Oleic acid, compound with 2-amino-2-methylpropan-1-ol (1:1)

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:

26 October 2017 to 23 November 2017

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)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

- A nominal 391.2 mg/L stock solution of the test material was prepared by weighing 0.0978 g of the test material into a 250 mL volumetric flask with reagent water. This stock solution was stirred for approximately 45 minutes. The COD of the test material was 2.456 mg O2/mg of test material. A 6-L volume of the test solution with a COD of 4.0 mg/L was prepared by pipetting 24.240 mL of stock solution into a 6-L Erlenmeyer flask and making this up to volume using inoculated mineral medium. This test solution was dispensed into 14 BOD bottles (i.e., one set of duplicate bottles for each sampling period).

Oxygen conditions:

anaerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: secondary effluent was collected from the Guelph Wastewater Treatment Plant (Guelph, Ontario). The Guelph Wastewater Plant treats sewage of predominantly domestic origin.
- The secondary effluent was continuously aerated during transport to, and storage at the testing laboratory, and then pre-conditioned for testing. During pre-conditioning, the secondary effluent was maintained at test temperature (22 ± 2°C) prior to test initiation. The secondary effluent was settled for approximately 30 minutes prior to the clear supernatant being decanted for use as the inoculum.

Duration of test (contact time):

28 d

Initial conc.:

1.63 mg/L

Based on:

test mat.

Initial conc.:

4 mg/L

Based on:

COD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral medium: The composition is equivalent to that described in OECD Guideline 301 D (OECD, 1992), with the exception that Na2HPO4·2H2O is replaced by the appropriate amount of Na2HPO4. The solution was aerated continuously overnight.
On the day prior to test initiation, 28 L of mineral medium was prepared and the dissolved oxygen, pH and temperature were confirmed prior to use in the test. The dissolved oxygen concentration was 8.7 mg/L. The pH was within the required range (7.4 ± 0.2) and did not require adjustment. Temperature of the mineral media was also within the required range (22 ± 2°C).
- pH adjusted: not required
- Suspended solids concentration: 5 mL/L
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: Glass, with ground glass stoppers and plastic caps (BOD bottles), 300 mL.
- Number of culture flasks/concentration: 2 bottles for inoculated control, reference, inhibition and test series; 1 bottle for the non-inoculated control
- Measuring equipment: Oxygen electrode
- Test performed in closed vessels: yes

SAMPLING
- Sampling frequency: Days 0, 4, 7, 11, 14, 21 and 28

CONTROL AND BLANK SYSTEM
- Non-Inoculated and Inoculated Blanks: A single non-inoculated control and duplicate inoculated control test vessels (BOD bottles) were established for each of the sampling periods. The pH of the mineral medium was measured prior to inoculation. The temperature of the mineral medium was monitored to ensure that it was within the required temperature range of 22 ± 2°C. The control bottles were treated similarly to the test bottles, except that no test material was added. Oxygen content of these bottles was measured in the same fashion as the test, reference and inhibition series.
- Reference Series (Procedural Control): A reference series was conducted in parallel with the test material series, to verify that the test system was working appropriately and that the reference substance by itself was not inhibitory to sewage bacteria. The reference substance, KHP with a COD of 1.174 mg/mg KHP, was tested at a concentration of 4 mg/L COD under the same conditions and with the same sampling intervals used in the test material series. A stock solution of KHP with a nominal COD of approximately 1000 mg/L (equivalent to 854 mg KHP/L) was prepared by weighing 0.854 g of the reference substance into a 1-L volumetric flask and making this up to volume in Millipore MilliQ™ water. The stock solution was hand mixed immediately prior to testing. The final COD of the stock solution was estimated to be 1002.5 mg/L (based on the average of two samples). A 6-L volume of the reference solution with a final COD of 4.0 mg/L was prepared by pipetting 23.940 mL of stock solution into a 6-L Erlenmeyer flask and making this up to volume using inoculated mineral medium. This solution was dispensed into fourteen test vessels (i.e., one set of duplicate test vessels for each sampling period).
- Inhibition Series (Toxicity Control): An inhibition series was conducted in parallel with the test series, to determine whether the test material was inhibitory to sewage bacteria (i.e., the test material can be assumed to be inhibitory if less than 25% degradation occurs in this test within 14 days). The inhibition test utilised both the test material and the reference substance. The concentrations of the test material and reference substance used for the inhibition series were the same as in the test and reference series (i.e., 4 mg/L COD). As such, 24.240 mL of the test material stock solution and 23.940 mL of the reference substance stock solution were added into a 6-L Erlenmeyer flask and made up to volume using inoculated mineral medium. This solution was then dispensed into fourteen test vessels (i.e., one set of duplicate test vessels for each sampling period).

STATISTICAL METHODS:
The BOD was calculated as follows:
BOD = [(mg O2/L uptake of test material – mg O2/L uptake of blank) / mg test material/L in vessel ] = mg O2/mg test material
The amount of oxygen consumed within the test system was compared to the COD of the test material and the percent (%) degradation was calculated as follows:
% biodegradation at time t = (BOD (mg/L) at time t (days) / COD (mg/L)) x 100%
Using this method, the extent and rate of biodegradability was determined based on the cumulative uptake of molecular oxygen.

Reference substance:

other: Potassium Hydrogen Phthalate (KHP)

Test performance:

The definitive test met the test validity criteria:
- The reference substance achieved > 60% degradation within 14 days of test initiation.
- The difference of extremes of replicate values of the removal of the test material at the plateau, at the end of the test or at the end of the 10-day window, as appropriate, was less than 20%.
- Inoculated control (nutrient blank) did not exhibit more than 1.5 mg/L reduction in dissolved oxygen concentration in 28 days.
- The residual dissolved oxygen concentration in the test vessels did not fall below 0.5 mg/L.
- The toxicity control achieved > 25% degradation in 14 days.

Key result

Parameter:

% degradation (O2 consumption)

Value:

72.8

Sampling time:

28 d

Details on results:

CHEMICAL OXYGEN DEMAND OF THE TEST MATERIAL
- The mean COD of the test material was 2.456 mg O2/mg test material.

CONFIRMATION OF THE TEST MATERIAL STOCK SOLUTION
- The concentration of the stock solution of the test material was reported to be 403.11 mg/L. The concentration of the test material in the mineral medium was 1.63 mg/L.

NITRATE AND NITRITE ANALYSIS
- Dissolved oxygen values for the test solutions on days 4, 11, 14 and 21 of the test were not corrected for interference by nitrification where any change in DO concentration was <0.1 mg/L. However, the dissolved oxygen concentrations on Day 7 for T-1 (6.3 mg/L) and T-2 (6.3 mg/L) were corrected by a 0.16 mg/L gain in oxygen to the system due to nitrification. In addition, the dissolved oxygen concentrations on Day 28 for T-1 (5.7 mg/L) and T-2 (5.4 mg/L) were corrected by a 0.31 mg/L gain in oxygen to the test system due to nitrification.

READY BIODEGRADABILITY OF THE TEST MATERIAL
- Reference Series (Procedural Control): The reference material achieved 82.5% degradation in 14 days, thereby meeting the pass criteria of ≥ 60% within 14 days. Therefore, the test system was acceptable for the determination of biodegradability.
- Inhibition Series (Toxicity Control): Inhibition of the microbial population was not observed (i.e., > 25% degradation in 14 days).
- Test Material Series (Test Suspension): The test material achieved 72.8% degradation over the 28-day exposure. Based on visual inspection of the biodegradation curve, the test material also achieved approximately 61% degradation 10 days after achieving 10% biodegradation (i.e., the 10 day window).

Results with reference substance:

- The reference material achieved 82.5% degradation in 14 days, thereby meeting the pass criteria of ≥ 60% within 14 days. Therefore, the test system was acceptable for the determination of biodegradability.

 Table 1: Summary of Results

Series	Duration (Days)	Percent biodegradation (average of two replicates)
Reference substance	14	82.5
	28	85.0
Toxicity control	14	70.6
	28	75.0
Test material	28	72.8

 

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Under the conditions of this study, the test material can be considered to be readily biodegradable.

Executive summary:

The ready biodegradability of the test material was investigated in accordance with the standardised guideline OECD 301D using the closed bottle test, under GLP conditions for 28 days.

The concentration of the test material in the mineral medium was 1.63 mg/L. The corresponding Chemical Oxygen Demand (COD) was 4.0 mg/L. The quality of the test system was confirmed through the use of a reference substance and all of the criteria for test validity were met.

The test material achieved 72.8% degradation over the 28-day exposure. Furthermore, based on visual inspection of the biodegradation curve, the test material achieved approximately 61% biodegradation within 10 days after achieving 10% biodegradation (i.e., the 10 day window).

Under the conditions of this study, the test material can be considered to be readily biodegradable.

NOTE: Any of data in this dataset are disseminated by the European Union on a right-to-know basis and this is not a publication in the same sense as a book or an article in a journal. The right of ownership in any part of this information is reserved by the data owner(s). The use of this information for any other, e.g. commercial purpose is strictly reserved to the data owners and those persons or legal entities having paid the respective access fee for the intended purpose.

 

Description of key information

Under the conditions of the study, the test material can be considered to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The ready biodegradability of the test material was investigated in accordance with the standardised guideline OECD 301D using the closed bottle test, under GLP conditions for 28 days. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

The concentration of the test material in the mineral medium was 1.63 mg/L. The corresponding Chemical Oxygen Demand (COD) was 4.0 mg/L. The quality of the test system was confirmed through the use of a reference substance and all of the criteria for test validity were met.

The test material achieved 72.8% degradation over the 28-day exposure. Furthermore, based on visual inspection of the biodegradation curve, the test material achieved approximately 61% biodegradation within 10 days after achieving 10% biodegradation (i.e., the 10 day window).

Under the conditions of this study, the test material can be considered to be readily biodegradable.