Acetic acid, 2,2-difluoro-2-[[2,2,4,5-tetrafluoro-5-(trifluoromethoxy)-1,3-dioxolan-4-yl]oxy]-, ammonium salt (1:1)

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-03-02 until 2009-05-25

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Guideline-conform study under GLP without deviations.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-A (Determination of the "Ready" Biodegradability - Dissolved Organic Carbon (DOC) Die-Away Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Swiss Federal Office of Public Health, 2008-11-12

Specific details on test material used for the study:

- Name of test material (as cited in study report): cC6O4
- Substance type: water solution of pure substance
- Physical state: Liquid, pale yellow
- Analytical purity: Water solution containing 16% active ingredient
- Impurities (identity and concentrations): not reported
- Composition of test material, percentage of components: not reported
- Isomers composition: not reported
- Purity test date: not reported
- Lot/batch No.: 150/28
- Expiration date of the lot/batch: 31 December 2020
- Stability under test conditions: not reported
- Storage condition of test material: At room temperature at about 20°C, away from direct sunlight

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): aerobic activated sludge from a wastewater treatment plant (ARA Ergolz II, Füllinsdorf / Switzerland) treating predominantly domestic wastewater.
- Laboratory culture: not applicable
- Method of cultivation: not applicable
- Storage conditions: During the holding period of one day prior to use, the sludge was aerated at room temperature.
- Storage length: holding period of one day prior to use.
- Preparation of inoculum for exposure: The study was performed with aerobic activated sludge from a wastewater treatment plant (ARA Ergolz II, Füllinsdorf / Switzerland) treating predominantly domestic wastewater. The sludge was washed twice 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 water to obtain a concentration equivalent to 4 g (±10%) dry material per liter.
Prior to use, the dry weight of this diluted activated sludge was determined again and defined amounts were added to test water to obtain a final concentration of 30 mg dry material per liter.
- Pretreatment: see above
- Concentration of sludge: concentration equivalent to 30 mg of dry material per liter
- Initial cell/biomass concentration: see above
- Water filtered: no
- Type and size of filter used, if any: not applicable

Duration of test (contact time):

28 d

Initial conc.:

144 mg/L

Based on:

act. ingr.

Initial conc.:

28.8 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium:
The test water was prepared according to the testing guidelines. Analytical grade salts were dissolved in purified water to obtain the following stock solutions:
1) KH2PO4: 8.50 g/L,
K2HPO4: 21.75 g/L,
Na2HPO4 × 2H2O: 33.40 g/L,
NH4Cl: 0.50 g/L.
The pH of this solution was 7.4.

2) MgSO4 × 7H2O 22.50 g/L
3) CaCl2 × 2H2O 36.40 g/L
4) FeCl3 × 6H2O 0.25 g/L, stabilized with one drop of concentrated HCl per liter

To obtain the final test water, 10 mL of stock solution 1) and 1 mL each of stock solutions 2) - 4) were combined and made up to 1000 mL with purified water. The pH was adjusted from 7.8 to 7.4 with a diluted hydrochloric acid solution.

- Additional substrate: none
- Solubilising agent (type and concentration if used): none
- Test temperature: 21 - 23 °C
- pH: 7.4
- pH adjusted: yes
- Aeration of dilution water: aeration pump
- Suspended solids concentration: no data
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: 2000-mL Erlenmeyer flasks. The final volume was 1000 mL per flask.
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: The test media were continuously stirred by magnetic stirrers.
- Measuring equipment: TOC Analyzer
- Test performed in closed vessels due to significant volatility of test substance: Each flask was loosely covered with aluminium foil to allow the exchange of air between the flask and the surrounding atmosphere.
- Test performed in open system: Each flask was loosely covered with aluminium foil to allow the exchange of air between the flask and the surrounding atmosphere.
- Details of trap for CO2 and volatile organics if used: not applicable
- Other:

SAMPLING
- Sampling frequency: Test item and inoculum control: Exposure Day 0, 3, 7, 10, 14, 21 and 28
- Sampling frequency: Procedure control: Exposure Day 0, 3, 7, 14 and 28
- Sampling frequency: Toxicity control: Exposure Day 0, 7, 14 and 28.
- Sampling method: One sample of about 10 mL was taken from each test flask per sampling date. Prior to sampling, water evaporation losses were determined by weighing the flasks and were compensated by adding purified water. Deposits on the test vessels were resuspended.
- Sterility check if applicable: not applicable
- Sample storage before analysis: Samples were filtered through a 0.45-μm filter. The first 3–4 mL of the filtrate was discarded. Thereafter, the samples were analyzed for DOC on the day of sampling.
- Other:


CONTROL AND BLANK SYSTEM
- Inoculum blank: inoculum w/o test item w/o reference item
- Abiotic sterile control: no data
- Toxicity control: inoculum w/ test item w/ reference item
- Other: procedure control: inoculum w/o test item w reference item


STATISTICAL METHODS:

Reference substance:

benzoic acid, sodium salt

Preliminary study:

not applicable

Test performance:

The reference item sodium benzoate was completely (>90%) biodegraded within seven days of exposure, thus confirming suitability of the activated sludge.
In the toxicity control, containing the test item, the reference item sodium benzoate and activated sludge (inoculum), the initial DOC decreased by 49% within 14 days of exposure. Thus, according to the test guidelines the test item was not inhibitory to activated sludge at the tested concentration of 144 mg active ingredient per liter because degradation was >35% within 14 days.

Key result

Parameter:

% degradation (DOC removal)

Value:

ca. 5

Sampling time:

28 d

Details on results:

In the test flasks, containing the test item and activated sludge (inoculum), the mean concentration of DOC (dissolved organic carbon) varied between 27 and 30 mg/L over the exposure period of 28 days and thus was not significantly different from the initial mean DOC concentration of 29 mg/L measured on Day 0. Expressed as percentage DOC removal, mean values in the range from -3 to 5% were noted.

Results with reference substance:

In the procedure controls, containing the reference item sodium benzoate and activated sludge (inoculum), sodium benzoate was completely biodegraded (>90%) within seven days of exposure, thus confirming suitability of the activated sludge.

In the toxicity control, containing the test item, the reference item sodium benzoate and activated sludge (inoculum), the initial DOC decreased by 49% within 14 days of exposure. Thus, according to the test guidelines the test item was not inhibitory to activated sludge at the tested concentration of 144 mg active ingredient per liter because degradation was >35% within 14 days.

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

Test item cC6O4 ammonium salt was not biodegradable under the test conditions.

Executive summary:

The test item cC6O4 ammonium salt was investigated for its ready biodegradability in a "28-Day DOC Die- Away Test" according to the Commission Regulation (EC) No 440/2008, C.4-A and the OECD Guideline for Testing of Chemicals, No. 301 A (1992). In the test flasks, containing the test item cC6O4 ammonium salt and activated sludge (inoculum), the mean concentrations of dissolved organic carbon (DOC) were not significantly different from the initial mean DOC concentration measured on Day 0. The test was valid as indicated by the performance of the procedure controls and toxicity controls. Therefore, cC6O4 ammonium salt was not biodegradable under the test conditions.

Description of key information

The test item cC6O4 ammonium salt was investigated for its ready biodegradability in a "28-Day DOC Die- Away Test" according to the Commission Regulation (EC) No 440/2008, C.4-A and the OECD Guideline for Testing of Chemicals, No. 301 A (1992).
The study was performed under GLP without deviations.

In the test flasks containing the test item cC6O4 ammonium salt and activated sludge (inoculum) the mean concentrations of dissolved organic carbon (DOC) were not significantly different from the initial mean DOC concentration measured on Day 0. Under the test condition no significant biodegradation was observed. The test was valid as indicated by the performance of the procedure controls and toxicity controls.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater