Fatty acids, tall-oil, esters with ethylene glycol

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:

08 Mar - 18 Apr 2018

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

GLP compliance:

yes (incl. QA statement)

Remarks:

Hessisches Ministerium für Umwelt, Klimaschutz, Landwirtschaft und Verbraucherschutz, Germany

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Sewage treatment plant Bensheim, Germany
- Preparation of inoculum for exposure: Activated sludge used for this study was deposited for 15 min and washed by centrifugation. Aliquotes of washed sludge suspension, corresponding to 3.5 g dry material/L were mixed with test water and aerated overnight.
- Pretreatment: Sludge was washed by centrifugation, liquid phase was then decanted and solid material was re-suspended in tap water and centrifuged, procedure was repeated 3 times. An aliquot of the final sludge suspension was weighed, dried and ratio of wet sludge to dry weight was determined.

Duration of test (contact time):

28 d

Initial conc.:

103.1 mg/L

Based on:

test mat.

Initial conc.:

298.6 mg/L

Based on:

ThOD

Remarks:

ThODNH4

Initial conc.:

301.1 mg/L

Based on:

ThOD

Remarks:

ThODNO3

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: according to guideline
- Test temperature: 22 °C ± 1 °C
- pH: 7.4 - 7.9
- Suspended solids concentration in flask: 28.7 mg sludge/L
- Continuous darkness: yes
- Other: continuous stirring

TEST SYSTEM
- Culturing apparatus: Manometric Test System with test flasks containing a volume of approx. 500 mL.
- Number of culture flasks/concentration: 2
- Measuring equipment: BSB/BOD-Sensor-System, Aqualytic Dortmund, Germany
- Test performed in closed vessels: yes
- Details of trap for CO2: potassium hydroxide solution (45%)

SAMPLING
- Sampling method: The pressure decrease in the reaction vessels was measured daily.

CONTROL AND BLANK SYSTEM
- Inoculum control: 2 flasks
- Abiotic sterile control: 1 flask (poisoned with CuSO4)
- Toxicity control: 1 flask
- Other: procedure control: 1 flask

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

63

Sampling time:

28 d

Remarks on result:

other: mean of ThODNH4 and ThODNO3

Details on results:

Toxicity control: 61% biodegradation after 14 d and 62% after 28 d (the test item can be assumed to be not inhibitory to the aerobic activated sludge microorganisms as degradation was >25% within 14 d.)

Results with reference substance:

94% biodegradation of reference substance after 14 d and 103% after 28 days.

Table 1: Percentage Biodegradation of Test Item and of the Toxicity Control based on ThODNO3 and of Sodium Benzoate based on ThODNH4

Time	Percentage Biodegradation 1)
(Days)	Test Item		Sodium Benzoate 2)	Toxicity control 1), 2)
	Flask 1 [%]	Flask 2 [%]	Flask 5 [%]	Flask 7 [%]
1	3	3	32	11
2	10	10	47	16
3	12	13	65	29
4	17	17	71	33
5	20	20	76	36
6	22	22	76	38
7	23	25	79	41
8	31	35	91	51
9	35	38	91	53
10	38	40	91	55
11	38	42	94	56
12	40	43	94	58
13	43	45	94	60
14	45	47	94	61
15	46	47	97	61
16	48	48	97	62
17	50	50	97	62
18	53	52	97	62
19	55	53	97	62
20	55	55	97	62
21	56	55	100	62
22	56	57	100	62
23	58	57	100	62
24	60	58	103	62
25	60	58	103	62
26	61	60	103	62
27	63	62	103	62
28	63	62	103	62

1) ThODNO3 of Test Item: 2.921 mg O2/mg test item
2) ThODNH4 of sodium benzoate: 1.666 mg O2/mg reference item

Table 2: Validity criteria

Criterion from the guideline	Outcome	Validity criterion fulfilled
Difference of extremes of replicate values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-d window, as appropriate, is less than 20%.	2%	Yes
Percentage degradation of the reference compound has reached the pass levels by day 14.	>60%	Yes
The toxicity control should degrade to at least 35% (based on DOC) or at least 25% (based on ThOD or ThCO2) within 14 d.	62%	Yes
The oxygen uptake of the inoculum blank is normally 20-30 mg O2/L and should not be greater than 60 mg/L in 28 days.	25 mg O2/L	Yes

 

Validity criteria fulfilled:

yes

Remarks:

See Table 2 in section "Any other information on results incl. tables"

Interpretation of results:

readily biodegradable

Description of key information

Readily biodegradable (63% degradation after 28 d, OECD 301 F)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

One study is available, in which the biodegradability of Fatty acids, tall-oil, esters with ethylene glycol (CAS 68187-85-9) was tested. The study was conducted according to the OECD guideline 301 F and GLP. Non-adapted activated sludge was used as inoculum and was exposed to 103.1 mg/L test material (298.6 mg/L based on ThODNH4 and 301.1 based on ThODNO3) for 28 d. Oxygen consumption was measured daily by decreasing of the pressure in the bottles in order to monitor the biodegradation of the substance. A reference and a toxicity control were run in parallel. 63% biodegradation (mean of ThODNH4 and ThODNO3) was recorded after 28 d. Since the test item is a UVCB substance and consists of structurally similar constituents with different chain-lengths, sequential (instead of concurrent) biodegradation of the individual structures can take place, but all can be considered as readily biodegradable. Thus, referring to Annex I to the OECD Guideline for Testing of Chemicals ‘Revised introduction to the OECD guidelines for testing of chemicals, section 3’ (OECD, March 2006), the 10-day window should not be considered for UVCB substances and due to a degradation of >60 % within 28 days the substance is considered readily biodegradable.