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Environmental fate & pathways

Biodegradation in water: screening tests

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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

In the ready biodegradability test, performed according to OECD guideline 301A (key study), a DOC removal of 1.2 % was observed; hence, the substance is not readily biodegradable (Ciba-Geigy Ltd., 1992).

The QSAR based screening criterion for identifying substances for persistency (P and vP) confirmed that the substance is expected to be persistent and this estimated behaviour is further supported by the results obtained from some BOD5:COD studies available: in all cases the ration BOD5:COD resulted lower than 0.5, thus it can be expected that the substance is not readily biodegradable (BASF SE, 2014).

 

Additional information are given from two Zahn Wellens tests, performed according to the OECD 302B. One of them indicates a biodegradation of 24 % after 28 days (Ciba-Geigy Ltd., 1992): this value is obtained at about the fifth day, afterwards the degradation process seems to stop. The slope of the 28 days curve and the second test of inherent biodegradation (Novartis Services AG., 1997) reported suggest that the 24 % of DOC removal recorded in the first test can still be related to a slow adsorption process more than a biological degradation.

In conclusion, the substance is considered as neither readily nor inherently biodegradable.