4-propylcyclohexanone

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:

activated sludge, non-adapted

Details on inoculum:

- Source of activated sludge: 1 L from the total effluent of a sludge plant and 1 L reflux from an activated sludge plant (ex Klärwerk Neuenfelde, Hamburg)
- Pretreatment: Tha activated sludge was filtered, discarding the first 200 mL. Further, 100 g of a standard soil (a mixture of humus and loamy soil from the region of Speyer) were dispersed in 1000 mL of demineralized water and then filtered, again discarding the first 200 mL of the filtrate. 100 mL of each filtrate were mixed for the composite inoculum.

Duration of test (contact time):

28 d

Initial conc.:

1.007 g/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral nutrient solution according to OECD 301D
- Additional substrate: no
- Test temperature: 20 °C
- CEC (meq/100 g): not available
- Aeration of dilution water: yes
- Suspended solids concentration: not available
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: BOD-bottles
- Number of culture flasks/concentration: 3
- Measuring equipment: 0X1 530 with a TriOX E0 200-electrode (ex Wissenschaftlich-Technische Werkstätten GmbH, 8120 Weilheim i. OB)
- Test performed in open system: no

CONTROL AND BLANK SYSTEM
- Control series: distilled water with nutrient solutions without inoculum
- Blind series: distilled water with nutrient solutions with inoculum
- Reference series: a solution of sodium-n-dodecylsulfate (SDS) with nutrient solutions and inoculum
- Inhibition series: a solution of the test substance and SDS with nutrient solutions and inoculum

Reference substance:

other: sodium-n-dodecylsulfate

Key result

Parameter:

% degradation (O2 consumption)

Value:

1.2

Sampling time:

28 d

Details on results:

For the test substance the following results were obtained: 0.0 % after 5 days, 0.0 % after 15 days, 1.2% after 28 days. Therefore, the test substance cannot be described as ready biodegradable under the test conditions.

For the test substance the following BOD-values can be given:
BOD (5 days) = 0.00 g O2/g test item
BOD (15 days) = 0.00 g O2/g test item
BOD (28 days) = 0.03 g O2/g test item

Parameter:

BOD5

Value:

0 g O2/g test mat.

Results with reference substance:

For the reference substance (as active substance (AS)) the following figures were obtained: 43.7 % after 5 days, 61.2 % after 15 days, 72.8 % after 28 days.

Inhibition test:
The difference A has negative value at the end of the test
A = 02-consumption (test substance + reference substance) -[02-consumption (test substance) + 02-consumption (reference substance)]
However, a significant inhibitory effect on the biodegradation of the reference substance can not be assumed.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The degradation rate of the test material was 1.2% after 28 days and did not reach 60 % within the 10-day window and after 28 days of incubation.Therefore the test substance cannot be described as ready biodegradable under the test conditions.

Executive summary:

The test item was investigated for its ready biodegradability in a Closed Bottle Test over a period of 28 days according to OECD TG 301D. The biodegradation was followed by the oxygen depletion of the microorganisms during exposure. As a reference substance sodium-n-dodecylsulfate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. The oxygen depletion was measured after 5, 15, and 28 days by means of an oxygen electrode. Control- and blank-series without the test substance were run simultaneously and the effectiveness of the inoculum was confirmed (in a third series with sodium-n-dodecylsulfate as reference substance) and found to be 72.8 % after 28 days under the conditions of the test. The value of chemical oxygen demand (TOD) of the test substance was calculated to be 2.86 mg 02/mg active substance. For the test substance, a biodegradability of about 1.2 % (after 28 days) was found. Therefore the test substance cannot be described as ready biodegradable under the test conditions. Moreover it should be tested, whether the test substance exerts an inhibiting effect on biological degradation processes. As a result it was established that the test substance has no inhibiting effect on the biological degradation of the reference substance.

Description of key information

The degradation rate of the test material was 1.2% after 28 days and did not reach 60 % within the 10-day window and after 28 days of incubation. Therefore the test substance cannot be described as ready biodegradable under the test conditions (reference 5.2.1-1).

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

The test item was investigated for its ready biodegradability in a Closed Bottle Test over a period of 28 days according to OECD TG 301D. The biodegradation was followed by the oxygen depletion of the microorganisms during exposure. As a reference substance sodium-n-dodecylsulfate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. The oxygen depletion was measured after 5, 15, and 28 days by means of an oxygen electrode. Control- and blank-series without the test substance were run simultaneously and the effectiveness of the inoculum was confirmed (in a third series with sodium-n-dodecylsulfate as reference substance) and found to be 72.8 % after 28 days under the conditions of the test. The value of chemical oxygen demand (TOD) of the test substance was calculated to be 2.86 mg 02/mg active substance. For the test substance, a biodegradability of about 1.2 % (after 28 days) was found. Therefore the test substance cannot be described as ready biodegradable under the test conditions. Moreover it should be tested, whether the test substance exerts an inhibiting effect on biological degradation processes. As a result it was established that the test substance has no inhibiting effect on the biological degradation of the reference substance (reference 5 .2.1-1).