Registration Dossier

Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

No biodegradation is expected in water and sediment simulation testing

Key value for chemical safety assessment

Additional information

A simulation study according to OECD 303A was performed on the similar substance 3a-DSA for which a summary is available, indicating a %TOC of 4 %.

Both the substance and 3a-DSA substances are hexasulphonated sodium salts. The diethylamino substituent of the substance is less polar, less reactive and makes the molecule slightly less soluble compared to the dihydroxyethylamino derivative (201 vs. 278 g/l); the latter can therefore considered as a representative conservative analogous for the biodegradability endpoint.

The anaerobic degradation was evaluated on the analogous substance 3a-MSA that is in turn the analogous tetrasulphonated of 3a-DSA, with the same kind of reactivity, but even higher water solubility, 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 (2 -A) 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 would be non biodegradable in simulation tests.

Considering all biotic degradation studies for the members of the category (see Category Reporting Document in section 13), 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 for textile and paper application 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 would a potential for exposure, but the quantities used and secondary process of photooxidation lower the amount of the substance available in the environment.