Ethyl 2-cyclohexylpropionate

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 13 November to 11 December 1991

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: According to the OECD Method 301D and it is GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1992

Report date:

1992

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Ethyl 2-cyclohexylpropionate

EC Number:

412-280-5

EC Name:

Ethyl 2-cyclohexylpropionate

Cas Number:

2511-00-4

Molecular formula:

C11H20O2

IUPAC Name:

ethyl 2-cyclohexylpropanoate

Details on test material:

- Physical state: clear liquid
- Storage condition of test material: in darkness at 4ºC

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

other: Activated sewage sludge bacteria

Details on inoculum:

Source: The aeration stage of the HRC limited sewage treatment plant treating predominantly domestic sewage.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

2 mg/L

Based on:

test mat.

Details on study design:

Vessels: 280 ml BOD bottles (darkened glass) with ground glass stoppers.
Test concentrations:
(a) Non-inoculated dilution water.
(b): Inoculated dilution water
(c): Inoculated dilution water plus filter paper.
(d): 2 mg/l test substance plus filter paper.
(e): 3 mg/l sodium benzoate
(f): 2 mg/l aniline plus filter paper.
(g): 2 mg/l test substance plus 3 mg/l sodium benzoate plus filter paper
Test media b,c,d,e,f and g were inoculated with activated sludge filtrate at the rate of 1 drop of inoculum per litre.
Procedure: BOD bottles were filled, by siphnon, and firmly stoppered to exclude all air bubbles. Sufficient bottles were prepared to all a single oxygen determination per bottle to be made at 0,5,15 and 28 days for each test media (a)-(f), (duplicate bottle at each sampling time). Two bottles of preparation (g) were prepared to allow a single oxygen determination per bottle to be made at 28 days.
Bottles were incubated in a water bath at 20±1ºC for 0,5,15 or 28 days as appropriate.
Observation: Dissolved oxygen concentrations for each test medium were determined, in duplicate, at 0,5,15 and 28 days by means of Yellow Springs BOD Probe (Model 50B).
Series (g) containing both the test substance and sodium benzoate was included as a check for possible inhibition effects.

Reference substance

Reference substance 1

Reference substance:

benzoic acid, sodium salt

Reference substance 2

Reference substance:

aniline

Results and discussion

% Degradation

Parameter:

% degradation (CO2 evolution)

Value:

13

Sampling time:

28 d

Details on results:

Dissolved oxygen measurements for the test substance and standard substance solutions, together with the inoculated and non-inoculated blank controls, at 0,5,15 and 28days ere given in Table 1. Mean oxygen depletion values and percentage degradation values (% of ThOD NO3) are given in Table 2.
After 28 days the oxygen depletion value for the inhibition check culture (g) was 102% of the sum of the individual component substance i.e. the test substance plus filter paper plus sodium benzoate (see Table 2). This indicates that no significant inhibition occurred at the test concentration of 2 mg/L.
Oxygen depletions in the inoculated and non-inoculated control series were within the prescribed limits.*
*Non-inoculated control: <0.3 mgO2/L after 5 days, <0.4 mgO2/L after 28 days
Inoculated control: <0.5 mgO2/L after 5 days, <0.6mgO2/L after 28 days.

BOD5 / COD results

Results with reference substance:

Sodium benzoate attained 97% biodegradation within 28 days.
Aniline attained 69% biodegradation within 28 days.

Any other information on results incl. tables

TABLE 1
Dissolved oxygen measurements (mgO2/L)
Culture medium		Day
		0	5	15	28
(a)Dilution water without inoculum	R1	8,9	8,81	8,85	8,78
	R2	8,9	8,76	8,75	8,6
	Mean	8,9	8,785	8,8	8,69
(b) Dilution water with inoculum	R1	8,9	8,7	8,82	8,45
	R2	8,9	8,86	8,77	8,51
	Mean	8,9	8,78	8,795	8,48
( c) Dilution water with inoculum	R1	8,9	8,69	8,64	8,6
	R2	8,9	8,65	8,64	8,59
	Mean	8,9	8,67	8,64	8,595
(d) Test substance (2mg/l) plus filter	R1	8,9	8,73	8,69	7,91
	R2	8,9	8,75	8,78	7,92
	Mean	8,9	8,74	8,735	7,915
( e) Standard substance (3mg/l) Sodium benzoate	R1	8,9	5,31	5,12	3,47
	R2	8,9	5,41	4,97	3,79
	Mean	8,9	5,36	5,045	3,63
(f) Standard substance (2 mg/l) Aniline plus filter paper	R1	8,9	8,51	5,38	4,27
	R2	8,9	8,46	5,21	4,39
	Mean	8,9	8,485	5,295	4,33
(g) Test substance (2mg/l) plus filter paper plus standard substance sodium benzoate (3 mg/l)	R1	8,9	N/A	N/A	3,11
	R2	8,9	N/A	N/A	2,83
	Mean	8,9	N/A	N/A	2,97
R1 and R2 Replicates 1 and 2
N/A Not applicable
TABLE 2
Mean oxygen depletion and percetage biodegradation values
Culture medium		Day
		5	15	28
(a) Dilution water without inoculum	} O2depletion (mgO2/l)	0,115	0,1	0,21
(b) Dilution water with inoculum	} O2depletion (mgO2/l)	0,12	0,105	0,42
( c) Dilution water with inoculum and filter paper	} O2depletion (mgO2/l) }	0,23	0,26	0,305
(d) Test substance (2 mg/l) plus filter paper	} O2depletion (mgO2/l) }	<0,070> <1>	<0,095> <2>	0,680 13
( e) Standard substance (3mg/l) Sodium benzoate	} O2depletion (mgO2/l) } % degradation	3,420 68	3,750 75	4,850 97
(f) Standard substance (2 mg/l) Aniline plus filter paper	} O2depletion (mgO2/l) } % degradation	0,185 3	3,345 54	4,265 69
(g) Test substance (2 mg/l) plus filter paper plus standard sodium benzoate (3 mg/l)	} O2depletion (mgO2/l) } }	N/A	N/A	5,625

<Increase>

N/A Not applicable

(i) Test substance

Oxygen depletion= (a-d)-(a-c) from Table 1

(ii) Standard substance (sodium benzoate)

Oxygen depletion = (a-e)-(a-b) from Table 1

(iii) Standard substance (aniline)

Oxygen depletion = (a-f)-(a-c) from Table 1

(iv) Inoculated and non-inoculated dilution water (plus filter paper blank)

Oxygen depletion=initial O2 concentration - measured value

(v) % Degradation= Oxygen (depletion/conc.of substance x ThOD NO3 or COD) x 100

(vi) Inhibition check

Oxygen depletion = (a-g)-(a-c) from Table 1

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Conclusions:

The test substance cannot be termed as readily biodegradable.

Executive summary:

The substance was tested for ready biodegradability accroding to the OECD 301D Closed-Bottle-Test. The test substance concentration was 2mg/, the oxygen depletion after 28 days was 0.68 mg O2/L and the theoretical oxygen demand was 5.22 mgO2/L. Under the chosen conditions a degradation of 13% was measured after 28 days. The substance cannot be termed as readily biodegradable.