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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Experiment test result performed using standard test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Principles of method if other than guideline:
Short term toxicity of test chemical to aquatic algae was performed according to the 201 OECD guideline in a static system.
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
yes
Remarks:
Acetone
Details on test solutions:
The stock solution 100 g/l was prepared by dissolving colourless liquid in acetone. Test solutions of required concentrationas were prepared by mixing the stock solution of the test sample with reconstituted test water.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Green algae
- Strain: 86.81 SAG
- Source (laboratory, culture collection): Institute of botany of the ASCR
- Initial biomass concentration: 5x10(3) cells /ml
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Remarks on exposure duration:
±1 hour
Test temperature:
23±2°C
pH:
Test at highest concentration: 7.8 (Change to 7.7 during tests)
Control: 7.9 (changed to 7.6 during test)
Control + acetone: 7.9 (changed to 7.6 during test)
Nominal and measured concentrations:
0, 0, 5, 10, 20, 40, 80 mg/l nominal concentration
Details on test conditions:
TEST SYSTEM
- Test vessel: 50 ml Glass vessel
- Type (delete if not applicable): closed (with air permeable stopper)
- Sample volume: 15 ml
- Initial cells density: 5x10(3) cells/ml
- No. of vessels per concentration (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: Continuous
- Light intensity and quality: 6000-8000 lx

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: microscope with counting chamber Cyrus I or electronic particle counter.
- Other: ErC50 was calculated using non-linear regression by the software Prism 4.0
Reference substance (positive control):
yes
Remarks:
Potassium dichromate (K2Cr2O7)
Key result
Duration:
72 h
Dose descriptor:
other: ErC50
Effect conc.:
71.1 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95 % CI was 62.6 - 80.8 mg/l
Results with reference substance (positive control):
Results with reference substance valid
- EC50: 0.75 mg/L
Reported statistics and error estimates:
ErC50 is calculated from the inhibition of growth rate by non-linear regression using software Prism 4.0, GraphPad.
Validity criteria fulfilled:
yes
Conclusions:
The median effective concentration (ErC50) for the test substance on Desmodesmus subspicatus was determined to be 71.1 mg/L on the basis of effects on growth rate in a 72 hour study.
Executive summary:

Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance. Test was conducted according to OECD Guideline 201. The stock solution 100 mg/l was prepared by dissolving colourless liquid in acetone. Test solutions of required concentrationas were prepared by mixing the stock solution of the test sample with reconstituted test water. The test substance was tested at the concentrations 0, 0, 5, 10, 20, 40, 80 mg/L. Effects on growth rate were observed for 72 hours. The median effective concentration (ErC50) for the test substance, on Desmodesmus subspicatus was determined to be 71.1 mg/L for growth rate effects. This value indicates that the substance is likely to be hazardous to aquatic algae and can be classified as aquatic chronic 3 category as per the CLP criteria. But as the chemical was readily biodegradable thus it can be concluded that the chemical was nontoxic and not classified as per the CLP classification criteria.

Description of key information

Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance. Test was conducted according to OECD Guideline 201. The stock solution 100 mg/l was prepared by dissolving colourless liquid in acetone. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with reconstituted test water. The test substance was tested at the concentrations 0, 0, 5, 10, 20, 40, 80 mg/L. Effects on growth rate were observed for 72 hours. The median effective concentration (ErC50) for the test substance, on Desmodesmus subspicatus was determined to be 71.1 mg/L for growth rate effects. This value indicates that the substance is likely to be hazardous to aquatic algae and can be classified as aquatic chronic 3 category as per the CLP criteria. But as the chemical was readily biodegradable thus it can be concluded that the chemical was nontoxic and not classified as per the CLP classification criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:
71.1 mg/L

Additional information

Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance. Test was conducted according to OECD Guideline 201. The stock solution 100 mg/l was prepared by dissolving colourless liquid in acetone. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with reconstituted test water. The test substance was tested at the concentrations 0, 0, 5, 10, 20, 40, 80 mg/L. Effects on growth rate were observed for 72 hours. The median effective concentration (ErC50) for the test substance, on Desmodesmus subspicatus was determined to be 71.1 mg/L for growth rate effects. This value indicates that the substance is likely to be hazardous to aquatic algae and can be classified as aquatic chronic 3 category as per the CLP criteria. But as the chemical was readily biodegradable thus it can be concluded that the chemical was nontoxic and not classified as per the CLP classification criteria.

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