Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
2009-03-02 until 2009-05-25
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The experimental study on the supporting substance is guideline-conform under GLP without deviations.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009
Report Date:
2009

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-A (Determination of the "Ready" Biodegradability - Dissolved Organic Carbon (DOC) Die-Away Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
Swiss Federal Office of Public Health, 2008-11-12

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): cC6O4
- Molecular formula (if other than submission substance): C6H4F9NO6
- Molecular weight (if other than submission substance): 357
- Smiles notation (if other than submission substance): [NH4+].FC1(F)OC(F)(OC(F)(F)C([O-])=O)C(F)(OC(F)(F)F)O1
- InChl (if other than submission substance): no data
- Structural formula attached as image file (if other than submission substance): see Fig.1 (C6O4 Structural formula)
- 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
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
cC6O4 ammonium salt

PHYSICO-CHEMICAL PROPERTIES
- Melting point: 64.6 °C
- Boiling point: > 138 °C (the substance decomposes before boiling)
- Vapour pressure: 0.00000075 hPa at 25 °C
- Henry's law constant (for volatie substances):not applicable
- Water solubility (under test conditions): higly soluble (>= 667 g/L at 21.7 °C)
- log Pow: -0.38 at 22 °C

OTHER PROPERTIES
- Toxicity to microorganisms: no inhibiting effects on activated sludge (NOEC > 1000 mg/L)

Study design

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: no data
- Storage length: no data
- 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. During the holding period of one day prior to use, the sludge was aerated at room temperature.
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 test substance concentrationopen allclose all
Initial conc.:
144 mg/L
Based on:
act. ingr.
Initial conc.:
28.8 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation
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
Reference substance:
benzoic acid, sodium salt

Results and discussion

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.
% Degradation
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.

BOD5 / COD results

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.

Any other information on results incl. tables

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.

Applicant's summary and conclusion

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.
The same conclusion can be applied to F-Diox acid.
Executive summary:

In order to evaluate the ready biodegradability of F- Diox acid it was deemed appropriate to use the Read Across approach based on the experimental study performed on cC6O4 ammonium salt by virtue of similarity of chemical structure between F- Diox acid and cC6O4 ammonium salt (CAS no: 1190931-27-1).

C6O4 ammonium salt is the carboxylic acid derivative of F-DIOX acid and therefore C6O4 ammonium salt differs from F-DIOX acid only for the presence of the cationic part NH4+.

C6O4 ammonium salt is a salt with an high degree of solubility (solubility > 667g/L at 21°C) therefore under the study conditions it is present in ionic form in the test water. The anionic form is the organic species subjected to biodegradation. The same for F-DIOX acid since it is an organic strong acid highly soluble in water and therefore it is assumed as completely dissociated when it is present in water.

Basing on the considerations reported above, it is appropriate to assume the same degree of biodegradability between the two substance.

 

The test item cC6O4 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.

Considering the above, the same conclusion can be applied to F-Diox acid.

This conclusion is consistent with the data published in literature about biodegradability of fluorinated compounds.