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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The test material attained 1 % biodegradation after 28 days in an aerobic aqueous medium, OECD 301B, EU Method C.4-C and US EPA OPPTS 835.3110

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

A study was performed to assess the ready biodegradability of the test material in an aerobic aqueous medium. The method followed was designed to be compatible with the standardised guidelines OECD 301B, EU Method C.4-C and US EPA OPPTS 835.3110 under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (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.

The biodegradation 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.

The results of the inorganic carbon analysis of samples from the first absorber vessels on Day 29 showed an increase in all replicate vessels. Inorganic carbon analysis of the samples from the second absorber vessels on Day 29 confirmed that no significant carry-over of CO2 into the second absorber vessels occurred.

The test material attained 1 % biodegradation after 28 days and therefore cannot be considered to be readily biodegradable.

Statistical analysis of the Day 29 IC values for the control and test material vessels showed there were no statistically significant differences (p>=0.05) between the control and the test material. The test material was therefore considered not to have a toxic effect on the sewage sludge microorganisms used in the study and this was confirmed by the toxicity control results.

The toxicity control attained 28 % biodegradation after 14 days and 46 % biodegradation after 28 days thereby confirming that the test material did not exhibit an inhibitory effect on the sewage treatment microorganisms used in the test.

Under the conditions of this study, the test material cannot be considered to be readily biodegradable.