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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Koc is likely to be in the order of 2.138E-07 L/kg with the substance in its salt form.

Key value for chemical safety assessment

Koc at 20 °C:

Additional information

The adsorption/desorption coefficient for HEDTA or its structural analogue EDTA has not been determined in experimental studies. Due to the ionic structure under environmentally relevant pH conditions, no adsorption onto the organic fraction of soil or sediments is expected (EU Risk Assessment, 2004). HEDTA is expected to behave in a similar manner to EDTA given their similar ionisation and binding potentials. As such it is likely that HEDTA will remain in salt form in typical environmental conditions (e.g. neutral to mild acidic/alkaline conditions). Based on QSAR modelling (KOCWIN) the Koc is likely to be in the order of 2.138E-07 L/kg in salt form. In highly alkaline conditions the Koc is estimated to be in the order of 10 L/kg for the ionised compound. It should also be noted that, in accordance with REACH Regulation 1907/2006, Annex VIII, Column 2 an Adsorption/Desporption screen does not need to be conducted as HEDTA has a low potential for adsorption based on a log Pow of -11.36.