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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
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 nature of test chemical when it exposed with the green algae 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:
yes
Remarks:
DMSO
Details on test solutions:
The stock solution 100 g/l was prepared by dissolving colourless in DMSO. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. The substance formed a few small balls in the growth medium above the concentration of 58 mg/l.
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
Total exposure duration:
72 h
Test temperature:
23±2°C
pH:
Test at highest concentration 100 mg/l: pH 8 did not change during test
Control: pH 8 did not change during test
Control + acetone: pH 8 changed to 8.2 during test
Nominal and measured concentrations:
0, 0, 10, 18, 32, 58 and 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: 7.5 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:
EC50
Effect conc.:
50.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95 % CI is 42 to 60.6 mg/l
Results with reference substance (positive control):
- Results with reference substance valid
- ErC50: 0.77 mg/L (24 hours)
Reported statistics and error estimates:
ErC50 was calculated using non linear regression by the software Prism 4.0
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 ErC50 was determine to be 50.4 mg/l.
Executive summary:

Objective of this study was to observe the nature of test chemical when it exposed with the green algae Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) for 72 hrs. Test conducted in accordance with OECD Guideline 201 (Alga, Growth Inhibition Test). The stock solution 100 g/l was prepared by dissolving colourless in DMSO. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. The substance formed a few small balls in the growth medium above the concentration of 58 mg/l. 0, 0, 10, 18, 32, 58 and 100 mg/l nominal concentrations were used in the study. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration ErC50 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, the ErC50 was determine to be 50.4 mg/l. Based on the ErC50 value, which 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 classification criteria. But as the chemical is readily biodegradable in water, thus on that basis, it states that the chemical was nontoxic and not classified as per the CLP classification criteria.

Description of key information

Objective of this study was to observe the nature of test chemical when it exposed with the green algae Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) for 72 hrs. Test conducted in accordance with OECD Guideline 201 (Alga, Growth Inhibition Test). The stock solution 100 g/l was prepared by dissolving colourless in DMSO. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. The substance formed a few small balls in the growth medium above the concentration of 58 mg/l. 0, 0, 10, 18, 32, 58 and 100 mg/l nominal concentrations were used in the study. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration ErC50 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, the ErC50 was determine to be 50.4 mg/l. Based on the ErC50 value, which 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 classification criteria. But as the chemical is readily biodegradable in water, thus on that basis, it states that the chemical was nontoxic and not classified as per the CLP classification criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:
50.4 mg/L

Additional information

Objective of this study was to observe the nature of test chemical when it exposed with the green algae Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) for 72 hrs. Test conducted in accordance with OECD Guideline 201 (Alga, Growth Inhibition Test). The stock solution 100 g/l was prepared by dissolving colourless in DMSO. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. The substance formed a few small balls in the growth medium above the concentration of 58 mg/l. 0, 0, 10, 18, 32, 58 and 100 mg/l nominal concentrations were used in the study. With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration ErC50 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, the ErC50 was determine to be 50.4 mg/l. Based on the ErC50 value, which 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 classification criteria. But as the chemical is readily biodegradable in water, thus on that basis, it states that the chemical was nontoxic and not classified as per the CLP classification criteria.