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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

The test item mesityl oxide contains no nitrogen, therefore the evaluation of biodegradation has to be based on ThODNH4. The criterion for ready biodegradability under the conditions of a manometric respirometry test is the 10-day window, describing the period between reaching at least 10% degradation and 60% degradation. This period should not exceed 10 days.

The mean biodegradation after 28 days of mesityl oxide was 75% (ThODNH4); the 10 day window criterion was passed.

Therefore, mesityl oxide is considered to be readily biodegradable.

The reference item sodium benzoate was sufficiently degraded to a mean of 88% after 14 days and to a mean of 92% after 28 days of incubation, thus confirming the suitability of theaerobic activatedsludge inoculum used.

In the toxicity control containing both, the test item and the reference item sodium benzoate, a mean of 55% biodegradation was noted within 14 days and 58% biodegradation after 28 days of incubation. Thus, the test item can be assumed to be not inhibitory to the aerobic activated sludge micro organisms.