Ethyl hexanoate

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:

1999-11-25 to 1999-12-23

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study according to OECD 301F

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1992

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: aeration tank of a waste plant treating predominantly domestic sewage (Wupper area water authority)
- Pretreatment: none
- Concentration of sludge: 30 mg sewage sludge/L in the test flask
- Other: type: mixed population of aquatic micro organisms
- Other: sampling: 1999-11-22

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Test temperature: 20 ± 1 °C
- Continuous darkness: yes

TEST SYSTEM
- Number of culture flasks/concentration: 3
- Measuring equipment: respirometer

SAMPLING
- Sampling frequency: after 4, 6, 8, 12, 14, 18, 20, 22, 26 and 28 d

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Toxicity control: yes

Reference substance:

other: sodium benzoate

Key result

Parameter:

% degradation (O2 consumption)

Value:

79

Sampling time:

28 d

Remarks on result:

other: mean value

Details on results:

Within the test period of 28 days, a degradation of 79 % was determined for Ethyl hexanoate.
Toxicity control: The test substance showed no inhibitory effects on microorganisms at the tested concentration of 100 mg/L.

Results with reference substance:

The reference substance reached a biodegradation of 89 % within 14 days

Mean BOD concentration

BOD, mean in [mg O2/L] after n days
day	4	6	8	12	14	18	20	22	26	28
corrected Test substance* (mean of 3 values; minus blank)	95	117	134	158	165	174	177	181	188	192
Reference substance (mean of 2 values; minus blank)**	111	127	135	145	148	151	152	154	157	158
Toxicity control (1 value; minus blank)**	186	232	264	290	298	309	314	319	328	332

*       Blank value is measured and considered

**      Data of 1 additional replicate each is not reported because these units were not air tight

Mean degradation based on oxygen consumption

Degradation, mean [%] after n days
day	4	6	8	12	14	18	20	22	26	28
test substance	39	48	55	65	67	71	73	74	77	79
reference substance	67	76	81	87	89	91	91	92	94	95
toxicity control	45	57	64	71	73	75	76	78	80	81

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The biodegradation of Ethyl hexanoate was determined according to OECD 301 F under GLP conditions. Within the test period of 28 days, a degradation of 79 % was determined for the test substance. The test substance showed no inhibitory effects on the microorganisms at the tested concentration of 100 mg/L and was, therefore, classified as "readily biodegradable" according to OECD criteria.

Description of key information

Readily biodegradable: 79% after 28 days (O2 consumption, OECD 301 F)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The biodegradation of Ethyl hexanoate was determined in in a reliable GLP study according to OECD 301 F. Within the test period of 28 days, a degradation of 79 % was determined for the test substance and the test substance was classified as "readily biodegradable" according to OECD criteria. Ethyl hexanoate further showed no inhibitory effects on microorganisms at a concentration of 100 mg/L.