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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:
2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Principles of method if other than guideline:
The OECD 301 B Screening Test Study aim at assessing the ready biodegradability in a laboratory system designed to represent either the aerobic treatment stage. A positive result in a test of ready biodegradability, it may be assumed that the chemical will undergo rapid and ultimate biodegradation in the environment.
A measured volume of inoculated mineral medium, containing a known concentration of the test substance (10-20 mg DOC or TOC/l) as the nominal sole source of organic carbon is aerated by the passage of carbon dioxide-free air at a controlled rate in the dark or in diffuse light. Degradation is followed over 28 days by determining the carbon dioxide produced. The CO2 is trapped in barium hydroxide and is measured by titration of the residual hydroxide or as inorganic carbon.
The amount of carbon dioxide produced from the test substance (corrected for that derived from the blank inoculum) is expressed as a percentage of ThCO2.
A substance is classified as ready biodegradable when the amount of CO2 indicates a degradation greater than 60 %.
GLP compliance:
yes
Specific details on test material used for the study:
Batch: FU310317
Preparation date:31/03/17
Expiration date: 03/2022
Receiving date: 23/6/2017
Lab ID: 17.596163.0001
Purity: 99,86%
Composition: Reaction product of stearic acid and diglycerol Ester
Oxygen conditions:
aerobic
Remarks:
The system was aerated in continuous with CO2 free air with a flux between 30 mL/min e 100 mL/min
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
activated sludge, domestic, not adapted Collect in Camposampiero ( PD) WT from Aerobic Aereation Re-circulation 15/11/17.
Inoculum final concentration in every single bottle:
- UFC/L 43 000 000
- Suspended solids = 29,3 mg/L
Duration of test (contact time):
>= 28 d
Initial conc.:
> 10 - < 20 mg/L
Based on:
TOC
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: KH2PO4,K2HPO4, Na2HPO4. 2H2O,NH4Cl, CaCl2, CaCl2. 2H2O, MgSO4.7H2O,FeCl3. 6H2O and water.
- Test temperature: 20-24°C
- pH: 7.1-7.4
- pH adjusted: NO
- CEC (meq/100 g):
- Aeration of dilution water:
- Suspended solids concentration:

TEST SYSTEMS:
A measured volume of inoculated mineral medium, containing a known concentration of the test substance (10-20 mg DOC or TOC/l) as the nominal sole source of organic carbon is aerated by the passage of carbon dioxide-free air at a controlled rate in the dark or in diffuse light. Degradation is followed over 28 days by determining the carbon dioxide produced. The CO2 is trapped in barium hydroxide and is measured by titration of the residual hydroxide or as inorganic carbon.

SAMPLING
- During the first ten days titrations were made every second or third day and then at least every fifth day.


Reference substance:
benzoic acid, sodium salt
Remarks:
sigma aldrich; purity 99.8%
Test performance:
All operative procedures applied are in accordance with the OECD 301- B method.
Interpretation and use of degradability data are in accordance with OECD GUIDELINES FOR THE TESTING OF CHEMICALS part 1: principles and strategies related to the testing of degradation of organic chemicals – march 2006

-The difference of the results of replicate values is inferior to 20%
-CO2 evolved from the blank is less than 70 mg/l
-At the 14th test day, the biodegradability of the reference substance is superior to the 60%.
-At the 10th test day from 10%, the biodegradability of the test item is superior to the 60%.(10-d windows).
Key result
Parameter:
% degradation (CO2 evolution)
Remarks:
YES
Value:
ca. 85.3
Sampling time:
3 d
Remarks on result:
other: During the first ten days titrations were made every second or third day and then at least every fifth day.
Details on results:
Sample solutions at the end of the test study:
A - pH start= 7.4; pH end = 7.1
B - pH start= 7.4; pH end = 7.4
BIODEGRADABILITY OF TEST SUBSTANCE: 85.3 %
BIODEGRADABILITY OF REFERENCE SUBSTANCE: 99.2 %
Blank control: 21.8 mg CO2/L
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Test sample Biodegradation after 28 days > 60 % ThCO2
ESTER B is readily biodegradable
Executive summary:

A measured volume of inoculated mineral medium, containing a known concentration of the test substance (10-20 mg DOC or TOC/L) as the nominal sole source of organic carbon is aerated by the passage of carbon dioxide-free air at a controlled rate in the dark or in diffuse light.

Degradation is followed over 28 days by determining the carbon dioxide produced.

The amount of carbon dioxide produced from the test substance (corrected for that derived from the blank inoculum) is expressed as a percentage of ThCO2.

Test sample Biodegradation after 28 days > 60 % ThCO2

Description of key information

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Ester B is readily biodegradable.

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