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Environmental fate & pathways

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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, log Kow), or the substance and its relevant degradation products decompose rapidly. Diethanolamine (CAS 111-42-2) has a log Kow of -2.46 (@ 25 °C, Sasol, 2009) and is readily biodegradable.

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, diethanolamine 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 (not reliable due to applicability domain of the model). The latter method resulted in a Koc of 0.05. These estimates are representative for uncharged molecules. However, the substance is outside the applicability domain of both models as the number of occurrence of one fragment was exceeded (2 instead of 1). In case of the Kow method, the log Kow was also slightly outside of the range of the training set. Therefore, the Koc estimates may be less accurate.

At environmentally relevant conditions, diethanolamine will be present in ionised form (pKa = 8.99; BASF AG, 1991). 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 5 to pH 8 is 10 L/kg.

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


Henry’s Law Constant (HLC):

The Henry’s Law Constant was calculated by the bond estimation method of HENRYWIN v3.20 (EPISuite v 4.11) to be 3.97E-06 Pa*m³/mol. The estimation refers to the uncharged molecule. The substance is within the applicability domain of the model.

Based on the calculated data the substance is not expected to evaporate into the atmosphere from the water surface.


Distribution Modelling:

Based on the results of the Mackay LEVEL 1 calculation, the uncharged substance will over time preferentially distribute into the compartment water (97%) and air (3%). However, since the substance will be ionized under environmentally relevant conditions, the distribution into water may still be underestimated.