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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 anionic direct dye, amino azo compound, coupled to N-phenylamino-5-naphthol-7-sulfonic acid.

The substance is not expected to be ready biodegradable because of its chemical structure and its specific function. Commonly, dyes undergo a primary transformation, i.e. discolourization due to the interrupting the conjugation. Nevertheless, the degradation process involves more steps and take more time.

The QSAR based screening criterion for identifying substances for persistency (P and vP) confirmed that the substance is expected to be not readily biodegradable.

The substance (commercial formulation) was assayed for the biodegradability potential accordign to the ETAD reccomendations, using statistical method Zahn and Wellen. Unfortunately, only a sheet of test results is currently available; therefore, there are no details about actual test conditions and results. The information has been here mentioned for completeness sake.

Biological elimination was indicated to reach the 92 % within the first 14-days period of the test. However, it was also indicated that disappearance of the dye from the water test was mainly caused by precipitation and adsorption of the dye on the activated sludge and not by biodegradability (sheet of results, 1987).


Complete reference are included into the CSR file.