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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Adsorption to the solid soil phase is not expected.

Key value for chemical safety assessment

Koc at 20 °C:
28

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-[2-(dimethylamino)ethoxy]-N-methylethanamine (TMAEE) (CAS 93240-93-8) (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 of adsorption potential:

Experimental data for the adsorption potential of TMAEE (CAS 93240-93-8) are not available and not required according to Annex VIII section 9.3.1 of Regulation (EC) 1907/2006 as the substance has estimated log Kow of -0.75 and, therefore, a low potential for adsorption can be expected.

However, in order to assess the adsorption potential of the substance, the Koc value was also estimated using QSAR models. According to the MCI method of KOCWIN v2.00 (EPI Suite v4.11), the log Koc of the target substance is estimated to be 1.15. The MCI module is more reliable than the log Kow method of KOCWIN v2.00, which estimated a similar adsorption coefficient (log Koc = 0.31) based on the estimated n-octanol/water partition coefficient of TMAEE (log Kow = ‑0.75, KOWWIN v1.68). The substance was within the applicability domain of both estimation models. These estimates are representative for uncharged molecules.

However, the target substance’s pKa of 9.77 (estimated; see IUCLID chapter 4.21) indicates that the substance will primarily exist as a cation in the environment. Cations generally adsorb stronger to soils containing organic carbon and clay than their neutral counterparts. Franco & Trapp 2008/2009/2010) developed a method to take this effect into consideration when assessing the adsorption potential. The model is not yet validated; in addition, the applicability domain is not clearly defined. Nevertheless, 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 n-octanol/water partition coefficient (log Kow) for the uncharged molecule. Regarding the charged molecule at pH 7, the log Koc TMAEE (CAS 93240-93-8) was estimated to be 1.45 based on a log Kow of -0.75 and a pKa of 9.77. 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, adsorption of TMAEE (CAS 93240-93-8) to the solid soil phase is not to be expected.

[LogKoc: 1.45]