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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The biodegradation of the test substance was >95% after 15 days. Therefore, the test substance is inherently biodegradable in the Zahn-Wellens test.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable

Additional information

In order to assess the biotic degradation, a inherent biodegradability test was performed which allows the biodegradability to be measured in an aerobic medium. The inherent biodegradability was determined in the Zahn-Wellens test according to OECD 302B and ISO 9888, and in compliance with the OECD principles of Good Laboratory Practice. In the biodegradability tests, sludge was inoculated into a chemically defined liquid medium containing the test substance as sole carbon and energy source. The test compound is exposed to the inoculum, consisting of relatively low numbers of microorganisms from an activated sludge plant, under aerobic conditions. The biodegradation of the test substance was >95% after 15 days. Hence, the test substance is inherently biodegradable in the Zahn-Wellens test. The reference substance was degraded more than 70% after 14 days.