(2R)-2-(2,4-difluorophenyl)-1,1-difluoro-1-{5-[4-(2,2,2-trifluoroethoxy)phenyl]pyridin-2-yl}-3-(1H-tetrazol-1-yl)propan-2-ol

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:

2020-02-04 to 2020-03-24

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)

Version / remarks:

1992-07-17

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Expiration date of the lot/batch: 2020-06-06 (Retest date)

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: 20 +/- 5 °C, in the dark

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: Dispersal by stirring in the test flasks to achieve a homogenous solution:

FORM AS APPLIED IN THE TEST (if different from that of starting material) solution

OTHER SPECIFICS
- pH at test start: 7.5

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, 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 domestic wastewater treatment plant (sewage treatment plant of Rossdorf, Germany).
- Preparation of inoculum for exposure: Settling for 15min, washed by centrifugation and the supernatant liquid phase was decanted. Solid material was re-suspended in test water and centrifuged again. The procedure was repeated 3 times. An aliquot was weighted, dried and the ration of wet sludge to dry weight was determined. Calculated aliquots of washed sludge suspension were mixed with test water, aerated overnight and used for the experiment.
- Concentration of sludge: 3.5 g dry material/L

Duration of test (contact time):

28 d

Initial conc.:

102.9 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Test temperature: 22 +/-1°C
- pH: 7.5
- pH adjusted: yes with HCl
- Suspended solids concentration: 3.5 g/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: glass test flasks
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: continuous stirring
- Measuring equipment: Manometric method: BSB/BOD Sensor System, Aqualytic, Dortmund.
- Details of trap for CO2 and volatile organics if used: aqueous solution (45%) of potassium hydroxide

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: yes
- Toxicity control: yes
- Reference substance: sodium benzoate

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Details on results:

The mean biodegradation at test end after 28 days was 0%.

Results with reference substance:

The reference item sodium benzoate was sufficiently degraded to 96% after 14 days and to 101% after 28 days of incubation.

Biodegradation of test item: The mean biodegradability and biological oxygen demand, corrected by the mean BOD of inoculum was 0% and 0 mg/L, respectively, over the test duration of 28 days.

Validity Criteria:

Inoculum control: The oxygen demand of the inoculum control was 27.5 mg O₂/L and thus not greater than 60 mg O₂/L within 28 days as required by the test guideline

pH value: The pH-value of the test item flasks at the end of the test was 7.4 and therefore within the range of pH 6.0 to 8.5 as required by the test guideline.

Reference item: The reference item sodium benzoate was degraded to more than 60% after 4 days of incubation.

Test item: The difference of duplicate values for the degradation of the test item at the plateau, at the end of the test and at the end of the 10-day window was less than 20%. The difference of duplicate values at day 28 was 0%.

Toxicity control: If in a toxicity test, containing both the test item and a reference item less than 25% biodegradation (based on ThODNH₄) occurred within 14 days, the test item can be assumed to be inhibitory. The biodegradation was 41% at day 14; the test item was not inhibitory.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The degradation rate of (2R)-2-(2,4-difluorophenyl)-1,1-difluoro-3-(tetrazol-1-yl)-1-[5-[4-(2,2,2-trifluoroethoxy)phenyl]pyridin-2-yl]propan-2-ol never reached 60% within the incubation period of 28 days.
Therefore, (2R)-2-(2,4-difluorophenyl)-1,1-difluoro-3-(tetrazol-1-yl)-1-[5-[4-(2,2,2-trifluoroethoxy)phenyl]pyridin-2-yl]propan-2-ol is considered to be not readily biodegradable.

Executive summary:

The purpose of this study was to determine the ready biodegradability of the test item (2R)-2-(2,4-difluorophenyl)-1,1-difluoro-3-(tetrazol-1-yl)-1-[5-[4-(2,2,2-trifluoroethoxy)phenyl]pyridin-2-yl]propan-2-ol. The test item was exposed to aerobic activated sludge from the aeration tank of a domestic waste water treatment plant for 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.

This study was designed to comply with the following methods:

-       Commission Regulation 440/2008/EC, Method C.4-D of May 30, 2008: Manometric Respirometry Test (EEC Publication No. L 142/496, May 2008)

-       OECD Guideline for Testing of Chemicals No. 301 F: "Ready Biodegradability: Manometric Respirometry Test", adopted July 17, 1992

All validity criteria were fulfilled, there were no deviations from the guidelines. The degradation rate of (2R)-2-(2,4-difluorophenyl)-1,1-difluoro-3-(tetrazol-1-yl)-1-[5-[4-(2,2,2-trifluoroethoxy)phenyl]pyridin-2-yl]propan-2-ol never reached 60% within the incubation period of 28 days. The mean % biodegradation and biological oxygen demand of the test item, corrected for the inoculum blank, were 0% and 0 mg/L O₂, respectively, over the incubation period of 28 days. Therefore, (2R)-2-(2,4-difluorophenyl)-1,1-difluoro-3-(tetrazol-1-yl)-1-[5-[4-(2,2,2-trifluoroethoxy)phenyl]pyridin-2-yl]propan-2-ol is considered to be not readily biodegradable.

Description of key information

The purpose of this study was to determine the ready biodegradability of the test item (2R)-2-(2,4-difluorophenyl)-1,1-difluoro-3-(tetrazol-1-yl)-1-[5-[4-(2,2,2-trifluoroethoxy)phenyl]pyridin-2-yl]propan-2-ol. The test item was exposed to aerobic activated sludge from the aeration tank of a domestic waste water treatment plant for 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control.

This study was designed to comply with the following methods:

-       Commission Regulation 440/2008/EC, Method C.4-D of May 30, 2008: Manometric Respirometry Test (EEC Publication No. L 142/496, May 2008)

-       OECD Guideline for Testing of Chemicals No. 301 F: "Ready Biodegradability: Manometric Respirometry Test", adopted July 17, 1992

All validity criteria were fulfilled, there were no deviations from the guidelines. The degradation rate of (2R)-2-(2,4-difluorophenyl)-1,1-difluoro-3-(tetrazol-1-yl)-1-[5-[4-(2,2,2-trifluoroethoxy)phenyl]pyridin-2-yl]propan-2-ol never reached 60% within the incubation period of 28 days. The mean % biodegradation and biological oxygen demand of the test item, corrected for the inoculum blank, were 0% and 0 mg/L O₂, respectively, over the incubation period of 28 days. Therefore, (2R)-2-(2,4-difluorophenyl)-1,1-difluoro-3-(tetrazol-1-yl)-1-[5-[4-(2,2,2-trifluoroethoxy)phenyl]pyridin-2-yl]propan-2-ol is considered to be not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater