Registration Dossier
Registration Dossier
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EC number: 205-743-6 | CAS number: 149-57-5
Adsorption / desorption
Administrative data
Link to relevant study record(s)
Description of key information
After exposure to soil, significant adsorption to solid soil phase is not expected.
Key value for chemical safety assessment
- Koc at 20 °C:
- 83
Additional information
QSAR-disclaimer
In Article 13 of Regulation (EC) No 1907/2006, it is laid down that information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI (of the same Regulation) are met.
According to Annex XI of Regulation (EC) No 1907/2006 (Q)SAR results can be used if (1) the scientific validity of the (Q)SAR model has been established, (2) the substance falls within the applicability domain of the (Q)SAR model, (3) the results are adequate for the purpose of classification and labeling and/or risk assessment and (4) adequate and reliable documentation of the applied method is provided.
For the assessment of 2-ethylhexanoic acid (CAS 149-57-5) (Q)SAR results were used for the estimation of the adsorption potential. The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint(s) sufficiently covered and suitable for risk assessment.
Therefore, further experimental studies on the adsorption potential are not provided.
Assessment
According to Regulation (EC) No 1907/2006, Annex VIII, Section 9.3.1, Column 2, the study on adsorption/desorption screening does not need to be conducted if based on the physicochemical properties the substance can be expected to have a low potential for adsorption (e.g. the substance has a low octanol water partition coefficient), or the substance and its relevant degradation products decompose rapidly.
The substance is readily biodegradable according to OECD criteria (99% DOC removal after 28 d, Finnish Chemicals Oy, report no. E2807; see IUCLID Ch. 5.2.1). In addition, the substance has a log Kow of 2.7 (measured, BASF AG, see IUCLID Ch. 4.7). Therefore, a study does not need to be conducted.
However, the adsorption coefficient was calculated according to Franco & Trapp (2008, 2009, 2010) to correct for the charged molecule at pH 5, 7, and 8 as the substance is present in ionized form under environmentally relevant conditions (pKa = 4.76; acid, REAXYS, see IUCLID Ch.4.21). The range of Ph 5 to pH 8 is representative for 98% of the European soils. The Koc values of the Franco & Trapp method give a good estimate on the adsorption potential of a substance depending on the pH conditions of soil. The method is based on the dissociation constant pKa and the log Kow for the uncharged molecule. The substance is within the applicability domain of the method. The resulting Koc at pH 7 is 83 (log Koc 1.92) (range pH 5 to 8: 378 to 74).
Additionally, a non-GLP test according to OECD TG 106 without detailed information on test conditions and results is used to support the estimated values. However, the results vary strongly depending on the tested soil. Therefore, the results were not used as key study. From three soils tested only one soil revealed results with an acceptable variability of the results and equilibrium. Hence, the Koc estimated from the test with this soil was estimated to be 140.87 (log Koc = 2.1).This value is in line with the estimated adsorption coefficients based on Franco & Trapp.
Based on the available estimated and experimental data for the substance, it can be concluded that under environmentally relevant conditions, adsorption to the solid soil phase is not expected.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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