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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:
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 action 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:
yes
Remarks:
Acetone
Details on test solutions:
The stock solution 1 g/l was prepared by dissolving white powder in acetone. 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: algae
- 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 0.16 mg/l: 7.9 change to 7.2
Control 1: 8 changed to 7.4 during test
Control 1+ acetone: 7.9 change to 7.3
Control 2: 8.1 changed to 7.6 during test
Control 2 + acetone: 7.9 change to 7.3
Nominal and measured concentrations:
0, 0.0025, 0.0050, 0.0100, 0.0200, 0.0400, 0.0800, 0.1600 mg/l concentrations were used in the study.
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.:
0.034 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95 % CI was 0.0237 mg/l to 0.0500 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

Control solution: OECD growth medium without the sample, the coefficient of variation of average growth rate in replicates during the whole test period was 1.5 % in control 1 and 3.7 % in control 1 + acetone, 4.2 % in control 2 and 0.5 % in control 2 + acetone

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 0.0344 mg/l.
Executive summary:

Objective of this study was to observe the action 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). The stock solution 1 g/l was prepared by dissolving white powder in acetone. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Test conducted on various nominal concentration of test chemcal is 0, 0.0025, 0.0050, 0.0100, 0.0200, 0.0400, 0.0800, 0.1600 mg/l. 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, the ErC50 was determine to be 0.0344 mg/l. Thus on the basis of ErC50 value, chemical concluded to be toxic and can be consider to be classified in aquatic acute category 1 as per the CLP classification criteria.

Description of key information

Objective of this study was to observe the action 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). The stock solution 1 g/l was prepared by dissolving white powder in acetone. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Test conducted on various nominal concentration of test chemical is 0, 0.0025, 0.0050, 0.0100, 0.0200, 0.0400, 0.0800, 0.1600 mg/l. 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, the ErC50 was determine to be 0.0344 mg/l. Thus on the basis of ErC50 value, chemical concluded to be toxic and can be consider to be classified in aquatic acute category 1 as per the CLP classification criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:
0.034 mg/L

Additional information

Various studies were reviewed to determine the toxic nature of test chemical on the growth of aquatic algae and cyanobacteria. The studies are as mentioned below:

 

Objective of this study was to observe the action 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). The stock solution 1 g/l was prepared by dissolving white powder in acetone. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Test conducted on various nominal concentration of test chemical is 0, 0.0025, 0.0050, 0.0100, 0.0200, 0.0400, 0.0800, 0.1600 mg/l. 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, the ErC50 was determine to be 0.0344 mg/l. Thus on the basis of ErC50 value, chemical concluded to be toxic and can be consider to be classified in aquatic acute category 1 as per the CLP classification criteria.

 

First study was supported by the second study from peer reviewed journal. The present study was based on the effect of test chemical on the growth of the freshwater algae Pseudokirchneriella subcapitata. Test conducted in accordance with the OECD guideline 201 with some modification. 1000 mg/l stock solution of test chemical was prepared in methanol. The freshwater unicellular green alga P. subcapitata Hinda´k was obtained from the Algae Culture Collection. Test conducted under the static system for 72 hrs. Five to six concentrations of each test substance in a geometric series (common ratio = 2) were used and performed in triplicates. Yield of algal cells was calculated indirectly by measuring the optical density of the cell suspension at a wavelength of 442 nm using a Helios Alpha spectrophotometer. The effects of test chemical on the growth of the green alga P. subcapitata over 72-h were determined. The Low observed effect concentration (LOEC) of test chemical in Pseudokirchneriella subcapitata in 72hr study on the basis of growth was observed to be 0.01 mg/l. Whereas, the NOEC of test chemical in Pseudokirchneriella subcapitata in 72hr study on the basis of growth was determine to be < 0.01 mg/l. Also, inhibitory concentration (IC50) in 72hr on the basis of growth was observed 0.017 mg/l. Thus chemical consider to be toxic and classified in aquatic acute category 1.

 

 

Similar acute toxicity of test chemical on aquatic green algae were determine under the static system. The effects of test chemical on the growth of the green alga (Pseudokirchneriella subcapitata) over 72-h were determined. The effective concentration (EC50) of test chemical on Pseudokirchneriella subcapitata in 72hr study on the basis of growth rate inhibition was determine to be 0.029 mg/l. Thus based on the EC50 value, chemical consider to be toxic and classified as aquatic acute 1 as per the CLP classification criteria.

 

Thus based on the above all studies from various sources, chemical consider to be toxic and classified as aquatic acute category 1 as per the CLP classification criteria.