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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The test substance was not readily biodegradable in CO2 evolution test.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

A study was conducted to determine the ready biodegradability of the test substance according to OECD Guideline 301B and EU Method C.4 -C (CO2 evolution test), in compliance with GLP. Domestic activated sludge was exposed to the test substance at concentrations of 0 or 12 mg TOC/L for 28 days followed by sampling at regular intervals to measure CO2 evolution. A positive control (sodium acetate) and a toxicity control were included in the experiment. The amount of CO2 produced was determined by titrating the remaining Ba(OH)2 with standardised HCl. Each sample was measured in duplicates. The relative biodegradation values, calculated from the measurements performed during the test period, revealed no biodegradation of the test substance (based on ThCO2), for the duplicate bottles tested. Thus, the criterion for ready biodegradability (i.e., at least 60% biodegradation within a 10-day window) was not met. In the toxicity control, the test substance was found not to inhibit microbial activity. Since all criteria for acceptability of the test were met, this study was considered to be valid. Under the study conditions, the test substance was considered not readily biodegradable (Desmares-Koopmans, 2017).