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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:
September 26-28, 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2017
Report Date:
2017

Materials and methods

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

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: flakes
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Mitsubishi-Chemical Foods Corporation; 63281211
- Expiration date of the lot/batch: March 27, 2018
- Purity test date: May 30, 2017


STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: below 15 degrees C, in dark well-ventilated space
- Stability under test conditions: stable

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Concentrations: all
- Sampling method: Two samples from each test solution and control were taken prior to addition of alga, and at the end of the test
- Sample storage conditions before analysis: samples were stored at -25 degrees C

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 100.03 mg of test substance was added to 1 L glass bottles. Growth medium was added, and the solution placed in an ultrasonic bath at 30 degrees C for 2 hrs. It was then stirred for 2.5 days at room temperature. The test solution was then filtered.
- Eluate: The eluate was used as the highest test concentration. Lower test concentrations were prepared by additional dilutions with growth medium.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Source (laboratory, culture collection): SAG, Culture Collection of Algae at Pflanzenphysiologisches Institut of the University of Gottingen


ACCLIMATION
- Acclimation period: 3 days

Study design

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

Test conditions

Test temperature:
22 degrees C
pH:
7.21-7.70
Nominal and measured concentrations:
Due to difficulties analyzing the concentration of test substance in the test medium, nominal concentrations were reported.
The nominal concentrations were 0, 6.25, 12.5, 25.0, 50.0, and 100.0 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 250 mL glass flasks
- Type (delete if not applicable): open (air-permeable silicone-sponge caps)
- Material, size, headspace, fill volume: glass, 250 mL fill volume
- Aeration: No
- Initial cells density: 10,000 cells/mL
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 8


GROWTH MEDIUM
- Standard medium used: yes

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


OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Light intensity and quality: 92.17 to 93.28 uE m^-2 s^-1

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

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study
- Test concentrations: 0, 6.25, 12.5, 25.0, 50.0, and 100 mg/L
- Results used to determine the conditions for the definitive study: at 100 mg/L the yield was inhibited 45.1%
Reference substance (positive control):
yes
Remarks:
The sensitivity of the test organism is tested twice a year with 3.5-dichlorophenol.

Results and discussion

Effect concentrations
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 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
- Observation of abnormalities (for algal test): no abnormalities were observed
- Unusual cell shape: no
- Colour differences: no

Any other information on results incl. tables

Inhibition of Algal Growth at 72 hrs

Concentration (mg/L)

Growth rate (1/d)

% Inhibition – Growth Rate

Yield

(cells x 104/mL)

% Inhibition - Yield

0

1.6143

--

127.4625

--

6.25

1.5476

4.13*

102.8725

19.29*

12.5

1.6687

-3.37

148.5000

-16.50

25.0

1.5926

1.35

117.8750

7.52

50.0

1.5414

4.52*

100.9725

20.78*

100.0

1.5532

3.79

105.0925

17.55

* Significantly different from Controls

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The 72-hr EC50 based on both growth rate and yield is > 100 mg/L.
Executive summary:

The toxicity to algae for the test substance LMDT was determined in an OECD guideline 201 test. The nominal concentrations tested were 0, 6.25, 12.5, 25.0, 50.0, and 100.0 mg/L. Due to difficulties in analyzing the substance, analytical concentrations were not determined. The 72-hr EC50 based on both growth rate and yield is > 100 mg/L.