Registration Dossier

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:
2017-08-24 to 2017-09-22
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report Date:
2017

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

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

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Municipal sewage treatment plant, 31137 Hildesheim, Germany
- Pretreatment: The activated sludge was washed twice with chlorine free tap water. After the second washing the settled sludge was resuspended in mineral salts medium and was maintained in an aerobic condition by aeration for 2 ½ hours. Thereafter the sludge was homogenized with a blender. After sedimentation the supernatant was decanted and maintained in an aerobic condition by aeration with CO2 free air until test start (7 days). 10 mL/L of this mixture were used to initiate inoculation.
- Initial cell/biomass concentration: Approx. 10e7 - 10e8 CFU/L
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
20 mg/L
Based on:
test mat.
Initial conc.:
10.4 mg/L
Based on:
TOC
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Test temperature: Nominal 22 ± 2 °C, actually measured 20.0 - 24.0 °C
- pH: 7.61 - 7.76
- pH adjusted: no
- Aeration of dilution water: 30 - 100 ml/min

TEST SYSTEM
- Number of culture flasks/concentration: 2

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Toxicity control: yes
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Key result
Parameter:
% degradation (CO2 evolution)
Value:
2
Sampling time:
28 d
Details on results:
• The total C02 evolution in the inoculum control at the end of the test was 21. 7 mg/L (validity criterion: < 40 mg C02 /L after 28 days).
• The degradation of the functional control reached the pass level of ~ 60% within 6 days (degradation: 62% on day 6).
• The differences of extremes of replicate values of removal of the test item at the end of the test was less than 20% (1% difference on day 28).
• The degradation of the toxicity control reached the pass level of 25% within 6 days (degradation: 33% on day 6).

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
Under the test conditions the test item is classified as not readily biodegradable within the 28 day period of the study.