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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The test substance was found to be not readily biodegradable in an OECD 301B and not inherently biodegradable in an OECD 302B guideline study.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The biodegradation potential of the substance in water was determined in two screening studies.

 

In the first study, the ready biodegradability of the substance was examined according to OECD TG 301B (CO2 Evolution Test) and in compliance with GLP criteria. In this study, ca. 161 mg/L the test substance (corresponding to 20 mg/LTOC) was inoculated with activated sludge from a predominantly domestic sewage for 28 days under aerobic conditions. At regular intervals throughout the incubation period the evolved CO2, measured as mg total inorganic carbon (TIC), was determined and compared to the ThCO2 as indication of biodegradation. Additionally, dissolved organic carbon (DOC) concentration was determined at the start and after 28 days exposure. Based on CO2/ThCO2, 20 - 30% of the test substance was biodegraded after the 28 -day exposure period. Based on DOC measurements, biodegradation was 20%.

 

In a second study, the inherent biodegradability was examined according to OECD TG 302B (Zahn-Wellens/EMPA Test) and in compliance with GLP criteria. In this study, ca 2044 mg/L test substance was inoculated with activated sludge from a predominantly domestic sewage for 28 days under aerobic conditions. At regular intervals throughout the incubation period the concentration of dissolved organic carbon was measured as indication of biodegradation. After the 28 -day exposure period, 10 - 20% of the test substance was biodegraded. Overall, the substance was determined to be poorly eliminable from water.