Registration Dossier
Registration Dossier
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EC number: - | CAS number: 42355-78-2
Biodegradation in water: screening tests
Administrative data
Link to relevant study record(s)
Description of key information
Under test conditions no biodegradation observed.
Key value for chemical safety assessment
- Biodegradation in water:
- under test conditions no biodegradation observed
Additional information
No ready biodegradation was tested on the substance, but according to the estimation modelling BIOWIN v.4.10, the substance is predicted as non biodegradable; all substances of the Stilbene Fluorescent Whitening Agents category are predicted as non readily biodegradable and for many members of the category readily and inherently biodegradability tests have been performed confirming the previsions (see the Category Justification Report attached to the section 13).
The studies performed on OB 3a-MSA, the analogue dihydroxyethylamino derivative tetrasulphonated, are reported here as the main reference. Both the substance under registration OB 1 -MSA and the analogue OB 3a-MSA are tetrasulphonated sodium salts. The diethylamino substituent is less polar, less reactive and makes the molecule slightly less soluble compared to the dihydroxyethylamino derivative. The latter can therefore considered as a representative conservative analogous for the biodegradability endpoint.
In a ready biodegradability test according to OECD guideline 301A (Ciba-Geigy, 1992) a DOC removal of 1.2 % was observed. Hence, the substance OB 3a-MSA is considered not readily biodegradable. Three BOD5 tests, in which no oxygen consumption was measured, confirm the non rapid biodegradability of the test substance. Additional information is given from two Zahn Wellens tests OECD 302B (Ciba-Geigy, 1992 and Novartis Services AG., 1997). One of the two indicates a biodegradation of 24 % after 28 days. This value is obtained at about the fifth day; afterwards the degradation process seems to stop. The slope of the 28 days curve, the second test of inherent biodegradation and the BOD5/COD reported suggest that the 24 % of DOC removal recorded in the first Zahn Wellens test can still be related to a slow adsorption process more than a biological degradation.
In conclusion, the substance can be considered as neither readily nor inherently biodegradable.
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