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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The test material attained 45 % biodegradation after 28 days and therefore cannot be considered to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable

Additional information

The ready biodegradability of the test material was assessed in the key study in accordance with the standardised guidelines OECD 301B and EU Method C.4-C under GLP conditions. It was assigned a reliability score of 1 in accordance with the criteria set forth in Klimisch (1997).

The test material, at a concentration of 10 mg Carbon/L, was exposed to activated sewage sludge micro-organisms with mineral medium in sealed culture vessels in the dark at approximately 21 °C for 28 days.

Following the recommendations of the International Standards Organisation (ISO, 1995) due to the test material being insoluble, the test material was dissolved in an auxiliary solvent prior to being adsorbed onto a filter paper and subsequent dispersal in test media. Using this method, the test material is evenly distributed throughout the test medium and the surface area of test material exposed to the test organisms is increased, thereby increasing the potential for biodegradation.

A surfactant, Synperonic PE/P 105, was also added to the test system to aid in solubilising the test material in the mineral media.

The degradation of the test material was assessed by the determination of carbon dioxide produced. Control solutions with inoculum and the reference material, sodium benzoate, together with a toxicity control were used for validation purposes

Under the conditions of this study, the test material attained 45 % biodegradation after 28 days and therefore cannot be considered to be readily biodegradable.