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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The test substance was evaluated for ready biodegradability in the Closed Bottle test (OECD 301D) at the initial test concentrations of 3 and 6 mg/L. The relative biodegradation values calculated from the O2 measurements performed during the test period of 28 days revealed 22 and 24% degradation of VC at the low and high concentration respectively (mean values on day 28). Thus, biodegradation of at least 60% was not reached within 10 days of biodegradation exceeding 10% and so VC is considered not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

Two biodegradation screening tests were performed on VC. The two tests give opposite results: readily biodegradable versus not readily biodegradable.

Although both studies, the MITI and the Closed Bottle Test, have been performed without any demonstrative errors, the results are different. Because in the MITI-test no indication is stated on the condition of the activated sludge used, there is the possibility that the sludge was adapted to the substance or similar substances, which may account for the high degree of biodegradation.

The Closed Bottle Test was taken as the key study as both the condition (non-adapted) of the activated sludge used in this study is confirmed and the result represents a worst case situation.