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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Value calculated by QSAR, based on physical form and no release.

Key value for chemical safety assessment

Koc at 20 °C:
74.86

Additional information

CFC-12 is not considered to show significant adsorption on the basis of this data.

No information was found pertaining to the adsorption of dichlorodifluoromethane onto soils and sediments. Given the physical form of the substance (gaseous) and the fact that it is a “CFC” and hence release is prohibited in accordance with Regulation (EC) No 2037/2000 on substances that deplete the ozone layer, significant exposure to soil is not anticipated. As such, it is deemed appropriate to assess the potential for soil adsorption utilising a QSAR technique. US EPA On-Line EPI Suite™ model KOCWIN Program (v2.00) for the estimation of soil adsorption coefficent (Koc) of organic compounds was chosen, as the substance is included in the data set for this model, and is known to be of sufficient accuracy. A QPRF detailing this justification is appended within the study summary. The substance was found to have an estimated Koc value of 43.89 L/kg (MCI Estimate) and 74.86 L/Kg (Log Kow estimate).  The value from the Log Kow value is taken as the definitive value, as CFC-12 itself is an “Experimental Database Structure Match” andis used as a reference source in KOWWIN v 1.68, which is used to derive calculations of log Kow as part of the programme. On the basis of the results, the substanceis not proposed to adsorb/desorb strongly within soil. This estimate fits with the physical form of the substance.