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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:
19 August - 19 October 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Test material information:
Composition 1
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Batch No.of test material: 05X034
- Expiration date of the lot/batch: Not specified

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: stored at room temperature in the dark
- Solubility and stability of the test substance in the solvent/vehicle: Soluble in deionised water

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Final preparation of a solid: In stock solution
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Stromness Treatment Works, Bu Point
- Date of collection: 14 September 2016
- Initial cell/biomass concentration: 9.9 x 10^4 CFU/mL (at collection); 1.6 x 10^4 CFU/mL (on test initiation day 1)
- Water filtered: yes
- Type and size of filter used: 1 µm Whatman filter

INOCULUM PROPERTIES:
- pH: 7.00
- Temperature: 19.9 °C
- Conductivity: 1473 µS/cm
- Dissolved oxygen: 3.94% saturation
- Volume of inoculum added: 1.5 mL/L
Duration of test (contact time):
28 d
Initial conc.:
9.02 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: Deionised water. 1 L of medium contains 1 mL of stocks A, B, C and D. (Stock A = KH2PO4 8.5 g/L; K2HPO4 21.75 g/L; Na2HPO4.2H2O 33.40 g/L; NH4Cl 0.5 g/L. Stock B = CaCl2 27.50 g/L. Stock C = MgSO4.7H2O 22.50 g/L. Stock D = FeCl3.6H2O 0.25 g/L; EDTA, Di-sodium salt 0.4 g/L).
- Test temperature: 22 ± 2 °C
- pH: Test water = pH 7.46 on collection; Inoculum = pH 7.00
- Aeration of dilution water: 20 minutes
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 270-276 mL glass BOD bottles
- Number of culture flasks/concentration: 3 replicate bottles per time point for test material, oxygen blank, reference material and toxicity control
- Measuring equipment: Luminescent dissolved oxygen meter (Hach HQ40d) and probe (Hach LD010101)

SAMPLING
- Sampling frequency: 7 day intervals

CONTROL AND BLANK SYSTEM
- Inoculum blank: Measure of background oxygen consumption in test medium
- Toxicity control: Mixture of sodium benzoate and test material
Reference substance:
benzoic acid, sodium salt
Test performance:
The biodegradation of the test material achieved the pass level of 60% removal of ThOD within the 10 (or 14) day window from reaching 10% biodegradation or by the test end day.

The original test was conducted in accordance with the study plan, but failed the blank oxygen consumption validity criterion. A repeat test was conducted in accordance with the study plan and met all relevant validity criteria. There were no deviation in this test.
Key result
Parameter:
% degradation (O2 consumption)
Value:
73
Sampling time:
28 d
Parameter:
% degradation (O2 consumption)
Value:
61
Sampling time:
21 d
Parameter:
% degradation (O2 consumption)
Value:
63
Sampling time:
14 d
Parameter:
% degradation (O2 consumption)
Value:
51
Sampling time:
7 d
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
0 d
Details on results:
Test material percentage biodegradation: After 0 days = 0%; After 7 days = 51%; After 14 days = 63%; After 21 days = 61%; After 28 days = 73%
Test material + sodium benzoate percentage biodegradation = After 0 days = 0%; After 7 days = 58%; After 14 days = 58%; After 21 days = 64%; After 28 days = 71%

See attached background material for full results tables.
Key result
Parameter:
ThOD
Value:
1.211 mg O2/g test mat.
Results with reference substance:
Sodium benzoate exhibited 84% biodegradation in 28 days

See attached background material for full results tables.

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The percentage biodegradation for glutaric acid over 28 days was found to be 73%. The registered substance can therefore be considered readily biodegradable under the conditions of this test.
Executive summary:

The ready biodegradation of glutaric acid was analysed in a GLP study carried out according to the OECD Guideline for the Testing of Chemicals 301D 'Read biodegradability - Closed bottle method'. This procedure seeks to determine the biodegradability of an organic test material in a freshwater environment. The percentage biodegradation for the registered substance was found to be 73% over the duration of the 28 day study. The ThOD was determined as 1.211 mgO2/mg and the 28-day inhibition was found to be 8%. The validity criteria for this test were all met. Therefore, the registered substance can be considered readily biodegradable under the conditions of this test.

Description of key information

The ready biodegradation of glutaric acid was analysed in a GLP-certified key study, which was carried out according to the OECD Guideline for the Testing of Chemicals 301D 'Read biodegradability - Closed bottle method'. This procedure seeks to determine the biodegradability of an organic test material in a freshwater environment. The percentage biodegradation for the registered substance was found to be 73% over the duration of the 28-day study. The ThODNH3was determined as 1.211 mgO2/mg and the 28-day inhibition was found to be 8%. The validity criteria for this test were all met. Therefore, the registered substance can be considered readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information