Eugenol

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

20 Nov 2012 to 23 Nov 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study in compliance with international recognised guidelines

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

2011

Deviations:

yes

Remarks:

The pH of the control changed by 1.9 units in the main study due to test design. As growth in the controls was in a normal range this was stated as uncritical.

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

2009

Deviations:

yes

Remarks:

The pH of the control changed by 1.9 units in the main study due to test design. As growth in the controls was in a normal range this was stated as uncritical.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0, 10, 18, 32, 56, 100 mg/L

Vehicle:

no

Details on test solutions:

A stock solution containing 102.85 mg/L in nutrient medium was prepared. The lower treatments were prepared by dilution of this stock solution with nutrient medium.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: CHODAT
- Source (laboratory, culture collection): MBM Sciencebridge GMBH (Institut füf Pflanzenphysiologie of Universität Göttingen)
- Method of cultivation: the aglae are kept as stock culture on solid agar at 8°C. From the stock culture, a permanent culture was prepared. From an aliquot of the permanent culture, the pre-culture was prepared.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23°C

pH:

7.4-9.3

Nominal and measured concentrations:

Nominal: 0, 10, 18, 32, 56, 100 mg/L
measured (geometric mean):

Details on test conditions:

TEST SYSTEM
- Test vessel: glass flasks
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: nominal volume 50 mL
- Aeration: none
- Initial cells density: 6618 cell counts/mL
- Control end cells density: 316561 cell counts/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: continuous
- Light intensity and quality: 5800 Lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: photometric measurement of optical density

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

23 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

23 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

23 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

38 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

38 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

38 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

23 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

35 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

< 22 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

24 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

36 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

23 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Duration:

72 h

Dose descriptor:

EC100

Effect conc.:

38 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC100

Effect conc.:

38 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC100

Effect conc.:

38 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

cell number

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): none noted
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: none
- Effect concentrations exceeding solubility of substance in test medium: no

Results with reference substance (positive control):

- Results with reference substance valid? Yes
-72h-ErC50: 1.1 mg/L

Reported statistics and error estimates:

The measured start concentrations showed a correlation with nominal concentrations in a range of 119% to 131%. After 72h, no test item was detectable in the two lowest concentrations. The other three concentrations showed a percentage to nominal from 21% to 97%, increasing with the treatment concentration. Since during the validation of the analytical method the test item had been stable over 72h in test medium (85% to the nominal concentration), the additional loss could be attributed to the presence of algae during the test (Ingestion or metabolisation of the test item by the alga).

The estimation of the EC50s of the test item was accomplished using the software Origin.

Validity criteria fulfilled:

yes

Conclusions:

The following results for the test item Eugenol USP 906 were determined:
72h NOEC = 23 mg/L
72h LOEC = 38 mg/L
72h ErC50 = 24 mg/L

Description of key information

OECD guideline 201, GLP, key study, validity 1 
72h-ErC50 = 24 mg/L.
72h- NOEC = 23 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:

24 mg/L

EC10 or NOEC for freshwater algae:

23 mg/L

Additional information

One toxicity study was performed to assess the acute toxicity of eugenol to the freshwater algae species Desmodesmus subspicatus (LAUS GmbH, 2013). The study was conducted under GLP and according to OECD Guideline 201. The study was conducted in a static system. Algae were exposed to the substance at a range of concentrations from 10 to 100 mg/L in freshwater. The test was performed with 3 replicates per test concentration and 6 replicates for the control. The following OECD 201 validity criteria were met: cell concentration in the control increased by a factor of 38 within 72h; the mean coefficient of variation of the daily growth rates were 33% and the coefficient of variation of average growth rate during the whole test period was 4%. However, the pH of the control changed by 1.9 units due to carbon dioxide decrease in the headspace as the carbon dioxide was absorbed during photosynthesis of the algae due to the closed test design; growth in the controls was normal. Under the conditions of the test, the 72 hour ErC50 was 24 mg/L.