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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
April 16-June 25, 2020
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2020
Report date:
2020

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
(Z)-non-6-enal
EC Number:
218-900-9
EC Name:
(Z)-non-6-enal
Cas Number:
2277-19-2
Molecular formula:
C9H16O
IUPAC Name:
(Z)-non-6-enal
Test material form:
liquid

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Concentrations: all concentrations

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
The test substance was added to brown sterile bottles and sterilized synthetic growth medium was added with a sterilized stir bar. The test solution was then stirred for 72 hrs. It was then allowed to settle for 1 hr. Since the test substance had a higher density than water, it settled to the bottom of the flask. The settled test substance in the bottom 300 mL was drawn off, and the test solution taken from the higher water layer saturated with test substance.
- Controls:
No test substance.
- Evidence of undissolved material (e.g. precipitate, surface film, etc.):
At higher concentration some precipitate may have formed.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Strain: 61.81 SAG
- Source (laboratory, culture collection): SAG, Culture Collection of Algae at Pflanzenphysiologisches Institut of the University of Gottingen
- Method of cultivation: Cultures were maintained according to OECD guidelines

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h

Test conditions

Test temperature:
21-24 degrees C
pH:
7.35-7.72
Nominal and measured concentrations:
Nominal: 9.53, 17.1, 30.9, 55.6, 100 mg/L active ingredient
Measured: 0.63, 1.74, 3.79, 7.64, 12.7 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: conical flasks
- Type (delete if not applicable): air-permeable silicon sponge caps
- Material, size, headspace, fill volume: 250 mL glass
- Initial cells density: 5000 cells/mL
- Control end cells density: 822,000 cells/mL
- No. of organisms per vessel:
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 8

GROWTH MEDIUM
- Standard medium used: yes
- Detailed composition if non-standard medium was used:

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: purified water


OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Light intensity and quality: 4440-8880 Lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) cell concentration at 24, 48, and 72 hrs after start of exposure
- Determination of cell concentrations: electronic particle counter


TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.8
- Justification for using less concentrations than requested by guideline:
- Range finding study
- Test concentrations: 1,10, and 100 mg/L
- Results used to determine the conditions for the definitive study:
Reference substance (positive control):
yes
Remarks:
3,5-dichlorophenol was used as a positive control twice a year.

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
3.31 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.5 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
< 0.63 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Details on results:
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): Abnormalities were seen at all test concentrations of 1.74 mg/L and above.
- Unusual cell shape: Low numbers of normal cells were seen at concentrations of 1.74 mg/L and above.
- Flocculation: Cell debris was seen at all test concentrations, increasing as concentration increased.
Results with reference substance (positive control):
- Results with reference substance valid? yes
- EC50: 2.92 mg/L
Reported statistics and error estimates:
95% confidence limit for EC50: 2.97-3.67 mg/L

Any other information on results incl. tables

Nominal Concetration (mg a.s./L)

Measured Concentration (Geometric Mean, mg a.s./L)

Growth Rate (1/day)

% Inhibition of Growth Rate

Yield (Cells x 104mL)

% Inhibition

Control

--

1.695

--

81.7

--

9.53

0.63

1.416

+16.5

34.8

+57.4

17.1

1.74

1.139

+32.8

15.4

+81.1

30.9

3.79

0.801

+52.8

5.1

+93.7

55.6

7.64

0.397

+76.6

1.2

+98.6

100

12.7

0.114

+93.3

0.2

+99.7

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The 72-hr EC50 based on growth rate was 3.31 mg/L based on measured concentrations.
Executive summary:

The toxicity of the test substance to algae was tested in an OECD Guideline 201 test. Algae were exposed to measured concentrations of 0.63, 1.74, 3.79, 7.64, and 12.7 mg/L for 72 hours. Negative controls were also performed. Four replicates were performed. The NOEC was less than 0.63 mg/L based on measured concentrations. The 72-hr EC50 based on growth rate was 3.31 mg/L based on measured concentrations.