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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Expected as not readily biodegradable.

Key value for chemical safety assessment

Additional information

The substance is a pyrazole azo dye derivative. The substance is not expected to be ready biodegradable based on its chemical structure and its specific function. Commonly, dyes undergo a primary transformation, i.e. discolouration due to the interrupting the conjugation. Nevertheless, the degradation process involves more steps and takes more time.

The QSAR based screening criterion for identifying substances for persistency (P and vP) confirmed that the substance is expected to be persistent.

The test item was investigated for biodegradability potential in the inherently Zahn-Wellens test, over a period of 28 days. The substance was inoculed with a mixed population of activated sewage sludge microorganisms. Based on the DOC removal, the substance attained 71 % degradation within 14 days; during the subsequent period, the DOC removal ranged between 69 - 77 %.

Based on the chemical characteristics of the substance, it is likely that a a primary transformation occurred, followed by the substance adsorption. Therefore, the study outcomes cannot be considered as complete representative for the substance under registration.

In any case, the substance can more than likely be considered as not readily biodegradable.