4-(cyclohex-1-en-1-yl)-3-methylbutan-1-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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Qualifier:

according to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

Qualifier:

according to guideline

Guideline:

ISO 10707 Water quality - Evaluation in an aqueous medium of the "ultimate" aerobic biodegradability of organic compounds - Method by analysis of biochemical oxygen demand (closed bottle test)

GLP compliance:

yes

Specific details on test material used for the study:

- Test substance storage In refrigerator (2-8°C) in the dark
- Description: Clear colourless liquid
- Expiry date: 19 March 2015

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Details on inoculum:

Source: The source of test organisms was secondary effluent freshly obtained from a municipal sewage treatment plant: 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands, receiving predominantly domestic sewage.
Treatment: Secondary effluent was filtered through a coarse filter paper, the first 200 ml was discarded. The filtrate was kept aerated until inoculation.
Inoculation: 4 mL filtrate of secondary effluent per litre of final volume.

Duration of test (contact time):

28 d

Initial conc.:

1 mg/L

Based on:

ThOD

Initial conc.:

3 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Test concentrations and preparation of test solutions: Nominal concentrations of 1 and 3 mg/L were tested. No correction was made for the purity/composition of the test substance. Preparation of the test media started with a stock solution of 5 mg/L by adding 15.02 mg test substance to 3000 ml of mineral medium. Thorough mixing was used to accelerate dissolution of the test substance in mineral medium. Exact volumes of the stock solution corresponding to the test concentrations and microbial organisms were added to the test medium.

Reference substance concentrations and preparation of test solutions: For the preparation of the test media a stock solution of 2 g/L was prepared in mineral medium. Exact volumes of the stock solution corresponding to the final sodium acetate concentration (2 mg/l) were added to the test medium of the procedure control and the toxicity control.

Test procedure and conditions:
- Test duration: 28 days for the inoculum blank and test suspension; 14 days for the procedure and toxicity control
- Test bottles: 250-300 mL BOD bottles with glass stoppers.
- Milli-RO water: Tap-water purified by reverse osmosis (Millipore Corp., Bedford, Mass., USA).
- Stock solutions of mineral components: A) 8.50 g KH2PO4; 21.75 g K2HPO4; 67.20 g Na2HPO4.12H2O; 0.50 g NH4Cl dissolved in 1 litre Milli-RO water, pH 7.4 ± 0.2. B) 22.50 g MgSO4.7H2O dissolved in 1 litre Milli-RO water. C) 36.40 g CaCl2.2H2O dissolved in 1 litre Milli-RO water. D) 0.25 g FeCl3.6H2O dissolved in 1 litre Milli-RO water.
- Mineral medium: 1 mL of solution (A) to (D) was mixed and made up to 1 litre with Milli-RO water. The concentration of dissolved oxygen was measured for control purposes. The mineral medium was left at test temperature to obtain a saturated solution at the start of the test.
- Test set up: Inoculum blank: Containing only inoculum (no test substance); Procedure control: Containing reference substance and inoculum; Test suspension: Containing test substance and inoculum (applicable for both test concentrations); Toxicity control: Containing test substance at the lowest concentration, reference substance and inoculum.
- Number and groups of test bottles Individual BOD bottles were prepared for each measuring point, except that the bottles measured at the start were also measured on day 7. Parallel groups were prepared to allow duplicate measurements of oxygen consumption at the test intervals.
- Illumination: The test bottles were protected from light.

Reference substance:

other: Sodium acetate

Test performance:

Acceptability of the test:
1. Oxygen depletion in the inoculum blank was less than 1.5 mg O2/L after 28 days (0.47 mg O2/L)
2. The residual concentration of oxygen in the test bottles was > 0.5 mg/l at any time.
3. All differences of duplicate biodegradation values expressed as mg O2/L were less than 20% (0-12%).
4. The reference substance was degraded by at least 60% (104%) within 14 days.
Since all criteria for acceptability of the test were met, this study was considered to be valid.

Key result

Parameter:

% degradation (O2 consumption)

Value:

98

Sampling time:

28 d

Remarks on result:

other: 1 mg/L

Parameter:

% degradation (O2 consumption)

Value:

52

Sampling time:

28 d

Remarks on result:

other: 3 mg/L

Details on results:

- Theoretical Oxygen Demand: The ThOD of the test substance was calculated to be 2.95 mg O2 per mg. The ThOD of sodium acetate (reference substance) was calculated to be 0.78 mg O2/mg.
- Biodegradation: The relative biodegradation values calculated from the O2 measurements performed during the test period of 28 days revealed significant biodegradation of the test substance at both concentrations, i.e. an average of 98% and 52%, at 1 and 3 mg /l respectively. Furthermore, biodegradation of the test substance of at least 60% was reached within a 14-days window at a concentration of 1 mg/L. In the toxicity control more than 25% biodegradation occurred within 14 days (49%, based on ThOD). Thus, the toxicity control showed that the test substance did not inhibit microbial activity at a concentration of 1 mg/L.
- Test conditions: The pH values at the start of the test were 7.4 or 7.5. The temperature recorded in a vessel with water in the same room varied between 21.8 and 22.5°C.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Description of key information

The test substance is readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The ready biodegradability was tested in a closed bottle test in accordance with OECD guideline 301 D and following GLP. Nominal concentrations of 1 and 3 mg/l were tested. No correction was made for the purity/composition of the test substance. The Theoretical Oxygen Demand (ThOD) of the test substance was calculated to be 2.95 mg O2/mg. The following test set up was applied: Inoculum blank (only inoculum, no test substance); Procedure control (sodium acetate at 2 mg/L and inoculum); Test substance at 1 mg/l and inoculum; Test substance at 3 mg/l and inoculum); Toxicity control (sodium acetate at 2 mg/L, test substance at 1 mg/l and inoculum). The test was performed in duplicate. Preparation of the test media started with a stock solution of 5 mg/L in mineral medium. Subsequently, exact volumes of the stock solution corresponding to the test concentrations and microbial organisms were added to the test medium. Measurements of the oxygen concentrations were performed at the start of the experiment (day 0) and at day 7, 14, 21 and 28. The relative biodegradation values calculated from the O2 measurements performed during the test period of 28 days revealed significant biodegradation of the test substance at both concentrations, i.e. an average of 98% and 52%, at 1 and 3 mg /l respectively. Furthermore, biodegradation of the test substance of at least 60% was reached within a 14-days window at a concentration of 1 mg/L. The toxicity control showed that the test substance did not inhibit microbial activity at a concentration of 1 mg/L. Since all criteria for acceptability of the test were met, this study was considered to be valid. In conclusion, the test substance is designated as readily biodegradable.