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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The test item attained 63 % biodegradation after 28 days and can therefore be considered to be readily biodegradable (OECD 301B).

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

INTRODUCTION

A study was performed to assess the ready biodegradability of the test item in an aerobic aqueous medium. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (1992) No 301B "Ready Biodegradability; CO2 Evolution Test" referenced as Method C.4 -C of Commission Regulation (EC) No 440/2008 and US EPA Fate, Transport, and Transformation Test Guidelines OCSPP 835.3110 (Paragraph m).

 

METHODS

The test item, at a concentration of 10 mg Carbon/L, was exposed to activated sewage sludge micro-organisms with mineral medium in sealed culture vessels in the dark at 18 to 23 °C for 28 days.

 

The biodegradation of the test item was assessed by determination of carbon dioxide produced. Control solutions with inoculum and the reference item, sodium benzoate, together with a toxicity control were used for validation purposes.

RESULTS

The test item attained 63 % biodegradation after 28 days and therefore be considered to be readily biodegradable.

CONCLUSION

The test item attained 63 % 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, (2006), 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.