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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:
July - August 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Version / remarks:
2011
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Version / remarks:
2016
Qualifier:
according to guideline
Guideline:
EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II) (January 2012)
Version / remarks:
1996
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
Six formulation samples were analysed from the test concentration (100 mg/L) and from the control at the start and at the end of experiment.
Vehicle:
no
Details on test solutions:
The test solution used in the test was prepared by mechanical dispersion without using of any solubilising agent.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Green algae
- Strain: 61.81 SAG (identical strains: CCAP 278/4; UTEX 1648; ATCC 22662)
- Source: SAG: Collection of Algal Cultures, Inst. Plant Physiology, University of Göttingen, Untere Karspüle 2, D-37073 Göttingen, Germany
- Age of inoculum: 4 days

ACCLIMATION
- Acclimation period: no
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Test temperature:
21.5 – 21.9°C
pH:
7.69 – 9.13
Nominal and measured concentrations:
nominal concentration: 100 mg/L
measured concentration: 96 - 99 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Material, size, fill volume: glass, ~250 mL volume, 100 mL test medium
- Aeration: no
- Initial cells density: 1 × 10E4 cells/mL
- Control end cells density: 98 × 10E4 cells/mL
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes, OECD Medium

TEST MEDIUM / WATER PARAMETERS
- Preparation of dilution water: Reconstituted algal growth medium (OECD medium, according to OECD 201) was used as dilution water. Separate stock solutions were prepared in deionised water (prepared in TOXI-COOP ZRT. by MILLIPORE ELIX 3 water purification system). Then, the growth medium was prepared by adding an appropriate volume of these different stock solutions to deionised water in order to achieve the final concentrations.
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: continuous illumination
- Light intensity and quality: 7914 lux, fluorescent lamps (400-700 nm)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: at 24, 48 and 72 h manual cell counting using microscope with counting chamber

TEST CONCENTRATIONS
- Justification for using less concentrations than requested by guideline: results of range finding study
- Range finding study: no significant toxic effects observed
- Test concentrations: 0.1, 1, 10, 100 mg/L
- Results used to determine the conditions for the definitive study: yes

STATISTICAL ANALYSIS
Statistical comparisons of average specific growth rates and yield in control and in treated group were carried out using Independent Samples T-Test (2-tailed; α = 0.05) by SPSS software.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate (K2Cr2O7)
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
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Key result
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Details on results:
The measured EC50 is >100 mg/L, the calculated value for anhydrous substance is >85.8 mg/L
- Exponential growth in the control: yes (factor 98)
- Observation of abnormalities: no
- Unusual cell shape: no
- Colour differences: no
- Flocculation: no
- Adherence to test vessels: no
- Aggregation of algal cells: no
- Any observations that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: no
Results with reference substance (positive control):
- Results with reference substance valid - yes
- ErC50: 0.99 mg/L; EyC50: 0.59 mg/L
Validity criteria fulfilled:
yes
Conclusions:
The effect of the test item to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined according to the principles of OECD 201 and Council Regulation (EC) No. 761/2009 C.3. The EC50-values for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were above 100 mg/L. The NOEC-values for both inhibition of growth rate and yield after 72 hours were 100 mg/L, respectively.
Executive summary:

The effect of the test item to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined according to the principles of OECD 201 and Council Regulation (EC) No. 761/2009 C.3 (reference 6.1.5 -1). The study was conducted under static conditions. The definitive test was carried out with one concentration of 100 mg/L because of the results of the pretest. In this study, following effect values were measured (based on nominal test item concentrations): The EC50-values for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours for the test item were 100 mg/L, the calculated value for anhydrous form is >85.8 mg/L. The EC-10-values for inhibition of growth rate (ErC10) and yield (EyC10) after 72 hours for the test item were 100 mg/L, the calculated values for anhydrous form are >85.8 mg/L.. The NOEC-values for both inhibition of growth rate and yield after 72 hours were 100 mg/L for the test item and 85.8 mg/L for the anhydrous form, respectively.

Description of key information

The effect of the test item to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined according to the principles of OECD 201 and Council Regulation (EC) No. 761/2009 C.3 (reference 6.1.5 -1).

The EC50-values for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours for the test item were 100 mg/L, the calculated value for anhydrous form is >85.8 mg/L. The EC-10-values for inhibition of growth rate (ErC10) and yield (EyC10) after 72 hours for the test item were 100 mg/L, the calculated values for anhydrous form are >85.8 mg/L..

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

The effect of the test item to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined according to the principles of OECD 201 and Council Regulation (EC) No. 761/2009 C.3 (reference 6.1.5 -1). The study was conducted under static conditions. The definitive test was carried out with one concentration of 100 mg/L because of the results of the pretest. In this study, following effect values were measured (based on nominal test item concentrations): The EC50-values for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours for the test item were 100 mg/L, the calculated value for anhydrous form is >85.8 mg/L. The EC-10-values for inhibition of growth rate (ErC10) and yield (EyC10) after 72 hours for the test item were 100 mg/L, the calculated values for anhydrous form are >85.8 mg/L.. The NOEC-values for both inhibition of growth rate and yield after 72 hours were 100 mg/L for the test item and 85.8 mg/L for the anhydrous form, respectively.