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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:
9- 01-2017 to 12-01-2017
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:
Aim of this study was to evaluate the nature of chemical when comes in contact with the test organism. Test was conducted according to the OECD guideline 201.
GLP compliance:
not specified
Analytical monitoring:
not specified
Vehicle:
not specified
Details on test solutions:
The solution 100 mg/l was prepaired by dissolving colourless liquid 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
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: 100 mg/l pH = 7.8 , 7.6 during the test
Control: 8.0 changes to 7.9 during the test
Nominal and measured concentrations:
100 mg/l
Details on test conditions:
TEST SYSTEM
- Test vessel: 50 ml Glass vessel
- Type : closed
- 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: [I%]
Effect conc.:
1.5 other: %
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: Inhibition percentage
Results with reference substance (positive control):
- Results with reference substance valid
- EC50: 0.69 mg/L (24 hours)
Reported statistics and error estimates:
EC50 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 inhibition percentage [I%] was determine to be 1.5%.
Executive summary:

Aim of this study was to evaluate the nature of chemical 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. The solution 100 mg/l was prepaired by dissolving colourless liquid 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. The inhibition percentage for the test substance in algae was determined to be 1.5% on the basis of growth rate inhibition effects in a 72 hour study. Based on the EC50 value, indicates that the substance is likely to be non-hazardous to aquatic algae and cannot be classified as aquatic acute as per the CLP criteria.

Description of key information

Toxicity of aquatic algae and cyanobacteria:

Aim of this study was to evaluate the nature of chemical 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.The solution 100 mg/l was prepaired by dissolving colourless liquid 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. The inhibition percentage for the test substance in algae was determined to be 1.5% on the basis of growth rate inhibition effects in a 72 hour study. Based on the EC50 value, indicates that the substance is likely to be non-hazardous to aquatic algae and cannot be classified as aquatic acute as per the CLP criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:
100 mg/L

Additional information

Toxicity of aquatic algae and cyanobacteria:

Experimental study to evaluate toxicity of aquatic algae and cyanobcateria for the test material was performed according to OECD guideline , and along with the experimental report description of few peer reviewed journals and secondary sources were also described as mentioned below:

Aim of this study was to evaluate the nature of chemical 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.The solution 100 mg/l was prepared by dissolving colourless liquid 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. The inhibition percentage for the test substance in algae was determined to be 1.5% on the basis of growth rate inhibition effects in a 72 hour study. Based on the EC50 value, indicates that the substance is likely to be non-hazardous to aquatic algae and cannot be classified as aquatic acute as per the CLP criteria.

 

Similar short term toxicity to Chlorococcales (green algae) study was carried out for 24 hrs. The study was based on the effects of the test compound on green algae in a static fresh water system. Based on effect on physiology of the test organism Chlorococcales(green algae), the 24 hr EC10 and EC50 value was determined to be 340 and 1000 mg/l, respectively. Thus, based on the EC50 value, it can be concluded that the substance can be considered to be non-toxic to aquatic environment and can be considered to be not classified as per the CLP classification criteria.

 

In the third study toxicity of aquatic algae and cyano bacteria was evaluated for the test material . The test material was tested for 8 days on green algae Microcystis aeruginosa. The effect concentration (EC0) was observed to be 700 mg/l after 8 days. No toxic effects were observed on the test organism. Based on the above effect concentration it can be considered that test material is non toxic to aquatic algae and can not be classified as per CLP criteria.

 

Similarly in toxicity to green algae study for test material the biological effect was evaluated by using analogous methods of the cell multiplication inhibition test. Prepare dilutions with varying volume ratios using sterile double-distilled water. These dilutions each contain 1 part v/v of pollutant solution in 2 o to 214 parts v/v mixture. When preparing the two parallel dilution series in 300-ml Erlenmeyer flasks proceed as follows: the first flask of each dilution series contains 80 ml of pollutant solution at the start. Starting from this flask, prepare subsequent dilutions using a constant dilution ratio of 40 ml preliminary pollutant dilution + 40 ml double-distilled water. So each flask will first contain 40 ml of liquid. Then, complete each flask from the dilution series to be inoculated to the rated value of 50 ml by adding 5 ml each of stock solution I and 5 ml each of the algal suspension of the preliminary culture having a known adjusted extinction value. Scenedesmus quadricauda was used as test organism. Store stock cultures of the test strain Scenedesmus quadricauda in 20ml nutrient solution I in 100-ml Erlenmeyer flasks stoppered with metal caps, on a white surface protected against daylight and exposed to constant lighting by Luminescent worm white tubes at 60cm distance from each other, at 27°C and a relative humidity of 50%. For maintenance of the test strain, prepare fresh stock cultures continuously at 10days' intervals. The toxicity threshold (TT) of test material was determined to be 47mg/l for Scenedesmus quadricauda. Therefore LOEC was considered to be 47 mg/l for test material for 7 days in Scenedesmus quadricauda.

 

Long term toxicity to Scenedesmus quadricauda (green algae) study was carried out for 8 days. The study was based on the effects of the test compound on green algae in a static fresh water system at a temperature of 27°C and pH 7.0 respectively. Scenedesmus quadricauda was used as a test organism. Test substance was in double – distilled water, and the stock solution subsequently neutralized. Two parallel concentration series were tested, which is obtained by stepwise diluting (factor: 0.5) from one stock solutions. Start of test by adding aldehyde suspension with defined extinction value at 578 nm (water at unvaccinated Controls) and nutrient medium to the dilution series solutions. From each inoculated mixture, three cultured tubes of 10 ml solution (= test volume), one tube per tube control approach. 1 x daily shake the test cultures. Determination of the cell density at the photometric test at 578 nm (436 and 691 nm, respectively, in chemical-chemical cases conditional strong color of the culture medium) against algae-free blank. For the evaluation of the measurement results were cell density values ​​against the concentration of the test substance semi-logarithmic. The inhibition commencement was graphical determined from the cell density values ​​of the cultures with the highest non-toxic and the lowest toxic pollutant concentration. The TGK is maintained at 3% (standard deviation) below the cell density of cultures. Based on effect on cell density of the test organism Scenedesmus quadricauda, the LOEC value was determined to be > 47 mg/l, respectively.

 

Eventhough , some studies suggest that the test material has the potential to cause growth inhibition , but according to the effect values of experimental report and other authoratives databases and peer reviewed journal it can be considered that the test material has no negative impact on the growth rate of algae and can not be classified as per CLP criteria.