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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: Scientifically accepted calculation method.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Model:
calculation according to Mackay, Level III
Media:
other: air-water-soil-sediment

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
not specified
Details on test material:
- Name of test material: Benzenesulfonic acid, mono C-20-24-alkyl-derivs., magnesium salts
- CAS number: 231297-75-9
- Molar mass: 927.77 g/mol
- Molecular formula: C54H94O6S2Mg
- Smiles code: CC(CCCCCCCCCCCCCCCC)c1ccc(cc1)S(=O)(=O)O[Mg]OS(=O)(=O)c2ccc(cc2)C(CCC)CCCCCCCCCCCCCCCCCCCC

Study design

Test substance input data:
- Name of test material: Benzenesulfonic acid, mono C-20-24-alkyl-derivs., magnesium salts
- CAS number: 231297-75-9
Environmental properties:
Emission default values are used for estimation:
Air, water and soil: 1000 kg/h
Sediment: 0 kg/h

Results and discussion

Percent distribution in media

Air (%):
0.003
Water (%):
0.63
Soil (%):
99.4
Sediment (%):
0
Other distribution results:
Half-lives:
Air: 4.42 h, water: 100000 h, soil: 100000 h, sediment: 100000 h
Persistence Time: 54300 h

Applicant's summary and conclusion

Conclusions:
The study report describes a scientifically accepted calculation method to determine the soil adsorption coefficient using the US-EPA software EPIWIN/LEVEL3NT.EXE. No GLP criteria are applicable for the usage of this tool and the QSAR estimation is easily repeatable.
Executive summary:

Distribution modelling for magnesium sulfonate target substance (CAS 231297-75-9) is performed with the scientifically accepted computer program EPIWIN by US-EPA (Chemservice S.A., 2012). The executable file for this Mackay Level III fugacity model is called LEVEL3NT.EXE. The partitioning of an organic compound in an evaluative environment is predicted by fugacity models, in general. The software is no stand-alone version and it contains a direct adaption of the Level III fugacity model developed by Dr. Donald Mackay et al. (Mackay, 1991; Mackay et al., 1996). Level III modelling assumes a steady-state, but no common equilibrium conditions between the different environmental compartments. 4 main compartments are concerned: air, water, sediment and soil. Between these compartments, mass transport is modeled via volatilization, diffusion, deposition and runoff. A fixed temperature of 25 °C is assumed. No substance properties are entered manually, thus default values are used.

In general, disappearance of a chemical occurs via two processes: reaction and advection. The abiotic or biotic degradation belongs to reaction, whereas the removal from a compartment through losses other than degradation is called advection. The rate of advection is determined by a specific flow rate, which may be specified by the user. Furthermore, the user can specify emission rates; otherwise the default emission rate is equal amounts to air, water and soil. For the sediment compartment, no direct emissions are considered. If half-lives in the different compartments are known, the values should be entered manually. Otherwise, EPIWIN software BIOWIN (Biowin 3 – Ultimate Biodegradation Timeframe) and AOPWIN are used to make these estimations by default. If a chemical is susceptible to abiotic hydrolysis, HYDROWIN may be able to provide the half-life. If a combination of hydrolysis, photolysis and biodegradation is likely for the compound, the half-lives shall be converted to rate constants and added together. The resulting overall half-life should be entered into the modelling. The output of Biowin 3 cannot be used directly by the Level III mass balance model. The mean value is converted to a half-life using a set of conversion factors, which consider that 6 half-lives constitute complete degradation with first-order kinetics.

Ultimate biodegradation is generally slower under anaerobic conditions than under aerobic conditions. The program concerns aerobic conditions; only for sediment an anaerobic environment is assumed. The rate of ultimate degradation in sediment is on average one-ninth (1/9) of that in the water column. A further adjustment is taken into account: In general, the biodegradation rate in soil is, on average, one-half (1/2) that in water. Therefore, a half-life in soil twice that estimated for water is assigned. The default environmental emission rates are 1000 kg/h to air, water and soil (sediment: 0 kg/h), which may be altered manually. The advection lifetimes of the substance in air, water and sediment compartments are set to the default values of 100, 1000 and 50000 hours, respectively. These lifetimes are used to determine the advective flow rate (m³/h). If no advection to any compartment is expected, the lifetime should be set to some arbitrarily large value (such as 1E20); this effectively changes the advective flow rate to zero. A soil Koc value is also required for the fugacity model. By default, the connectivity-based adsorption coefficient is used (MCI result by KOCWIN).

For the four compartments, i. e. air, water, soil and sediment, the following mass amounts are predicted: 0.0031 %, 0.629 %, 99.4 % and 3.04E-10 %, respectively. The half-life of the test substance in air will be 4.42 h and 100,000 h in the water, sediment and soil compartment. The overall persistence time gives a measure of how long the chemical remains in the model environment and is estimated as 54,300 h (ca. 6.2 years) for the test substance.