Registration Dossier

Diss Factsheets

Environmental fate & pathways

Adsorption / desorption

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Adsorption to solid soil phase is not 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. 


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 morpholine (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:


In accordance with column 2 of REACH Annexes VIII and IX, the study 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. Morpholine is readily biodegradable (OECD 301E, BASF AG, 1990; report no.: 1901337). 


 


In order to assess the adsorption potential of the substance, the Koc value was estimated using a QSAR model from Franco and Trapp (2008), Franco et al. (2009) and Franco (2010), which considers the charged status of a substance, e.g. cations generally adsorb stronger to soils containing organic carbon and clay than their neutral counterparts. The method is based on the dissociation constant pKa and the log Kow for the uncharged molecule.


Morpholine has a pKa value of 8.49 which indicates that the molecule will primarily exist as a cation in the environment. The pKa of morpholine is 8.49 (measured; HSDB, 2007). For the log Kow of the uncharged molecule, the measured value of -0.84 (BASF AG, 1989; at 25°C, pH 10.3) was used.


 


Regarding the charged molecule, at pH 7 the log Koc was estimated to be 1.88 (Koc = 76 L/kg) following the method of Franco & Trapp (2008, 2009, 2010) based on these data. 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.


 


Referring to the charged molecule at pH 7, the substance is not expected to adsorb to the solid soil phase. Moreover, the substance is readily biodegradable.

Categories Display