3-Fluorphenylboric acid

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:

30 Nov - 01 Dec 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Municipal sewage treatment plant, D-31137 Hildesheim
- Pretreatment: The activated sludge was washed twice with autoclaved tap water. After the second washing the settled sludge was filled up with mineral salts medium and was maintained in an aerobic condition by aeration for 2-4 hours. Thereafter the sludge was homogenized with a blender. The supernatant was decanted and maintained in an aerobic condition by aeration with CO2-free air for 6 days. 10 mL/L were used to initiate inoculation.
- Concentration of sludge: 10 mL/L
- Initial cell/biomass concentration: 10^7 - 10^8 CFU/L
- Water: demineralized

Duration of test (contact time):

28 d

Initial conc.:

36 mg/L

Based on:

test mat.

Initial conc.:

53.6 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral salts medium according to OECD 301 F
- Additional substrate: no
- Test temperature: 20.5 - 21.5 °C
- pH: 6.0 - 8.5
- pH adjusted: no
- Aeration of dilution water: no
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: Brown glass bottles (volume 500 mL)
- Number of culture flasks/concentration: 2
- Measuring equipment: OxiTop® OC110 controller, WTW OxiTop® measuring heads, WTW
- Test performed in closed vessels due to significant volatility of test substance: The bottles were closed with Oxi-Top® measuring heads.
- Details of trap for CO2 and volatile organics: A rubber sleeve with soda lime was hung into the opening of the bottles to absorb evolved CO2.
- Measurements: The temperature in the incubator was documented continuously throughout the test by a hygrothermograph. At test start the pH-values of the test solutions in the measuring flasks (before dividing) and at test end the pH-values of the test solutions in the brown glass bottles were determined. The oxygen consumption was determined continuously from the pressure in the incubation vessels by OxiTop® measuring system at 360 measuring points (every 112 minutes) during the 28 d incubation period.

CONTROL AND BLANK SYSTEM
- Inoculum blank: test medium, inoculum
- Functional control: reference item, test medium, inoculum
- Toxicity control: reference item, test item, test medium, inoculum

STATISTICAL METHODS: Excel, MICROSOFT CORPORATION; SigmaPlot, SPSS CORPORATION. All data were computer generated and rounded for presentation from the full derived data.

Reference substance:

benzoic acid, sodium salt

Test performance:

Results of the Functional Control: The pass level of a biodegradation > 60 % was reached on day 4. The validity criterion that the degradation should be > 60 % after 14 d was fulfilled
Results of the Toxicity Control: In the toxicity control the biodegradation achieved 50 % after 14 days. After 28 days the biodegradation came to 55 %. The validity criterion that the test item should not inhibit the biodegradation of the reference item was fulfilled.
The mean oxygen depletion in the inoculum control was 9.0 mg oxygen/L on day 28 (validity criterion: < 60 mg oxygen/L). The pH-value of all test replicates was in the range of 6.0 - 8.5 at the end of the test. The difference of extremes of replicate values of removal of the test item at the end of the test was less than 20 % (0% difference on day 28). The percentage degradation of the toxicity control reached the pass level of 25 % within 5 days (validity criterion: 25 % after 14 days).

Key result

Parameter:

% degradation (O2 consumption)

Value:

2

Sampling time:

28 d

Details on results:

Both test item replicates did not reach the 10 % level (beginning of biodegradation) within the 28 d period of the study. The mean biodegradation on day 28 was 2 %.

Results with reference substance:

The pass level for ready biodegradation (> 60% degradation) was reached on day 4. The validity criterion that the degradation should be > 60% after 14 d was fulfilled. Stages of Biodegradation: The adaptation phase changed to degradation phase within 2 days (degradation > 10%) and the biodegradation came to a maximum of 80% on day 19.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test item is classified as not readily biodegradable within the 28 day period of the study according to OECD 301F.

Executive summary:

The ready biodegradability of the test item was determined with non-adapted activated sludge in the Manometric Respirometry Test for a period of 28 days according to OECD 301F. The test item concentration selected as appropriate was 36.0 mg/L, corresponding to a ThOD of 53.6 mg O2/L per test vessel. The oxygen was depleted by the respiration of bacteria and the degradation was followed by measuring the oxygen concentration. The biodegradation rate is therefore expressed as the percentage BOD (biological oxygen demand) and was calculated for each study day. The mean oxygen depletion in the inoculum control was 9.0 mg O2/L on day 28. In order to check the activity of the test system sodium benzoate was used as functional control. The pass level > 60% was reached on day 4. The biodegradation reached a maximum of 80% degradation on day 19. In the toxicity control containing both test and reference item 50% degradation occurred within 14 days. After 28 days the biodegradation came to 55%. The degradation of the reference item was not inhibited by the test item. The biodegradation of the test item in both replicates did not reach the 10% level (beginning of biodegradation) within the 28 day period of the study. The mean biodegradation on day 28 was 2%. The validity criteria of the guideline are fulfilled.The test item is classified as not readily biodegradable within the 28 day period of the study.

Description of key information

The test item is classified as not readily biodegradable within the 28 day period of the study according to OECD 301F (reference 5.2.1-1).

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater

Additional information

The ready biodegradability of the test item was determined with non-adapted activated sludge in the Manometric Respirometry Test for a period of 28 days according to OECD 301F. The test item concentration selected as appropriate was 36.0 mg/L, corresponding to a ThOD of 53.6 mg O2/L per test vessel. The oxygen was depleted by the respiration of bacteria and the degradation was followed by measuring the oxygen concentration. The biodegradation rate is therefore expressed as the percentage BOD (biological oxygen demand) and was calculated for each study day. The mean oxygen depletion in the inoculum control was 9.0 mg O2/L on day 28. In order to check the activity of the test system sodium benzoate was used as functional control. The pass level > 60% was reached on day 4. The biodegradation reached a maximum of 80% degradation on day 19. In the toxicity control containing both test and reference item 50% degradation occurred within 14 days. After 28 days the biodegradation came to 55%. The degradation of the reference item was not inhibited by the test item. The biodegradation of the test item in both replicates did not reach the 10% level (beginning of biodegradation) within the 28 day period of the study. The mean biodegradation on day 28 was 2%. The validity criteria of the guideline are fulfilled.The test item is classified as not readily biodegradable within the 28 day period of the study (reference 5.2.1-1).