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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:
2007-04-19 to 2007-10-02
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)
Deviations:
no
Remarks:
The testing facility indicated that th eprotocol was followed without deviation.
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
Deviations:
no
Remarks:
The testing facility indicated that th eprotocol was followed without deviation.
GLP compliance:
yes (incl. certificate)
Remarks:
The Federal Office of Public Health, the Swiss Agency for Therapeutic Products and the Swiss Agency for the Environment, Forests and Landscape with respect to the compliance with the Swiss legislation on Good Laboratory Practice.
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: ARA Ergolz II, Fϋllinsdotf, Switzerland
- Laboratory culture: not applicable
- Method of cultivation: no data
- Storage conditions:at room temperature with aeration until use
- Storage length: one day prior to use
- Preparation of inoculum for exposure: The sludge was washed three times with tap water by centrifugation and the supernatant liquid phase was decanted. A homogenized aliquot of the final sludge suspension was weighed, thereafter dried and the ratio of wet to dry weight was calculated. Based on this ratio, calculated amounts of wet sludge were suspended in test to obtain a concentration equivalent to 4 g ± 10% dry material per liter. During the holding period of one day prior to use, the sludge was aerated at room temperature. Prior to use, the sludge was first thoroughly mixed and then diluted with test water to a concentration of 1 g per liter (dry weight basis). Based on the determined dry weight of this diluted activated sludge defined amounts were added to test water to obtain a final concentration of 30 mg dry material per liter.
- Pretreatment: no data
- Concentration of sludge: 1 g per liter (dry weight basis)
- Initial cell/biomass concentration: no data
- Water filtered: The test water was prepared according to the testing guidelines
- Type and size of filter used, if any: not applicable
Duration of test (contact time):
28 d
Initial conc.:
174 mg/L
Based on:
ThOD/L
Initial conc.:
173 mg/L
Based on:
ThOD/L
Initial conc.:
100 mg/L
Based on:
test mat.
Initial conc.:
101 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: aerobic activated sludge prepared with test water
- Additional substrate: no
- Solubilising agent:none
- Test temperature: 22 °C
- pH: 7.4 - 7.6
- pH adjusted: The pH of the test water was adjusted from 7.8 to 7.4 with a diluted hydrochloric acid solution
- Aeration of dilution water: no data
- Suspended solids concentration: 30 mg dry material per liter
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 500 mL Erlenmeyer flasks
- Number of culture flasks/concentration: two (101 mg/L test substance (ThOD 174 mg O2/L), 100 mg/L test substance (ThOD 173 mg O2/L))
- Method used to create aerobic conditions: the consumed oxygen is replaced by electrolytically generated oxygen from copper sulfate solution
- Method used to create anaerobic conditions: not applicable
- Measuring equipment: electrode type manometer (The biodegradation process consumes the dissolved oxygen in the liquid and generates C02. The C02 is adsorbed by soda lime and the total pressure decreases in the airtight test flasks. The pressure drop is detected and converted into an electrical signal by means of an electrode type manometer)
- Details of trap for CO2 and volatile organics if used: adsorbed by soda lime

SAMPLING
- Sampling frequency: continious measurement

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes (in duplicate = two flasks without test substance or reference substance)
- Abiotic sterile control: no
- Toxicity control: yes
- Other: two procedure controls with 100 mg/L reference substance

Reference substance:
benzoic acid, sodium salt
Test performance:
No circumstances that may have affected the results during the test.

Key result
Parameter:
% degradation (O2 consumption)
Value:
1
Sampling time:
28 d
Remarks on result:
other: The mean 28 day biodegradation of both replicates was 1%
Details on results:
The BOD of the test item T002675 in the test media was in the normal range found for the inoculum controls. T002675 was found to be not biodegradable under the test condition within 28 days.
Results with reference substance:
The reference item (sodium benzoate) was degraded by an average of 90% by day 14, and reached an average biodegradation of 91% by the end of the test (day 28), thus confirming suitability of the activated sludge.

According to the test guidelines, the test substance had no inhibitory effect on activated sludge microorganisms at the tested concentration of 100 mg/L because biodegradation in the toxicity control was >25% within 14 days.

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
A 28-d ready biodegradability test (OECD 301F) using unadapted activated sludge from a predominantly domestic waste water treatment plant indicated that T002675 was not readily biodegradable under the conditions of the test. The test substance did not inhibit microbial activity at the concentration used in the test. The results of the test can be considered reliable without restriction.

Description of key information

One study (Seyfried, 2007) is included in this dossier and regarded as a key study (Klimisch score of 1).  The biodegradability of T002675 was determined according to OECD Guideline 301F and EU Method C.4-D. Under the conditions of the test, T002675 was determined to be not biodegradable within 28 days.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:
freshwater

Additional information