Lavender, Lavandula angustifolia, ext.

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017-06-07 to 2017-07-11

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

This study was performed according to OECD Guideline 209 with GLP statement. All validity criteria were fulfilled.

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

Deviations:

no

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Remarks:

signed on 14 January 2016

Specific details on test material used for the study:

Not applicable

Analytical monitoring:

no

Vehicle:

yes

Remarks:

deionized water

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
Based on the Sponsor’s information, the test item is not soluble in water and was consider overall respiration only; it was directly diluted in osmosed water. No analytical estimation was done during this study.

- Preparation:
In order to evaluate information about the range of concentrations used in the main test, a range-finding test, non GLP, was done. The test solutions of the range finding test were: 10, 100 and 1000 mg/L. This test had indicated that inhibiting effects could be expected around 1000 mg test item /L (nominal concentration).
According to these preliminary results, 5 concentrations were tested (geometric series): 305 – 488 – 781 – 1250 and 2000 mg/L
According to OECD 209, the abiotic control do not need to be repeated because there was no oxygen uptake in the preliminary test.

- Protocol:
The test was carried out into 1000 mL glass flasks containing 500 mL as below:
- 16.0 ml synthetic sewage feed
- Adequate weight of test item and osmosed water for different concentrations (final volume: 500 mL)
- 250 mL of sludge suspension
Replicates: Six replicates for controls (Control a to Control f)
Three replicates (a to c) per treatment (1 to 5) for the test item
One replicate per treatment for the reference item (3,5 DCP)

The concentrations for the 3,5 DCP were : 0,5 – 1,6 – 5,1 – 16,4 – 52,4 mg/L

At the start of the test, the first control (Control a) was prepared and covered with parafilm. Then, every 10 -15 minutes the others flasks with test item and concentrations with reference item were prepared in turn. Finally, the last control (Control f) was prepared.

All suspensions were aerated with purified air (0.5 to 1 L/min), and stirred during 3 hours at 20 ± 2°C. Then, each suspension was poured into Karlsruher flask (following the order preparation).

The Oxygen was measured every minute, during 10 minutes, with a Dissolved Oxygen Sensor (WTW StirrOx G) integrated Stirrer, inserted into the Karlsruher flask.

- Test medium:
The medium was prepared from concentrated stock solutions in ultrapure water as described in the guideline.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: 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: STEP de Lille, 33290 BLANQUEFORT - FRANCE.
- Justification: Activated sludge micro-organisms have been selected following the recommendations of OECD Guideline No 209.
- Preparation of inoculum for exposure: A filtration through a fine sieve (around 1 mm) was performed in order to remove coarse particles. After removal of any coarse particles, the sludge was washed by decantation in osmosed water and test medium 50/50 (v/v) to adjust concentration of dry extract around 3 g/L.
The activated sludge was continuously aerated until usage in the test and fed daily with 50 mL/L synthetic sewage feed for one or two additional days.

Test type:

not specified

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

None

Hardness:

None

Test temperature:

20 ± 2 °C

pH:

7.6 to 8.2

Dissolved oxygen:

7.8 mg/L

Salinity:

None

Conductivity:

No data

Nominal and measured concentrations:

Nominal test item concentrations: 305 – 488 – 781 – 1250 and 2000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Test was performed in 1000 mL glass flasks containing 500 mL of incubation mixture: 16.0 ml synthetic sewage feed; Adequate weight of test item and osmosed water for different concentrations (final volume: 500 mL); 250 mL of sludge suspension.
- Synthetic Sewage Feed (The synthetic sewage feed was prepared to contain the following constituents per liter: 16 g peptone, 11 g meat extract, 3 g urea, 0.7 g NaCl, 0.4 g CaCl2 × 2H2O, 0.2 g MgSO4 × 7H2O, 2.8 g K2HPO4). The pH of this solution was measured to be pH 7.5 +/- 0.5.
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): Six blank controls

TEST MEDIUM / WATER PARAMETERS
Na2HPO4, 2H2O: 33.4 mg/l; CaCL2, 2H2O: 36.4 mg/l; K2HPO4: 21.75 mg/l; MgSO4, 7H2O: 22.5 mg/l; NH4Cl: 0.5 mg/l; FeCl3, 6H2O: 0.25 mg/l; KH2PO4: 8,5 mg/l
This mineral medium was diluted 50/50 (v/v) with osmosed water for the preparation of the activated sludge

EFFECT PARAMETERS MEASURED
- The inhibition of respiration of an activated sludge by the test item was performed in this test. The respiration rates of samples of activated sludge fed with synthetic sewage were measured in an enclosed cell containing an oxygen electrode after a contact time of three hours.

TEST CONCENTRATIONS
- Range finding study: Based on the test guideline, a range-finding test using the following three nominal test item concentrations of 10 mg/L, 100 mg/L and 1000 mg/L was performed.
- Results used to determine the conditions for the definitive study: The results of the preliminary test showed an inhibitory effect at 1000 mg/L (nominal test item concentration)
Based on the results of the range-finding test and in agreement with the Sponsor a definitive test with the following nominal test item concentrations was performed (geometric series): 305 – 488 – 781 – 1250 and 2000 mg/L to primarily permit the determination of the 3h-EC50.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

1 230 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks on result:

other: 95% Cl: 1000 - 1580 mg/L

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

488 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Duration:

3 h

Dose descriptor:

LOEC

Effect conc.:

781 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

EC50 value including the associated lower and upper 95% confidence limit was calculated with Minitab 17 (scientific software). To compute the EC50, the inhibitions means (y) versus Logarithm concentrations (x) were subjected to regression analysis.

The equation was: Y=-268.3+103.0 Log(x)
Y: % average inhibition
X: concentration

With EC50 = 1230 mg/L (1000 – 1580)

NOEC/LOEC was determined with Dunnett test (Minitab 17):
The concentration 488 mg/L was stated as NOEC.
The concentration 781 mg/L was stated as LOEC.

Results with reference substance (positive control):

The 3-hour EC50 of the reference item 3,5-dichlorophenol (positive control) was calculated to be 9.4 mg/L. The 3-hour EC50 is within the guideline-recommended range of 2–25 mg/L, confirming suitability of the activated sludge used.

Reported statistics and error estimates:

None

O2 consumption and inhibition

Treatment	Name	O2consumption in mg O2/(L*h)	% inhibition	pH (end of the test)
Inoculum Control	Control a	43.500	/	8.0
	Control b	32.667	/	8.2
	Control c	45.000	/	8.1
	Control d	50.571	/	8.1
	Control e	51.429	/	8.2
	Control f	48.000	/	8.2
Reference Item	3,5 DCP Conc 1	43.5	3.75	8.2
	3,5 DCP Conc 2	39.3	13.04	8.1
	3,5 DCP Conc 3	40.7	9.94	8.0
	3,5 DCP Conc 4	10.7	76.32	7.8
	3,5 DCP Conc 5	6.0	86.72	7.7
Test Item	1a	51.00	-12.8	7.7
	1b	45.60	-0.9	7.9
	1c	51.00	-12.8	7.9
	2a	35.00	22.6	7.8
	2b	46.00	-1.8	7.8
	2c	50.00	-10.6	7.8
	3a	32.00	29.2	7.7
	3b	32.00	29.2	7.7
	3c	34.00	24.8	7.8
	4a	22.00	51.3	7.6
	4b	21.33	52.8	7.6
	4c	16.67	63.1	7.7
	5a	14.67	67.5	7.6
	5b	13.33	70.5	7.6
	5c	12.67	72.0	7.6

 

-      Inoculum Control (Control a to f)

-      Reference item (3,5 DCP C1 to C5)

-      Test item 305 mg/L (1a to 1c)

-      Test item 488 mg/L (2a to 2c)

-      Test item 781 mg/L(3a to 3c)

-      Test item 1250 mg/L(4a to 4ac)

-      Test item 2000 mg/L (5a to 5c)

Validity of the Test

Validity criteria	Conformity for OECD 209	Conformity for the test
Oxygen uptake in the control	≥ 20mg O2/g activated sludge (dry weight of suspended solids)/ h	Yes (29.1 mg O2/g sludge/h)
Coefficient of variation of O2uptake rate in control replicates at the end of the definitive test	≤ 30%	Yes (6.2 to 15.9%)
EC50of 3,5 dichlorophenol for total respiration	Between 2 to 25 mg/L	Yes (9.4 mg/L)

The validity criteria for OECD 209 were successful.

Validity criteria fulfilled:

yes

Conclusions:

The 3-hour EC50 of the test item LAVENDER OIL POPULATIONwas found to be 1230 mg/L with confidence interval 95% between 1000 and 1580 mg/L. The 3-hour NOEC was determined to be 488 mg/L and the 3h-LOEC was 781 mg/L.

Executive summary:

The inhibitory effect of the test item LAVENDER OIL POPULATION on the respiration rate of aerobic wastewater micro-organisms of activated sludge was investigated in a 3-hour respiration inhibition test according to the OECD Guideline 209 in compliance with GLP.

The study was performed using five concentrations, ranging from 305 to 2000 mg/L nominal concentrations. The dry matter of the activated sludge was determined as 3.11 g suspended solids/L, giving a concentration of 1.555 g suspended solids/L in this test.

As a positive control, the reference item 3,5-dichlorophenol was tested.

The result of this study is presented as follows:

 

Validity criteria	Conformity for OECD 209	Conformity for the test
Oxygen uptake in the control	≥ 20mg O2/g activated sludge (dry weight of suspended solids)/ h	Yes (29.1 mg O2/g sludge/h)
Coefficient of variation of O2uptake rate in control replicates at the end of the definitive test	≤ 30%	Yes (6.2 to 15.9%)
EC50of 3,5 dichlorophenol for total respiration	Between 2 to 25 mg/L	Yes (9.4 mg/L)

 

The validity criteria for OECD 209 were successful.

 

 

CE50-3h “LAVENDER OIL POPULATION” (confidence interval 95%)	1230 mg/L ( 1000 –1580)
NOEC	488 mg/L
LOEC	781 mg/L

The results are presented in nominal test item concentration.

Description of key information

The 3-hour EC50 of the test item LAVENDER OIL POPULATION was found to be 1230 mg/L with confidence interval 95% between 1000 and 1580 mg/L. The 3-hour NOEC was determined to be 488 mg/L and the 3h-LOEC was 781 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

1 230 mg/L

EC10 or NOEC for microorganisms:

488 mg/L

Additional information

For that endpoint, an experimental study performed on the registered substance was available. This study intended to assess the inhibitory effect of the test item LAVENDER OIL POPULATION on the respiration rate of aerobic wastewater micro-organisms of activated sludge. This study was investigated in a 3-hour respiration inhibition test according to the OECD Guideline 209 in compliance with GLP.

The study was performed using five concentrations, ranging from 305 to 2000 mg/L nominal concentrations. The dry matter of the activated sludge was determined as 3.11 g suspended solids/L, giving a concentration of 1.555 g suspended solids/L in this test. As a positive control, the reference item 3,5-dichlorophenol was tested.

The results of the study are presented in nominal test item concentration.

All the validity criteria for OECD 209 were successful.

This study was considered acceptable for that endpoint.