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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The test substance was investigated for its ready biodegradadability according to OECD guideline 301 A. The substance was not readily biodegradable, however some biodegradation was observed (19%).

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Additional information

The submission substance was investigated for its ready biodegradability in a "28-Day DOC Die-Away Test" according to the Commission Regulation (EC) No 440/2008, C.4-A, the EU Commission Directive 92/69 EEC, C.4-A and the OECD Guideline for Testing of Chemicals, No. 301 A (1992).

In the test flasks, containing the submission substance and activated sludge (inoculum), the mean concentration of dissolved organic carbon (DOC) very slowly decreased by 19% of the initial value within the test period of 28 days. Therefore, submission substance was found to be biodegradable by 19% under the test conditions. However, the pass level for ready biodegradability, i.e. at least 70% removal of DOC in a 10-day window within the 28-day period of the test was not reached.

The reference item sodium benzoate was completely (>90%) biodegraded within seven days of exposure, thus confirming suitability of the activated sludge.

In the toxicity control, containing the test item, the reference item sodium benzoate and activated sludge (inoculum), the initial DOC decreased by 56% within 14 days of exposure. Thus, according to the test guidelines the submission substance was not inhibitory to activated sludge at the tested concentration of 86 mg/L because degradation was >35% within 14 days.