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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The substance has been shown to be readily degradable in the closed bottle test.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Ready biodegradability was tested according to the Closed Bottle test (OECD 301 D, EC C.4-E) and in compliance with GLP (Wildlife International Ltd., 1998, for Royal Dutch Shell plc). Nominal initial test substance concentrations were 2 mg/L and 5 mg/L, corresponding to 1.33 mg DOC/L and 3.33 mg DOC/L. Measured day-0 solutions were 1.2 and 2.8 mg DOC/L. The test was performed with inoculum prepared by filtering through glass wool the supernatant fraction collected from the secondary clarifier of Prospect Bay Wastewater Treatment Facility, which was then aerated until used. The test substance at 2 and 5 mg/L achieved mean degradations of 70 and =61% by day 7, and 98 and =57% by the end of the study, respectively. The 5 mg/L concentration achieved the maximum percent biodegradation possible based on the theoretical oxygen demand of the test substance and the amount of oxygen present in the test system, even by day 7. The viability of the inoculum and validity of the test were supported by the results of the reference substance, sodium benzoate, which degraded approximately 108% by the end of the test, and achieved greater than 60% biodegradation by day 14. The day-7 results clearly show that the 10-day window criterion was met. The substance is considered to be readily biodegradable under the conditions of the test. Please refer to the document attached to Section 13 for further discussion of the studies.