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Adsorption / desorption

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Endpoint:
adsorption / desorption, other
Remarks:
adsorption
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
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:
1. SOFTWARE
EPI Suite v4.11 Estimation Programs Interface Suite™ for Microsoft® Windows v 4.11. US EPA, United States Environmental Protection Agency, Washington, DC, USA.

2. MODEL (incl. version number)
KOCWIN v2.00, Log Kow based model

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See “Test material information”

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached information on the model provided by the developer. Further information on the OECD criteria as outlined by the applicant is provided below under "Any other information of materials and methods incl. tables"

5. APPLICABILITY DOMAIN
See attached information and information as provided in "Any other information on results incl. tables".

6. ADEQUACY OF THE RESULT
See assessment of adequacy as outlined in the "Overall remarks, attachments" section.
Qualifier:
according to guideline
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version: EPI Suite v4.11
- Model(s) used: KOCWIN v2.00
Full reference and details of the used formulas can be found in:
1. Doucette, W.J. 2000. Soil and sediment sorption coefficients.  In: Handbook of Property Estimation Methods, Environmental and Health Sciences. R.S. Boethling & D. Mackay (Eds.): Lewis Publishers (ISBN 1-56670-456-1). 
2. US EPA. [2012]. Estimation Programs Interface Suite™ for Microsoft® Windows, v 4.11 or insert version used]. United States Environmental Protection Agency, Washington, DC, USA.
- Model description: see field 'Justification for non-standard information', 'Attached justification' and 'any other information on Material and methods'
- Justification of QSAR prediction: see field 'Justification for type of information', 'Attached justification' and/or 'overall remarks'
GLP compliance:
no
Type of method:
other: calculation
Media:
soil
Details on test conditions:
BASIS FOR CALCULATION OF Koc:
- Estimation software: EPI Suite™ v4.11, KOCWIN v2.00, Log Kow based method
- Result based on measured log Pow of: 2.6

Type:
Koc
Value:
338.9 L/kg
Temp.:
25 °C
Type:
log Koc
Value:
2.53 dimensionless
Temp.:
25 °C

For detailed information on the results please refer to the attached report.

Endpoint:
adsorption / desorption, other
Remarks:
adsorption
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
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:
1. SOFTWARE
EPI Suite v4.11 Estimation Programs Interface Suite™ for Microsoft® Windows v 4.11. US EPA, United States Environmental Protection Agency, Washington, DC, USA.

2. MODEL (incl. version number)
KOCWIN v2.00

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See “Test material information”

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached information on the model provided by the developer. Further information on the OECD criteria as outlined by the applicant is provided below under "Any other information of materials and methods incl. tables"

5. APPLICABILITY DOMAIN
See attached information and information as provided in "Any other information on results incl. tables".

6. ADEQUACY OF THE RESULT
See assessment of adequacy as outlined in the "Overall remarks, attachments" section.
Qualifier:
according to guideline
Guideline:
other: REACH Guidance on QSARs R.6
Principles of method if other than guideline:
- Software tool(s) used including version: EPI Suite v4.11
- Model(s) used: KOCWIN v2.00, MCI based method
Full reference and details of the used formulas can be found in:
Meylan, W., P.H. Howard and R.S. Boethling, "Molecular Topology/Fragment Contribution Method for Predicting Soil Sorption Coefficients", Environ. Sci. Technol. 26: 1560-7 (1992)
- Model description: see field 'Justification for non-standard information', 'Attached justification' and 'any other information on Material and methods'
- Justification of QSAR prediction: see field 'Justification for type of information', 'Attached justification' and/or 'overall remarks'
GLP compliance:
no
Type of method:
other: calculation
Media:
soil
Details on test conditions:
BASIS FOR CALCULATION OF Koc:
- Estimation software: EPI Suite™ v 4.11, KOCWIN v2.00, MCI based method

Type:
Koc
Value:
491.8 L/kg
Temp.:
25 °C
Type:
log Koc
Value:
2.69 dimensionless
Temp.:
25 °C

For detailed information on the results please refer to the attached report.

Description of key information

Adsorption is not expected based on the low log Pow (2.6 at 25 °C and pH3, undissociated form). 

Key value for chemical safety assessment

Koc at 20 °C:
338.9

Additional information

Experimental studies on the adsorption potential of 2,5-Xylenol to particles are not available. The adsorption potential of the substance is expected to be low based on a log Pow of 2.6 at 25 °C and pH3. The log Pow was determined for the undissociated form of the molecule which is expected to be the predominant form at environmentally relevant pH. The pKa of 2,5-Xylenol is 10.41 at 25 °C indicating that the substance will not dissociate within an environmentally relevant pH range (pH 5-9, ECHA Guidance document R.7a, 2017).

A low adsorption potential is also indicated by(Q)SAR using the KOCWIN v2.00 model based on the Molecular Connectivity Index (MCI) and the log Kow method (EPI Suite v4.11). The estimated log Koc was 2.69 for the undissociated form based on the MCI method. The log Koc value obtained by the log Kow method was 2.53 using the experimentally determined log Pow of 2.6 as input parameter. Both models indicate a low potential for sorption to particles of soil and sediment as well as to particulate matter. The slightly lower log Koc obtained by the log Kow method is the worst case for the aquatic compartment and is used as key value for the PNEC derivation for sediment and soil.