Registration Dossier

Environmental fate & pathways

Adsorption / desorption

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Adsorption ot the substance to the solid soil phase under environmentally relevant conditions is expected.

Key value for chemical safety assessment

Koc at 20 °C:
38 306

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. Furthermore, according to Article 25 of the same Regulation testing on vertebrate animals shall be undertaken only as a last resort.


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 modified 2-ethyl-N,N-bis(2-ethylhexyl)hexylamine (CAS 1860-26-0) (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:


The Koc value was estimated using a calculation method according to Franco & Trapp (2008, 2009, 2010).


At environmentally relevant conditions, the substance will be present in ionised form (pKa = 10.4; see IUCLID Ch.4.21). Therefore, the adsorption coefficient was calculated according to Franco & Trapp (2008, 2009, 2010) to correct for the charged molecule at pH 5, 7, and 8. This pH range is representative for 98% of the European soils. The substance is within the model's applicability domain. The Koc values of the Franco & Trapp method give a good indication 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.


Regarding the charged molecule, at pH 7 the log Koc was estimated to be 4.6 (Koc = 38306 L/kg) following the method of Franco & Trapp (2008, 2009, 2010) and using the estimated pKa of 10.4 (BASF SE 2017, see IUCLID Ch. 4.21) and the calculated log Kow for the uncharged molecule of 10.1, EPI Suite v4.11, BASF SE, 2019). The correction was performed for pH 5, 7, and 8, which represents 98% of the European soils. The value at pH 7 will be used as key value, i.e. for PEC and PNEC calculations.


In conclusion, the log Koc of the charged molecule is expected to be > 3 (pH 7, 25 °C). Therefore, adsorption of the substance to the solid soil phase is expected.


The Koc value at pH 7 will be used as key value, i.e. for PEC and PNEC calculations.