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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

Screening tests for biodegradation of Reactive Black 5 and Reactive Blue 203 in water showed that the test substance is not readily or inherently biodegradable. However, this reactive dye is rapidly removed from the dye-bath as shown by decolorisation of the test medium.

A study was conducted to assess the ready biodegradability of the Structural Analogue 01 according to EU Method C.4-D (which is in most parts equivalent to OECD Guideline 301 F), in compliance with GLP.

100 mg/L of the test substance was inoculated (in triplicate) with non-adapted activated sludge in a closed flask at a constant temperature (22±2°C) for up to 28 d. Degradation was assessed by the determination of Biochemical Oxygen Demand (BOD) on Days 2, 6, 8, 12, 14, 16, 20, 22, 26 and 28. A toxicity test and a control solution containing the reference substance benzoic acid, sodium salt (100 mg/L) together with inoculum were used for validation purposes. The test substance degraded 0% by Day 28. No toxicity of the test substance was observed in the toxicity control. The reference compound showed 90% degradation at Day 14.

Hence, under the study conditions, the test substance was considered to be ‘not readily biodegradable’.