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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), 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).

The Henry's Law Constant was estimated according to the bond estimation method resulting in a value of 8.72E-06 Pa*m³/mol (HENRYWIN Program, v3.20; EPI Suite v4.10; BASF SE, 2012), which is representative for the uncharged molecule. At environmental conditions the molecule is expected to be ionised (pKa = 8.52; measured, Perrin, 1978), therefore a pH-corrected Koc was calculated according to the REACH Guidance document (2008). The resulting Henry's Law constant was 2.56 E-07 at pH 7 (range pH 5 to 9: 2.63E-0p to 6.55 E-06 Pa m³/mol; BASF SE, 2012).

Based on the pH-corrected HLC, the substance will not evaporate from the water surface into the atmosphere.

Based on the results of the Mackay LEVEL 1 calculation, over time the uncharged substance will preferentially distribute into water (100%).