Allyl 3-cyclohexylpropionate

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)

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic, non-adapted

Remarks:

Secondary effluent from a domestic sewage treatment plant

Details on inoculum:

- Source of inoculum/activated sludge: municipal sewage treatment plant Hochdahl
- Storage conditions: not reported
- Storage length: not reported
- Preparation of inoculum for exposure: not reported
- Pretreatment: not reported
- Concentration of inoculum: one drop per litre of mineral medium

Duration of test (contact time):

28 d

Initial conc.:

2 mg/L

Based on:

test mat.

Initial conc.:

5 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: not reported
- Additional substrate: no
- Solubilising agent (type and concentration if used): yes, but not specified
- Test temperature: 20 ± 1 °C
- pH: not reported
- pH adjusted: no
- Aeration of dilution water: yes, prior to test
- Suspended solids concentration: not applicable
- Continuous darkness: yes

TEST SYSTEM
- Number of culture flasks/concentration: 10
- Method used to create aerobic conditions: aeration of test water
- Measuring equipment: iodometric determination of oxygen concentration
- Test performed in closed vessels due to significant volatility of test substance: yes

SAMPLING
- Sampling frequency: weekly

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Toxicity control: no
- Other: solvent control

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

60

Sampling time:

7 d

Remarks on result:

other: Obtained with 2 mg/L

Key result

Parameter:

% degradation (O2 consumption)

Value:

86

Sampling time:

28 d

Remarks on result:

other: Obtained with 2 mg/L

Key result

Parameter:

% degradation (O2 consumption)

Value:

62

Sampling time:

28 d

Remarks on result:

other: Obtained with 5 mg/L

Details on results:

The concentration of dissolved oxygen fell below 0.5 mg/L at the 5 mg/L test concentration, which should normally be avoided according to the validity criteria of the test. However, no such effect was seen at the lower test concentration of 2 mg/L, which is given as the generally applicable test concentration for the closed bottle test (see OECD guideline 301-D).

Results with reference substance:

The test with the positive reference substance sodium benzoate gave a degradation of 84% after 2 weeks and a degradability of 90% after 28 days. This test demonstrated the suitability of the test system.

Validity criteria fulfilled:

yes

Remarks:

for the lower test concentration of 2 mg/L; for the higher test concentration the oxygen demand was too high leading to an unacceptable depletion in the dissolved oxygen concentration

Interpretation of results:

readily biodegradable

Conclusions:

The substance was readily biodegradable in the closed bottle test and the 10-day window was fulfilled.

Executive summary:

The ready biodegradability of the test substance allylcyclohexylpropionate was studied under GLP in accordance with OECD TG 301-D in a closed bottle test. Secondary effluent from a municipal treatment plant processing mainly domestic sewage was used as inoculum. The tests were performed with concentrations of the test substance at 2 mg/L and 5 mg/L and a concentration of one drop of inoculum per L mineral medium. An unknown solvent was used to dissolve the poorly water-soluble substance. The dissolved oxygen concentration (DOC) in the test medium was maximised by vigorously aerating the mineral medium prior to the test and the DOC was 9.14 mg/L at the beginning of the test. Tightly closed bottles were incubated in the dark at a temperature of 20 ± 1 °C for 28 days. The oxygen consumption was determined every 7 days by iodometric measurement and the percentage of degradation was calculated by comparing the measured oxygen consumption with the theoretical consumption. With 2 mg/L test concentration, 60% degradation was obtained after 7 days and 86% degradation was obtained after 28 days. A significant depletion in the DOC below 0.5 mg/L was seen with 5 mg/L test concentration at the third sampling timepoint. This was obviously due to a too high oxygen consumption at this concentration and this test was not fulfilling the validity criteria. A parallel test with the reference substance sodium benzoate gave 81% degradation after 7 days and 84% degradation after 14 days showing the suitability of the test system and inoculum. Based on the test with 2 mg/L test concentration, the substance was considered as readily biodegradable fulfilling the 10-day window.

Description of key information

Readily biodegradable

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

A valid closed bottle test using 2 mg/L test substance according to OECD TG 301-D demonstrated the ready biodegradability of allyl 3-cyclohexylpropionate (86% degradation, 10-day window fulfilled).