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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The test substance was assessed for inherent biodegradation according to OECD Test Guideline 302 B (Zahn-Wellens / EMPA Test), EU Method C9 and EPA OPPTS 835.3200.  The test item attained 9% biodegradation after 28 days and cannot therefore be considered as inherently biodegradable under the experimental conditions employed in this study.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The study was performed to assess the inherent biodegradability of the test item in an aerobic aqueous media. 

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The test item was exposed to activated sewage sludge micro-organisms at a concentration of 50 mg carbon/L with mineral medium in the dark at temperatures of between 21 to 24 ºC for 28 days. The biodegradation of the test item was assessed by the determination of dissolved organic carbon removal. Control cultures with inoculum and the reference item, diethylene glycol and toxicity control were used for validation purposes.

The test item attained 9% biodegradation after 28 days.

 

OECD Guideline No 302B does not give any definitive pass levels for test items, however the “Summary of Considerations in the Report from the OECD Expert Group on Degradation and Accumulation” suggests that a figure of more than 20% biodegradation may be regarded as evidence for inherent, primary biodegradability. A figure of more than 70% mineralisation may be regarded as evidence for ultimate biodegradation.

 

The test item can therefore be considered not to have exhibited evidence of inherent, primary biodegradation under the experimental conditions employed in this study.