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Environmental fate & pathways

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Additional information

No experimentally-determined soil and/or sediment adsorption/desorption data are available for dimethyl cyclohexyl bisphenol (DMBPC); therefore, estimation methods were used in a weight-of-evidence approach for determining the adsorption behaviour of DMBPC in the environment. Per ECHA (2008), estimation methods of Koc are not appropriate for ionisable substances. To demonstrate that DMBPC is not ionisable at environmental pH, the acid dissociation constant was estimated for each of DMBPC's two ionisable protons using the SPARC Performs Automated Reasoning in Chemistry (SPARC) program. Based on pKa1 and pKa2 values of 10.5 and 10.7, greater than 99 % of DMBPC will be non-ionised at environmentally-relevant pH.

The organic carbon normalised partition coefficient (Koc) was estimated using two estimation methods, EPIWIN v4.10, a Quantitative-Structure-Activity-Relationship (QSAR) model, and the Gerstl correlation, which relates the log octanol-water partition coefficient (log Kow) to the log Koc.

The EPIWIN and Gerstl correlation estimates of Koc were ca. 940.8 L/kg and 158.5 L/kg, respectively (log Koc values of 2.97 and 2.2 at 25 °C). The geometric mean of these two values is taken as the key value for the chemical safety assessment, 386 L/kg. This value indicates a low potential for DMBPC to adsorb to soil/sediment (i.e., high mobility in the environment).