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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Not readily biodegradable, OCED 301 B, EU Method C.4-C, Grade 1999

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The biodegradability of the test material was determined in a key study (Grade, 1999), where degradation of the test material was measured in a carbon dioxide evolution test. Activated sludge was exposed to the test material at 17.5 and 18.0 mg ThOC/L over a period of 29 days at a constant temperature under diffused light. The evolved COwas trapped in sodium hydroxide and measured as inorganic carbon by a carbon analyser.

Sodium benzoate was run concurrently as a reference material to demonstrate the activity of the test system, this reached 85 % degradation within the 10 day window. A toxicity and inhibition control was run where the inoculums was exposed to both the reference substance and the test material, the high rate of COevolution observed confirmed that the test material had no inhibitory effect on the activated sludge. Result obtained from these and blank controls confirmed the validity of the test system.

Under the conditions of the test, the test material was determined to be not readily biodegradable. By Day 29 biodegradation was determined to be 1.9 and 0.9 mg TOC/1.5 L when exposed to the test material at 17.5 and 18.0 mg ThOC/L, respectively, representing degradation of 5 %. 

 

The study was performed according to GLP and standardised guidelines, with a high level of reporting and have thus been assigned a reliability score of 1 in line with the principles for assessing data quality set out by Klimisch (1997). The study is considered to be reliable, relevant and adequate for risk assessment purposes. The conclusion was taken forward for risk assessment.

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