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Environmental fate & pathways

Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Remarks:
adsorption
Type of information:
calculation (if not (Q)SAR)
Remarks:
Estimated by calculation
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Principles of method if other than guideline:
Calculated usind KOWIN v2.00 of EPI-Suite software as well as according to Sabljic (1995) and Gerstl (1990).
The calculation using KOWIN program is based upon the molecule structure using the molecular connectivity method.
The calculation according to Sabljic (1995, QASR Modelling of Soil Sorption. Improvements and Systematics of logKoc vs. logKow Correlations. Chemosphere, Vol. 31, pp. 4498-4514) is based on a statistical relationships between Koc and the octanol/water partition coefficient.
The calculation according to Gerstl (1990, Estimation of Organic Chemical Sorption by Soils, Journal of Contaminant Hydrology, 6, pp. 357-375) is based on a statistical relationships between Koc and the octanol/water partition coefficient.
GLP compliance:
no
Type of method:
other: Estimation
Media:
soil
Radiolabelling:
no
Sample No.:
#1
Type:
log Koc
Value:
3.75 dimensionless
Remarks on result:
other: Substance class: predominantly hydrophobics (calculation according to Sabljic, 1995)
Sample No.:
#2
Type:
log Koc
Value:
3.72 dimensionless
Remarks on result:
other: Substance class: all compounds (calculation according to Gerstl, 1990)
Sample No.:
#3
Value:
5.75 dimensionless
Remarks on result:
other: Calculation according to molecular connectivity method (KOCWIN v2.00)
 logKoc Calculation according to  Substance class  Equation  Input parameter (Reference)
 3.75  Sabljic (1995) predominantly hydrophobics  logKoc = 0.81 logKow + 0.1  logKow = 4.5 (Monsanto, 1985)
3.72  Gerstl (1990)  all compounds  logKoc = 0.679 logKow + 0.663  logKow = 4.5 (Monsanto, 1985)
 5.75 KOCWIN v2.00  ./.  molecular connectivity method  ./.
Conclusions:
The calculated log Koc-values of 3.72, 3.75 and 5.75 indicate a high sorption potential to soil and sediment and suggests a slow migration potential to ground water.
Executive summary:

The calculated log Koc-values of 3.72 (Gerstl 1990), 3.75 (Sabljic 1995), and 5.75 (EPIWIN) indicate a high sorption potential to soil and sediment and suggests a slow migration potential to ground water (Currenta, 2010). The lowest log Koc of 3.72 is used for further assessment as a worst case assumption.

Description of key information

The calculated log Koc-values of 3.72 (Gerstl 1990), 3.75 (Sabljic 1995), and 5.75 (EPIWIN) indicate a high sorption potential to soil and sediment and suggests a slow migration potential to ground water (Currenta, 2010). The lowest log Koc of 3.72 is used for further assessment as a worst case assumption.
The log Koc of the potential metabolites of MBTS, such as MBT, BT, and MeSBT, are mostly higher than 3 indicating moderate to strong potential for soil and sediment adsorption as the same as MBTS. Only BTon (estimated log Koc of 1.93) has very low adsorption potential.

Key value for chemical safety assessment

Koc at 20 °C:
5 248

Additional information

[LogKoc: 3.72]