5-hexyldihydro-5-methylfuran-2(3H)-one

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010-11-24 and 2011-03-14

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

2008

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Commission Directive 92/69 EEC, C.4-D, Manometric Respirometry Test, 1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: wastewater treatment plant (ARA Ergolz II, Füllinsdorf, Switzerland)
- Preparation of inoculum for exposure: The sludge was washed twice with tap water by centrifugation and the supernatant liquid phase was decanted. A homogenized aliquot of the final sludge suspension was weighed, thereafter dried and the ratio of wet to dry weight was calculated.
- Concentration of sludge (final): 30 mg dry material per liter

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Initial conc.:

261 mg/L

Based on:

ThOD

Initial conc.:

262 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral medium accroding to OECD guideline
- Additional substrate: none
- Test temperature: 22°C
- pH: 7.4
- pH adjusted: yes, with a diluted hydrochloric acid solution
- Aeration of dilution water: no
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: 500 mL reaction vessels
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: The flask were incubated under continuous stirring in a SAPROMAT D12.
- Measurement equipment: electro-chemical analysis process: The generated CO2 is absorbed by soda lime, resulting in a decrease of the total pressure in the airtight flasks. The pressure drop is detected and converted into an electrical signal by means of an electrode type manometer.
- Test performed in open system: Yes

SAMPLING
- Sampling frequency: daily on each working daily

CONTROL AND BLANK SYSTEM
- Inoculum blank: mineral medium containing only inoculum
- Toxicity control: mineral medium containing test substance, reference substance and inoculum

Reference substance:

benzoic acid, sodium salt

Preliminary study:

Not performed

Key result

Parameter:

% degradation (O2 consumption)

Value:

82

Sampling time:

28 d

Remarks on result:

other: 10-day window passed

Details on results:

At the end of the 28-day exposure period, the mean biodegradation of the test item amounted to 82%. The pass level for ready biodegradability, i.e. biodegradation of at least 60% of the ThOD in a 10-day window within the 28-day period of the test, was reached. In the toxicity control, biodegradation amounted to 42% within 14 days of exposure. Thus, the test item had no inhibitory effect on activated sludge microorganisms at the tested concentration of 100 mg/L. Please refer to 'any other information on results' for more details.

Results with reference substance:

The reference item sodium benzoate was degraded by an average of 90% by exposure day 14, and reached an average biodegradation of 96% by the end of the test (Day 28).

Biodegradation in the test flasks

Time (days)	Percentage Biodegradation*
	Test item		Procedure control		Toxicity control
	Replicate No.		Replicate No.		Replicate No.
	1	2	1	2	1
0	0	0	0	0	0
1	-1	1	16	13	9
2	0	1	56	56	23
3	0	1	72	71	28
4	0	1	77	75	29
5	0	2	81	79	30
6	5	8	83	81	31
7	16	13	84	82	31
8	27	30	86	83	32
9	-	-	-	-	-
10	-	-	-	-	-
11	45	51	89	86	35
12	50	57	90	87	37
13	55	60	91	88	39
14	58	63	91	88	42
15	62	67	92	89	47
16	66	72	94	90	51
17	68	75	94	91	53
18	70	77	94	91	55
19	72	79	95	92	58
20	73	81	96	92	60
21	75	82	96	92	62
22	76	82	97	92	65
23	-	-	-	-	-
24	-	-	-	-	-
25	78	84	97	93	69
26	79	84	98	93	70
27	79	84	98	93	71
28	80	84	98	93	73
Mean (day 28)	82		96		Not applicable

* Corrected for the mean oxygen uptake of the inoculum controls

- not determined

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

At the end of the 28-day exposure period, the mean biodegradation of the test item amounted to 82%.

Executive summary:

The test item was investigated for its ready biodegradability in a manometric respirometry test over 28 days according to OECD TG 301 F, Commission Directive 92/69 EEC, C.4 -D and Commission Regulation (EC) No 440/2008, C.4 -D. The percent of biodegradation of the test item was calculated based on the theoretical oxygen demand (ThOD) of 2.61 mg O2/ mg test item). The biochemical oxygen demand (BOD) of the test item in the test media significantly increased from exposure day 6 until test termination after 28 days. At the end of the 28 -day exposure period, the mean biodegradation of the test item amounted to 82%. Consequently, the test item was found to be biodegradable by 82% under the test conditions within 28 days. Moreover, the pass level for ready biodegradability, i.e. biodegradation of at least 60% of the ThOD in a 10-day window within the 28-day period of the test, was reached. In the toxicity control, containing both test item and the reference item sodium benzoate, the test item had no inhibitory effect on the activity of activated sludge microorganisms at the tested concentration of 100 mg/L. In the procedure controls, the reference item sodium benzoate was degraded by an average of 90% by exposure day 14, and reached an average biodegradation of 96% by the end of the test (Day 28), thus confirming suitability of the activated sludge.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Please refer to attached "Read-across justification".

Reason / purpose for cross-reference:

read-across source

Key result

Parameter:

% degradation (O2 consumption)

Value:

82

Sampling time:

28 d

Remarks on result:

other: 10-day window passed

Description of key information

Based on an read-across approach, the test substance is considered to be readily biodegradable according to OECD criteria.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

For the test substance no biodegradation tests are available.

Therefore, an analogy approach to the read-across substance Reaction mass of trans-5 -hexyldihydro-4 -methylfuran-2(3H)-one and cis-5 -hexyldihydro-4 -methylfuran-2(3H)-one is applied.

In this test, the read-across substance was incubated in mineral medium with activated sludge under aerobic conditions for an exposure period of 28 days (OECD 301F). The read-across substance was found to be readily biodegradable by 82% under the test conditions within 28 days. The pass level for ready biodegradability in a 10 -day window within the 28 -day period of the test, was reached.