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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

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. Methyldiethanolamine (CAS 105 -59 -9) has a log Kow of -1.16 (@ 23 °C, pH 10.5; BASF SE, 2011, report no. 10L00407) and is readily biodegradable in freshwater.

In addition the Koc value was estimated using QSAR models. According to the MCI method of the KOCWIN v2.00 module of EPI Suite v4.10, methyldiethanolamine has a Koc of 1.0. 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 0.25.These estimates are representative for the uncharged molecule. However at environmentally relevant conditions, methyldiethanolamine will be present in ionised form (pKa = 8.68). 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 at pH 7 is 42 (range pH 5 to 8: 38 to 43).