Fatty acids, C8-10, C12-18-alkyl 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:

22 Oct - 19 Nov 1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

The degradation in one replicate was below the pass level and differed by > 20%. However, the mean biodegradation based on BOD was > 70% (replicate 1: 88.5%; replicate 2: 51.56%; replicate 3: 84.79%). Moreover, the primary degradation measured by HPLC was 83, 74 and 100% in the three test vessels supports the assumption that the substance is readily biodegradable according to the OECD criteria. Therefore, the study is considered to be valid.

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

pH was not measured at the end of the study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

other: mixture of activated sludge from STP with freshwater from rivers and lakes, marine water and marine sediment

Details on inoculum:

- Source of inoculum/activated sludge: 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
- Storage conditions: observed apparance and general condition of sludge, determined sediments, pH, temperature and dissolved oxygen and observed with a light microscope, if it is normal.
- Storage length: started to use: 15 Oct 1991
- Concentration of sludge: 3900 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

Parameter followed for biodegradation estimation:

DOC removal

Parameter followed for biodegradation estimation:

test mat. analysis

Details on study design:

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

TEST SYSTEM
- Culturing apparatus: closed oxygen consumption measuring machine with 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
- Details of trap for CO2 and volatile organics if used: soda lime

SAMPLING
- Sampling frequency: Continuously
- Sterility check if applicable: no

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 1 bottle
- Abiotic sterile control: no
- Toxicity control: no

Reference substance:

aniline

Key result

Parameter:

% degradation (O2 consumption)

Value:

75.3

Sampling time:

28 d

Parameter:

% degradation (test mat. analysis)

Value:

86

Sampling time:

28 d

Details on results:

No 10-day window required. Substance was readily biodegradable.

Results with reference substance:

The oxygen consumption for aniline in the above used test system reached 60% and 72% degradation after 7 days and 14 days.

The degradation in one replicate was below the pass level (51.56%). However, the mean biodegradation based on BOD was > 70%. Moreover, the primary degradation measured by HPLC was 83, 74 and 100% in the three test vessels supports the assumption that the substance is readily biodegradable according to the OECD criteria.

Table 1. Result of BOD, DOC and HPLC after 28 days

		water + test sub.	sludge + test sub.			Theoretical Amount
		sample No. 6	sample No. 3	sample No. 4	sample No. 5
BOD (*1)	mg	0.0	85.0	49.5	81.4	96.0
DOC	mg	0.0	1.1	0.5	1.0	24.4
HPLC	mg	30.2	5.0	7.7	0.0	30
	% (*2)	101	17	26	0	-

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

(*2) Residue percentage was calculated as followed.

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

Validity criteria fulfilled:

no

Remarks:

Biodegradation in one replicate differed by more then 20%.

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:

08 Nov - 06 Dec 1991

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), biodegraadation test

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

other: mixture of activated sludge from STP with freshwater from rivers and lakes, marine water and marine sediment

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 potasium orthophosphate, to the settled material and re-commence aeration. This procedure was repeated once per day.
- Temperature: 25 ± 2 °C
- Storage conditions: appearance and general condition of sludge were observed with a light microscope, sediments, pH, temperature and dissolved oxygen
- Storage length: started to use: 15 Oct 1991
- Concentration of sludge: 5500 mg/L
- Water filtered: no

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Parameter followed for biodegradation estimation:

TOC removal

Parameter followed for biodegradation estimation:

test mat. analysis

Details on study design:

TEST CONDITIONS
- Composition of medium: recommended medium in the guideline
- Test temperature: 25 ± 1 °C
- Suspended solids concentration: 30 mg/L
- Continuous darkness: no data

TEST SYSTEM
- Culturing apparatus: closed oxygen consumption measuring machine
- Number of culture flasks/concentration: 1 (water + test substance), 3 (sludge + test sub.), 1 (sludge + reference sub.), 1 (sludge)
- Measuring equipment: Coulometer
- Details of trap for CO2 and volatile organics if used: soda lime

SAMPLING
- Sampling frequency: continuously until day 28
- Sterility check if applicable: no
- Sample storage before analysis: no data

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes

Reference substance:

aniline

Key result

Parameter:

% degradation (O2 consumption)

Value:

67

Sampling time:

28 d

Remarks on result:

other: BOD/ThOD

Parameter:

% degradation (test mat. analysis)

Value:

94

Sampling time:

28 d

Details on results:

No 10-day window required. Substance was readily biodegradable.

Results with reference substance:

The oxygen consumption for aniline in the above used test system reached 58% and 75% degradation after 7 days and 14 days.

Table 1. Results of analysis for BOD, DOC and GC

		water + test sub.	sludge + test sub.			Theoretical amount
		sample No. 6	sample No. 3	sample No. 4	sample No. 5
BOD	mg	0	60.8	64.5	60.6	92.7
DOC	mgC	-	0.8	1.1	1.2	23.8
	% (*1)	-	3	5	5	-
GC of C9H14O6	mg	30.4	2.1	0.0	3.0	30
	% (*1)	101	7	0	10	-

(*1): Residue percentage = Residue amount (mg) / Theoretical amount (mg) x 100

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

22 Oct - 19 Nov 1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

GLP-Guideline study with acceptable restrictions (The degradation in one replicate was below the pass level and differed by > 20%. However, the mean biodegradation based on BOD was > 70% (replicate 1: 88.5%; replicate 2: 51.56%; replicate 3: 84.79%). Moreover, the primary degradation measured by HPLC was 83, 74 and 100% in the three test vessels supports the assumption that the substance is readily biodegradable according to the OECD criteria. Therefore, the study is considered to be valid.

Justification for type of information:

see Category justification document attached to chapter 13

Reason / purpose for cross-reference:

read-across source

Duration of test (contact time):

28 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

75.3

Sampling time:

28 d

Parameter:

% degradation (test mat. analysis)

Value:

86

Sampling time:

28 d

Validity criteria fulfilled:

no

Interpretation of results:

readily biodegradable

Reference 4

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

According to the ECHA guidance document “Practical guide 6: How to report read-across and categories (March 2010)”, the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance.

Justification for type of information:

see Category justification document attached to chapter 13

Reason / purpose for cross-reference:

read-across source

GLP compliance:

yes

Key result

Parameter:

% degradation (O2 consumption)

Value:

67

Sampling time:

28 d

Remarks on result:

other: BOD/ThOD

Parameter:

% degradation (test mat. analysis)

Value:

94

Sampling time:

28 d

Interpretation of results:

readily biodegradable

Description of key information

Readily biodegradable: 67% (BOD) after 28 d (OECD 301C, read across)

Readily biodegradable: 75.3% (BOD) after 28 d (OECD 301C, read across)

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

Since no studies investigating the ready biodegradability of fatty acids, C8-10, C12-18-alky esters (CAS 95912-86-0) are available for this endpoint, in accordance to Regulation (EC) No. 1907/2006 Annex XI, 1.5 a read across to the structurally related category members tetradecyl myristate (CAS 3234-85-3) and docosyl docosanoate (CAS 17671-27-1) was conducted. The read-across substances are characterized by a longer alcohol chain length (1-tetradecanol and 1-docosanol, respectively) and a longer fatty acid chain length (myristic acid and docosanoic acid, respectively). These two read-across substances can therefore be used for read-across as a worst case approach since the chain length of the fatty alcohol and the fatty acid are the determining factor for biodegradation.

The first study with tetradecyl myristate was performed according to OECD 301C (GLP) under aerobic conditions using a mixture of activated sludge from STP with freshwater from rivers and lakes, marine water and marine sediment as inoculum (Ministry of Economy, Trade and Industry, Japan, 1992a). The inoculum of 100 mg/L showed a biodegradation of 67% (BOD) after 28 d. Since the substance reached the pass level for OECD 301C (biodegradation is > 60% after 28 d, no 10-day window required) tetradecyl myristate is readily biodegradable according to the OECD criteria.

The second study with docosyl docosanoate was performed according to OECD 301C (GLP) under aerobic conditions using a mixture of activated sludge from STP with freshwater from rivers and lakes, marine water and marine sediment as inoculum incubated with a test substance concentration of 100 mg/L (Ministry of Economy, Trade and Industry, Japan, 1992b). A biodegradation of 75.3% (BOD) was observed after 28 d. Since the substance reached the pass level for OECD 301C (biodegradation is > 60% after 28 d, no 10-day window required), docosyl docosanoate is readily biodegradable according to the OECD criteria.

Based on the results from structurally related read-across substances (in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5) it can be concluded that fatty acids, C8-10, C12-18-alky esters is readily biodegradable according to the OECD criteria.