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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

No biodegradation is expected in water and sediment simulation testing

Key value for chemical safety assessment

Additional information

A test for biological elimination was performed on the substance under registration (CAS 16324-27-9). The test was conducted according to the OECD guidelines 303A, but actually only the summary is available, which does not report all the details for a complete evaluation. The mean value of elimination was reported at 0 % based on the TOC removal within 21 days (Ciba-Geigy Ltd., 1989).

Further studies are available on the analogous substance CAS 16470-24-9 and they were performed according to procedures outlined into the ECETOC Technical Report No. 28. The resulting degradation rates are different: the reason of this difference is not evaluable.

A further field study at a full-scale STP on a similar substance in the category of the Stilbene Fluorescent Whitening Agents (CAS 16090-02-1) gave no evidence of biodegradation when the mass flow was monitored (Poiger, 1994 – Section 5.5.2: Field studies).

In virtue of a conservative approach, it is assumed that the test substance under registration (CAS 16324-27-9) would be non biodegradable in simulation tests.

Considering all biotic degradation available studies for the members of the category (see Category Reporting Document to the section 13 of the dossier), structural similarities, estimated and calculated data, metabolic previsions, it can be assumed that all members have the same behaviour in the biotic compartment.

Further biotic degradation testing shall be proposed only if the Chemical Safety Assessment, according to Annex I, indicates the need to investigate further degradation of the substance and its degradation products. Based on the Chemical Safety Assessment the exposure of sediment and soil will be negligible, since the substance and its formulations are produced and used in plants with internal Sewage Treatment Plant, where the sludge is sent to incineration. The only potential dispersive use could be in the detergency field, with public consumer use. In this case there is a potential for exposure, but the quantities and secondary process of photooxidation lower the amount of the substance available in the environment.