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Environmental fate & pathways

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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. For the structural analogues of Zinc bis( di C8-C10, branched, C9 rich, alkylnaphthalene sulphonate), QSAR approaches as recommended by the Guidance document (Chapter R.7a, 2012) using multiple models for a sensitivity check, were used.

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 bySabljic 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 structural analogues of ZnDNNSA which is consistent with the guideline caution that the method may be inappropriate for compounds expected to be surface active and with low solubility "difficult substances". In accordance 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 ZnDNNSA that will be used for the environmental assessment will be 5.10, the average of the 2 values estimated by modelling.