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Environmental fate & pathways

Distribution modelling

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Administrative data

Endpoint:
distribution modelling
Type of information:
calculation (if not (Q)SAR)
Remarks:
Migrated phrase: estimated by calculation
Adequacy of study:
key study
Study period:
2004
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Peer reviewed data

Data source

Reference
Reference Type:
secondary source
Title:
Unnamed
Year:
2004

Materials and methods

Model:
calculation according to Mackay, Level I
Calculation programme:
Trent University (1999 & 2004). Fugacity-based Environmental Equilibrium Partitioning Model. Version 2.2.
Release year:
2 002
Media:
air - biota - sediment(s) - soil - water

Test material

Reference
Name:
Unnamed
Type:
Constituent

Study design

Test substance input data:
- Molar mass: 116.07 g/mol
- Data temperature: 25 °C
- Water solubility: 407,000 g/m³
- Vapour pressure: 4.8 x 10-3 Pa
- log Pow: -2.61
- Melting point: 84.2 ºC
- Reaction half-life estimates for
- Air: 29.3 hours
- Water: 208 hours
- Soil: 208 hours
- Sediment: 832 hours

Results and discussion

Percent distribution in media

Air (%):
0
Water (%):
100
Soil (%):
0
Sediment (%):
0
Susp. sediment (%):
0
Biota (%):
0
Aerosol (%):
0

Any other information on results incl. tables

    
The material was modeled as a Type 1 chemical, i.e., it was assumed  capable of partitioning into all media. A more correct approach would  have been to model the material as a Type 2 chemical with a Z value of  zero or near-zero in air and an initial estimate of Z in water of 1.0.  This partitioning model would be calculated using the equivalence  approach instead of the fugacity calculation. However, the required  partition coefficients for Type 2 chemicals are not those used for Type 1  chemicals and were not available. Appropriate partition coefficients are  not readily estimated for Type 2 chemicals. In the absence of data,  errors and uncertainty from using estimated parameters would be likely to  counteract any improved accuracy from using a better model. Consequently,  more detailed modeling would be unlikely to significantly affect the  prediction of environmental fate if greater water solubility were assumed  (Zwater = 1.0).

Resulting distributions of maleic acid (resulting from hydrolysis of maleic anhydride) were:
Level II
Air: < 0.01%
Water: 100%
Soil: 0.0%
Sediment: 0.0%
Resulting distributions of maleic acid (resulting from hydrolysis of  maleic anhydride) were:
Level III
Air:       0.0%
Water:       50%
Soil:       50%
Sediment: 0.02%

Applicant's summary and conclusion