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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:
from 2000-07-27 to 2000-11-08
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
Version / remarks:
1992
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Type: Mixed microbial population (activated sewage sludge)
- Source of inoculum/activated sludge: Effluent of municipal sewage treatment plant of the city of Darmstadt (Sudhessische Gas und Wasser AG) in Germany. Day of sampling: 04.08.2000.
- Method of cultivation: Aerobic and dark conditions at 19 - 21 °C
- Preparation of inoculum for exposure: Aeration for 5 days
- Pretreatment: Not performed
- Concentration of sludge: 5 mL/L
- Water filtered: Yes
- Type and size of filter used, if any: Filtration through a coarse folded filter



Duration of test (contact time):
28 d
Initial conc.:
4 mg/L
Based on:
test mat.
Details on study design:
TEST CONDITIONS
- Composition of medium: Mineral medium according to OECD 301 D
- Additional substrate: no
- Solubilising agent: no
- Test temperature: 20 +/- 1 °C
- Aeration of dilution water: yes
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: Flasks according to OECD 301 D
- Number of culture flasks/concentration: 2
- Measuring equipment: Normal laboratory apparatus. Apparatus for determining dissolved oxygen, to check that the flask contents are aerobic.
- Test performed in closed vessels: yes

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes. Inoculum and mineral medium without test substance
- Procedure control: yes. Performed with the reference material aniline
- Toxicity control: yes
Reference substance:
aniline
Preliminary study:
Not performed
Test performance:
The test was considered valid. In the parallel tests with the reference material aniline, a degradation of 97 % was reached after 14 days. In addition, the percent of biodegradation in the toxicity control, containing both the test substance and reference substance, was determined to be 54 % (> 25 %), therefore the test substance can be assumed to be not inhibitory.
Key result
Parameter:
% degradation (CO2 evolution)
Value:
1
Sampling time:
28 d
Details on results:
Within the study period of 28 days, a degradation of 1 % was determined for the test substance, therefore the test substance is to be classified as being „not readily biodegradable".
Results with reference substance:
In the parallel tests with the reference material aniline, a degradation of 97 % was determined reaching the pass level of the ready biodegradation test (> 60 % within 14 days).
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
The ready biodegradability of the test item was determined according to OECD 301D. Within the study perios of 28 days, a degradation of 1 % was determined for the test substance. Therefore, the test substance cannot be considered to be readily biodegradable.
Executive summary:

The ready biodegradability of the test substance was investigated according to the OECD guideline 301 D: Closed bottle test (1992). The biodegradation of the test substance was followed by exposing it in a mineral medium, inoculated with a population of microorganisms from the effluent of municipal sewage treatment plant of the city of Darmstadt (Sudhessische Gas und Wasser AG) in Germany and incubated for 28 days under aerobic conditions in the dark at 20 ± 1 °C. During this period, the biodegradation of the test substance was determined on the basis of the reduction of dissolved oxygen. The ThOD of test item was calculated to be 1189 mg of O2/g. The test material concentration was 4 mg/L. An inoculum blank control, a procedure control and a toxicity control were used. The reference substance attained a 97 % biodegradation level (greater than 60 % degradation) within 14 days based on ThOD. In addition, the percent of biodegradation in the toxicity control, containing both the test substance and reference substance, was determined to be 54 % (> 25 %), therefore the test substance can be assumed to be not inhibitory and the validity criteria were met. Within the study period of 28 days, a degradation of 1 % was determined for the test substance, therefore the test substance is to be classified as being „not readily biodegradable".

Description of key information

The ready biodegradability of the test item was determined according to OECD 301 D (reference 5.2.1 -1). Within the study period of 28 days, a degradation of 1 % was determined for the test substance. Therefore, the test substance cannot be considered to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:
freshwater

Additional information

The ready biodegradability of the test substance was investigated according to the OECD guideline 301 D: Closed bottle test (1992). The biodegradation of the test substance was followed by exposing it in a mineral medium, inoculated with a population of microorganisms from the effluent of municipal sewage treatment plant of the city of Darmstadt (Sudhessische Gas und Wasser AG) in Germany and incubated for 28 days under aerobic conditions in the dark at 20 ± 1 °C. During this period, the biodegradation of the test substance was determined on the basis of the reduction of dissolved oxygen. The ThOD of test item was calculated to be 1189 mg of O2/g. The test material concentration was 4 mg/L. An inoculum blank control, a procedure control and a toxicity control were used. The reference substance attained a 97 % biodegradation level (greater than 60 % degradation) within 14 days based on ThOD. In addition, the percent of biodegradation in the toxicity control, containing both the test substance and reference substance, was determined to be 54 % (> 25 %), therefore the test substance can be assumed to be not inhibitory and the validity criteria were met. Within the study period of 28 days, a degradation of 1 % was determined for the test substance, therefore the test substance is to be classified as being „not readily biodegradable".