Glycerides, C16-18 and C18-unsatd. mono-, di- and tri-, citrates, potassium salts

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

other: effluent of a domestic sewage plant

Details on inoculum:

- Source of inoculum/activated sludge: domestic sewage plant (Taunusstein-Bleidenstadt, Germany)
- Laboratory culture: no
- Storage conditions: under aerobic conditions
- Storage length: not mentioned
- Preparation of inoculum for exposure: A mixture of 103.4 g soil was suspended in 1000 mL drinking-water and shaken at a laboratory shaker for approx. 30 min. filtration (paper filter), the first 200 mL were rejected
- Pretreatment: not mentioned
- Concentration of sludge: not mentioned
- Initial cell/biomass concentration: not mentioned
- Water filtered: not mentioned

Duration of test (contact time):

28 d

Initial conc.:

> 4 - < 5 mg/L

Based on:

COD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Nutrient mineral solutions
- Additional substrate: none
- Solubilising agent (type and concentration if used): dichloromethane, evaporated before testing
- Test temperature: mean value = 20.03 °C
- pH: not measured
- pH adjusted: not applicable
- Aeration of dilution water: not specified
- Suspended solids concentration: not mentioned
- Continuous darkness: not mentioned
- Other: none

TEST SYSTEM
- Culturing apparatus: 290 mL glass bottles with glass stoppers
- Number of culture flasks/concentration: 2 flask for t0; 7, 14, 21 days 3 flasks; and after 28 days 4 flasks
- Method used to create aerobic conditions: not mentioned
- Method used to create anaerobic conditions: not applicable
- Measuring equipment: oxygen electrode (WTW)
- Details of trap for CO2: not applicable
- Other: none

SAMPLING
- Sampling frequency: on days 0, 7, 14, 21 and 28
- Sampling method: not mentioned
- Sample storage before analysis: not mentioned
- Other: none

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes (vessels with inoculum without test substance)
- Abiotic sterile control: not performed
- Toxicity control: not performed
- Other: none

STATISTICAL METHODS: no statistics performed

Reference substance:

benzoic acid, sodium salt

Preliminary study:

not performed

Test performance:

The BOD bottles were filled by means of a lift tube and were closed without gas-bubbles inside. The number of bottles were chosen in such a way that only one oxygen measurement after 0, 7, 14, 21 and 28 days / bottle and batch (parallels) had to be performed.

Key result

Parameter:

% degradation (O2 consumption)

Value:

68

Sampling time:

28 d

Results with reference substance:

Benzoic acid, sodium salt was degraded to 76 % after 28 d.

Table: Degradation kinetic

days	% degradation of test substance	% degradation of reference substance
0	0	0
7	28	70
14	39	75
21	62	77
28	68	76

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

The test substance is readily biodegradable (68 % degradation in 28 days) but fails the 10-day-window criterion.

Executive summary:

The test substance (CAS 91744-38-6, Glycerides, C16-18 mono-, di- and tri-, hydrogenated, citrates, potassium salts) was tested for ready biodegradability according to OECD Guideline 301D (Closed Bottle Test) under GLP following the O₂ consumption over a period of 28 days. The substances was tested at an initial concentration of >4 - < 5 mg/L COD. Effluent of a domestic sewage plant was used as inoculum and benzoic acid, sodium salt served as reference substance. Oxygen measurements were performed at Days 0, 7, 14, 21, and 28. Benzoic acid, sodium salt was degraded to 76 % after 28 d whereas 68 % degradation could be observed for the test substance. The test substance was evaluated to be readily biodegradable, however, the 10-day-window criterion was not met.

Reference 2

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:

Read-across to K1 study therefore K2 is the highest score that can be assigned

Justification for type of information:

Please see the read-across report attached to section 13 of this dossier.

Reason / purpose for cross-reference:

read-across source

Oxygen conditions:

aerobic

Inoculum or test system:

other: effluent of a domestic sewage plant

Details on inoculum:

- Source of inoculum/activated sludge: domestic sewage plant (Taunusstein-Bleidenstadt, Germany)
- Laboratory culture: no
- Storage conditions: under aerobic conditions
- Storage length: not mentioned
- Preparation of inoculum for exposure: A mixture of 103.4 g soil was suspended in 1000 mL drinking-water and shaken at a laboratory shaker for approx. 30 min. filtration (paper filter), the first 200 mL were rejected
- Pretreatment: not mentioned
- Concentration of sludge: not mentioned
- Initial cell/biomass concentration: not mentioned
- Water filtered: not mentioned

Duration of test (contact time):

28 d

Initial conc.:

> 4 - < 5 mg/L

Based on:

COD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Nutrient mineral solutions
- Additional substrate: none
- Solubilising agent (type and concentration if used): dichloromethane, evaporated before testing
- Test temperature: mean value = 20.03 °C
- pH: not measured
- pH adjusted: not applicable
- Aeration of dilution water: not specified
- Suspended solids concentration: not mentioned
- Continuous darkness: not mentioned
- Other: none

TEST SYSTEM
- Culturing apparatus: 290 mL glass bottles with glass stoppers
- Number of culture flasks/concentration: 2 flask for t0; 7, 14, 21 days 3 flasks; and after 28 days 4 flasks
- Method used to create aerobic conditions: not mentioned
- Method used to create anaerobic conditions: not applicable
- Measuring equipment: oxygen electrode (WTW)
- Details of trap for CO2: not applicable
- Other: none

SAMPLING
- Sampling frequency: on days 0, 7, 14, 21 and 28
- Sampling method: not mentioned
- Sample storage before analysis: not mentioned
- Other: none

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes (vessels with inoculum without test substance)
- Abiotic sterile control: not performed
- Toxicity control: not performed
- Other: none

STATISTICAL METHODS: no statistics performed

Reference substance:

benzoic acid, sodium salt

Preliminary study:

not performed

Test performance:

The BOD bottles were filled by means of a lift tube and were closed without gas-bubbles inside. The number of bottles were chosen in such a way that only one oxygen measurement after 0, 7, 14, 21 and 28 days / bottle and batch (parallels) had to be performed.

Parameter:

% degradation (O2 consumption)

Value:

68

Sampling time:

28 d

Results with reference substance:

Benzoic acid, sodium salt was degraded to 76 % after 28 d.

Table: Degradation kinetic

days	% degradation of test substance	% degradation of reference substance
0	0	0
7	28	70
14	39	75
21	62	77
28	68	76

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

The test substance is readily biodegradable (68 % degradation in 28 days) but fails the 10-day-window criterion.

Executive summary:

The test substance (CAS 91744-38-6, Glycerides, C16-18 mono-, di- and tri-, hydrogenated, citrates, potassium salts) was tested for ready biodegradability according to OECD Guideline 301D (Closed Bottle Test) under GLP following the O₂ consumption over a period of 28 days. The substances was tested at an initial concentration of >4 - < 5 mg/L COD. Effluent of a domestic sewage plant was used as inoculum and benzoic acid, sodium salt served as reference substance. Oxygen measurements were performed at Days 0, 7, 14, 21, and 28. Benzoic acid, sodium salt was degraded to 76 % after 28 d whereas 68 % degradation could be observed for the test substance. The test substance was evaluated to be readily biodegradable, however, the 10-day-window criterion was not met.

Description of key information

The test substance (CAS 91744-38-6, Glycerides, C16-18 mono-, di- and tri-, hydrogenated, citrates, potassium salts) is readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The test substance (CAS 91744-38-6, Glycerides, C16-18 mono-, di- and tri-, hydrogenated, citrates, potassium salts) was tested for ready biodegradability according to OECD Guideline 301D (Closed Bottle Test) under GLP following the O2 consumption over a period of 28 days. The substance was tested at an initial concentration of >4 to < 5 mg/L COD. Effluent of a domestic sewage plant was used as inoculum and benzoic acid, sodium salt served as reference substance. Oxygen measurements were performed at Days 0, 7, 14, 21, and 28. Benzoic acid, sodium salt was degraded to 76 % after 28 d whereas 68 % degradation could be observed for the test substance. The test substance was evaluated to be readily biodegradable; however, the 10 -day-window criterion was not met.

According to the "Introduction to the OECD Guidelines for Testing of Chemicals - Section 3, Part 1: Principles and Strategies related to the Testing of Degradation of Organic Chemicals" ready biodegradability tests are intended for pure chemicals. "It is sometimes relevant to examine the ready biodegradability of mixtures of structurally similar chemicals like oils and surface-active substances (surfactants). As a sequential biodegradation of the individual structures is anticipated, the 10-day window should not be applied to interpret the results of test with mixtures of structurally related chemicals." Therefore, the 10-day window does not apply for the UVCB "Glycerides, C16-18 mono-, di- and tri-, hydrogenated, citrates, potassium salts" and the substance is readily biodegradable.