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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:
2008
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Deviations:
no
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: sewage treatment works A-2500 Baden, which waste-water catchment is predominantly domestic
- Laboratory culture: On arrival in the laboratory and after sedimentation the clear supernatant was decanted and the sludge was filled up with tap water to its origin volume of 6 L to reduce the carbon content. The sample was aerated by means of a filtered compressed air before being used for the study.
- Pretreatment: none.
- Concentration of sludge: The concentration of the final suspended solids of the sludge in all vessels was nominally ca. 20 mg/L.
Duration of test (contact time):
28 d
Initial conc.:
112.5 mg/L
Based on:
test mat.
Initial conc.:
15 mg/L
Based on:
other: carbon
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: mineral medium as in the guideline.
- Additional substrate: none.
- Solubilising agent (type and concentration if used): none.
- Test temperature: 22 +- 2 °C.
- pH: determined.
- pH adjusted: no
- Suspended solids concentration: 20 mg/L.
- Continuous darkness: yes.

TEST SYSTEM
- Culturing apparatus: 5 L flasks.
- Number of culture flasks/concentration: 2 negative control flasks, 2 test substance flasks, 1 positive control flask, 1 toxicity control flask.
- Method used to create aerobic conditions: Apparatus for carbon dioxide scrubbing and a mixture of CO2-free oxygen and CO2-free nitrogen, from gas cylinders, in the correct proportions (20 % O2: 80 % N2) were used.
- Test performed in closed vessels.

SAMPLING
- Sampling frequency: The CO2 evolution was determined on Days 1, 2, 4, 6, 8, 10, 14, 19, 24 and 28/29.
Day 0 was the day of the addition of the test substance to the medium.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: yes, containing test substance and positive reference substance.
- Other: Positive reference substance.

STATISTICAL METHODS: no.
Reference substance:
benzoic acid, sodium salt
Preliminary study:
None.
Test performance:
No unusual observations were made.
Key result
Parameter:
% degradation (CO2 evolution)
Value:
12.6
Sampling time:
28 d
Results with reference substance:
Positive control: 70.4 % biodegradation after 6 days. The plateau of biodegradation was reached on about Day 10 and the degradation of the positive reference substance sodium benzoate exceeded the pass level of 60 % on about Day 5. The test is considered to be valid.
Toxicity control: 39.8 % biodegradation after 28 days. Degradation in the toxicity control, which contained sodium benzoate and the test substance, was not indicative of an inhibition of the microbial activity by the test substance.
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
The biodegradability of "Tazobactam acid" was analysed by the determination of carbon dioxide evolution at frequent intervals over a 28 day period.
The method used was that described in Part C.4-C of the EC Commission Directive 92/69/EEC and in the OECD Guideline 301B.

Results
• The reference substance sodium benzoate was degraded by 87.6 % within 10 days.
• Degradation in the toxicity control, which contained sodium benzoate and the test substance, was not indicative of an inhibition of the microbial activity by the test substance.
• The carbon dioxide evolution from "Tazobactam acid" with a nominal concentration of 15 mg carbon/L reached 12.6 % after 28 days of incubation at mean temperatures of
22.5 °C.

Classification
According to the results of this study, "Tazobactam acid" cannot be classified as readily biodegradable.
Executive summary:

The biodegradability of "Tazobactam acid" was analysed by the determination of carbon dioxide evolution at frequent intervals over a 28 day period. The method used was that described in Part C.4-C of the EC Commission Directive 92/69/EEC and in the OECD Guideline 301B.

 

Results

·     The reference substance sodium benzoate was degraded by 87.6 % within 10 days.

·     Degradation in the toxicity control, which contained sodium benzoate and the test substance, was not indicative of an inhibition of the microbial activity by the test substance.

·     The carbon dioxide evolution from "Tazobactam acid" with a nominal concentration of 15 mg carbon/L reached 12.6 % after 28 days of incubation at mean temperatures of 22.5 °C.

Classification

According to the results of this study, "Tazobactam acid" cannot be classified as readily biodegradable.

Description of key information

Key study. Test method according to OECD 301B. GLP study. The carbon dioxide evolution from "Tazobactam acid" with a nominal concentration of 15 mg carbon/L reached 12.6 % after 28 days of incubation at mean temperatures of 22.5 °C. The substance is not ready biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information