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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Adsorption to solid soil phase is expected.

Key value for chemical safety assessment

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 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.

Discussion

Based on the Molecular Connectivity Index (MCI), the log Koc for the uncharged molecule was calculated to be 6.29 (Koc =1954000). Based on the estimated log Kow of 10.13, the log Koc for the uncharged molecule was calculated to be 6.46 (Koc = 2904000) (both estimates by KOCWIN v2.00; BASF SE, 2014).

This value refers to the uncharged molecule (pKa value: 10.38). This pKa indicates that the molecule will exist primarily as a cation in the environment and cations generally adsorb stronger to soils containing organic carbon and clay than their neutral counterparts. Hence, the KOCWIN-model may underestimate adsorption to organic carbon since it does not consider the ionic structure of the molecule. Under environmental conditions (pH from 5 to 9) the test substance is almost completely present in its charged form.

Regarding the charged molecule, the log Koc was estimated to be 4.51 (Koc = 32185) at physiologically relevant pH 7, following the method of Franco & Trapp (2008, 2009, 2010) (BASF SE, 2014).