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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Results of HPLC testing (OECD 121) demonstrated the method was not suitable for DNNSA which is consistent with the guideline caution that the method may be inappropriate for strong acids and surface acting compounds.
The log Koc for DNNSA that will be used for the environmental assessment will be 5.19, the average of the 3 values estimated by QSAR modeling.

Key value for chemical safety assessment

Koc at 20 °C:
154 882

Additional information

There are experimental and QSAR approaches for the determination of the Soil Adsorption Coefficient (Koc). REACH guidance (Chapter R.7a, 2012) indicates that calculation and read-across should be the first step in estimating the Koc. No similar compounds were found which would provide read-across for DNNSA. The Guidance document (Chapter R.7a, 2012) recommends estimates be made using multiple models for a sensitivity check, therefore, a calculation of the Koc was conducted using the EPIWIN model KOCWIN and the models developed by Sabljic et al. (1995) which are described in TGD Part III (2003) and utilized by EUSES.

 

Results of HPLC testing (OECD 121) demonstrated the method was not suitable for DNNSA which is consistent with the guideline caution that the method may be inappropriate for strong acids and surface acting compounds. In accord with REACH guidance indicating that “Estimated values are essential for substances for which experimental measurement is not feasible i.e. for difficult substances”, the log Koc for DNNSA that will be used for the environmental assessment will be 5.19, the average of the 3 values estimated by modeling.

[LogKoc: 5.19]