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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:
Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance test chemical according to OECD Guideline 201.
GLP compliance:
no
Analytical monitoring:
not specified
Vehicle:
yes
Details on test solutions:
The stock solution (50 mg/L) was prepared by dissolving colourless liquid in OECD growth medium. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Desmodesmus subspicatus
- 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:
The sample at test concentration 10.0 mg/l : pH = 8.0 changed to pH = 7.7 during the test.
Control: 8.0 (changed to 7.5 during test)
Nominal and measured concentrations:
0, 0.7, 5, 1.2, 2.0, 3.5, 5.8 and 10 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): 3
- Other:
Control solution: OECD growth medium without the sample, the coefficient of variation of average growth rate in replicates during the whole test period was 2.0%.

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) was used as a reference substance for the study.
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
1.6 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL: 1.3 - 2.1
Results with reference substance (positive control):
Results with reference substance valid
- EC50: 0.75 mg/L
Validity criteria fulfilled:
yes
Conclusions:
The median effective concentration (EC50) for the test substance in Desmodesmus subspicatus was determined to be 1.6 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 in accordance with OECD Guideline 201 (Alga, Growth Inhibition Test). The stock solution (50 mg/L) was prepared by dissolving colourless liquid in OECD growth medium. Test solutions  of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Conc. of test chemical used for the study were 0, 0.7, 5, 1.2, 2.0, 3.5, 5.8 and 10 mg/L, respectively. The test was performed under static conditions in a static fresh water system at a temp. of 23±2°C. Initial cell density of test organism used was 5x10(3) cells/ml. Determination of cell counting involve the use of microscope with counting chamber Cyrus I or electronic particle counter.. ErC50 was calculated using non-linear regression by the software Prism 4.0. The median effective concentration (EC50) for the test substance in Desmodesmus subspicatus was determined to be 1.6 mg/L on the basis of effects on growth rate in a 72 hour study. Thus, based on this value, test chemical can be considered as toxic to aquatic organisms and thus can be classified as aquatic chronic category 2 as per the CLP criteria.

Description of key information

Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance in accordance with OECD Guideline 201 (Alga, Growth Inhibition Test). The stock solution (50 mg/L) was prepared by dissolving colourless liquid in OECD growth medium. Test solutions  of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Conc. of test chemical used for the study were 0, 0.7, 5, 1.2, 2.0, 3.5, 5.8 and 10 mg/L, respectively. The test was performed under static conditions in a static fresh water system at a temp. of 23±2°C. Initial cell density of test organism used was 5x10(3) cells/ml. Determination of cell counting involve the use of microscope with counting chamber Cyrus I or electronic particle counter.. ErC50 was calculated using non-linear regression by the software Prism 4.0. The median effective concentration (EC50) for the test substance in Desmodesmus subspicatus was determined to be 1.6 mg/L on the basis of effects on growth rate in a 72 hour study. Thus, based on this value, test chemical can be considered as toxic to aquatic organisms and thus can be classified as aquatic chronic category 2 as per the CLP criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:
1.6 mg/L

Additional information

Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance in accordance with OECD Guideline 201 (Alga, Growth Inhibition Test). The stock solution (50 mg/L) was prepared by dissolving colourless liquid in OECD growth medium. Test solutions  of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Conc. of test chemical used for the study were 0, 0.7, 5, 1.2, 2.0, 3.5, 5.8 and 10 mg/L, respectively. The test was performed under static conditions in a static fresh water system at a temp. of 23±2°C. Initial cell density of test organism used was 5x10(3) cells/ml. Determination of cell counting involve the use of microscope with counting chamber Cyrus I or electronic particle counter.. ErC50 was calculated using non-linear regression by the software Prism 4.0. The median effective concentration (EC50) for the test substance in Desmodesmus subspicatus was determined to be 1.6 mg/L on the basis of effects on growth rate in a 72 hour study. Thus, based on this value, test chemical can be considered as toxic to aquatic organisms and thus can be classified as aquatic chronic category 2 as per the CLP criteria.