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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Adsorption to solid soil phase is not expected.

Key value for chemical safety assessment

Additional information

 Experimental data for the adsorption coefficient are available via a read across approach to 4 -acetylmorpholine (CAS 1696 -20 -4) which was determined by an HPLC screening method (proposal for OECD 121) to be log Koc < 1.25 (Koc < 17.8; BASF AG, 2011).

 

In addition, the Koc value was estimated using QSAR models. According to the MCI method of the KOCWIN v2.00 module of EPI Suite v4.11, 4-Morpholineethanol has a Koc of 1.2. The MCI module is more reliable than the log Kow method of KOCWIN v2.00, which estimates the KOC based on the n-octanol/water partition coefficient (log Kow: -1.32; KOWWIN v1.68). The latter method resulted in a Koc of 0.4. These estimates are representative for uncharged molecules; the substance is within the applicability domain of the estimation models.

 

However, at environmentally relevant conditions, the substance will preferentially be present in ionised form (pKa = 6.9; calculated, SPARC v4.6). 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 resulting Koc values at pH 5 to pH 8 were calculated to be in a range from 3 to 19 L/kg.

 

It can be concluded that adsorption to the solid soil phase is not to be expected.

 

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 4-Morpholineethanol (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.