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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The method followed that described in the OECD Guidelines for Testing of Chemicals (1992) No 301B, "Ready Biodegradability; CO2 Evolution Test" referenced as Method C.4-C of Commission Directive 92/69/EEC.
The test material attained 92% degradation after 28 days and can therefore be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No 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 material in an aerobic aqueous medium. The method followed that described in the OECD Guidelines for Testing of Chemicals (1992) No 301B, "Ready Biodegradability; CO2 Evolution Test" referenced as Method C.4-C of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC), and US EPA Fate, Transport, and Transformation Test Guidelines OPPTS 835.3110 Paragraph (m).

Methods:

The test material, at a concentration of 10 mg Carbon/l, was exposed to activated sewage sludge micro-organisms with culture medium in sealed culture vessels in the dark at approximately 21°C for 28 days.

Following the recommendations of the International Standards Organisation (ISO 1995) and the published literature (Handley et al, 2002), the test material was adsorbed onto granular silica gel prior to dispersion in the test medium to aid dispersion of the test material in the test medium and to increase the surface area of the test material exposed to the test organisms.

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

Results:

The test material attained 92% degradation after 28 days and satisfied the 10-Day window validation criterion, whereby 60% degradation must be attained within 10 days of the degradation exceeding 10%. The test material can therefore be considered to be readily biodegradable under the strict terms and conditions of OECD Guideline No 301B.