Lithium bis[ethanedioato(2-)-κO1,κO2]difluorophosphate(1-)

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:

From 2009-03-02 to 2009-04-01

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch No.: 08111121
Purity: 98%

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: collected from sewage treatment works, which treats predominantly domestic waste.
- Treatment: Aliquots (10 mL) of a homogenised sample were filtered through dried (approximately 105°C) and pre-weighed Whatman GF/C filter papers. The filters were dried for at least one hour, allowed to cool and re-weighed. The solids level in the sludge was calculated and then an appropriate volume used to inoculate the biotic vessels to give a final suspended solids concentration of 30 mg/L.

Duration of test (contact time):

29 d

Initial conc.:

10 other: mgC/L

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS
- Composition of medium: Stock 1(Potassium dihydrogen phosphate 8.50 g/L, di-Potassium hydrogen phosphate 21.75 g/L, di-Sodium monohydrogen phosphate dihydrate 33.40 g/L, Ammonium chloride 0.50 g/L); Stock 2 (Magnesium sulphate heptahydrate 22.50 g/L); Stock 3 (Calcium chloride dihydrate 36.40 g/L); Stock4 (Iron (III) chloride hexahydrate 0.25 g/L)
- Preparation of the mineral salts medium: The mineral salts medium (MSM) for the Modified Sturm test was prepared by mixing 10 mL of stock solution 1 with 800 mL dilution water and then adding 1 mL of solutions 2 to 4 to each litre of water required for the test.
- Test temperature: 21.9 °C to 23.3 °C during the test period
- pH: The pH of each biotic mixture ranged from 7.2 to 7.6 at the start of the test and 7.5 to 7.7 at the end.
- pH adjusted: The pH of each biotic culture was determined in situ and no adjustment was required.
- Aeration: Each vessel was then fitted with a stopper holding an air inlet tube reaching approximately 10 cm below the liquid surface and an air outlet just below the stopper.

CONTROL AND BLANK SYSTEM:
- Control (1, 2): Inoculated mineral salts medium
- Reference (3): Inoculated mineral salts medium plus sodium benzoate (10 mgC/L)
- Test (4, 5): Inoculated mineral salts medium plus the test substance (10 mgC/L)
- Test plus Reference (6): Inoculated mineral salts medium plus the test substance (10 mgC/L) plus sodium benzoate (10 mgC/L)
- Abiotic control (7): Ultrapure water plus mercury (II) chloride (10 mg/L)
- Abiotic Test (8): Ultrapure water plus the test substance (10 mgC/L) plus mercury (II) chloride (10 mg/L)

Theoretical Carbon Dioxide Production (TCO2):
The theoretical amount of CO2 that can be generated by a 3.0-litre mixture containing the test or reference substance at a concentration of 10 mgC/L was calculated in the following way:
TCO2 /mg carbon = mw of carbon dioxide / atomic weight of carbon
Test mixture TCO2 = Volume (3.0 L) x conc. (10 mgC/L) x 3.67

Calculation of CO2 Production:
Carbon dioxide production by control, reference and test mixtures was calculated.

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

10

Sampling time:

1 d

Key result

Parameter:

% degradation (CO2 evolution)

Value:

60

Sampling time:

4 d

Key result

Parameter:

% degradation (CO2 evolution)

Value:

79

Sampling time:

29 d

Details on results:

The results obtained for the degradation of sodium benzoate (64% of its TCO2 after 8 days and 82% after 29 days) and for cumulative CO2 production by the control mixtures (113.9 and 117.7 mgCO2) fulfil the validity criteria for this test.
Carbon dioxide production by the abiotic test mixture had achieved 24% of the theoretical value (TCO2, 110.1 mgCO2) by Day 3 and showed a plateau until Day 29 when CO2 production was 27% of the TCO2.

Results with reference substance:

The degradation of sodium benzoate :
TCO2: 64% after 8 days and 82% after 29 days

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Mean cumulative CO2 production (biotic and abiotic) by mixtures containing the test substance was equivalent to 60% of the theoretical value after approximately 4 days of incubation and 79% by the end of the test on Day 29. The test substance was considered to be readily degradable.

Executive summary:

The ready biodegradability of the test substance was assessed in the CO2 Evolution (Modified Sturm) test according to OECD Guideline 301B (adopted 1992) .

The test substance was added to two, five-litre vessels containing three litres of mineral salts medium inoculated with activated sludge (30 mg solids/L) to give a nominal test concentration of 10 mgCarbon[C]/L. Two control vessels contained inoculated mineral salts medium alone and one contained inoculated mineral salts medium plus the reference substance sodium benzoate (10 mgC/L). An additional mixture containing sodium benzoate (10 mgC/L) and the test substance (10 mgC/L) was established in order to assess the potential inhibitory effects of the test substance on the activity of the microbial inoculum. An additional (abiotic) control was established by the addition of the test substance to ultrapure water alone.

Sodium benzoate had been biodegraded by 64% after 8 days and 82% after 29 days in the absence ofthe test substance, and by 60% after 5 days in its presence, which confirmed that the test substance was not inhibitory to the activity of the microbial inoculum. Cumulative levels of CO2 production in the controls after 29 days (113.9 and 117.7 mgCO2) were within the acceptable range for this assay system (recommended maximum = 120 mgCO2 for a three - litre culture). These results confirm that the inoculum was viable and that the test was valid.

Carbon dioxide production by the abiotic test mixture had achieved 24% of the theoretical value (TCO2, 110.1 mgCO2) by Day 3 and showed a plateau until Day 29 when CO2 production was 27% of the TCO2.

Mean cumulative CO2 production (biotic and abiotic) by mixtures containing the test substance was equivalent to 10% of the theoretical value after approximately one day of incubation, 60% after approximately 4 days and 79% by the end of the test on Day 29.

Substances are considered to be readily degradable in this test if CO2 production is equal to or greater than 60% of the theoretical value within ten days of the level achieving 10%. The test substance was considered to be readily degradable.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

From 2015-12-11 to 2016-01-12

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Batch No.: 150209
Purity: 97.7 wt%

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: Sludge was sampled from aeration tank of Liede Sewage Treatment Plant of Guangzhou
- Treatment of activated sludge: The sludge was removed any coarse particles and impurities on the surface, then was washed with test medium (1100 g, 10 min, repeated for 4 times), the supernatant was decanted and the solids were re-suspended in the medium. The dry weight of the suspended solids was determined as 9.4 g/L. Before the test, 85 mL of the above inoculum was taken into triangular flask and added test medium to 200 mL to obtain a concentration equivalent to 4.0 g suspended solids per liter. The sludge suspension was kept at aerobic until required. When testing, 15.0 mL of the above inoculum was added into each test bottle to give a final concentration of 30 mg suspended solids per liter.

Duration of test (contact time):

28 d

Initial conc.:

64.5 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

Test conditions
- Composition of medium: a) Potassium dihydrogen orthophosphate 8.50 g, Dipotassium hydrogen orthophosphate 28.50 g, Sodium phosphate dibasic dodecahydrate 67.15 g, Ammonium chloride NH4Cl 0.50 g (Dissolved in water and made up to 1L. The pH value is 7.40.); b) Anhydrous calcium chloride 13.75 g (Dissolved in water arid made up to 0.5 L.); c) Magnesium sulphate heptahydrate 11.25 g (Dissolved in water and made up to 0.5L.); d) Iron (Ⅲ) chloride hexahydrate (Dissolved in water and made up to 0.5 L.)
- Stock solutions for test medium: 180 mL of solution (a) was mixed with about 16 L of deionized water, then 18 mL of solutions (b), (c) and (d) were added and made up to 18 L with deionized water.
- Other: The test was started by bubbling CO2-free air through the suspensions with a rate of 30-100 mL/min at 22 ± 2 °C (actually 20.5-54.0 °C) in the dark.

Test system
- TOC concentration from the test substance: 12.3 mg/L
- Reference substance concentration : 21.1 mg/L
- TOC concentration from the reference substance : 12.3 mg/L
- Inoculum concentration: 30 mg/L
- Total volume: 2000 mL

Test groups
- Flasks 1 & 2 (test suspension): Containing test substance, inoculum and test medium
- Flasks 3, 4 & A (inoculum blank): Containing only inoculum and test medium
- Flask 5 (procedure control): Containing reference substance, inoculum and test medium
- Flask 6 (toxicity control): Containing test substance, reference substance, inoculum and test medium
- Flask 7 (abiotic control): Containing test substance, bactericide and test medium

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (CO2 evolution)

Value:

ca. 60.7

Sampling time:

10 d

Remarks on result:

other: Based on the total ThCO2

Key result

Parameter:

% degradation (DOC removal)

Value:

ca. 99.6

Sampling time:

28 d

Remarks on result:

other: The test substance had obvious abiotic degradation in abiotic control (DOC removal was 72.4%).

Details on results:

Percentage biodegration
- Procedure control: 71.4% (14 d), 71.2% (28 d)
- Toxicity control: 64.0% (14 d), 60.7% (28 d)
- Test suspension (28 d): 59.0%, 62.4% (2 replicates), 60.7% (average)

DOC removal
- Test suspension (28 d): 99.1%, 100% (2 replicates), 99.6% (average)
- Abiotic control (28 d): 72.4%

Detection limits (LOD, LOQ) (the total organic carbon analyzer): LOD = 0.226 mg/L, LOQ=0.754 mg/L
- Linearity range (DOC concentration): 0.800 - 40.0 mg/L
- Linear equation: y=-2.247814x10^-4x+2.463904X 10^7, r=0.999862

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The percentage biodegradation of the test substance was 60.7% (based on the total ThCO2) and 99.6% (based on initial DOC amount) on day 28. The test substance was considered to be readily degradable.

Executive summary:

The study was performed to determine the ready biodegradability of the test substance according to OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test).

There are five test groups, which are test suspension (containingtest substance, inoculum and test medium), inoculum blank (containing only inoculum and test medium), procedure control (containing reference substance, inoculum and test medium), toxicity control (containing test substance, reference substance, inoculum and test medium) and abiotic control (containing test substance, bactericide and test medium).The carbon dioxide produced from each test system was measured at intervals. DOC concentrations of test solutions in test suspension, inoculum blank and abiotic control were determined at the end of the test.

Under the conditions of the study, the percentage biodegradation of the test substance was greater than 60% at the end of 10-d window, was 60.7% (based on the total ThCO2) and 99.6% (based on initial DOC amount) on day 28. That should be paid attention to is, the test substance had obvious abiotic degradation in abiotic control (DOC removal was 72.4%). The percentage biodegradation of the test substance in the report may contain a part of the abiotic degradation.

The test substance was considered to be readily degradable.

Description of key information

For this endpoint two studies are available.

In a study to OECD guideline 301 B, which was determined in 2009, it was found that mean cumulative CO2 production (biotic and abiotic) by mixtures containing the test substance was equivalent to 10% of the theoretical value after approximately one day of incubation, 60% after approximately 4 days and 79% by the end of the test on Day 29. The test substance is therefore considered to be readily biodegradable.

In a study to OECD guideline 301 B, which was determined in 2016, it was found thatthe percentage biodegradation of the test substance was greater than 60% at the end of 10-d window, was 60.7% (based on the total ThCO2) and 99.6% (based on initial DOC amount) on day 28. The test substance is therefore considered to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

Key study (in 2009):

The ready biodegradability of the test substance was assessed in the CO2 Evolution (Modified Sturm) test according to OECD Guideline 301B (adopted 1992) .

The test substance was added to two, five-litre vessels containing three litres of mineral salts medium inoculated with activated sludge (30 mg solids/L) to give a nominal test concentration of 10 mgCarbon[C]/L. Two control vessels contained inoculated mineral salts medium alone and one contained inoculated mineral salts medium plus the reference substance sodium benzoate (10 mgC/L). An additional mixture containing sodium benzoate (10 mgC/L) and the test substance (10 mgC/L) was established in order to assess the potential inhibitory effects of the test substance on the activity of the microbial inoculum. An additional (abiotic) control was established by the addition of the test substance to ultrapure water alone.

Sodium benzoate had been biodegraded by 64% after 8 days and 82% after 29 days in the absence ofthe test substance, and by 60% after 5 days in its presence, which confirmed that the test substance was not inhibitory to the activity of the microbial inoculum. Cumulative levels of CO2 production in the controls after 29 days (113.9 and 117.7 mgCO2) were within the acceptable range for this assay system (recommended maximum = 120 mgCO2 for a three - litre culture). These results confirm that the inoculum was viable and that the test was valid.

Carbon dioxide production by the abiotic test mixture had achieved 24% of the theoretical value (TCO2, 110.1 mgCO2) by Day 3 and showed a plateau until Day 29 when CO2 production was 27% of the TCO2.

Mean cumulative CO2 production (biotic and abiotic) by mixtures containing the test substance was equivalent to 10% of the theoretical value after approximately one day of incubation, 60% after approximately 4 days and 79% by the end of the test on Day 29.

Substances are considered to be readily degradable in this test if CO2 production is equal to or greater than 60% of the theoretical value within ten days of the level achieving 10%. The test substance was considered to be readily degradable.

Support study (in 2016):

The study was performed to determine the ready biodegradability of the test substance according to OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test).

There are five test groups, which are test suspension (containingtest substance, inoculum and test medium), inoculum blank (containing only inoculum and test medium), procedure control (containing reference substance, inoculum and test medium), toxicity control (containing test substance, reference substance, inoculum and test medium) and abiotic control (containing test substance, bactericide and test medium).The carbon dioxide produced from each test system was measured at intervals. DOC concentrations of test solutions in test suspension, inoculum blank and abiotic control were determined at the end of the test.

Under the conditions of the study, the percentage biodegradation of the test substance was greater than 60% at the end of 10-d window, was 60.7% (based on the total ThCO2) and 99.6% (based on initial DOC amount) on day 28.That should be paid attention to is, the test substance had obvious abiotic degradation in abiotic control (DOC removal was 72.4%). The percentage biodegradation of the test substance in the report may contain a part of the abiotic degradation.

The test substance was considered to be readily degradable.