Fatty acids, C18-36, 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:

07 July 2017 to 10 August 2017

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)

Qualifier:

according to guideline

Guideline:

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

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: Totnes Sewage Treatment Works, Totnes, Devon, UK
- Storage conditions: aerated at room temperature at pH 7.0 ± 1.0.
- Storage length: 2 days
- Preparation of inoculum for exposure: Six days prior to the exposure start the activated sludge was centrifuged, washed and re suspended in the mineral medium and the solids concentration determined. This sludge was then diluted in medium, added to test bottles and stirred until required for use. The seeded mineral medium was pre-conditioned for six days to reduce the blank oxygen uptake readings in the test.
- Concentration of sludge: 30 mg/L

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Remarks:

calculated as BOD/COD

Details on study design:

TEST CONDITIONS
- Composition of medium: according to the guideline
- Additional substrate: none
- Solubilising agent (type and concentration if used): none
- Test temperature: 22 ± 1 °C
- pH: 7.4 ± 0.2 (actual 6.98-7.34)
- pH adjusted: no
- Sludge concentration: 30 mg/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: dark glass 500 mL bottle placed in incubator
- Number of culture flasks/concentration: 3 (One replicate for the substance was excluded as an outlier (Dixon’s Q test)performed on day 10 results), this did not adversely affect the outcome of the study as two replicates are reported which complies with the minimum given in the OECD 301F guideline
- Method used to create aerobic conditions: continuously stirred
- Measuring equipment: Oxitop respirometer
- Details of trap for CO2 and volatile organics if used: KOH

Examiniations
- Frequency: daily
- Method: measurement of decrease in pressure over 240 min period

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes (3 replicates)
- Abiotic sterile control: none
- Toxicity control: yes (3 replicates)

STATISTICAL METHODS: NA

Reference substance:

benzoic acid, sodium salt

Parameter:

other: % degradation BOD/COD

Value:

5

Sampling time:

28 d

Details on results:

Initial pH 7.36, at 28 days 7.41 for substance
Initial pH 7.2, at 28 days 7.3 for inoculum blank

Day	Biodegradation(%) Reference Substance	Biodegradation(%) Substance	Biodegradation(%) Tox control
	Mean	Mean (based on 2 replicates)	Mean
1	1	1	1
2	42	1	19
3	52	0	23
4	58	0	28
5	61	1	30
6	64	1	32
7	66	0	32
8	68	0	34
9	68	0	35
10	69	1	35
11	70	1	36
12	72	0	36
13	71	2	37
14	71	2	37
15	72	2	38
16	72	3	37
17	73	3	38
18	72	2	38
19	73	2	39
20	73	4	39
21	73	3	40
22	73	4	40
23	73	4	40
24	75	5	40
25	75	5	41
26	75	4	41
27	74	4	41
28	75	5	42

Biodegradation (%) =       Biological Oxygen Demand (g O₂/g)× 100 / ThOD (1.67 g O₂/g) and/or COD (1.94 g O₂/g)

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The substance is not readily biodegradable

Executive summary:

Subject	Determination of Ready Biodegradability
Guideline	OECD 301F: Manometric respirometry
Test concentration	Control and 100 mg/L
Length of test	28 days
Nominal test temperature	22 ± 1°C
Mean degradation after 28 days	5%
Classification	Not readily biodegradable (Ref 1)
Reference substance	Sodium benzoate
Experimental values	substance		Reference substance
	Day	Mean percentage biodegradation	Day	Mean percentage biodegradation
	5	1	5	61
	10	1	10	69
	15	2	15	72
	20	4	20	73
	28	5	28	75
Comments	The COD of the test substance was calculated as2.04 g O2/g and the mean BOD value after 28 days was 0.10 g O2/g. The percentage degradation was calculated as (BOD/COD)´100
Conclusions	the substance attained a mean level of biodegradation (based on the BOD:COD ratio) of 5% after 28 days and the results showed good replication. Less than 60% degradation was achieved within 28 days, so the substance cannot be classified as readily biodegradable (Ref 1).

Description of key information

In a test according to OECD 301F the substance showed a biodegradation of 5% over the 28 day test period. Therefore the substance is considered not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater