Homosalate

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

March 15, 2013

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The calculation is based on the software of Estimation Program Interface (EPI) Suite develped by US EPA and it meets the five agreed OECD principles on (Q)SAR model. It is considered an acceptable calculation method.

Justification for type of information:

QSAR prediction: migrated from IUCLID 5.6

Qualifier:

according to guideline

Guideline:

other: Koc Win v2.00 (Kow Method)-EPI-Suite

Deviations:

no

Principles of method if other than guideline:

Calculated by the EPI-Suite version 4.11 using Koc Win v2.00 (Kow Method).

Key result

Type:

Koc

Value:

18 999 L/kg

Remarks on result:

other: Mean of MCI and log Kow Method

Key result

Type:

log Koc

Value:

4.28 L/kg

Remarks on result:

other: Mean of MCi and log Kow Method

Type:

Koc

Value:

31 220 L/kg

Remarks on result:

other: Koc estimate from log Kow

Type:

log Koc

Value:

4.49 L/kg

Remarks on result:

other: log Koc estimate from log Kow

Type:

Koc

Value:

6 778 L/kg

Remarks on result:

other: Koc estimate from MCI method

Type:

log Koc

Value:

3.831 L/kg

Temp.:

20

Remarks on result:

other: log Koc estimate from 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: Esters, Phenols, Salicylates. 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 6.16 was used.

3. Applicable domain:

With a molecular weight of 262.34 g/mole the substance is within the range of the training set (32 - 665 g/mole) as well as in the validation set (27 - 991 g/mole). Regarding the structure of homosalate, 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 adsob to organic carbon.

Adequacy of prediction:

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

The calculation is based on the software of Estimation Program Interface (EPI) Suite developed by US EPA.

Soil Adsorption Coefficient (KOCWIN v2.00):

Koc : 6778 L/kg (MCI method)

Log Koc: 3.831 (MCI method)

Koc : 2.714E+004 L/kg (Kow method)

Log Koc: 4.434 (Kow method)

According to the Guidance on information requirements and chemical safety assessment Chapter R.7a: Endpoint specific guidance, a correlation for a large diverse data set can be performed for the test substance.

log Koc = 0.679 log Kow + 0.094 (n = 419, r²= 0.831 )

Based on the available log Kow 6.16, log Koc of 4.28 can be derived, which is very similar to the result derived from EPI-Suite 4.11 developed by US EPA.

Validity criteria fulfilled:

yes

Executive summary:

The results is based on the software of Estimation Program Interface (EPI) Suite develped by US EPA. It meets the five agreed OECD principles on (Q)SAR model.

The Koc and Log Koc of the substance was derived with the MCI and log Kow method. The mean of both methods is used as key value for the chemical safety assessment.

Koc: 18999 L/kg

log Koc: 4.28 L/kg

Description of key information

The log Koc value was predicted with the program KOCWIN: QSAR estimate using EPIsuite v4.11. The mean of the MCI and log Kow method is used for chemical safety assessment.
The log Koc = 4.28 indicates that the substance is immobile in soil and sediment according to the classification scheme of McCall et al. (1981).

Key value for chemical safety assessment

Koc at 20 °C:

18 999

Additional information

The log Koc was calculated using KOCWIN v2.00 from the Estimation Program Interface (EPI) Suite developed by US EPA. It meets the five agreed OECD principles on (Q)SAR model.

The Koc and Log Koc of the substance was derived using several methods.

MCI method: Koc: 6778 L/kg; Log Koc: 3.831 L/kg;

Kow method: Koc: 31220 L/kg; Log Koc: 4.434 L/kg;

Mean: Koc: 18999 L/kg; Log Koc: 4.28 L/kg

The mean of the MCI and log Kow method is used for chemical safety assessment.

The log Koc of 4.28 L/kg indicates that the substance is immobile in soil and sediment according to the classification scheme of McCall et al. (1981).

As additional adsorption/desorption testing cannot be expected to reveal new results with any added value concerning the risk assessment of this substance, additional Annex IX studies on adsorption/desorption are not considered necessary.