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Environmental fate & pathways

Adsorption / desorption

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Description of key information

In accordance with Column 2 of REACH Annex IX, the study does not need to be conducted as the substance can be expected to have a low potential for sorption (log Kow ≤3). The estimated Koc values for homologous components of this UVCB substance range from 10 to 760 L/kg for the lowest (least sorptive) and highest (most sorptive) molecular weight homologues.  The components of this UVCB substance can be regarded as having low affinity for adsorption to soils and activated sludge biosolids.

Key value for chemical safety assessment

Additional information

The KOCWIN software is shown to produce estimated log Koc values which are typically within 0.3 log units of measured values for a set of amine- and alcohol-bearing substances which are expected to have log Koc values bracketing that of the test substance. Because the software training set includes measured Koc values for several aliphatic and aromatic amine substances, it is expected to provide accurate predictions of adsorption for amine-initiated NLP polyols, which may adsorb to soil by a combination of cation-exchange and hydrophobic partitioning mechanisms. These results are therefore expected to provide a more realistic estimation of adsorption potential than the HPLC estimation method, which may be confounded by the surface-activity of the test substance components and lack of relevant reference substances (i.e., alcohols, ethers, amines) employed in the OECD 121 guideline.

Adsorption/Desorption was investigated using the OECD 121 method, and results indicated Koc <17.8 to and Log Koc <1.25 at pH 5.4.