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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Key: Unilever 1996: Not readily biodegradable. 

Key value for chemical safety assessment

Additional information


The ready and ultimate biodegradability of the test substance was examined in a CO2 evolution test which was conducted to a method largely in accordance with the OECD 301B, and in accordance with studies aimed at harmonising tests of ready biodegradability, and was conducted to GLP standard. The study was assigned a reliability score of 1, in accordance with Klimisch (1997).

The test substance was assessed to have achieved 21.5 % (95 % CL of -5.7 to 48.6) degradation after 28 days. The test substance can therefore not be considered to be readily and ulimately biodegradable.


In the supporting study, assessing the ready biodegradability of the test substance, in a modified MITI test using activated sludge, the test substance was concluded to be not readily biodegradable. No biodegradation was observed. The study was conducted in accordance with the OECD 301C guideline and to GLP standard. It is included only as supporting data as the pre-treatment of the inoculum such as in the MITI test (OECD 301C) impacts on the diversity of the microbes and hence the MITI test often gives lower levels of biodegradation than other OECD ready tests. 

Further supporting information is provided in an extended ready test. In this test, the substance was assessed to have achieved 28.5 % (95 % CL of 20.8 - 36.2) degradation after 56 days confirming the partial degradation seen in the key ready biodegradability study.