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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
September 14 1995 to January 23 1996
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
GLP compliance:
yes (incl. QA statement)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum: Sewage treatment plant, Hochdahl
- Concentration of sludge: 1 mL/L
Duration of test (contact time):
ca. 28 d
Initial conc.:
2 mg/L
Based on:
act. ingr.
Initial conc.:
5 mg/L
Based on:
act. ingr.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Inoculum and test material in a mineral culture medium were placed in closed flasks and kept at a constant tempetarture of 20 +/- 1°C either in the dark or under diffuse light. O2 consumption was measured iodometrically.
Biodegradability was estimated by comparing actual and the theoretical O2 consumption.
Negative (no test substance) and positive (sodium benzoate) controls were run in parallel.
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (O2 consumption)
Value:
ca. 84
Sampling time:
28 d
Remarks on result:
other: at 2 mg/L of test substance.
Key result
Parameter:
% degradation (O2 consumption)
Value:
ca. 71
Sampling time:
28 d
Remarks on result:
other: at 5 mg/L test substance. Insufficient O2 left in the flask.
Details on results:
Plateau for ready biodegradability of the test substance reached within 14 d of time point when 10% degradation occured. The 14 d window was therefore respected.
Results with reference substance:
The degradation of sodium benzoate was equivalent to 89% within 28 d. 73% degradation was reached within 7 d

None.

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Under the study conditions, the test substance was considered to be readily biodegradable
Executive summary:

A study was performed to assess the ready biodegradability of the test substance, C12-18 and C18-unsatd. DEA, according to OECD Guideline 301D (Closed bottle test), in compliance with GLP. The test substance at 2 and 5 mg/L was incubated with sludge from a domestic wastewater treatment plant and O2 consumption was followed over a period of 28 d. A total of 84% O2 consumption was obtained at 2 mg/L and the plateau for ready biodegradability was reached within 14 d, at which point there was 10% degradation. At 5 mg/mL, 71% O2 consumption was obtained, although there was insufficient O2 left in the flask at the end of the test. Under the study conditions, the test substance was considered to be readily biodegradable (Werner, 1996).

Description of key information

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information

A study was performed to assess the ready biodegradability of the test substance, C12-18 and C18-unsatd. DEA, according to OECD Guideline 301D (Closed bottle test), in compliance with GLP. The test substance at 2 and 5 mg/L was incubated with sludge from a domestic wastewater treatment plant and O2 consumption was followed over a period of 28 d. A total of 84% O2 consumption was obtained at 2 mg/L and the plateau for ready biodegradability was reached within 14 d, at which point there was 10% degradation. At 5 mg/mL, 71% O2 consumption was obtained, although there was insufficient O2 left in the flask at the end of the test. Under the study conditions, the test substance was considered to be readily biodegradable (Werner, 1996).