2-ethylhexyl 3,5,5-trimethylhexanoate

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

(Q)SAR

Adequacy of study:

key study

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

Guideline:

other:

Version / remarks:

EPISUITE QSAR

Principles of method if other than guideline:

EPISUITE QSAR Calculated from Log Kow

GLP compliance:

no

Type of method:

other: QSAR estimate

Radiolabelling:

no

Test temperature:

not applicable

Computational methods:

Log Koc and Koc have been estimated by QSAR using KOCWIN 2.00 embedded in EPI Suite™ (2000) software, that was developed by the EPA's Office of Pollution Prevention Toxics and Syracuse Research Corporation (SRC)

Type:

Koc

Value:

7 585 dimensionless

Key result

Type:

log Koc

Value:

3.88 dimensionless

Validity criteria fulfilled:

yes

Conclusions:

Log Koc (based on Molecular Connectivity Index (MCI)): 3.88

Executive summary:

Based on the estimated log Koc value, it can be concluded that the substance has a high tendency for adsorption to soil.

The estimated log Koc value meets in an adequate way, the required information on adsorption/desorption for a chemical safety assessment under Regulation (EC) No. 1907/2006, Annex VIII, 9.3.1 (Adsorption/desorption). Given the higher accuracy of the MCI model (see 3.4 in QPRF and corresponding QMRF-document) the estimated Koc of 7585 (log Koc 3.88) is taken forward for hazard and risk assessment.

Description of key information

 The test on adsorption/desorption cannot be performed due to low water solubility of test substance and subsequent analytical difficulties. As surrogate, a QSAR estimation was performed using KOCWIN 2.00 that estimated the Koc to be 7585 (log Koc 3.88). 

Key value for chemical safety assessment

Koc at 20 °C:

7 585

Additional information

The test item was found to be inherently biodegradable under the test conditions within 28 days (biodegradation of 59% achieved). However, the pass level for ready biodegradability, i.e. biodegradation of at least 60% of the ThOD in a 10-day window within the 28-day period of the test, was not reached. Hence, the substance is considered inherently biodegradable and bioelimination is expected. In addition, the substance is highly insoluble in water as shown in the test on water solubility (result <1 µg/L) but also in the acute algae study where a loading rate of 100 mg/l resulted in an analytical concentration below the limit of quantification (10 µg/l). Thus, conducting the study is technically not feasible and is waived in line with the criteria in Annex VIII, column 2 REACH.

As surrogate data, the Koc (and log Koc) were estimated by KOCWIN, version 2.00, a validated QSAR model developed by the US EPA's Office of Pollution Prevention Toxics and Syracuse Research Corporation (SRC).

The model uses two different algorithms. The first algorithm is based on the Molecular Connectivity Index (MCI), while the second one uses the log Kow value as the starting point (either calculated by KOWWIN or as manual input based on measured results).

Overall, the MCI methodology is somewhat more accurate than the Log Kow methodology, although both methods yield good results. If the training datasets are combined into one dataset of 516 compounds (69 having no corrections plus 447 with corrections), the MCI methodology has an r², standard deviation and average deviation of 0.916, 0.330 and 0.263, respectively, versus 0.86, 0.429 and 0.321 for the Log Kow methodology. Consequently, the results delivered by the MCI method have been preferred. The MCI model delivered a result for Koc of 7585 (L/kg) and a log Koc of 3.88, respectively. In lack of experimental data, this value is used for risk assessment.

[LogKoc: 3.88]

[LogKoc: 3.88]

[LogKoc: 3.88]