Butanone

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:

1998

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:

yes

Remarks:

; incubation temperature was 18 to 21ºC, instead of constant temperature (± 1ºC)

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

; incubation temperature was 18 to 21ºC, instead of constant temperature (± 1ºC)

Qualifier:

according to guideline

Guideline:

EPA OTS 796.3200 (Ready Biodegradability: Closed Bottle Test)

Deviations:

yes

Remarks:

; incubation temperature was 18 to 21ºC, instead of constant temperature (± 1ºC)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic (adaptation not specified)

Remarks:

There are no details of pre-adaptation, therefore it can be assumed that were not pre-adapted to the test substance prior to testing.

Details on inoculum:

The supernatant fraction from the secondary clarifier was collected from Prospect Bay Wastewater Treatment Facility, Grasonville, Maryland on February 10, 1998. This fraction was filtered through glass wool to produce the inoculum, which was then aerated until used. 1.6 mL/L of inoculum was spiked to the test bottles.

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:
The following stock solutions used to prepare the test medium:
Potassium dihydrogen orthophosphate, KH2PO4 ..... 8.50 g
Dipotassium hydrogen orthophosphate, K2HPO4 ..... 21.75 g
Disodium hydrogen orthophosphate dihydrate, Na2HPO4 – 2 H2O ..... 33.40 g
Ammonium chloride, NH4CI ..... 0.50 g
Dissolve in high quality water and make up to 1 litre.
(b) Calcium chloride solution, CaCI2 ..... 27.50 g
Dissolve in high quality water and make up to 1 litre.
Magnesium sulfate, MgSO4-7 H2O ..... 22.50 g
Dissolve in high quality water and make up to 1 litre.
Ferric chloride, FeCI3 – 6 H2O ..... 0.25 g
Dissolve in high quality water and make up to 1 litre.
The test medium will contain the following standard reagent solutions per liter of high quality water:
1 mL of phosphate buffet solution, APHA, pH 7.2
1 mL of calcium chloride solution, APHA, 2.75%
1 mL of magnesium sulfate solution, APHA, 2.25%
1 mL of ferric chloride solution, APHA, 0.025%

- Test temperature: 18 to 21°C

TEST SYSTEM
- Culturing apparatus: 300-mL BOD bottles
- Number of culture flasks/concentration: 10

SAMPLING
- Sampling frequency: Dissolved oxygen measurements were performed on two test chambers from the control, reference and treatment groups on days 0, 7, 14, 21, and 28.

Reference substance:

benzoic acid, sodium salt

Remarks:

. Reported as sodium benzoate

Test performance:

The validity criteria were met:
reference substance: degradation of sodium benzoate had reached 84% by day 14
10 day window: degradation of MEK had reached 70% by day 7
Inhibitory effect: there had been no evidence of toxicity of test substance to inoculum, therefore it was not considered necessary to prepare extra bottles to test this. It is evident from the high rate of degradation achieved that MEK was not toxic to inoculum at the concentrations tested
oxygen depletion in inoculum blank: oxygen depletion was 0.1 mg/l DO by the end of the test, therefore within the acceptable limit of 1.5 mg/l DO. The DO in the test vessels decreased to 3 mg/L at day 28 for the 2 mg/L MEK concentration. THe 5 mg/L MEK concentration fell below 1 mg/L on day 7 and thus most likely below 0.5 mg/L by the end of the test, indicating too high test substance concentration. 12.2 mg ThOD/L at this concentration are above the recommended 10 mg ThOD/L in the OECD TG.

Key result

Parameter:

% degradation (O2 consumption)

Value:

70

Sampling time:

7 d

Remarks on result:

other: 2 mg/L sample

Key result

Parameter:

% degradation (O2 consumption)

Value:

98

Sampling time:

28 d

Remarks on result:

other: 2 mg/L sample

Key result

Parameter:

% degradation (O2 consumption)

Value:

>= 61

Sampling time:

7 d

Remarks on result:

other: 5 mg/L sample

Details on results:

The 5 mg/L (12.2 mg ThOD/L) concentration achieved the maximum percent biodegradation possible based on the theoretical oxygen demand of the test substance and the amount of oxygen present in the test system. Degradation was therefore limited by the test system; however, it is evident from the results with bottles dosed at 2 mg/l that MEK is readily biodegradable.

Results with reference substance:

degradation of sodium benzoate had reached 84% by day 14

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Biodegradation values of 70% after 7 days and 98% after 28 days were determined for the substance using a relevant test method and in compliance with GLP. The result is considered to be reliable.

Description of key information

Biodegradation: 98% degradation in 28 days (OECD 301D)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

Ready biodegradability was tested according to the Closed Bottle test (OECD 301D, EC C.4-E) and in compliance with GLP (Wildlife International Ltd., 1998, for Royal Dutch Shell plc). Nominal initial test substance concentrations were 2 mg/L and 5 mg/L, corresponding to 1.33 mg DOC/L or 4.88 mg ThOD/L and 3.33 mg DOC/L or 12.22 mg ThOD/L. Measured Day 0 solutions were 1.2 and 2.8 mg DOC/L. The test was performed with inoculum prepared by filtering through glass wool the supernatant fraction collected from the secondary clarifier of Prospect Bay Wastewater Treatment Facility, which was then aerated until used. The test substance at 2 mg/L and 5 mg/L achieved mean degradations of 70% and 61% by Day 7, and 98% and 57% by the end of the study at day 28 respectively.

The 5 mg/L concentration achieved the maximum percent biodegradation possible based on the theoretical oxygen demand of the test substance and the amount of oxygen present in the test system, even by Day 7. The viability of the inoculum and validity of the test were supported by the results of the reference substance, sodium benzoate, which attained 84% degradation by Day 14. The Day 7 results clearly show that the 10-day window criterion was met for the biodegradation of the test material. The substance is considered to be readily biodegradable under the conditions of the test. Please refer to the document attached to Section 13 for further discussion of the study.