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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

OECD Guideline 301D, GLP, key study, validity 1:
63% biodegradation after 28 days (10 day window not required, UVCB substance).
Readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

One valid key study is available to assess the biodegradation potential of the registered substance. This study was performed according to OECD Guideline 301D with GLP statement. The test substance was exposed to activated sewage sludge micro-organisms at a concentration of 2 mg/L with culture medium in closed bottles in the dark at 22-24 °C for 7, 14, 21 and 28 days. The degradation of the test substance was assessed by the measurement of oxygen consumption. The test substance attained 63% degradation after 28 days. Hence, the test substance is classified as readily biodegradable. However, this substance did not fulfill the time window criterion for ready biodegradable substance. As this substance is an UVCB substance, the biodegradation of the constituents requires the concerted action of different microorganisms as a single organism usually lacks the full complement of enzymatic capabilities. The biodegradation of each constituent may be fully in line with the time window criterion when judged as separate chemicals. The biodegradation of the chemicals in a multi-constituent by different microorganisms is the reason for not applying the time window as pass/fail criterion. In conclusion, the registered substance can be considered to be readily biodegradable. In addition, according to this study, no inhibition of the biodegradation due to the initial test substance concentration is expected.