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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Significant adsorption to solid soil phase is not to be expected.

Key value for chemical safety assessment

Additional information

In accordance to Column 2 of REACH Annexes VIII and IX a study on adsorption 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.

 

2-Propanol, 1,1',1''-nitrilotris- has an experimentally determined n-octanol/water partition coefficient (log Kow) of -0.015 (BASF AG, 1987).

 

In order to assess the substance’s adsorption potential, the Koc value was estimated using (Q)SAR models. According to the MCI method of the KOCWIN v2.00 module of EPI Suite v4.11, 2-Propanol, 1,1',1''-nitrilotris- has a Koc of 10. The MCI module is more reliable than the second method of KOCWIN v2.00, which estimates the KOC based on the log Kow. The latter method resulted in a Koc of 1.07, based on the measured log Kow of -0.015 (BASF AG, 1987). These estimates are representative for uncharged molecules.

However at environmentally relevant conditions, 2-Propanol, 1,1',1''-nitrilotris- will be present in ionised form (pKa = 9.25). Therefore, the adsorption coefficient was additionally calculated for the charged molecule at pH 5, 7, and 8 according to Franco & Trapp (2008, 2009, 2010). This pH range is representative for 98% of the European soils. The resulting Koc at pH 7 is 548 (log Koc 2.74) (range pH 5 to 8: 616 to 288). The Franco & Trapp-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.

 

Based on the available calculated data, significant adsorption to the solid soil phase is not to be expected under environmentally relevant conditions.

 

 

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-Propanol, 1,1',1''-nitrilotris- (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.