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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:
2016-06-20 to 2016-09-26
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2016
Report date:
2016

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
Mandelic acid
EC Number:
202-007-6
EC Name:
Mandelic acid
Cas Number:
90-64-2
Molecular formula:
C8H8O3
IUPAC Name:
hydroxy(phenyl)acetic acid
Test material form:
solid
Specific details on test material used for the study:
Designation: Art. 806913
Synonym: DL-Mandelic acid
Appearance: white crystalline powder
Released until: August 15, 2016
ThOD: 1.78 mg O2/mg

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, D-31137 Hildesheim

- Pretreatment:
The activated sludge was washed twice with autoclaved tap water. After the second washing the settled sludge was filled up with mineral salts medium and was maintained in an aerobic condition by aeration for 2-4 hours. Thereafter the sludge was homogenized with a blender. The supernatant was decanted and maintained in an aerobic condition by aeration with CO2-free air for 6 days. 10 mL/L were used to initiate inoculation.

- Concentration of sludge: 10 mL/L
- Initial cell/biomass concentration: 10^7 - 10^8 CFU/L
- Water: demineralized
Duration of test (contact time):
28 d
Initial test substance concentrationopen allclose all
Initial conc.:
30 mg/L
Based on:
test mat.
Initial conc.:
53.4 mg/L
Based on:
ThOD
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Preparation of Test Flasks:
All test solutions were prepared in measuring flasks in demineralised water with the required amounts of mineral medium stock solutions and 10 mL/L inoculum. The test item was weighed out and demineralised water was added. After ultrasonic treatment it was transferred into the measuring flasks.

The reference item was weighed out and transferred into the measuring flasks with demineralised water.

250 mL measuring flasks were used to place 250 mL of the test solutions in the brown glass bottles.

A rubber sleeve with soda lime was hung into the opening of the bottles to absorb evolved CO2. The bottles were closed with Oxi-Top® measuring heads and the measuring system was activated.


Measurements:
The temperature in the incubator was documented continuously throughout the test by a hygrothermograph.
At test start the pH-values of the test solutions in the measuring flasks (before dividing) and at test end the pH-values of the test solutions in the brown glass bottles were determined.
The oxygen consumption was determined continuously from the pressure in the incubation vessels by OxiTop® measuring system at 360 measuring points (every 112 minutes) during the 28 d incubation period.



Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

Test performance:
Results of the Functional Control
The pass level of a biodegradation > 60 % was reached on day 4. On day 24, a maximum degradation of 93 % was observed. The validity criterion that the degradation should be > 60 % after 14 d was fulfilled

Results of the Toxicity Control
In the toxicity control the biodegradation achieved 83 % after 14 days. After 28 days the biodegradation came to 91 %. The validity criterion that the test item should not inhibit the biodegradation of the reference item was fulfilled.
% Degradation
Key result
Parameter:
% degradation (O2 consumption)
Value:
99
Sampling time:
28 d
Details on results:
After 28 days, a biodegradation of 99% was observed.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test item is classified as readily biodegradable within the  10-day window and within the 28 day period of the study.
Executive summary:

The test item is classified as readily biodegradable within the  10-day window and within the 28 day period of the study.

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