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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
Study period:
21.05.2018 to 24.05.2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
Experimental test result performed using standard test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Principles of method if other than guideline:
Objective of this study was to observe the effect of test chemical when it exposed with the Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) for 72 hrs. Test conducted in accordance with OECD Guideline 201 (Alga, Growth Inhibition Test).
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
The stock solution 100 mg/l was prepared by dissolving white crystalline substance in OECD growth medium.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name:
- Strain: 86.81 SAG
- Source (laboratory, culture collection): Institute of botany of the ASCR
- Initial biomass concentration: 5x10(3) cells /ml
- Method of cultivation: No data available

ACCLIMATION - No data available
- Acclimation period:
- Culturing media and conditions (same as test or not):
- Any deformed or abnormal cells observed:
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Test temperature:
23±2°C
pH:
Test at highest concentration: 8.1 change to 8 during test
Control: 8.1 changes to 8
Nominal and measured concentrations:
100 mg/l
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): 6

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: Inhibitiory percent
Effect conc.:
100 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: Only 2 % inhibition were observed
Results with reference substance (positive control):
- Results with reference substance valid
- ErC50: 0.77 mg/L (24 hours)
Reported statistics and error estimates:
The differences in means of control and sample were estimated by the t-test for independent groups at a 95 % confidence level, all individual replicates were used (STATISTICA CZ – data analysis software system, version 9.0, StatSoft, Inc.). Statistically significant differences are for p < 0.05.
Validity criteria fulfilled:
yes
Conclusions:
Based on the growth rate inhibition of algae Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) due to the exposure of chemical the for 72 hrs, only 2 % inhibition were observed at 100 mg/l.
Executive summary:

Aim of this study was to evaluate the nature of test chemical when comes in contact with the test organism Desmodesmus subspicatus (previous name: Scenedesmus subspicatus). Test was conducted according to the OECD guideline 201. Limit test performed using 100 mg/l. The stock solution 100 mg/l was prepared by dissolving white crystalline substance in OECD growth medium. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs. Based on the growth rate inhibition of algae Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) due to the exposure of chemical for 72 hrs, only 2 % inhibition were observed at 100 mg/l. Thus based on the above effect, chemical consider to be non-hazardous to aquatic algae and cannot be classified as per the CLP classification criteria.

Description of key information

Aim of this study was to evaluate the nature of test chemical when comes in contact with the test organism Desmodesmus subspicatus (previous name: Scenedesmus subspicatus). Test was conducted according to the OECD guideline 201. Limit test performed using 100 mg/l. The stock solution 100 mg/l was prepared by dissolving white crystalline substance in OECD growth medium. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs. Based on the growth rate inhibition of algae Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) due to the exposure of chemical for 72 hrs, only 2 % inhibition were observed at 100 mg/l. Thus based on the above effect, chemical consider to be non-hazardous to aquatic algae and cannot be classified as per the CLP classification criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:
100 mg/L

Additional information

Based on the experimental studies for the test chemical, studies were reviewed and mention as below:

In the first experimental study toxicity were evaluated. Aim of this study was to evaluate the nature of test chemical when comes in contact with the test organism Desmodesmus subspicatus (previous name: Scenedesmus subspicatus). Test was conducted according to the OECD guideline 201. Limit test performed using 100 mg/l. The stock solution 100 mg/l was prepared by dissolving white crystalline substance in OECD growth medium. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs. Based on the growth rate inhibition of algae Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) due to the exposure of chemical for 72 hrs, only 2 % inhibition were observed at 100 mg/l. Thus based on the above effect, chemical consider to be non-hazardous to aquatic algae and cannot be classified as per the CLP classification criteria.

 

First study was supported by the second study. The effect of test substance was studied on the growth of fresh water green alga Chlorella vulgaris. The study was conducted following OECD guideline 201- Alga growth inhibition test. The test concentration chosen for the study were 6.25 mg/l, 12.5 mg/l, 25 mg/l, 50 mg/l, 100 mg/l and 200 mg/l were prepared using stock solution of the test substance using de-ionized water. The green alga was exposed to the test concentration for a period of 72 hours to observe average specific growth rate and % growth inhibition under the effect of test substance. After 72 hours of exposure to test chemical to various nominal test concentration, EC25 was observed to be at 200 mg/L on the basis of growth rate inhibition, graphically through probit analysis. Thus based on the effect concentration, chemical consider to be nontoxic and not classified as per the CLP classification criteria.

Thus based on the above both studies, chemical consider to be nontoxic and not classified as per the CLP classification criteria.