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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The test substance is inherently biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable, fulfilling specific criteria

Additional information

Two reliable biodegradation tests are available - a ready biodegradability test according to OECD 301 F and an inherent biodegradability test based on OECD 302C.

The ready biodegradability was determined with a non-adapted activated sludge to the substance over a period of 28 days by method of OECD guideline 301 F (Manometric Respirometry Test). In this study 40 mg/L was selected as the initial test item concentration, corresponding to a ThOD of 97.2 mg O2/L in the test vessel. The degradation was followed by measuring the oxygen consumption. The test results showed that the 10 % level (beginning of biodegradation) was reached after 13 days for the test item. After 28 days a maximum biodegradation of 21% was reached. Thus, the test substance cannot be considered as readily biodegradable. In the toxicity control containing both test and reference item 38%degradation occurred within 14 days. The degradation of the reference item was not inhibited by the test item.

In a second experiment the inherent biodegradability was investigated in a test based on the OECD 302C method. No test item specific analysis was performed. The test was terminated after 28 days, before the biodegradation of the test item reached a plateau. The substance exhibited a biodegradation of 70.2% within 28 days in this test. Therefore the substance can be regarded as inherently and ultimately biodegradable.