Fatty acids, C12-16 (even numbered) and C18 unsatd., Me esters

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

31 Aug - 28 Sep 1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: Circular on Test Methods of New Chemical Substances (Japan), Biodegrability test

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

mixture of sewage, soil and natural water

Details on inoculum:

- Source of inoculum/activated sludge (location, sampling depth): location: 10 sites (4 sewage plants, 3 rivers, 1 lake and 2 bays) around Japan, sampling depth: return sludge in sewage plants, surface water and surface soil of foreshore
- Laboratory culture: Thirty minutes after stopping of aeration, discard about one third of the whole volume of supernatant and add an equal volume of a solution (pH adapted to 7.0 with NaOH) containing 0.1% each of glucose, peptone and pottasium orthophosphate, to the settled material and re-commence aeration. This procedure was repeated once per day.
- Temperature: 25 ± 2 °C
- 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

Details on study design:

TEST CONDITIONS
- Composition of medium: recommended medium in the guideline (JIS K 0102-1993)
- Test temperature: 25 ± 1 °C
- Suspended solids concentration: 30 mg/L

TEST SYSTEM
- Culturing apparatus: 300 mL culture bottle
- Number of culture flasks/concentration: 1 (water + test substance), 3 (sludge + test sub.), 1 (sludge + reference sub.), 1 (sludge)
- Measuring equipment: Coulometer
- Test performed in closed vessels due to significant volatility of test substance: Yes
- Details of trap for CO2 and volatile organics if used: soda lime

SAMPLING
- Sampling frequency: 7, 14, 21, 28 days

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: no

Reference substance:

aniline

Key result

Parameter:

% degradation (O2 consumption)

Value:

78

Sampling time:

28 d

Details on results:

No 10-day window required. Substance was readily biodegradable.
Partial hydrolisation of the test substance in water to form dodecanoic acid and methanol was described.

Results with reference substance:

The oxygen consumption for aniline in the above used test system reached 62% and 75% degradation after 7 days and 14 days.

Table 1. Table of BOD

	7^thday		14^thday		21^stday		28^thday
	BOD (mg)	Deg(%)	BOD (mg)	Deg(%)	BOD (mg)	Deg(%)	BOD (mg)	Deg(%)	MeanDeg. %
Sludge+Aniline	57.4	62	71.0	75	71.5	75	75.0	76
Water + Testsub.	0	-	0.2	-	0.2	-	0.2	-
Controlblank	1.6	-	3.4	-	3.7	-	6.7	-
Sludge+ Testsub.	40.5	46	57.1	64	68.3	77	73.1	79	78
Sludge+ Testsub.	31.3	35	48.2	53	60.1	67	68.3	73
Sludge+ Testsub.	32.3	37	51.7	58	65.5	74	75.3	82

Deg. =( BOD- control blank) / TOD x 100 TOD of test substance: 83.9 mg TOD of aniline: 90.3 mg

 

Table 2.Result of analysis for BOD and GC

		water+ testsub.	sludge+ testsub. (*1)			TheoreticalAmount
		sampleNo. 2	sampleNo. 4	sampleNo. 5	sampleNo. 6
BOD	mg	0.2	66.4	61.6	68.6	83.9
GC (residue of test substance)	mg	26.9	0.0	0.0	0.0	30.4
	% (*2)	89	0	0	0	-
GC (production ofdodecanoicacid)	mg	1.1	0.0	0.0	0.0	28.4
	% (*2)	4	0	0	0	-

(*1) (sludge+ test sub.)was calculated by subtracting blank values.

(*2) Residue and production percentage was calculated as followed.

Residue percentage = Residue amount (mg) /Theoretical amount (mg) x 100

Production percentage = Production amount (mg) /Theoretical amount (mg) x 100

 

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 Dec 1993 - 19 Jan 1994

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

ISO Draft (BOD Test for Insoluble Substances)

Deviations:

yes

Remarks:

, intermediate determination of %BOD

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Sewage treatment plant KA Hochdahl (discharging population equivalent of 27.000)

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

COD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Test temperature: 20-25 °C
- Suspended solids concentration: approx. 30 mg
- Other: Samples on a shaker


TEST SYSTEM
- Culturing apparatus: Conical flasks
- Number of culture flasks/concentration: 1
- Measuring equipment: amperometrical determination of oxygen (OXI 2000)


SAMPLING
- Sampling frequency: Day 0, 14, 21 and 28

Reference substance:

acetic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

75

Sampling time:

28 d

Results with reference substance:

The reference substance achieved 80% degradation within 14 days

The test substance is readily biodegradable under conditions tested. The biodegradation was > 60% (75%) within 28 days and 2 of the replicates reached the 14-day-window. The replicate with 35% degradation after 14 days was disregarded, as the difference of this replicate value is more than 20% in comparison to both other replicate values at all sampling days (14, 18 and 28 days).

Table 1: Percentage biodegradation of test and reference substance

Day	Test substance		Reference substance
	Replicates	Average	Replicates	Average
14	64 35 65	55	78 81 82	80
21	75 53 74	67	81 87 85	85
28	82 63 79	75	82 90 88	87

 

 

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 Apr - 13 May 1994

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

other: secondary effluent of STP

Details on inoculum:

- Source of inoculum/activated sludge: 10% by volume of activated sludge plant secondary effluent, filtered , sparged with nitrogen after adjustment to pH 6.5
- Type and size of filter used, if any: Whatman filter paper (541)

Duration of test (contact time):

28 d

Initial conc.:

10.09 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: mineral salts medium
- Test temperature: 20 °C, incubated and set on rotary shaker
- pH adjusted: yes (to 6.5)

TEST SYSTEM
- Culturing apparatus: 160 mL hypovials with a butyl rubber septum and aluminium crisp seal
- Number of culture flasks/concentration: 11 (1 measured at day 4, 7, 11, 14, 18 and 21, 5 measured at day 28)
- Measuring equipment: concentration of headspace gas


CONTROL AND BLANK SYSTEM
- Inoculum blank: yes

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

90.4

St. dev.:

1.5

Sampling time:

28 d

Remarks on result:

other: 88.9-91.9% (95% C.L.)

Details on results:

The test substance reached 90.4% biodegradation within 28 days and therefore can be considered readily biodegradable (the 10-day window criterion was fulfilled)

Results with reference substance:

Sodium benzoate reached > 60% biodegradation within 14 days

Table 1. Biodegradability values in % of test and reference substance:

Day	TS	Ref substance
4	62.8	71.9
7	74.5	81.5
11	84.2	82.2
14	87.5	92.4
18	86.6	89.8
21	88.3	90.5
28	90.4	89.8

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Description of key information

Readily biodegradable: >70% in 28 days (OECD 301, read across)

                               

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

As no experimental data evaluating the potential for ready biodegradability of Fatty acids, C12-16 (even numbered) and C18 unstd., methyl esters (CAS No. 1234694-02-0) are available, in accordance to Regulation (EC) No. 1907/2006, Annex XI, 1.5, read-across from structurally related category members, methyl laurate (CAS No. 111-82-0), methyl palmitate (CAS No. 112-39-0) and methyl oleate (CAS No. 112-62-9) is performed. All four substances are characterized as esters of methanol and C12 (CAS No. 111-82-0), C16 (CAS No. 112-39-0), C18 (CAS No.112-62-9) and C12-16 (even numbered) and C18 unsaturated (CAS No. 1234694-02-0) fatty acids. Therefore, as representatives of the C-chain lengths of the individual fatty acid components that can be found in Fatty acids, C12-16 (even numbered) and C18 unstd., methyl esters, the read-across substances are expected to give a valid indication of its biodegradation potential.

The test available for methyl laurate (CAS No. 111-82-0) was conducted according to OECD 301C under GLP-conditions (Japanese Ministry of Economy, Trade and Industry, 1995). A mixture of sewage, soil and natural water was used as inoculum. After 28 days, the test substance reached 78% biodegradation. Since the 10-d window concept does not apply to the MITI method, methyl laurate can be considered readily biodegradable according to OECD criteria. A study performed according to ISO Draft (BOD Test for Insoluble Substances), under GLP conditions is available for methyl palmitate (CAS No. 112-39-0). Activated sludge was exposed for 28 days to the test substance and biodegradation followed by measuring O2 consumption in the test vessels. After 28 days the test substance reached 75% biodegradation, fulfilling the 14-day window criterion in two of the three replicates (the third replicate reached only 35% degradation after 14 days). Nevertheless, biodegradation values in the third replicate differed more than 20% in comparison to the values in the other two throughout the test (observed in samples collected at 14, 18 and 28 days). Therefore, the results from the third replicate are considered invalid and disregarded for the final biodegradability assessment, and the substance can be considered as readily biodegradable. Finally, the test conducted with methyl oleate (CAS No. 112-62-9) was performed according to OECD 301B, under GLP conditions (King, 1994). Secondary effluent from a STP was used as source of inoculum. After an incubation period of 28 days at 20°C, the substance reached 90.4% biodegradation, fulfilling the 10-day window criterion (84.2% biodegradation was reached on day 11) and therefore it is readily biodegradable as well according to OECD criteria.

Based on the results obtained for the structurally related category members (in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5) Fatty acids, C12-16 (even numbered) and C18 unstd., methyl esters can be considered as readily biodegradable.