Glycerol trimyristate

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:

2001

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP Guideline study with acceptable restrictions: No analytics of the test substance is performed. Analytical purity is not stated.

Qualifier:

according to guideline

Guideline:

ISO Draft (BOD Test for Insoluble Substances)

Qualifier:

equivalent or similar to guideline

Guideline:

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

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Activated sludge was collected from the sewage treatment plant Hochdahl (Germany), which predominantely process municipal sewage.
- Preparation of inoculum for exposure: Stabilized under laboratory conditions for one week

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
- Composition of medium: mineral test medium according to OECD 301 tests
- Test temperature: 20 ± 0.5 °C
- Other: The test vessels are shaken continuously.

TEST SYSTEM
- Culturing apparatus: 300 mL closed glass bottles containing 200 mL test solution
- Number of culture flasks/concentration: 3
- Method used to create aerobic conditions: The bottles were aerated with compressed air by means of a sintered glas tube until O2 saturation was reached.
- Measuring equipment: Microprocessor oximeter OXI 2000 with electrode model TriOxmatic EO 200

SAMPLING
- Sampling frequency: Samples were taken after 7, 14, 21 and 28 days.

Reference substance:

acetic acid, sodium salt

Remarks:

100 mg/L as ThOD

Parameter:

% degradation (O2 consumption)

Value:

78

Sampling time:

28 d

Details on results:

The test substance reached a biodegradation of 78% in 28 days but the 10-day or 14-day window criterion was not met. Nevertheless, as the substance is an UVCB substance and thus consist of constituents with different degrees of esterification, sequential (instead of concurrent) biodegradation is expected to take place. 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 criterion can be disregarded in this case and the substance considered as readily biodegradable.

Parameter:

COD

Value:

2 660 mg O2/g test mat.

Results with reference substance:

The reference substance was biodegraded to 98% within 28 days.

Table 1: Results of the biodegradability test

Ultimate biodegradability in the BODIS test
Test substance	Test. Conc. [mg/L]	Calculating basis	% degradation after x days
			7d	14d	21d	28d
Reference substance	100	ThOD	83	97	98	98
Test substance	100	COD	27	52	68	78

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1988

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with acceptable restrictions: Only measurements from two replicates.

Qualifier:

according to guideline

Guideline:

other: ISO 10708: Water quality - Evaluation in an aqueous medium of the ultimate aerobic biodegradability of organic compounds - Determination of biochemical oxygen demand in a two-phase closed bottle test

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: Sewage treatment plant Hochdahl, predominantly municipal sewage, serving for a population equivalent of approx. 27000
- Concentration of sludge: 2.5 - 3.5 mg/L test medium

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

other: ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Deionised water was used for preparation of test medium. Mineral medium (according to OECD 301) was inoculated with activated sludge and after addition of a magnetic stirrer stabilised under laboratory conditions for approximately one week
- Test temperature: 20-25 °C
- Suspended solids concentration: 2.5-3.5 mg activated sludge/L test medium
- Other: The test substance was weighed on a piece of glass to an amount of about 20 mg ThOD and directly put into the test flask. The homogeneous distribution of the test substance was supported by continuous shaking of the test flasks during the whole incubation period.

TEST SYSTEM
- Culturing apparatus: 300 mL bottles, containing 200 mL test medium
- Number of culture flasks/concentration: three replicates prepared but results only from two results
- Method used to create aerobic conditions: the bottles were aerated with compressed air until O2 saturation was reached
- Measuring equipment: O2 determinations were performed using a O2-electrode (WTW; FRG; micorprocessor oximeter OXI 2000 with electrode model TriOxmatic EO 200)

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

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 3
- Reference control: yes, 3

Reference substance:

acetic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

64

Sampling time:

28 d

Details on results:

The test substance is degraded in excess of 60% after 28 day test duration. However despite being biodegraded in excess of 60% after 28 days (64%), the test did not meet the "14-day window" criteria. Nevertheless, as the substance is an UVCB substance and thus consist of constituents with different degrees of esterification, sequential (instead of concurrent) biodegradation is expected to take place. 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 criterion can be disregarded in this case and the substance considered as readily biodegradable.

Results with reference substance:

82% of the reference substance sodium acetate was biodegraded after 7 days and 92% after 14 days, thus the validity criterion are fulfilled.

One replicate containing test substance was not measured. The oxygen uptake in the blank bottles after the first week of the test is lower than 3 mg O2 and in the following weeks lower than 1 mg O2 per week (validity criteria fulfilled)

Table 1: Results with test substance

% oxidation	Incubation time [d]
	7	14	21	28
Replicate 1	-	-	-	-
Replicate 2	2	29	56	65
Replicate 3	5	28	52	63
Mean (b+c)	3	28	54	64

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 Sep - 3 Oct 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP Guideline study

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Remarks:

Landesanstalt für Umwelt, Messungen und Naturschutz Baden-Württemberg, Karlsruhe, Germany

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Municipal wastewater treatment plant, Breisgauer Bucht, sampled on September 3rd, 2012
- Pretreatment: The activated sludge was washed twice by settling the sludge, decanting the supernatant and re-suspending the sludge in tap water
- Concentration of sludge: 30 mg dry solids per litre (dry solid of the activated sludge was 2.9 g/L by weight measurements after 2 h drying at 110 °C

Duration of test (contact time):

29 d

Initial conc.:

41 - 41.1 mg/L

Based on:

test mat.

Initial conc.:

20 mg/L

Based on:

other: TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium:
Solution A (per 1 liter demineralised water):
KH2PO4: 8.50 g
K2HPO4: 21.75 g
Na2HPO4 x 2 H2O: 33.40 g
NH4Cl: 0.50 g

Solution B:
CaCL2 x 2 H2O: 36.40 g

Solution C:
MgSO4 x 7 H2O: 22.50 g

Solution D:
FeCL3 x 6 H2O: 0.25 g

For the preparation of the mineral medium 10 mL of solution A is mixed with 800 mL demineralised water, 1 mL each of solutions B, C, and D are added and the volume is made up to 1L.

- Test temperature: 21 - 24 °C

TEST SYSTEM
- Culturing apparatus: Gas wash bottles (2000 mL) with lateral connecting pieces for butyl rubber septums were used as reactors. The liquid volume was fixed as 1500 mL each. Mixing was perfomred by a magnetic stirrer with 2 cm stir bars. The test item was added into the three test vessels. The reference compound was added to the three reference vessels. Reference compound and test item were added to the toxicity control vessel
- Number of culture flasks/concentration: 2 ( 1 flask was not considered due to preparation problems)
- Method used to create aerobic conditions: The CO2-free air production system consits of an air compressor, three 1000 mL gas wash bottles filled with dry soda lime in series followed by one bottle filled with 0.1 M NaOH. At the end of the system is one gas wash bottle filled with demineralised water, followed by an empty one to catch any drops of condensation water. A colour change of the soda lime from white to blue indicates that the CO2 absorption capacity is depleted. The CO2-free air is passed on to an air distributor with two input and 22 output channels and through PE-tubes.
- Test performed in closed vessels due to significant volatility of test substance: yes
- Details of trap for CO2 and volatile organics if used: The CO2 produced in the reactors was absorbed in two 250 mL gas wash bottles in series filled with 200 mL 0.2 M NaOH

SAMPLING
- Sampling method: Through the lateral connecting pieces through the butyl rubber septum using 5 mL PE syringes

CONTROL AND BLANK SYSTEM
- Inoculum blank: 3 flasks
- Toxicity control: 1 flask (5.15 mL of a stock solution of 10 g/L reference substance and 41.1 mg of the test item were added into the vessel. This corresponds to a concentration of 40.0 mg/L organic carbon)
- Reference: 3 flasks (5.15 mL of a stock solution of 10 g/L sodium benzoate was added into the reference vessels. This corresponds to a concentration of 20 mg/L organic carbon)

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

79.5

Sampling time:

28 d

Details on results:

- The test substance reached 79.5% biodegradation after 28 days and therefore, it is considered as readily biodegradable.

Results with reference substance:

The reference compound sodium benzoate reached the pass level of 60% within 7 days.

The test item had no toxic effect to the inoculum (55% degradation in the toxicity control after 14 days).

Table: Biodegradation after x days in % of ThCO2

	Day 0	Day 4	Day 7	Day 10	Day 14	Day 21	Day 28	Day 29
Test flasks	0	5.4	17.0	26.6	36.6	61.1	79.3	77.6
	0	14.2	38.6	50.8	62.7	77.6	82.0	81.5
Reference flasks	0	55.2	72.4	80.5	80.6	85.3	85.9	85.2
	0	64.1	78.7	85.3	85.3	90.9	90.1	90.2
	0	59.3	75.9	82.2	82.2	87.0	87.5	88.3
Toxicity control	0	27.2	43.1	49.2	55.0	66.5	75.0	77.1

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Since the test item is a UVCB substance and consists of structurally similar constituents with [e.g. different chain-lengths, degree and/or site of branching or stereo-isomers], 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 this UVCB substance and due to a degradation of >60 % within 28 days the substance can be regarded as readily biodegradable.

Reference 4

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model, but not (completely) falling into its applicability domain, with adequate and reliable documentation / justification

Remarks:

The predicted compound could be out of the Applicability Domain of the model. However, this calculation is used in a weight of evidence approach, in accordance to the REACh Regulation (EC) No 1907/2006, Annex XI General rules for adaptation of the standard testing regime set out in Annexes VII to X, 1.2. It is adequately documented and justified. For more details see field `overall remarks, attachments´.

Justification for type of information:

1. SOFTWARE
Vega version 1.1.3

2. MODEL (incl. version number)
Ready Biodegradability Model (IRFMN) v. 1.0.9

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
See “Test material information”

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached information on the model provided by the developer. Further information on the OECD criteria as outlined by the applicant is provided below under "Any other information of materials and methods incl. tables"

5. APPLICABILITY DOMAIN
See attached information and information as provided in "Any other information on results incl. tables".

6. ADEQUACY OF THE RESULT
See assessment of adequacy as outlined in the "Overall remarks, attachments" section.

Principles of method if other than guideline:

- Software tool(s) used including version: Vega v1.1.3

- Model(s) used: Ready biodegradability model (version 1.0.9)
Full reference and details of the used formulas can be found in:
Meylan W.M., Howard P.H., Boethling R.S. et al. Improved Method for Estimating Bioconcentration / Bioaccumulation Factor from Octanol/Water Partition Coefficient. 1999, Environ. Toxicol. Chem. 18(4): 664-672

- Model description: see field 'Justification for non-standard information', 'Attached justification' and 'any other information on Material and methods'

- Justification of QSAR prediction: see field 'Justification for type of information', 'Attached justification' and/or 'overall remarks'

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Remarks on result:

other: The substance was predicted to be readily biodegradable

For detailed information on the results please refer to the attached report.

Interpretation of results:

readily biodegradable

Description of key information

The substance is readily biodegradable but failling the 10-day window.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable but failing 10-day window

Additional information

Endpoint summary for Glycerol trimyristate (CAS 555-45-3); Biodegradation in water: screening tests

Since no studies investigating the biodegradation in water of Glycerol trimyristate (CAS 555-45-3) are available, in accordance with Regulation (EC) No 1907/2006 Annex XI, 1.5, a read-across to the structurally related source substances Glycerides, C12-18 di and tri (CAS 91744-28-4), Castor oil, hydrogenated (CAS 8001-78-3) and Docosanoic acid, ester with 1,2,3-propanetriol (CAS 77538-19-3) was conducted. The source substances are representative to evaluate the biodegradation in water of the target substance.

The target substance Glycerol trimyristate (CAS 555-45-3) is characterized by the alcohol component glycerol which is triply esterified by C14 fatty acid (myristic acid).

The source substance Glycerides, C12-18 di and tri (CAS 91744-28-4) is characterized by C12 as major fatty acid component and fatty acids C14-18 as minor fatty acid components. The alcohol component is glycerol which is esterified mainly twice and three times, respectively, by C12-18 fatty acids.

The source substance Castor oil, hydrogenated (CAS 8001-78-3) is characterized as tri(12-hydroxystearate) with glycerol as alcohol component.

The source substance Docosanoic acid, ester with 1,2,3-propanetriol (CAS 77538-19-3) is characterized as a complex composition of mainly C22 fatty acid and, to a lower content, of C20 and C24 fatty acids. The alcohol component is glycerol which can be esterified once, twice and three times in largely varying concentration ranges.

This read-across is justified in detail in the analogue justification in IUCLID section 13. In this case of read-across, the best suited (highest degree of structural similarity, nearest physico-chemical properties) read-across substance was used for the assessment.

The first study with the read-across substance Glycerides, C12-18 di and tri (CAS 91744-28-4) was conducted according to OECD 301B (GLP) under aerobic conditions using domestic, non-adapted activated sludge from a wastewater treatment plant. The initial test substance concentration was 41.0-41.1 mg/L (test material). A biodegradation rate of 79.5% (CO2 evolution) 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 this UVCB substance and due to a degradation of >60 % within 28 days the substance can be regarded as readily biodegradable.

The second study with the read-across substance Castor oil, hydrogenated (CAS 8001-78-3) was conducted according to guideline ISO 10708 under aerobic conditions using domestic activated sludge from a sewage treatment plant treating predominantly municipal sewage. The initial test substance concentration was 100 mg/L (ThOD). A biodegradation rate of 64.0% (O2 consumption) was observed after 28.0 days. The test substance did not meet the ‘14 day window’ criteria. However, as the substance is a UVCB substance and thus consists of constituents with different degrees of esterification, sequential (instead of concurrent) biodegradation is expected to take place. 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 14-day window criterion can be disregarded in this case and the substance considered as readily biodegradable.

The third study with the read-across substance Docosanoic acid, ester with 1,2,3-propanetriol (CAS 77538-19-3) was conducted according to ISO Draft (BOD Test for Insoluble Substances) under aerobic conditions using domestic, non-adapted activated sludge from a sewage treatment plant which predominantly processes municipal sewage. The initial test substance concentration was 100 mg/L (based on COD). A biodegradation rate of 78.0% (O2 consumption) was observed after 28 days. The test substance did not meet the ‘14 day window’ criterion. However, as the substance is a UVCB substance and thus consists of constituents with different degrees of esterification, sequential (instead of concurrent) biodegradation is expected to take place. 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 14-day window criterion can be disregarded in this case and the substance considered as 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 trimyristate (CAS 555-45-3) is readily biodegradable.