.0        0.1                0.0        0.1
Overall persistence (d)        0.023
Reaction persistence (d)        0.023
Advective persistence (d)        38

Emission to Soil Scenario        Air        Water        Soil        Sed        Total
Emission rate (kg/h)                        1000                
Distribution (%)        0.6        0.0        99.4        0.0        
Reaction losses (%)        5.3        0.0        94.5        0.0        99.7
Advective losses (%)        0.3        0.0                0.0        0.3
Overall persistence (d)        2.1
Reaction persistence (d)        2.1
Advective persistence (d)        742

Applicant's summary and conclusion