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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2017-06-05 to 2017-06-23
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
The test concentration and stability in test media were not analysed. The results were reported as nominal concentration only.
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
no
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 1000mg of the test substance were solved in 1.0mL solvent and filled up to 2mL with the solvent. This first stock solution was diluted with the solvent to prepare all needed stock solutions. 12µL of the respective stock solution were added to the test medium (120mL) to prepare the final test concentration.
- Controls: control and vehicle control
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): acetone
- Concentration of vehicle in test medium: 100µL/L (12µL added to 120mL)
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Strain: ATCC 22662
- Source (laboratory, culture collection): American Type Culture Collection, 10801, University of Boulevard, Manassas, Virginia, 20110-2209, USA
- Age of inoculum (at test initiation): 3 days
- Method of cultivation: static condition

ACCLIMATION
- Culturing media and conditions (same as test or not): yes
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
21 - 22°C
pH:
7.61 - 7.96
Nominal and measured concentrations:
control, vehicle control, 2.1, 4.7, 10.3, 227 and 50.0mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 230mL steril conical flasks filled with 120mL
- Initial cells density: 9583 cells/mL
- Control end cells density: 1014167 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes (OECD medium)

OTHER TEST CONDITIONS
- Photoperiod: continous light
- Light intensity and quality: 6277 - 6390 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: manual counting using haemocytometer and a microscope

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.2
- Range finding study: yes
- Test concentrations: control, vehicle control, 0.01, 0.1, 1.0, 10.0, 25.0 and 50.0mg/L
- Results used to determine the conditions for the definitive study: The percent inhibition of biomass was 1.66, 2.47, 3.91, 33.35, 74.85 and 96.73 at the test concentrations of 0.01, 0.1, 1.0, 10.0, 25.0 and 50.0 mg/L, respectively. The percent inhibition of growth rate was 0.18, 0.35, 0.35, 9.38, 32.04 and 77.17 at the test concentrations of 0.01, 0.1, 1.0, 10.0, 25.0 and 50.0 mgL/L, respectively.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
5.02 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
9.09 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
5.25 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
12.31 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
36.26 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
13.18 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
2.1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
4.7 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
4.7 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
10.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
- Exponential growth in the control (for algal test): yes
Results with reference substance (positive control):
- Results with reference substance valid? yes
- EC50: EbC50: 0.55mg/L; ErC50: 1.04mg/L; EyC50: 0.46mg/L

Mean Values of Algal Biomass, Yield, Specific Growth Rate

Test Concentration

(mg/L)

Mean Number of Cells Count/mL at

Specific Growth Rate

(0 - 3)

0 h

24 h

48 h

72 h

Yield

0.0 (Control)

9583

47917

222083

1014167

1004584

1.56

0.0 (vehicle control)

47917

218333

1012500

1002917

1.55

2.1

47500

217500

1010833

1001250

1.55

4.7

41667

185833

860000

850417

1.50

10.3

30000

133333

610000

600417

1.38

22.7

14167

64167

268333

258750

1.11

50.0

3333

10833

46667

37084

0.53

  Percentage (%) Inhibition of Biomass, Growth Rate, and Yield

Test Concentration

(mg/L)

Percentage (%) Inhibition of

Biomass

0 - 72 h

Growth Rate

0 - 72 h

Yield

0 - 72 h

0.0 (Control)

-

-

-

0.0 (vehicle control)

-

-

-

2.1

0.28

0.00

0.17

4.7

15.36

3.55

15.21

10.3

40.63

10.82

40.13

22.7

74.81

28.44

74.20

50.0

98.19

66.00

96.30

Validity criteria fulfilled:
yes
Conclusions:
The toxicity of the test item OEA was examined in an algae test according to OECD 201 and under GLP conditions. Cells of Pseudokirchneriella subcapitata were exposed to OEA in concentrations of 2.1, 4.7, 10.3, 227 and 50.0mg/L, a vehicle control and a control for 72 hours. The percent inhibition of biomass was 0.28, 15.36, 40.63, 74.81 and 98.19% for the test concentrations of 2.1, 4.7, 10.3, 22.7 and 50.0 mg OEA/L, respectively. The percent inhibition of growth rate was 0.00, 3.55, 10.82, 28.44 and 66.0% for the test concentrations of 2.1, 4.7, 10.3, 22.7 and 50.0 mg OEA/L, respectively. EC50 were calculated at 12.31 and 36.26mg OEA/L for biomass and growth rate, respectively. EC10 were calculated at 5.02 and 9.09mg OEA/L for biomass and growth rate, respectively.

Description of key information

ErC50 (72 -h) = 36.26 mg/L based on nominal concentration

ErC10 (72 -h) = 9.09 mg/L based on nominal concentration

Key value for chemical safety assessment

EC50 for freshwater algae:
36.26 mg/L
EC10 or NOEC for freshwater algae:
9.09 mg/L

Additional information

The toxicity of the test item OEA was examined in an algae test according to OECD 201 and under GLP conditions. Cells of Pseudokirchneriella subcapitata were exposed to OEA in concentrations of 2.1, 4.7, 10.3, 227 and 50.0mg/L, a vehicle control and a control for 72 hours. The percent inhibition of biomass was 0.28, 15.36, 40.63, 74.81 and 98.19% for the test concentrations of 2.1, 4.7, 10.3, 22.7 and 50.0 mg OEA/L, respectively. The percent inhibition of growth rate was 0.00, 3.55, 10.82, 28.44 and 66.0% for the test concentrations of 2.1, 4.7, 10.3, 22.7 and 50.0 mg OEA/L, respectively. EC50 were calculated at 12.31 and 36.26mg OEA/L for biomass and growth rate, respectively.

EC10 were calculated at 5.02 and 9.09mg OEA/L for biomass and growth rate, respectively.