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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1985-03-13 to 1985-04-10
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-GLP study. Guideline from 1981. Deviation to the updated OECD Guideline (adopted 1992): The volume of the test solution was reduced fron 3.0 to 1.5 L.
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
yes
Remarks:
: volume of test solution reduced to 1.5 L
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Bacteria collected from activated sludge of the sewage treatment plant of CH - 4153 Reinach on 12/03/85
- Preparation of inoculum for exposure: according to guideline
Duration of test (contact time):
28 d
Initial conc.:
10 mg/L
Based on:
test mat.
Initial conc.:
20 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Solubilising agent: in 300 mL of mineral solution were added 0.5 mL Nonylphenol 10E05P0 (solution of 31.2 mg in 100 ml bidist. water)
- Test temperature: 22 ± 2°C

TEST SYSTEM
- Culturing apparatus: 2 Liter flasks equipped with gas inlet and magnetic stirrer.
- Number of culture flasks/concentration: 1
- Test performed in closed vessels
- Method used to create aerobic conditions: 50 ml/min aeration free of carbon dioxide

SAMPLING
- Sampling frequency: day 5 / 9 / 13 / 16 / 19 / 22 / 27 and 28
- Sampling method: Titration of the carbondioxide, absorbed in the absorbers filled with 0.025 N Barium hydroxide on the days 5 / 9 / 13 / 16 / 19 / 22 / 27 and 28.
Reference substance:
aniline
Parameter:
% degradation (CO2 evolution)
Value:
5
Sampling time:
28 d
Remarks on result:
other: 10 mg test substance/L
Parameter:
% degradation (CO2 evolution)
Value:
7
Sampling time:
28 d
Remarks on result:
other: 20 mg test substance/L
Details on results:
Theoretical carbon dioxide formation:
10 mg test substance/L 37.00 mg CO2/1.5 L
20 mg test substance/L 74.01 mg CO2/1.5 L
Results with reference substance:
The biodegradation was calculated as 20 mg/L 93 % in 28 days.
Interpretation of results:
under test conditions no biodegradation observed
Endpoint:
biodegradation in water: screening tests
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
1985-03-14
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non GLP. Deivations: The test substance was dissolved in sulfuric acid containing silver sulfate instead of water
Qualifier:
according to
Guideline:
other: DIN 38 409
Deviations:
yes
GLP compliance:
no
Oxygen conditions:
aerobic
Duration of test (contact time):
2 h
Details on study design:
TEST CONDITIONS
- Composition of medium:
Potassium dichromate
Mercury sulfate
Silver sulfate
Sulfuric acid
- Test temperature: 148 +/- 3 °C
- Other:
Titration solution: Ammonia-iron-II-sulfate 0.012 mol/L. The preparation of the stock solution of the reagents was carried out according the method described in the guideline DIN 3O409

TEST SYSTEM
- Culturing apparatus: 250 mL round bottom flasks equiped with a condenser.
Reference substance:
other: Potassium hydrogen phthalate
Parameter:
COD
Value:
2.41 other: g COD/g test item
Results with reference substance:
201 mg COD/L

Description of key information

Not readily biodegradable (according to OECD criteria); poorly biodegradable. 

Key value for chemical safety assessment

Additional information

The ready biodegradability of the test item was assessed over a 28 day period by the modified Sturm test (OECD 301B). The nominal test concentrations were 10 and 20 mg a.s./L. The test material attained up to 5 and 7 % biodegradation after 28 days whereas the positive control substance (Aniline) was 93 % degraded after 28 days. These results indicate that the test item cannot be classified readily biodegradable under conditions of the test.

The COD calculted in a study according to DIN 38409 was determined to be 2.41 g COD/ g test item.