4-[4-(3,4-Difluorophenyl)-cyclohexyl]-cyclohexanone

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:

December 20, 2002 - January 17, 2003

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

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

1992

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch No.: L605517

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Remarks:

Source: stp Groß-Zimmern, Germany

Details on inoculum:

The activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was resuspended in tap water and again centrifuged. This procedure was repeated twice. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 1.5 g dry material per litre were mixed with test water and then aerated until use.

Duration of test (contact time):

28 d

Initial conc.:

104 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: reconstituted test water according to OECD 301 F
- Additional substrate: no
- Solubilising agent: no
- Test temperature: 21 - 22 °C
- pH: 7.6
- pH adjusted: no
- Suspended solids concentration: 30 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: Manometric Test System with test flasks containing a volume of 500 mL
- Number of culture flasks/concentration: 2
- Measuring equipment: BSB/BOD-Sensor-System, Aqualytic, 63231 Neu Isenburg, Germany
- Test performed in closed vessels due to significant volatility of test substance: yes
- Details of trap for CO2 and volatile organics if used: Evolved carbon dioxide was absorbed in an aqueous solution (45%) of potassium hydroxide

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 flasks (test water, activated sludge)
- Abiotic sterile control: 1 flask (test water, test item)
- Toxicity control: 1 flask (test water, test item, reference item, activated sludge)
- Procedure control: 1 flask (test water, reference item, activated sludge)

Reference substance:

aniline

Remarks:

25.6 mg/L

Test performance:

The oxygen demand of the inoculum control (medium and inoculum) was 7.4 mg O2/L and thus not greater than 60 mg O2/L within 28 days. The pH value of the test item flasks at the end of the test was pH 7.6 – 7.7 and is thus within the range of pH 6.0 – 8.5. The percentage of degradation of the reference item Aniline reached the level for ready biodegradability (about 60 %) within 8 days. The difference of duplicate values for the degradation of the test item at any time during the test was less than 20 %. Therefore all validity criteria for the study are fulfilled.

Key result

Parameter:

% degradation (O2 consumption)

Value:

-1

Sampling time:

28 d

Details on results:

After correction for the mean biochemical oxygen demand of the inoculum controls the percentage of the test item reached -1 % biodegradation after 28 days of incubation.

Results with reference substance:

The reference item was sufficiently degraded to a mean of 81 % after 14 days, and to 89 % after 28 days of incubation, thus confirming the suitability of the used activated sludge inoculum. In the toxicity control containing both, the test item and the reference item, 41 % biodegradation was noted within 14 days and 43 % biodegradation was determined after 28 days of incubation.

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The degradation rate of the test material was -1 % after 28 days and did not reach 60 % within the 10-day window and after 28 days of incubation. The test item can therefore be considered to be not readily biodegradable.

Executive summary:

The test item was investigated for its ready biodegradability in a Manometric Respirometry Test over a period of 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item aniline was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. The GLP study was performed according to OECD TG 301F. After correction for the mean biochemical oxygen demand of the inoculum controls the percentage of the test item reached -1 % after 28 days of incubation. The reference item was sufficiently degraded to a mean of 81 % after 14 days, and to 89 % after 28 days of incubation, thus confirming the suitability of the used activated sludge inoculum. In the toxicity control containing both, the test item and the reference item, 41 % biodegradation was noted within 14 days and 43 % biodegradation was determined after 28 days of incubation. Thus, the test item can be assumed to be not inhibitory on the activated sludge microorganisms. The degradation rate of the test material did not reach 60 % within the 10-day window and after 28 days of incubation. The test item can therefore be considered to be not readily biodegradable.

Description of key information

The degradation rate of the test material was -1 % after 28 days and did not reach 60 % within the 10-day window and after 28 days of incubation. The test item can therefore be considered to be not readily biodegradable (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 test item was investigated for its ready biodegradability in a Manometric Respirometry Test over a period of 28 days. The biodegradation was followed by the oxygen uptake of the microorganisms during exposure. As a reference item aniline was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. The GLP study was performed according to OECD TG 301F. After correction for the mean biochemical oxygen demand of the inoculum controls the percentage of the test item reached -1% after 28 days of incubation. The reference item was sufficiently degraded to a mean of 81% after 14 days, and to 89% after 28 days of incubation, thus confirming the suitability of the used activated sludge inoculum. In the toxicity control containing both, the test item and the reference item, 41% biodegradation was noted within 14 days and 43% biodegradation was determined after 28 days of incubation. Thus, the test item can be assumed to be not inhibitory on the activated sludge microorganisms. The degradation rate of the test material did not reach 60 % within the 10-day window and after 28 days of incubation. The test item can therefore be considered to be not readily biodegradable.