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Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
(Q)SAR
Adequacy of study:
key study
Study period:
02 May 2018
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:
According to annex VIII 9.3.1 of the REACH Regulation EC/2006/1907, “Adsorption/desorption screening” is standard information required for the registration of substances manufactured or imported in quantities of ten tonnes per year or more. REACH accepts and encourages the use of QSARs validated in accordance with the OECD Principles.The requirements for REACH can be considered as met as described in the reports ( attached below), and because full information is provided in the registration dossier. This includes a robust study summary and an endpoint summary included in the IUCLID dossier. As well as supported information from a QMR that describes the QSAR model, and a QPR that reports the predictions.
Principles of method if other than guideline:
The MCI methodology was selected to estimate the log Koc. QSAR estimation methodology based on the MCI methodology is described in a journal article (Meylan et al, 1992) and in a report prepared for the US EPA (SRC, 1991). The same methodology as described in (Meylan et al, 1992) was used to develop the QSAR equations utilizing Molecular Connectivity Index (MCI). Two separate regressions were performed in the MCI methodology. The first regression related log Koc of non-polar compounds (n = 69) to the first-order MCI. The second regression included the 447 compounds having correction factors; Correction factors are specific chemical classes or structural fragments. The regression coefficients were derived via multiple linear regression of the correction descriptors to the residual error of the prediction from the non-polar equation. See QPR and QMRF for more information.
GLP compliance:
no
Remarks:
Not required for a calculation based on QSAR methods
Type of method:
other: QSAR
Media:
soil
Details on study design: HPLC method:
Not required for a calculation based on QSAR methods
Key result
Type:
log Koc
Value:
>= 2.576 - <= 11.304 dimensionless
Temp.:
20 °C
Remarks on result:
other: Calculation based on QSAR

The predicted Log Kocvalues of the representative constituents of the UVCB “Soybean oil, epoxidized, methyl ester, reaction products with propylene glycol”

Constituent representative

Log Koc

Comment

 

(representative of the unsaturated methyl ester fatty acids)

4.6764

Within the applicability domain.

Represents 10-20% of the UVCB.

 

(representative of the unsaturated methyl ester fatty acids that are epoxidised)

4.0479

Within the applicability domain.

Represents 10-35% of the UVCB.

 

(representative of the monomers)

2.5757

Within the applicability domain.

Represents 25-50% of the UVCB.

 

(representative of the oligomers)

11.3040

Out of the applicability domain.

The value is only considered as “an indication”.

Represents 10-55% of the UVCB.

 

 

Validity criteria fulfilled:
yes
Remarks:
QSAR model validated to be compliant with the OECD recommendation for QSAR modelling (OECD, 2004) described within the QMRF.
Conclusions:
The predicted Log Koc of the representative constituents of the UVCB Soybean oil, epoxidized, methyl ester, reaction products with propylene glycol were determined to have a log Koc range of 2.58 to 11.30.
Executive summary:

A QSAR approach, based on EpiSuite KOCWIN MCI methodology, was used to predict the log Koc range for adsorption /desorption exposed to the test item Nourypol. Two separate regressions were performed in the MCI methodology. The first regression related log Koc of non-polar compounds (n = 69) to the first-order MCI. The second regression included the 447 compounds with correction factors.The regression coefficients were derived via multiple linear regression of the correction descriptors to the residual error of the prediction from the non-polar equation. All criteria for the application of QSARs under REACH were met. The predictions for adsorption/desorption in soil was considered to be adequate and fit-for-purpose, except for the 4th constituent representative, for which the proposed Log Koc can only be considered as an indication of the behaviour of such a polymerised structure. The predicted Log Koc of the representative constituents of the UVCB Nourypol were determined to have a log Koc range of 2.58 to 11.30.

Description of key information

A QSAR approach, based on EpiSuite KOCWIN MCI methodology, was used to predict the log Koc range for adsorption /desorption exposed to the test item Soybean oil, epoxidized, methyl ester, reaction products with propylene glycol. Two separate regressions were performed in the MCI methodology. The first regression related log Koc of non-polar compounds (n = 69) to the first-order MCI. The second regression included the 447 compounds with correction factors.The regression coefficients were derived via multiple linear regression of the correction descriptors to the residual error of the prediction from the non-polar equation. All criteria for the application of QSARs under REACH were met. The predictions for adsorption/desorption in soil was considered to be adequate and fit-for-purpose, except for the 4th constituent representative, for which the proposed Log Koc can only be considered as an indication of the behaviour of such a polymerised structure. The predicted Log Koc of the representative constituents of the UVCB Soybean oil, epoxidized, methyl ester, reaction products with propylene glycol were determined to have a log Koc range of 2.58 to 11.30.

Key value for chemical safety assessment

Additional information

For Nourypol the range of predicted log Koc values is 2.58- 11.3. This indicates medium to significant potential for adsorption