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Environmental fate & pathways

Adsorption / desorption

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Description of key information

log Koc > 5 (KOCWIN v2.00)

Key value for chemical safety assessment

Additional information

No studies investigating the adsorption/desorption behaviour of Sorbitan tristearate (CAS No. 26658-19-5) are available. Using KOCWIN Program (v2.00), log Koc values from 11.7 to 13.0 were calculated for the main constituents, based on molecular connectivity index (MCI) and 11.5 - 11.7 based on log Kow (Blum, 2012). These models have no universally accepted definition of model domain, but since the substance is outside the Kow range of the training set for both models, the results should be taken with caution. The definite values may not be fully reliable, but indicate a high adsorption potential, which is also to be expected based on the high Kow (>10) and low water solubility. Additionally, the results for the monoester constituents of Sorbitan stearate (CAS No. 1338-41-6), which are within the model domain, already indicate relatively high adsorption (log Koc 2.9 and 3.4). It can be assumed that the triester has even higher adsorption potential, since it contains more fatty acid chains. However, the definite values for Sorbitan esters should still be taken with caution, since the molecular structure indicates a potential of surface active properties, which may further increase the adsorption potential of the substances.

It can be concluded that although the definite values are not fully reliable, the adsorption potential of Sorbitan tristearate to soil is expected to be high.