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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:
2018-06-12 to 2018-10-15
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
1992
Deviations:
no
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Preparation of inoculum for exposure: 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 with CO2 free air untii test start (2 days). The amount of inoculum used to initiate inoculation was 4.0 mL/L (25.0 mg/L dw).
Duration of test (contact time):
28 d
Initial conc.:
46 mg/L
Based on:
test mat.
Remarks:
corresponding to an oxygen demand of 51.1 mg O2/L
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: Mineral salts medium according to OECD 301 F
- Test temperature: Nominal: 20 - 24 ± 1 °C; Actual: 21.0 - 21.2 °C
- pH: 7.42 - 7.71
- pH adjusted: no
- Suspended solids concentration: 25.0 mg/L dw
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: Brown glass bottles (volume 500 mL), continuous stirring
- Number of culture flasks/concentration:
- two for the inoculum control (C1, C2)
- one for the functional control (R1)
- two for the test item (P1, P2)
- one for the toxicity control (T1);
Separate replicates of test item and toxicity control were prepared for measurement of the pH-value at test start:
- one for the test item (PpH)
- one for the toxicity control (TpH)
- Measuring equipment:
OxiTop® OC1 10 controller with software Achat OC, WTW
OxiTop® measuring heads, WTW
Stirring platform, WTW
Climatic exposure test cabinet, RUMED RUBARTH APPARATE GMBH
pH-Meter, Multi 350i, WTW
Datalogger 174 T, TesTo
Analytical balance, SARTORlUS
Balance, KERN
Magnetic stirrer, M83000, lab 4 you
Spectralphotometer NANOCOLOR® UV/VlS, MACHEREY- NAGEL
Test Kits: Nitrat 50, Nitrit 2, all by MACHEREY-NAGEL
Multipette X-Stream, EPPENDORF
Various pipettes
- Details of trap for CO2 and volatile organics if used: A rubber sleeve with soda lime was hung into the opening of the bottles to absorb evolved CO2. The bottles were closed with OxiTop® measuring heads and the measuring system was activated.
CONTROL AND BLANK SYSTEM
- Inoculum blank: duplicate, The inoculated test medium, consisting of the required volumes of mineral medium stock solutions, ultrapure water and inoculum, was prepared in a measuring flask. 250 mL of this solution were filled in the brown glass bottles of the inoculum control, using a 250 mL measuring flask.
- Functional control: one test vessel, the reference item was weighed out and transferred into a measuring flask, the required volumes of mineral medium stock solutions, ultrapure water and inoculum, were added. 250 mL of this solution were filled in the brown glass bottle of the functional control, using a 250 mL measuring flask.
- Toxicity control: one test vessel, the test item was weighed out and directly transferred into the test vessels with 250 mL of the reference item medium, using a 250 mL measuring flask.
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (O2 consumption)
Value:
18
Sampling time:
15 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
67
Sampling time:
23 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
93
Sampling time:
28 d
Key result
Parameter:
% degradation (O2 consumption)
Remarks:
second test vessel
Value:
13
Sampling time:
17 d
Key result
Parameter:
% degradation (O2 consumption)
Remarks:
second test vessel
Value:
66
Sampling time:
27 d
Key result
Parameter:
% degradation (O2 consumption)
Remarks:
second test vessel
Value:
79
Sampling time:
28 d
Results with reference substance:
% degradation on day 1: 10
% degradation on day 10: 93
% degradation on day 28: 100
The pass level for ready biodegradation (≥ 60% degradation) was reached within 3 days. The validity criterion that the degradation should be ≥ 60% after 14 d was fulfilled. Stages of Biodegradation: The adaptation phase changed to the degradation phase within 1 day (degradation > 10%), with a maximum of 100% on day 15
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
After a test period of 28 days, the test item is classified as readily biodegradable within the 10-day-window and within the 28 day period of the study.

Description of key information

The ready biodegradability of the test item 2H-lsoindole-2 -ethanesulfonic acid, 1,3 -dihydro-1,3 -dioxo-, potassium salt (1:1) (TA-1) was determined with non-adapted activated sludge in the Manometric Respirometry Test for a period of 28 days according to OECD guideline 301 F. The validity criteria of the guideline are fulfilled. The test item is classified as readily biodegradable within the 10 -day-window and within the 28 day period of the study.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information