1-[4-(trans-4-propylcyclohexyl)-1-cyclohexen-1-yl]-4-trifluoromethoxybenzene

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017-11-02 to 2018-01-09

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

adopted July 17, 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

1-[4-(trans-4-propylcyclohexyl)-1-cyclohexen-1-yl]-4-trifluoromethoxybenzene

EC Number:

918-322-3

Cas Number:

1173392-85-2

Molecular formula:

C22H29F3O

IUPAC Name:

1-[4-(trans-4-propylcyclohexyl)-1-cyclohexen-1-yl]-4-trifluoromethoxybenzene

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Inoculum of the aqueous phase of non-adapted activated sludge from a municipal sewage treatment plant.

- Pretreatment: The activated sludge was washed twice with chlorine free tap water. After the second washing the settled sludge was resuspended in min-eral salts medium and was maintained in an aerobic condition by aera-tion for 2 hours. Thereafter the sludge was homogenized with a blender. After sedimentation the supernatant was decanted and maintained in an aerobic condition by aeration with CO2-free air for 7 days. 10 mL/L were used to initiate inoculation.

-Colony forming units in the test vessels: Approx. 10^7 - 10^8 CFU/L

Duration of test (contact time):

28 d

Initial test substance concentration

Initial test substance concentration 1

Initial conc.:

20 mg/L

Based on:

test mat.

Initial test substance concentration 2

Initial conc.:

50.6 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Preparation of the test vessels: Based on the calculated oxygen demand, the test concentration of 20 mg/L, corresponding to an oxygen demand of 50.6 mg O2/L in the vessel, was selected. The test solutions were prepared in measuring flasks and were placed in brown glass bottles as incubation vessels (inoculum control and functional control) or were prepared directly in brown glass bottles (test item and toxicity control).

Inoculum control: The inoculated test medium, consisting of the required volumes of mineral medium stock solutions, ultrapure water and inoculum, was prepared.
Functional control: The reference item was weighed out and transferred into a measuring flask, the required volumes of mineral medium stock solutions, ultrapure water and inoculum, were added.
Test Item: The test item was weighed out for each replicate and directly transferred into the test vessels with 250 mL of the inoculated test medium.
Toxicity control: The test item was weighed out and directly transferred into the test vessel with 250 mL of the reference item medium.

A rubber sleeve with soda lime was hung into the opening of the bottles to absorb evolved CO2. The bottles were closed with OxiTop measuring heads and the measuring system was activated.
 
Measurements: The temperature in the incubator was documented continuously throughout the test. At test start the pH-values of the prepared solutions in the measuring flasks (inoculum control and functional control) and the prepared solutions in the separate replicates (test item and toxicity control), were determined. At test end the pH-values of the test solutions in the brown glass bottles were determined. The oxygen consumption was determined in the incubation vessels by the OxiTop® measuring system at 360 measuring points (every 112 minutes) during the 28 d incubation period.

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

Test performance:

Results of the Functional Control:
The pass level for ready biodegradation (≥ 60% degradation) was reached within 3 days. 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 97% on day 26.

Results of the Toxicity Control:
In the toxicity control the biodegradation achieved 50% after 14 days. After 28 days the biodegradation came to 53%. The validity criterion that the test item should not inhibit the biodegradation of the reference item was fulfilled.

% Degradation

Key result

Parameter:

% degradation (O2 consumption)

Value:

7

Sampling time:

28 d

Details on results:

Both test item 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 7%.

Applicant's summary and conclusion

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.

Executive summary:

The test item is classified as not readily biodegradable within the 28 day period of the study.