Registration Dossier

Diss Factsheets

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

9.33 L/kg

Additional information

In accordance with EC 1907/2006, Annex IX, point 9.3.2, column 2, bioaccumulation in aquatic species (water and sediment) is not required due to the fact that the substance has a log Kow of < 3 (-3.326).

An experimental study with a structurally similar source substance (CAS 577-11-7, Arnot & Gobas 2006, 42-day exposure, steady state) resulted in a BCF of 9.33 L/kg in carp (4.1% lipid content). A further 72 -hour study with the same source substance CAS 577-11-7 (Goodrich et al. 1991) with rainbow trout resulted in a BCF of 3.78 L/kg in carcas. In addition to the experimental results, a QSAR using the BCFBAF (v3.01) module implemented in EPISuite 4.11 resulted in a BCF of 56.2 L/kg for the source substance. Hence, there was a good agreement between the experimental values and the QSAR with the indication that the result from the QSAR model results in more conservative values. For the registered substance, the same QSAR model as for the source substance resulted in a BCF of 3.16 L/kg. Hence, it can be assumed that the EPISuite result is conservative for the registered substance as well.

For the registered substance, a QSAR calculation with the model Catalogic resulted in a maximum BCF of 4.17 L/kg for the parent substance and its metabolites. As for EPISuite, a direct comparison of the experimental result and the Catalogic QSAR prediction for the BCF of docusate sodium, the source substance, resulted in the finding that the QSAR prediction from Catalogic for docusate sodium and its metabolites (13.8 L/kg) is slightly more conservative than the experimental finding (9.33 L/kg). Hence, it can be assumed that this is the case also for the registered substance.

For the risk assessment, the more conservative experimentally determined BCF of 9.33 L/kg will be used since this study with the source substance is considered to be scientifically most relevant study. The use of the less conservative QSAR result of the source substance would not have had a different qualitative outcome for, e.g., the PBT assessment. The QSAR results (two models) for the registered substances and its metabolites resulted in lower BCFs. Hence, the BCF of 9.33 L/kg is conservative and will be used for the risk assessment.

In conclusion, bioaccumulation of the substance is of no concern.