Ethyl isovalerate

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:

1999-04-30 to 1999-05-28

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

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure):secondary effluent of a domestic sewage treatment plant (Kläranlage Odenthal)
- Laboratory culture: none
- Pretreatment: separation of coarse particles by filtration
- Concentration of sludge: 5 mL/L
- Method of cultivation: aeration for 7 days

Duration of test (contact time):

28 d

Initial conc.:

3 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral medium
- Test temperature: 20 °C
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: flasks
- Number of culture flasks/concentration: 10
- Other: The test substance is suspended in a mineral medium, inoculated with a mixed population of aquatic microorganisms and incubated for 28 days under aerobic conditions in the dark at 20 +/-1°C. During this period, the biodegradation of the test substance is determined on the basis of the reduction of dissolved oxygen.

SAMPLING
- Sampling frequency: 0, 7, 14, 21 and 28 d

CONTROL AND BLANK SYSTEM
- Inoculum blank: 10 flasks/ concentration
- Toxicity control: yes

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

65

Sampling time:

28 d

Remarks on result:

other: mean value

Dissolved oxygen depletion

	Dissolved oxygen depletion after n days [mg/l]
	7 d		14 d		21 d		28 d
	DO [mg/l]	Degradation %	DO [mg/l]	Degradation %	DO [mg/l]	Degradation %	DO [mg/l]	Degradation %
Test substance: 3.0 mg/l; ThOD:2335 mg/g
Replicate 1	2.86	41	3.89	56	4.63	66	4.51	64
Replicate 2	2.98	43	4.12	59	4.56	65	4.54	65
Mean		42		58		66		65
Reference substance: 2.9 mg/l; ThOD:1665 mg/g
Replicate 1	3.29	68	3.77	78	4.05	84	4.08	84
Replicate 2	3.05	63	3.82	79	4.10	85	4.18	87
Mean		66		79		85		86
Toxicity control^*
Replicate 1	7.14	60	8.38	71	8.79	74	8.88	75
Replicate 2	7.20	61	8.25	70	8.45	71	8.86	75
Mean		61		71		73		75

^*In the toxicity control 3.0 mg/l test substance and 2.9 mg/l reference substance were used. The ThOD values respectively COD values of these substances are shown in the table above. Toxicity control: Test substance not inhibitory at tested concentration of 3.0 mg/L.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The biodegradation of Ethyl isovalerate was determined according to OECD 301 D and under GLP conditions. The test substance showed a biodegradation for at least 65% within 28 days of incubation at the tested concentration of 3.0 mg/L. The pass level of 60% degradation was reached in a 14-d window. Therefore, the test substance was classified as "readily biodegradable" according to OECD criteria.

Description of key information

Readily biodegradable: 65% within 28 days (O2 consumption, OECD 301 D).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The biodegradation of Ethyl isovalerate was determined according to OECD 301 D and in compliance with GLP. The test substance showed a biodegradation of 65% within 28 days of incubation at the tested concentration of 3.0 mg/L and reached the pass level of 60% degradation in a 14-d window. Furthermore, no inhibitory effects on microorganisms were observed up to 3 mg/L. The test substance was therefore classified as readily biodegradable according to OECD criteria.