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Environmental fate & pathways

Distribution modelling

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Administrative data

Endpoint:
distribution modelling
Remarks:
(Q)SAR calculated endpoint
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Study period:
not applicable
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
QSAR prediction:US EPA accepted QSAR method for organic chemicals properties assessment. Recognised method of fugacity calculations.

Data source

Reference
Reference Type:
other: QSAR
Title:
EPI Suite v 4.1/Level III Fugacity Model
Author:
US EPA
Year:
2014
Bibliographic source:
http://epa.gov/oppt/exposure/pubs/episuite.htm

Materials and methods

Model:
calculation according to Mackay, Level III
Calculation programme:
EPI Suite v 4.1/Level III Fugacity Model
Release year:
2 011
Media:
other: all

Test material

Reference
Name:
Unnamed
Type:
Constituent

Study design

Test substance input data:
- Parameters as per physicochemical summary data.
- Reaction half-life estimates for:
Air: 1e+005
Water: 360
Soil: 720
Sediment: 3240




Environmental properties:
- Environmental compartment sizes and character as per the TGD

Results and discussion

Percent distribution in media

Air (%):
0
Water (%):
26.2
Soil (%):
73.8
Sediment (%):
0.072
Susp. sediment (%):
0
Biota (%):
0
Aerosol (%):
0
Other distribution results:
The figures above represent the first emission scenario shown below

Any other information on results incl. tables

 

  

 Level III Fugacity Model (Full-Output):

=======================================

Chem Name  : Silica

 Molecular Wt: 60.08

 Henry's LC : 8.75e-014 atm-m3/mole (calc VP/Wsol)

 Vapor Press : 5.36e-008 mm Hg (Mpbpwin program)

 Liquid VP  : 1.13e-006 mm Hg (super-cooled)

Log Kow    : 0.53 (Kowwin program)

 Soil Koc   : 21.7 (KOCWIN MCI method)

 

 

TABLE 1

 

Mass Amount

(percent)

Half-Life

(hr)

Emissions

 

(kg/hr)

Air

3.16e-006

1e+005

1000

 

Water

26.2

360

1000

 

Soil

73.8

720

1000

 

Sediment

0.0717

3.24e+003

0

 

                  

 

TABLE 2A

 

Fugacity

(atm)

Reaction

(kg/hr)

Advection

(kg/hr)

Reaction

(percent)

Advection

(percent)

Air

1.46e-016

4.45e-007

0.000643

1.48e-008

2.14e-005

Water

3.87e-018

1.02e+003

532

34.1

17.7

Soil

1.48e-016

1.44e+003

0

48.1

0

Sediment

3.49e-018

0.312

0.0292

0.0104

0.000972 

 

 

 

Persistence Time: 678 hr

  Reaction Time:   824 hr

  Advection Time:  3.82e+003 hr

  Percent Reacted: 82.3

  Percent Advected: 17.7

 

  Half-Lives (hr), (based upon Biowin (Ultimate) and Aopwin):

     Air:     1e+005

     Water:   360

     Soil:    720

     Sediment: 3240

       Biowin estimate: 3.066 (weeks      )

 

  Advection Times (hr):

     Air:     100

     Water:   1000

     Sediment: 5e+004

Applicant's summary and conclusion

Conclusions:
Silica has no affinity to be in air and sediment. The direct emissions to soil and surface water are significant, therefore Silica will be almost exclusively be found in soil and surface water.
Executive summary:

Mackay fugacity modelling (level 3) indicates that, taking into account degradation and using inflow parameters which are consistent with the known production tonnage of this substance in, fugacity coefficient indicates that environmental concentrations in water are predicted to be  3.87e-018 (atm), in air (atm) 1.46e-016 and soil 1.48e-016 (atm) and sediment to be   3.49e-018 (atm).

These are negligible low levels. This can be considered a worse case prediction as it assumes all product is emitted with no emission control systems used.