Sodium olivoyl glutamate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2023

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SODIUM OLIVOYL GLUTAMATE
Common name: Sodium olivoyl glutamate
Chemical name: Glutamic acid, N-olivoyl derivs., sodium salts
CAS number: 1628321-85-6
EC number: 944-266-4

SOURCE OF TEST MATERIAL
Supplier: Sponsor
Batch number: 2072900-M
Expiry date: 29/07/2023
Purity: nominal content 100.0%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
Storage condition: at room temperature, light protection not needed.

Oxygen conditions:

aerobic

Remarks:

The study was performed using aerobic activated sludge from BRIANZACQUE civil wastewater treatment plant.

Inoculum or test system:

activated sludge (adaptation not specified)

Remarks:

aerobic activated sludge from BRIANZACQUE civil wastewater treatment plant

Details on inoculum:

A homogenized aliquot of the wet sludge was centrifuged, the supernatant was removed while the solid phase was weighed, dried and the ratio of wet to dry weight was calculated to be equal to 8.81%.
Based on this ratio, calculated amounts of wet sludge was centrifuged, the supernatant was removed and the solid phase was suspended in the test medium to get a concentration equivalent to 3 g dry material per litre.
The prepared sludge inoculum was pre-conditioned to the experimental conditions by aerating it in the dark. The concentrated suspension was used as inoculum to give a final concentration of 15 mg dry material per litre into test flasks.

Duration of test (contact time):

28 d

Initial conc.:

80 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Remarks:

BOD = Biochemical Oxygen Demand: the amount of oxygen consumed by microorganisms when metabolising a test item; it is expressed as mg of O2 required per mg of test item.

Parameter followed for biodegradation estimation:

other: ThOD = Theoretical Oxygen Demand: the total amount of oxygen required to oxidise a chemical completely. It is calculated from the molecular formula and it is expressed as mg O2 required per mg test item.

Details on study design:

EXPERIMENTAL DESIGN
The assay on test item was carried out in parallel with the following bottles:
- a known ready biodegradable reference item (one replicate), Sodium Benzoate, at 100 mg/L;
- two inoculum control replicates (blank);
- two test item replicates at 80.0 mg/L concentration.
- one abiotic control containing the test item at 100.0 mg/L and a sterilizing agent (HgCl2) at 100 mg/L (without inoculum);
- one toxicity control, containing the test item at 100.0 mg/L and reference item at 100 mg/L.
All reported results are related to the nominal concentration of test item since the test concentrations were not measured during the test.
The biodegradation was followed by measuring the oxygen uptake (mg/L) of the test item under defined conditions by the means of a manometric method and calculating from these values the BOD (Biochemical Oxygen Demand).
The ThODNH3 value (Theoretical Oxygen Demand without nitrification process) was calculated to be equal to 1.67 mg O2/mg for reference item, Sodium Benzoate, while COD value was assessed to be 1.07 mg O2/mg for the test item.
These values, 1.67 mg O2/mg for reference item and 1.07 mg O2/mg for the test item, were used to calculate per % biodegradation.
BOD flasks of 500 mL capacity, equipped with pressure sensors fitted on the bottle mouth, were used as test units.
The method is based on an electro-chemical analyses process. The biodegradation process consumes the dissolved oxygen in liquid and generates CO2. Evolved carbon dioxide is adsorbed by potassium hydroxide and the total pressure decreases in the test flasks. The pressure decrease is detected and converted into an electrical signal by means of an electrode type manometer.

TEST MEDIUM
The test medium was prepared according to the OECD Guidelines No. 301 A, 1992: salts of analytical grade were dissolved in purified water to obtain the following stock solutions (up to 1000 mL).

a) KH2PO4 8.50 g/L
K2HPO4 21.75 g/L
Na2HPO4 x 2H2O 33.40 g/L
NH4Cl 0.50 g/L
The pH of this solution was 7.41.

b) CaCl2 x 2H2O 36.40 g/L
or
CaCl2 27.50 g/L

c) MgSO4 x 7H2O 22.50 g/L

d) FeCl3 x 6 H2O 0.25 g/L

In order to allow the storage of solution, one drop of concentrated HCl was added. An aliquot of 10 mL of stock solution a) and 1 mL of stock solutions b), c) and d) were added to 800 mL of purified water, then made up to 1000 mL with purified water. The pH of test medium was 7.62 (mean value between two blank bottles), so adjustment with a diluted hydrochloric acid or sodium hydroxide solution, before making up to volume, was not needed.

TEST SOLUTION
Since the test item was soluble in water, a test item stock solution was prepared weighing 0.1007 g of test item directly in 500.0 mL of mineral medium, to obtain a final concentration of 200.0 mg/L.
A proper volume of stock solution was dosed in the test flasks to obtain the final concentrations of 80.0 mg/L of test item.

Moreover, stock solutions (10 g/L) of reference item Sodium Benzoate and sterilizing agent HgCl2 were prepared and an appropriate aliquot of the stock solution was added to the test medium (final volume: 250 mL or 150 mL) in the test flasks to obtain a final concentration of 100 mg/L. Activated sludge was added to each flask (with the exception of the abiotic control) before incubation.
Finally, the test flasks, containing stir bars covered with teflon, were kept under continuous stirring by the means of a magnetic stirrer for the 28-days test period.

Test Flask
Test Item (replicate 1) and (replicate 2)

Flask Content
- Test medium
- Sludge inoculum
- Test Item - Volume (128.7 mL, 1.3 mL, 100.0 mL)

Concentration
80.0 mg/L (Nominal test item concentration)

Temperature
The incubation temperature was continuously monitored during the course of the study by means of a data logger. It was in the range 21.8 – 22.1°C with a mean value of 21.9°C and a standard deviation of 0.05°C. The temperature range recommended by OECD guideline is 22 ± 2°C, this
range was corrected according to the data logger precision, therefore the range to be considered for the test was 20.4 – 23.6°C while the recorded temperature values were corrected according to the correction factor.
The recorded temperature values during the test period were within the recommended range, as recommended by the guideline.

Light conditions
Darkness.

Stirring
Continuous.

Test duration
28 days.

pH value

Test Item (replicate 1):
pH day 0: 7.63
pH day 28: 7.67


Test Item (replicate 2):
pH day 0: 7.66
pH day 28: 7.69

Reference substance:

benzoic acid, sodium salt

Preliminary study:

Preliminary study was not performed.

Test performance:

No unusual observations occurred during the test.

Key result

Parameter:

% degradation (O2 consumption)

Value:

ca. 49

Sampling time:

28 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

ca. 44

Sampling time:

10 d

Results with reference substance:

The reference item exceeded (75.4%) the biodegradation pass level (60%) within the range fixed by OECD Guideline 301F (first 14 days).

	% BIODEGRADATION
	REF. ITEM	TEST ITEM Replicate 1	TEST ITEM Replicate 2	TEST ITEM MEAN	TOXICITY CONTROL	ABIOTIC CONTROL
Day 1	3.6	11.7	8.2	9.9	10.6	0.0
Day 2	10.5	23.9	22.8	23.4	27.8	0.0
Day 3	11.7	26.3	23.9	25.1	33.6	0.0
Day 4	11.4	30.4	28.0	29.2	48.1	0.0
Day 5	21.0	32.7	30.4	31.5	53.3	0.0
Day 6	28.1	35.0	32.7	33.9	54.9	0.0
Day 7	32.9	39.7	35.0	37.4	56.8	0.0
Day 8	0.0	0.0	0.0	0.0	0.0	0.0
Day 9	0.0	0.0	0.0	0.0	0.0	0.0
Day 10	43.1	43.2	42.1	42.6	60.9	0.0
Day 11	47.0	45.0	42.6	43.8	62.8	0.0
Day 12	55.7	44.4	44.4	44.4	63.6	0.0
Day 13	70.7	45.6	45.6	45.6	64.2	0.0
Day 14	75.4	44.4	44.4	44.4	65.6	0.0
Day 15	80.8	46.7	46.7	46.7	65.6	0.0
Day 16	0.0	0.0	0.0	0.0	0.0	0.0
Day 17	89.8	45.6	47.9	46.7	66.1	0.0
Day 18	91.3	47.3	47.3	47.3	66.8	0.0
Day 19	93.7	47.3	48.5	47.9	66.8	0.0
Day 20	96.1	48.5	48.5	48.5	66.8	0.0
Day 21	96.1	48.5	48.5	48.5	68.3	0.0
Day 22	96.4	47.9	47.9	47.9	68.0	0.0
Day 23	0.0	0.0	0.0	0.0	0.0	0.0
Day 24	96.4	49.1	49.1	49.1	68.5	0.0
Day 25	97.6	49.1	49.1	49.1	68.5	0.0
Day 26	97.6	49.1	50.2	49.6	68.5	0.0
Day 27	98.2	50.2	50.2	50.2	69.6	0.0
Day 28	98.2	50.2	50.2	50.2	69.6	0.0
*	98.2	49.0	49.0	49.0	69.6	0.0

 

*NITRIFICATION CORRECTION (if appropriate) at test end

 

The difference between duplicate values of test item removal at the end of the 10-day window (at day 12/10/2022) was 0.0%; this value was within the maximum value provided by OECD Guideline of 20 %. Value of biodegradation at the end of the test after nitrification correction is 49%

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test item, SODIUM OLIVOYL GLUTAMATE was found to be not ready and completely biodegradable under the conditions applied in a manometric respirometry test. At the end of the 10-day window the biodegradation was 44.4% (mean percentage values between two replicates). At the end of the test (28 day) and after nitrification correction, a maximum biodegradation of 49.0% was found, (mean percentage values between two replicates).
No significant degradation was observed in the abiotic control.
The test item showed no inhibitory effects on the microorganism activity at the tested concentration, as demonstrated by the biodegradation percentage in the toxicity control exceeding the 25% pass level within 14 days of exposure (65.6%).

Executive summary:

A study to evaluate the ready biodegradability of the test item SODIUM OLIVOYL GLUTAMATE, following the “Manometric Respirometry” method, was performed.
Nitrate and nitrite concentration were measured at the start and at the test end.
At the start and test end no nitrite and nitrate were present.
At the test end nitrate concentration in the blank bottles (6.30 mg/L as mean value) was subtracted from the nitrate concentration found in test item bottles (7.35 mg/L as mean value), therefore the found value (1.05 mg/L), calculated as Total oxygen equivalent, was subtracted from the test biodegradation value at the end of the test.
At the end of the 10-day window (at day 12/10/2022) the biodegradation was 44.4% (mean percentage values between two replicates).
Therefore, the test item, was found to be not ready and completely biodegradable under the conditions applied in a manometric respirometry test.
At the end of the test (28 day) and after nitrification correction, a maximum biodegradation of 49.0% was found, (mean percentage values between two replicates).
No significant degradation was observed in the abiotic control (equal to 0% at the test end).
The toxicity control clearly showed that the test item does not cause inhibitory effect on the microorganisms activity at the tested concentration. The toxicity control exceeded the 25 % pass level within the 14 days of exposure (65.6%).
The reference item exceeded (75.4%) the biodegradation pass level (60%) within the range fixed by OECD Guideline 301F (first 14 days).

Description of key information

The determination of the aerobic ready biodegradability of SODIUM OLIVOYL GLUTAMATE has been performed following the OECD Guideline 301F, “Ready Biodegradability, Manometric Respirometry test”.
At the end of the 10-day window the biodegradation was 44.4% (mean percentage values between two replicates).
At the end of the test (28 day) and after nitrification correction, a maximum biodegradation of 49.0% was found, (mean percentage values between two replicates).
Therefore, the test item, was found to be not ready and completely biodegradable under the conditions applied in a manometric respirometry test.