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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The test item attained 96% degradation after 28 days and satisfied the 10-Day window validation criterion, whereby 60% degradation must be attained within 10 days of the degradation rate exceeding 10%. The test item can therefore be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301F.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Introduction:

The study was performed to assess the ready biodegradability of the test item in an aerobic aqueous media. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (1992) No 301F, "Ready Biodegradability; Manometric Respirometry Test" referenced as method C.4-D of Commission Regulation (EC) No. 440/2008 and US EPA Fate, Transport, and Transformation Test Guidelines OPPTS 835.3110 (Paragraph (q)).

Methods:

Initially a test concentration of 100 mg/L was employed, however after completion of the study information was received from the Sponsor which indicated that the test item contained water. Therefore after correction for a water content in the test item of 50.5%, the test concentration employed was 49.5 mg active ingredient (ai)/L. The test item at a concentration of 49.5 mg ai/L was exposed to sewage treatment micro-organisms with mineral medium in sealed culture vessels in diffuse light at approximately 22°C for 28 days.

The degradation of the test item was assessed by the measurement of daily oxygen consumption values on Days 0 to 28. Control solutions with inoculum and the reference item, aniline, together with a toxicity control were used for validation purposes.

Results:

The test item attained 96% degradation after 28 days and satisfied the 10-Day window validation criterion, whereby 60% degradation must be attained within 10 days of the degradation rate exceeding 10%. The test item can therefore be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No. 301F.