4-pentylcyclohexanone

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:

July - August 1990

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)

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 Klarwerk 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.:

1.968 mg/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:

59.4

Sampling time:

28 d

Details on results:

For the test substance the following results were obtained: 0.0 % after 5 days; 4.3 % after 15 days; 59.4 % after 28 days. Therefore, the test substance can be described as not ready biodegradable under the test conditions.
BOD (28 days) = 1.75 g O2/g test material
A inhibitory effect on the biodegradation of the reference substance can be excluded based on the oxygen consumption of the sum of the test substance and the reference substance.

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.
A biodegradability of > 60 % already after 28 days indicates a fully active inoculum and the experimental conditions of the degradation experiments are considered to be correct in the sense of the Guideline.

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable, fulfilling specific criteria

Conclusions:

The degradation rate of the test material was 59.4 % 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 inherently biodegradable.

Executive summary:

 The test item was investigated for its ready biodegradability in a Closed Bottle Test over a period of 28 days. The biodegradation was followed by the oxygen depletion of the microorganisms during exposure. As a reference itemsodium-n-dodecylsulfatewas 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 301D. After correction for the mean biochemical oxygen demand of the inoculum controls the percentage of the test item reached 59.4 % after 28 days of incubation. The reference item was sufficiently degraded to a mean of 72.8 % after 28 days of incubation, thus confirming the suitability of the used activated sludge inoculum. 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 inherently biodegradable.

Description of key information

The degradation rate of the test material was 59.4 % after 28 days in a test according to OECD 301 D 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 inherently biodegradable (reference 5.2.1 -1).

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable, fulfilling specific criteria

Type of water:

freshwater

Additional information

The test item was investigated for its ready biodegradability in a Closed Bottle Test over a period of 28 days. The biodegradation was followed by the oxygen depletion of the microorganisms during exposure. As a reference item sodium-n-dodecylsulfate 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 301D. After correction for the mean biochemical oxygen demand of the inoculum controls the percentage of the test item reached 59.4 % after 28 days of incubation. The reference item was sufficiently degraded to a mean of 72.8 % after 28 days of incubation, thus confirming the suitability of the used activated sludge inoculum. 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 inherently biodegradable (reference 5.2.1 -1).