Elemol-rich fraction of essential oil of Canarium commune (Burseraceae) obtained from exudate by fractional distillation

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:

From 2018-04-23 to 2018-07-03

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study is performed according to the OECD 301F guideline and under GLP compliance.

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Remarks:

Signed on 2017-11-22

Specific details on test material used for the study:

ThODNH4 = 2.820 mg O2 / mg test item

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, adapted

Details on inoculum:

- Source of inoculum/activated sludge: The inoculum was a fresh sample of activated sludge and was collected from the aeration tank of a sewage treatment plant receiving predominantly domestic sewage.
- Laboratory culture: A filtration through a fine sieve (about 1 mm) was performed in order to remove coarse particles. After removal of any coarse particles, the sludge was washed by decantation in a mineral medium until sludge was considered free from excess substrate or inhibitor.
- Inoculum preconditioning: Pre-conditioning consisted in aerating sludge (in mineral medium) for 5-7 days before the test and at the test temperature.

Sample site: Water treatment plant "STEP de Lille", 33290 Blanquefort (France), Tank 1
Date of sampling: April 18, 2018
Inoculum:
- physico-chemical characteristic
Suspended solid: 2.37 g/L
pH: 6.8
Dissolved oxygen: 9.0 mg/L

- Activated sludge preparation
1: Filtration through a 1 mm sieve
2: 3 Successive decantations into mineral medium
3: Activated sludge aeration during 5 days

Duration of test (contact time):

>= 28 - <= 60 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST ITEM PREPARATION:
- The test item is poorly soluble in water and in order to improve the dissolution the test item was dissolved in silicone oil AR 20 up to final concentration of 1 % v/v. Around 25 mg of test item was stirred with 2.5 mL silicone oil AR 20 by magnetically stirring until completely dissolved.
Then, this solution was directly supplemented or completed into 250 mL with mineral medium and sludge directly in each test vessels
The test medium was the mineral medium, a weakly saline aqueous medium.
The test item was tested at 100 mg/L in mineral medium containing 1 % v/v of silicone oil AR 20.

TEST PRINCIPLE
A measured volume of inoculated medium containing a known concentration of the test item (100 mg/L) as the nominal sole source of Carbon, is stirred in a closed vessel at a constant temperature up to 28 days with possible extension to 60 days.
Microbial respiration consumes O2 and releases CO2 which were absorbed by soda lime pellets present in the headspace of flasks. This produced a decrease in pressure in the flask proportional to the amount of oxygen taken up by the microbial population during biodegradation, which was expressed as a percentage of ThOD (Theoretical Oxygen Demand).
Allowance was made for the endogenous activity of the inoculum by running parallel blanks with inoculum but without the test item. Furthermore, in order to check the procedure, a reference item control (sodium benzoate + inoculum) and a
toxicity control (sodium benzoate + inoculum + test item + silicone oil AR 20) were run in parallel.
Moreover, a control with silicone oil AR 20 1% was performed to check that silicone was non-toxic to bacteria and nonbiodegradable.
The pH of the contents was measured at the start and the end of the experiment.

TEST CONDITIONS
- Composition of medium: Mineral medium according to OECD 301F guideline
- Continuous darkness: Yes
- Test performed in closed vessels: Yes
- The pH of the contents is measured at the start and the end of the experiment.
- Test duration: 28 days
- Temperature: 22.3 to 23.5°C, (constant temperature ± 1°C), The change in temperature between May 10 and May 15 is due to a power failure but did not have any influence on the results
- Incubation conditions: Closed test flasks incubated in environmental simulation chamber under continuous stirring
- Mineral medium
Batch number: 7/11041801 7/11041802
pH: 7.6 7.5

TEST SYSTEM
- Culturing apparatus: WTW Oxitop (FCBA reference: ACQU 1030)
- Number of culture flasks/concentration: 3
- Test performed in closed vessels: yes

SAMPLING
Oxygen consumption measured daily.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 3 flasks
- Inoculum silicone control
- Refernce item: 2 flasks
- Toxicity control: 2 flasks

Reference substance:

benzoic acid, sodium salt

Preliminary study:

An elementary analysis of the test item (non-GLP data) was performed by an external laboratory to calculate the Theoretical Oxygen Demand.
The test item «ELEMOL F7251»contains no nitrogen according to the elementary analysis, the evaluation of biodegradation has to be expressed as ThODNH4.

Test performance:

No data

Parameter:

% degradation (O2 consumption)

Value:

10

Sampling time:

3 d

Parameter:

% degradation (O2 consumption)

Value:

55.95

Sampling time:

13 d

Parameter:

% degradation (O2 consumption)

Value:

76.29

St. dev.:

0.9

Sampling time:

28 d

Details on results:

The test item «ELEMOL F7251»contains no nitrogen according to the elementary analysis, the evaluation of biodegradation has to be based in the following expressed as ThODNH4.
Following the ThODNH4, the degradation for the 10-day window beginning was reached on day 3, but at the end of the 10-day window (reaching at least 60%), on day 13, the mean degradation was 55.95%, therefore the 10-day window failed.
The degradation rate of the test item «ELEMOL F7251»reached 76.29%, following the ThODNH4, after 28 days of incubation.
In agreement with the study monitor, and as it had been anticipated in the study plan, the testing period was not extended to 60 days and stopped at 28 days.

Results with reference substance:

The reference item “Sodium benzoate” was degraded up to 85.70% and 82.91%( mean value: 84.31%) after 14 days and 88.09% and 94.08% respectively in both replicates after 28 days of incubation at the end of the test.
Therefore the suitability of the used aerobic sludge inoculum is confirmed.

Biodegradation results of test item at 28 days

Treatment	% Biodegradation at 28 days	pH at the end of the test (28 days)
	(with ThODNH4)
Test item “ELEMOL F7251”	77.12	7.5
	75.34
	76.41
Average (± SD)	76.29% (0.90)

Biodegradation of the Toxicity Control

A biodegradation of 42.76% and 38.83% after 14 days of incubation was noted in the Toxicity control (containing both of the test item and the reference item) based on ThODNH4.

At the end on the test, 28 days of incubation, the results were respectively 67.88% and 69.19%.

Therefore, the test item was not inhibitory at the tested concentration on the aerobic activated sludge micro-organisms because degradation was superior to 25% within 14 days (validity criterion).

Validity criteria conformity

Criteria	Validity for OECD 301F	Validity for the test
Oxygen uptake of the inoculum control in 28 days	< 60 mg/L	Yes (14.1 to 22.5 mg/L) (Silicone: 19.7 to 25.4 mg/L)
Biodegradability of the reference item within 14 days	> 60%	Yes (82.91 to 85.70%)
Biodegradability of the toxicity control within 14 days	> 25%	Yes (38.83% and 42.76%)
Variation between the test item replicates at 28 days	< 20%	Yes (Cv = 1.18%)
pH of the inoculum control at 28 days	6 to 8.5	7.5

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Under conditions of OECD Guideline 301F, the test item “ELEMOL F7251”, is readily biodegradable.

Executive summary:

The aim of this study was to determine the biodegradability of the test item «ELEMOL F7251», according to the OECD 301F guideline, within an experimental period of 28 days by respirometric method.

The amount of oxygen taken up by the microbial population during the biodegradation of the test item (corrected by blank inoculum, run in parallel) was determined from the change in pressure in apparatus and is expressed as percentage of theoretical Oxygen Demand (ThOD).

According to the OECD guideline 301F, the test item is considered to be readily biodegradable, following the ThODNH4.

Description of key information

Under conditions of OECD Guideline 301 F the registered substance is regarded as readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The aim of this study was to determine the biodegradability of the test item «ELEMOL F7251», according to the OECD 301F guideline, within an experimental period of 28 days by respirometric method.

The amount of oxygen taken up by the microbial population during the biodegradation of the test item (corrected by blank inoculum, run in parallel) was determined from the change in pressure in apparatus and is expressed as percentage

of theoretical Oxygen Demand (ThOD).

According to the OECD guideline 301F, the test item is considered to be readily biodegradable, following the ThODNH4.