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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
20.03.2000 to 19.07.2000
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
GLP guideline study with deviation

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2000

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Deviations:
yes
Remarks:
Pre adaption of the inoculum
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, adapted
Details on inoculum:
Mixed population of aquatic micro organisms (activated sludge) collected on 20.06.2000 from the aeration tanks (step II) of the joint sewage treatment plant Bürrig. The inoculum was adapted to 100mg/l of the test substance for approximately 4 weeks before the start of the study.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
ca. 100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
The test substance was suspended in a mineral medium, inoculated with a mixed population of aquatic micro organism (30mg ss/l) and incubated for 28 days under aerobic conditions in the dark at 20± 1°C. During this period the biodegradation of the test material was determined on days 2, 6, 8, 12, 14, 16, 20, 22, 26 and 28 by measuring the oxygen consumption with a respirometer.

TEST SET-UP:
- Blank: test medium only (3 replicates)
- Inoculum control: test medium and added reference substance sodium benzoate 100 mg/l (3 replicates)
- Test substance: test medium and added test substance 100 mg/l (3 replicates)
- Toxicity control: test medium added test substance (100 mg/l) and reference substance (100 mg/l). (2 replicates)
Reference substance
Reference substance:
benzoic acid, sodium salt
Remarks:
100 mg/l

Results and discussion

% Degradation
Key result
Parameter:
% degradation (O2 consumption)
Value:
35
Sampling time:
28 d
Details on results:
For the reference substance sodium benzoate biodegradation of 81% was acheived in 14 days.

See attached background information

Any other information on results incl. tables

See attached background information

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Interpretation of results:
other: not readily biodegradable
Conclusions:
The test item attained 35% degradation after 28 day and therefore cannot be considered to be readily biodegradable under the strict terms and conditions of the guidelines.
Executive summary:

The test was conducted to according to the Manometric Respiratory test Method Council Directive 92/69 EEC Method C.4 -D.

The test substance was degraded by 35% after 28 days.