Glycerol trioctanoate

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:

12 Feb -13 Mar 1991

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP-Guideline study with acceptable restrictions. The reference substance did not fulfil the validity criterion (60% biodegradation within 14 days). Nevertheless, since the test replicates were degraded extensively, passing clearly the 10-day window for ready biodegradation, the results of this study can be considered valid and used for risk assessment

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1981 version

Deviations:

yes

Remarks:

one incidental temperature extreme (23 °C)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: The activated sludge was freshly obtained from a municipal sewage treatment plant: Waterschap de Aa, Schijndel, the Netherlands
- Preparation of inoculum for exposure: the activated sludge was aerated for 4 hours. It was then left to settle for at least half an hour. The supernatant was decanted to provide a sufficiently large volume for a 1% inoculum for each test flask

Duration of test (contact time):

28 d

Initial conc.:

10 mg/L

Based on:

test mat.

Initial conc.:

20 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium:
Stock solutions
A) 8.50 g KH2P04
21.75 g K2HP04
67.20 g Na2HP04.12H20
0.50 g NH4Cl
dissolved in 1 L Milli-Q water, pH 7.4 ± 0.2
B) 22.50 g MgSO4.7H20 dissolved in 1 L Milli-Q water
C) 36.40 g CaCl2.2H20 dissolved in 1 Milli-Q water
0) 0.15 g FeCl3 dissolved in 1 Milli-Q water
E) 40.0 g (NH4)2S04 dissolved in 1 Milli-Q water
The following amounts were added per litre of Milli-Q water for the formulation of the nutrient medium: 2 mL of solution A, 1 mL of solution B, 1 mL of solution C, 4 mL of solution D, 1 mL of solution E
All nutrients were added to Milli-Q water in such a way that no precipitation occurred
- Solubilising agent (type and concentration if used):
- Test temperature: 20 ± 2 °C

TEST SYSTEM
- Culturing apparatus: 3L all-glass brown coloured bottles
- Number of culture flasks/concentration: 1
- Method used to create aerobic conditions: a mixture of oxygen (20%) and nitrogen (80%) was led through a bottle, containing 0.5-1 L 0.025 N Ba(OH)2 solution to trap CO2 which might be present in small amounts. The CO2-free air was sparged through the scrubbing solutions at a constant rate (approximately 1-2 bubbles per second, corresponding to 50-100 mL air/min)
- Details of trap for CO2 and volatile organics if used: the CO2 produced in each test bottle reacted with the barium hydroxide in the gas scrubbing bottle and precipitated out as barium carbonate. The amount of CO2 produced was determined by titrating the remaining Ba(OH)2 with 0.05N standardized HCL. Periodically the C02-absorber nearest to the test bottle was removed tor titration. The remaining two absorbers were each moved one position in the direction of the test bottle, and a new absorber filled with 80 mL of 0.025 N Ba(OH)2 (normalised the same day) was placed at the far end of the series

SAMPLING
- Sampling frequency and method: Titrations were made when necessary (before significant BaCO3 precipitate was evident in the second trap), approximately every other day for the first 10 days, and thereafter every fifth day until the 28th day. Phenolphthalein was used es pH-indicator. On the 26th day, the pH of the four test bottles was measured, and then 1 mL of concentrated HCl was added to drive off inorganic carbonate. The bottles were aerated overnight, and samples ware removed from each bottle to enable the possibility for Dissolved Organic Carbon (DOC) analysis. All samples are stored at -20 °C tor three months after delivery of this report. The final titration was made on day 28

CONTROL AND BLANK SYSTEM
- Inoculum blank: 1
- Reference control: 1

Reference substance:

acetic acid, sodium salt

Remarks:

20 mg/L

Parameter:

% degradation (CO2 evolution)

Value:

76.5

Sampling time:

28 d

Details on results:

The test substance reached the pass-level of 60% biodegradation within the 10-day window period, attaining a final degradation of 76.5% on day 28. Therefore, it can be considered readily biodegradable

Results with reference substance:

Sodium acetate reached 60% within 20 days

Table 1. Biodegradation (%) test results

Day	Biodegradation%
	Test substance (10 mg/L)	Test substance (20 mg/L)	Sodium acetate (20 mg/L)
2	6.9	1.5	8.9
5	33.0	14.2	23.4
7	47.1	28.1	29.9
9	55.5	39.8	34.2
12	60.2	51.5	38.3
16	68.2	65.5	52.4
21	75.2	73.1	66.9
28	76.5	75.9	71.0
28	76.5	76.2	71.0
28	76.5	76.5	71.0

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:

prior to 1990

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: The test inoculum was collected from the municipal sewage treatment plant Hochdahl, treating predominantly domestic sewage
- Preparation of inoculum for exposure: the effluent was filtered through a coarse paper filter, being the first 200 mL being discarded
- Initial cell/biomass concentration: 10xE3 - 10xE4 cells/mL

Duration of test (contact time):

30 d

Initial conc.:

2 mg/L

Based on:

act. ingr.

Initial conc.:

5 mg/L

Based on:

act. ingr.

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Aeration of dilution water: The deionised water used during the test was aerated prior application with compressed air by means of a sintered glass tube until O2 saturation was reached

TEST SYSTEM
- Number of culture flasks/concentration: 2
- Measuring equipment: O2 determinations were performed according to the "Winkler" titration (iodometric oxygen determination according to DIN method 38408 part G21-1)
- Test performed in closed vessels: yes

SAMPLING
- Sampling frequency: samples were collected on days 0, 5, 15 and 30

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Reference control: yes
- Emulsifier control: yes

Reference substance:

other: Dodecylsulfate

Parameter:

% degradation (DOC removal)

Value:

89

Sampling time:

30 d

Remarks on result:

other: 2 mg/L test concentration

Parameter:

% degradation (DOC removal)

Value:

73

Sampling time:

30 d

Remarks on result:

other: 5 mg/L test concentration

Details on results:

The test substance reached 60% biodegradation within the established test period, fulfilling the 10-day window criterion. Therefore, this substance can be considered readily biodegradable.

Results with reference substance:

Dodecylsulfate reached 87% biodegradation within 15 days

Table 1. Biodegradation values for reference, emulsifier and test substances

Sample	% BOD/COD respectively ThOD after X-days
	0	5	15	30
Reference substance	0	53	87	83
Test substance  2 mg/L	0	56	80	89
Test substance 5 mg/L	0	62	75	73
Emulsifier Rep 1	0	1	2	0
Emulsifier Rep 2	0	1	1	2

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:

4 Nov-10 Dec 1992

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

other: BODIS test (ISO 10708)

Deviations:

yes

Remarks:

, temperature range does not comply with guideline

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum: Activated sludge from the sewage treatment plant 'Marl Ost', Lippeverband, Germany
- Preparation of inoculum for exposure: the activated sludge was washed (sedimentation, decantation) several times with the test medium (which was prepared according to guideline)
- Concentration of sludge: The dry solids content of the inoculum was 3.2 g/L

Duration of test (contact time):

28 d

Initial conc.:

>= 35.5 - <= 37 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Test temperature: 19.3 - 21.7 °C
- pH: 7.6
- Suspended solids concentration: 3.2 g/L

TEST SYSTEM
- Culturing apparatus: glass bottles
- Number of culture flasks/concentration: 3
- Method used to create aerobic conditions: venting of the flasks after oxygen measurement
- Measuring equipment: 'OXY 2000' oxygen meter

SAMPLING
- Sampling frequency: days 7, 14, 21, 28
- Sampling method: direct sampling with oxygen meter probe

CONTROL AND BLANK SYSTEM
- Inoculum blank: 4
- Other: 3 flasks with reference substance

Reference substance:

diethylene glycol

Parameter:

% degradation (O2 consumption)

Value:

74.88

St. dev.:

0.15

Sampling time:

7 d

Parameter:

% degradation (O2 consumption)

Value:

86.27

St. dev.:

1.87

Sampling time:

14 d

Parameter:

% degradation (O2 consumption)

Value:

91.26

St. dev.:

1.16

Sampling time:

21 d

Parameter:

% degradation (O2 consumption)

Value:

92.71

St. dev.:

1.13

Sampling time:

28 d

Results with reference substance:

The reference substance is degraded by more than 60% after 14 days and by 84.3% after 28 days.

The test substance meets the 14-day-window and degrades by 92.17% after 28 days. Thus, the test substance is readily biodegradable.

-The temperature range and deviation (19°C - 21.7°C) do not comply with ISO 10708 guideline, but it was assumed to have no effects on the results of the test.

Table 1: Degradation (%) of test substance (TS) and reference substance (RS) after 7, 14, 21 and 28 days

Degradation (%) after 7, 14, 21 and 28 days (d)
	7 d	14 d	21 d	28 d
TS I	75.00	84.22	90.35	91.84
TS II	74.93	86.68	92.56	93.99
TS III	74.72	87.90	90.87	92.30
TS mean	74.88	86.27	91.26	92.71
RS I	60.32	75.41	82.10	83.76
RS II	61.69	80.36	84.68	84.68
RS III	43.02	74.20	80.12	84.57
RS mean	55.01	76.66	82.30	84.34

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)

Remarks:

Summary of available data used for the endpoint assessment of the target substance

Adequacy of study:

key study

Justification for type of information:

Please refer to the analogue justification provided in IUCLID section 13

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Parameter:

% degradation (CO2 evolution)

Value:

76.5

Sampling time:

28 d

Remarks on result:

other: Source: CAS 122-32-7, Croda 1991, Modified Sturm Test

Parameter:

% degradation (DOC removal)

Value:

89

Sampling time:

30 d

Remarks on result:

other: Source: CAS 65381-09-1; 2 mg/L test concentration; BASF, 2006, Closed Bottle

Parameter:

% degradation (DOC removal)

Value:

73

Sampling time:

30 d

Remarks on result:

other: Source: CAS 65381-09-1; 5 mg/L test concentration; BASF, 2006, Closed Bottle

Parameter:

% degradation (CO2 evolution)

Value:

95.4

Sampling time:

28 d

Remarks on result:

other: Source: CAS 73398-61-5; Sasol, 1993, BODIS

Conclusions:

The target substance Glycerol trioctanoate (CAS 538-23-8) is considered readily biodegradable.

Description of key information

The substance is considered readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Since no studies investigating the ready biodegradation of Glycerol trioctanoate (CAS 538-23-8) in water are available, in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5, a read-across to the structurally related source substances 9-Octadecenoic acid (Z)-, 1,2,3-propanetriyl ester (CAS 122-32-7), Decanoic acid, ester with 1,2,3-propanetriol octanoate (CAS 65381-09-1) and Triglycerides, mixed decanoyl and octanoyl (CAS 73398-61-5) was conducted. The source substances are representative to evaluate the ready biodegradation of the target substance in water. This read-across is justified in detail within the analogue justification in IUCLID section 13.

The target substance Glycerol trioctanoate (CAS 538-23-8) is a monoconstituent characterized by the alcohol component glycerol. Complete esterification with octanoic acid gives glycerol triesters of octanoic acid.

The source substance 9-Octadecenoic acid (Z)-, 1,2,3-propanetriyl ester (CAS 122-32-7) is a UVCB substance. Esterification of glycerol gives triesters of mainly C18:1 fatty acids.

The source substance Decanoic acid, ester with 1,2,3-propanetriol octanoate (CAS 65381-09-1) is a UVCB substance characterized by the alcohol component glycerol. Complete esterification with octanoic and decanoic fatty acids gives glycerol triesters of octanoic decanoic acid.

The source substance Triglycerides, mixed decanoyl and octanoyl (CAS 73398-61-5) is a UVCB substance characterized by the alcohol component glycerol and C8-10 (even numbered fatty acids). Esterification of glycerol gives largely triesters of C8 and C10 fatty acids.

The study with read-across substance 9-Octadecenoic acid (Z)-, 1,2,3-propanetriyl ester (CAS 122-32-7) was conducted according to OECD 301B (GLP) under aerobic conditions using domestic, non-adapted activated sludge from a wastewater treatment plant. Two test solutions with initial test item concentrations of 10 and 20 mg/L were prepared. A biodegradation rate of 76.5% (CO2 evaluation) was observed after 28 days. 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 can be regarded as readily biodegradable.

The study with read-across substance Decanoic acid, ester with 1,2,3-propanetriol octanoate (CAS 65381-09-1) was conducted according to OECD 301 D (Closed bottle test) under aerobic conditions using domestic sewage sludge as inoculum. The initial test substance concentration was 2 (replicate A) and 5 mg/L, respectively (replicate B), based on the active ingredient. A biodegradation rate of 89% (DOC removal) was observed after 30 days for replicate A and 73% for replicate B. The test substance met the ‘10 day window’ criterion and can be considered readily biodegradable.

The study with read-across substance Triglycerides, mixed decanoyl and octanoyl (CAS 73398-61-5) was conducted according to ISO 10708 (Two-phase closed bottle test) under aerobic conditions using domestic, activated sludge from a sewage treatment plant. The initial test substance concentration was 35.5-37 mg/L. A biodegradation rate of 92.71% (O2 consumption) was observed after 28 days. The test substance met the ‘10 day window’ criterion and can be considered readily biodegradable.

Based on the available results from structurally related read-across substances (in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5) which are characterized by a similar ecotoxicological profile and comparable structure, it can be concluded that Glycerol trioctanoate (CAS 538-23-8) is readily biodegradable.