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Biodegradation in water: screening tests

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Description of key information

Not readily or inherently biodegradable

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

A study was performed to assess the ready biodegradability of Reddish Blue. The study was conducted in accordance with the OECD Guideline for Testing of Chemicals No. 301 F 'Manometric respirometry Test' (adopted July 17, 1992). A solution of Reddish Blue in a mineral medium was inoculated and incubated for 28 d under aerobic conditions. During this period, degradation was followed by BOD determinations. Test item showed: 1% degradation after 28 days. Therefore, Reddish Blue is considered to be "Not Readily Biodegradable". The control substance monoethylene glycol showed 83% degradation, proving the validity of the test system.

In addition, a study for inherent biodegradability of Reddish Blue was performed according to the OECD Guidelines for the Testing of Chemicals, Inherent Biodegradability: Modified MITI Test II.: OECD, Adopted 12 May 1981.

As the test substance was difficult soluble in water, the test substance was dissolved with acetone, and some acetone solution of test substance was added to the flask. The acetone was volatile completely and the test substance remained absorbed to the bottom and inner surface of the flask uniformly.

Results of recovery tests showed that the percent recovery of the test substance from water + test substance was 72.2% and the recovery from test medium + inoculum + test substance was 72.1% at start of the study.

At the end of the test, the residual content of test substance of abiotic control and the three test suspensions were 10.7mg and 11.3mg, 11.0mg and 11.1mg (3 replicates), respectively. Considering the extracting efficiency, the reduction of the test substance in abiotic control might be due to the loss during extraction process of test substance but not non-biodegradation. The percentage primary biodegradation of test suspensions was 0%.

The percentage biodegradation at the end of the test substance by BOD was 0%.