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Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption, other
Remarks:
adsorption
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
2012
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Justification for type of information:
QSAR prediction
Guideline:
other: REACH guidance QSARs R6, May/July 2008
Principles of method if other than guideline:
Estimation Program Interface EPI-Suite version 4.1: KOCWIN (v2.00) for the estimation of the organic carbon-normalized sorption coefficient for soil and sediment (Koc).
The Estimation Program Interface was developed by the US Environmental Agency's Office of Pollution Prevention and Toxics, and Syracuse Research Corporation (SRC). © 2000 - 2011 U.S. Environmental Protection Agency for EPI SuiteTM (Published online in January 2011).
GLP compliance:
no
Type of method:
other: Estimation
Media:
soil
Radiolabelling:
no
Type:
log Koc
Value:
2.394 dimensionless
Remarks on result:
other: calculation (logKow method)
Type:
log Koc
Value:
1.945 dimensionless
Remarks on result:
other: calculation (MCI method)
Phase system:
other: Koc
Type:
other: Koc
Value:
247.9 L/kg
Remarks on result:
other: calculation (logKow method)
Key result
Phase system:
other: Koc
Type:
other: Koc
Value:
88.15 L/kg
Remarks on result:
other: calculation (MCI method)

Validity of the model:

1. Defined Endpoint: Organic carbon partition coefficient, given as logarithmic Koc and Koc

2. Unambigous algorithm: The molecule is first classified as a polar substance. Based on structure of the molecule, the following fragments were applied: 2 misc (C = O) group (aliphatic attach) and poly-chlorinated aromatic. The number of times of the fragments that occurs in the structure of the substance applied by the program is verified. For estimation of Log Koc according to Log Kow method an experimental Log Kow of 3.4 was used.

3. Applicable domain: With a molecular weight of 156.27 g/mole the substance is within the range of the training set (32 - 665 g/mol) as well as in the validation set (27 - 991 g/mol). Regarding the structure of DL-Menthol,the fragment descriptors found by the program are complete.

4a. Statistical characteristics (MCI method): N training set without corrections = 69; N training set with correction = 447; N validation set = 158; Correction coefficient of the total training set without corrections r² = 0.967; Correlation coefficient of the total training set with corrections r² = 0.900; Correlation coefficient of the total validation set r² = 0.850.

4b. Statistical characteristics (Kow method): N training set without corrections = 68; N training set with correction = 447; N validation set = 150; Correction coefficient of the total training set without corrections r² = 0.877; Correlation coefficient of the total training set with corrections r² = 0.855; Correlation coefficient of the total validation set r² = 0.778.

5. Mechanistic interpretation: Log Koc is estimated based on the likeliness of a substance for sorption to surfaces of soil/sediment particles. The log Koc is a physical inherent property used extensively to describe a chemical's likeliness to adsorb to organic carbon.

Adequacy of prediction:

The result for DL-Menthol falls within the applicability domain described above and the estimation rules applied for the substance appears appropriate.

Validity criteria fulfilled:
not applicable
Conclusions:
The QSAR determination of the carbon partition coefficient for DL-Menthol using the model KOCWIN included in the Estimation Program Interface (EPI) Suite v4.1 revealed values of 247.9 L/kg (logKow method using the log Kow of 3.4) and 88.15 L/kg (MCI method) for the unaffected molecule of the substance as any decomposition (e.g. hydrolysis) of the substance is not taken into account by the program.
Executive summary:

The organic carbon partition coefficient (Koc) for DL-Menthol was predicted using the QSAR calculation of the Estimation Program Interface (EPI) Suite v 4.1. The Koc was estimated to be 247.9 L/kg (logKow method), and 88.15 L/kg (MCI method). The results relate to the unaffected molecule of the substance as any decomposition (e.g. hydrolysis) of the substance is not taken into account by the program.

Description of key information

The QSAR determination of the carbon partition coefficient for Menthol using the model KOCWIN included in the Estimation Program Interface (EPI) Suite v4.1 revealed values of 247.9 L/kg (logKow method) and 88.15 L/kg (MCI method) for the unaffected molecule of DL-Menthol as any decomposition (e.g. hydrolysis) of the substance is not taken into account by the program.

Key value for chemical safety assessment

Koc at 20 °C:
88.15

Additional information