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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Not Readily Biodegradable (28 d, OECD 301 F, activated sludge, WWTP for domestic sewage)

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

One GLP guideline study is available, which assessed the "Ready Biodegradability" of the test substance according to OECD guideline 301 F (M-568076-01-1; 2016).

Activated sludge, composed of a mixed bacterial population of aquatic microorganisms, was collected from the aeration tank of a local WWTP treating predominantly domestic sewage and was continuously aerated until test start. The non-adapted activated sludge was inoculated with a nominal concentration of 100 mg/L test substance, equivalent to 1.698 mg O2/mg ThOD, during 28 d under aerobic conditions in the dark. Evolved carbon dioxide was absorbed in sodium hydroxide. An inoculum blank as well as procedure and toxicity controls were run in parallel. Degradation was followed by the continuous automated measurement of BOD. The amount of oxygen taken up by the test substance was corrected for the endogenous activity of the inoculum and expressed as a percentage of ThOD.

The toxicity control showed no toxic effects on bacteria at the tested concentration. Results showed 4% degradation after 7 and 14 d, 6% after 21 d and 4% after 28 d. Therefore, the test substance is considered to be not readily biodegradable.