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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Under the experimental conditions, the test substance is non readily biodegradable in the 28-day modified Sturm test. Since biodegradation of the test substance totalled 28% at the end of the test, the test substance is considered to be inherently biodegradable.

 

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable

Additional information

The ready biodegradability of the test substance was evaluated using a 28-day modified Sturm test according to OECD guideline No. 301B and EC method C.4 -C, where all validity criteria were respected. The test item contained approximately 75 % of peroxide and 25 % of stabilizing agent (Isododecane) and was dispersed in reconstituted water (OECD mineral medium).

The inoculum consisted of sewage sludge sampled from the aeration tank of a sewage treatment plant and then aerated for 6 days. Inoculum concentration was 12.0 mg/L (dry weight) in all test vessels. CO2 scrubbed air was bubbled through the flasks for the 28-day test period.

The obtained results showed that the 10-day window (the 10 days immediately following the attainment of 10% biodegradation) started on the 3rd day. Biodegradation of the test substance totalled 26% at the end of this 10-day window (13th day) and 28% at the end of the test. Therefore, the test substance is considered to be inherently biodegradable. Under the experimental conditions, the test substance is not readily biodegradable in the 28-day modified Sturm test.