4-(1,4-dioxa-spiro[4.5]dec-8-yl)-cyclohexanone

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:

1996-11-21 till 1996-12-19

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)

Version / remarks:

July 17, 1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

December 1992

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic, non-adapted

Details on inoculum:

- Source of inoculum: from the municipal sewage treatment plant Waterschap de Maaskant, `s-Hertogenbosch, the Netherlands
- Pretreatment: The secondary effluent was filtered through a coarse filter paper, the first 200 mL were discarded. The filtrate was kept aerated until inoculation.

Duration of test (contact time):

28 d

Initial conc.:

2 mg/L

Initial conc.:

5 mg/L

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral medium accoding to OECD 301D
- Additional substrate: no
- Test temperature: 20 - 22°C
- pH: 7.5 - 7.6
- pH adjusted: no
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: 250 - 300 mL BOD bottles with glass stoppers
- Number of culture flasks/concentration: 2
- Measuring equipment: Oxygen meter (WTW: OXI 530, TriOxmatic E0 200)

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes (only inoculum)
- Positive control: yes (reference substance sodium acetat and inoculum)
- Toxicity control: yes (test substance, reference substance and inoculum)

Reference substance:

benzoic acid, sodium salt

Test performance:

The relative biodegradation values calculated from the O2 measurements performed during the test period of 28 days revealed no significant (>10%) degradation of the test item at both concentrations. The oxygen depletion in the toxicity control was always more than 75% of the sum of the oxygen depletion of the positive control and the test substance (low). Therefore, the test item was assumed to be not inhibitory.
Acceptability of the test
Oxygen depletion in the inoculum blank was 0.75 mg O2/L after 28 days. The residual concentration of oxygen in the test bottles was > 0.5 mg/L at any time. The difference of duplicate values expressed as mg O2/L was less than 20% for all duplicate values throughout the incubation period of 28 days. The control substance was degraded by more than 60% within 7 days.

Key result

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Results with reference substance:

Points of degradation (reference substance):
74 % degradation after 7 d
79 % degradation after 14 d
76 % degradation after 21 d
76 % degradation after 28 d

Table 1: % Biodegradation at different time points

Test medium	Concentration (mg/L)	%Biodegradation after x days
		7	14	21	28
Positive control*	2	74	79	76	76
Test substance low**	2	2	0	-1	-2
Test substance high**	5	-1	0	0	-1

*ThOD positive control: 0.780 mg O2/mg

**ThOD test substance: 2.417 mg O2/mg

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The test item is not biodegradable in a test according to OECD 301 D.

Executive summary:

The test item was tested for its ready biodegradability in the closed bottle test at 2 and 5 mg/L. The study procedure was based on EU Method C.4-E and OECD guideline No. 301 D. The ThOD of the test item (molecular formula: C14H2203, MW= 238.3 g) was calculated to be 2.417 mg O2 per mg. The relative biodegradation values calculated from the O2 measurements performed during the test period of 28 days revealed no significant (0%) degradation at both concentrations. Since all acceptability criteria prescribed by the protocol were met, this study was considered to be valid. In conclusion, the test item was not biodegradable under the conditions in the closed bottle test presently performed.

Description of key information

The test item is not biodegradable in a test according to OECD 301 D (reference 5.2.1 -1).

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater

Additional information

The test item was tested for its ready biodegradability in the closed bottle test at 2 and 5 mg/L. The study procedure was based on EU Method C.4-E and OECD guideline No. 301 D. The ThOD of the test item (molecular formula: C14H2203, MW= 238.3 g) was calculated to be 2.417 mg O2 per mg. The relative biodegradation values calculated from the O2 measurements performed during the test period of 28 days revealed no significant (0%) degradation at both concentrations. Since all acceptability criteria prescribed by the protocol were met, this study was considered to be valid. In conclusion, the test item was not biodegradable under the conditions in the closed bottle test presently performed (reference 5.2.1 -1).