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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The ready biodegradability of the test item, TM 11-212 (FRET 08-0334) was assessed and attained 60% biodegradation after 28 days according to OECD Test Guideline 301D using the closed bottle method and can therefore be considered to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable but failing 10-day window

Additional information

Two studies were performed to investigate the ready biodegradability of the test item in the presence of unacclimatized sewage sludge micro-organisms.

The first study was performed according to OECD Test Guideline 301F - Manometric Respirometre Test method. The ready biodegradability of TM 11-212 was determined with unacclimatised sewage micro-organisms by measuring the amount of oxygen consumed over the 28-day test period. The test item was adsorbed onto a glass fibre filter and then added to test vessels at a level of 33.3 mg/L (equivalent to 96.8 mg ThOD/L) (n=2). The percentage biodegradation of TM 11-212 after 2 days averaged 29.0% (n=2), which was the initial day on which 10% biodegradation was exceeded, and when the 10-day window began. The percentage biodegradation in activated sludge averaged 64.8% (n=2) within 10-day window (after 12 days), and 76.7% after 28 days. The test item, TM 11-212 met criteria for "ready biodegradability" under the test conditions.

The second test was performed according to OECE Test Guideline 301D - Closed Bottle method. An amount of test item (0.65 μL) was dispensed onto a filter paper and added to the test vessel containing inoculated mineral medium to give a test concentration of 2.0 mg/L. The test item attained 60% biodegradation after 28 days and can therefore be considered to be readily biodegradable. The test item failed to meet the 10-Day window validation criterion, whereby 60% biodegradation must be attained within 10 days of the biodegradation exceeding 10%. However, in accordance with the Revised Introduction to the OECD Guidelines for Testing of Chemicals, Section 3, Paragraph 43 (Page 8), if testing on a complex mixture is performed, and it is anticipated that a sequential biodegradation of the individual structures takes place, then the 10-Day window should not be applied to interpret the results of the test.