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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:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
Experimental data of read across substance
Justification for type of information:
Data for the target chemical is summarized based on the structurally similar read across chemicals.
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
other: As mention below
Principles of method if other than guideline:
WoE report is prepared based on short term toxicity to aquatic invertebrates studies
GLP compliance:
not specified
Analytical monitoring:
yes
Remarks:
In first study analytical monitoring was done
Vehicle:
not specified
Details on test solutions:
WoE-2 Method: Test solutions were prepared by mixing a stock solution of the test substance, which was prepared by adding and stirring the substance under the water surface of the Erlenmeyer flask filled with medium.

WoE-3: The stock solution (150 mg/L) was prepared by dissolving colourless liquid in OECD growth medium. The solution was kept in ultrasonic bath for 20 min. It was not possible to prepare homogenous solution of higher concentration. Test solutions of required concentration were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture.
Test organisms (species):
other: 1. Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum), 2. Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
WoE-2 :Details on test organisms
TEST ORGANISM
- Common name: Green algae

WoE-3:
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:
no
Total exposure duration:
72 h
Test temperature:
WoE-2: 22.3 - 22.6 ° C
WoE-3: 23 ± 2°C
pH:
WoE-3: Without adjustment,
The sample at concentration 150 mg/l: pH= 7.7 did not changed during the test,
Control: pH= 8.1 changed to 7.9 during the test
Nominal and measured concentrations:
WoE-2: 500, 160, 50, 16, 5.0 mg/L (geometric ratio; square root of 10), control
WoE-3 : 0, 30, 45, 67, 100 and 150 mg/L
Details on test conditions:
WoE-2: TEST SYSTEM:
- Test vessel: Erlenmeyer flask
- Exposure system: rotary shaking culture (ca. 100 rpm),
- Material, size, headspace, fill volume: test solution volume; 600 mL/control (100 mL/vessel), 300 mL/ concentration (100 mL/vessel), (Separately, a vessel was reserved for analysis at 48 hours.)
- No. of vessels per concentration (replicates): 3 (Separately from that, another vessel for analysis at 48 hours was prepared.)
- No. of vessels per control (replicates):6

EFFECT PARAMETERS MEASURED:
- Measurement of biomass: Cell concentration

OTHER TEST CONDITIONS:
- Light intensity and quality: 98 - 99 microE/m2/s


WoE-3:
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:
for WoE-3: Potassium dichromate (K2Cr2O7)
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
250 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95 % CL: 220 - 270 mg/L
Remarks:
1st study
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
172.9 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL: 170.7 - 175.1 mg/l
Validity criteria fulfilled:
not specified
Conclusions:
After exposure of test chemical to aquatic algaefor 72 hrs the  EC 50 value of test chemical is expected to be in range from 172.9 to 250 mg/l. By considering this range EC 50 value test chemical is considered to be non toxic and not classified as per the CLP classification criteria.  
Executive summary:

Short term toxicity of test chemical on the growth of aquatic algae was carried out on the basis of it structurally and functionally similar read across chemicals. The results of both the studies are as mentioned below:

 

Freshwater algal growth inhibition test was carried out according to OECD Guideline 201. The test organism used in this study was on Desmodesmus subspicatus .The stock solution (150 mg/L) of test chemical was prepared by dissolving test chemical in OECD growth medium. The solution was kept in ultrasonic bath for 20 min. Test solutions of required concentration were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture and tested at the concentrations 0, 30, 45, 67, 100 and 150 mg/L. Effects on the growth rate of the organism were studied. The median effective concentration (EC50) for the test chemical, in Desmodesmus subspicatus was determined to be 172.9 mg/L. This value indicates that the substance is likely to be non-hazardous to aquatic algae and can be considered as not classified as per the CLP criteria.

 

 In another study the Growth Inhibition of Alga (Pseudokirchneriella subcapitata) was determined by the exposing the test chemical for 72 hrs. Test conducted according to OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test). Test solutions were prepared by mixing a stock solution of the test substance, which was prepared by adding and stirring the substance under the water surface of the Erlenmeyer flask filled with medium. Test was conducted at the different concentrations 500, 160, 50, 16, 5.0 mg/L (geometric ratio; square root of 10), control. Analytical monitoring was also done using the GC were the Frequency of analysis was at the start of exposure, after 4 hours from start of exposure, and at the end of exposure. Based on the growth rate inhibition of test organism Pseudokirchneriella subcapitata due to exposure of test chemical for 72 hrs, the effect concentration EC50 and NOEC value was determined to be 250 mg/l and 16 mg/l respectively. Thus on the basis of EC50, test chemical was consider as nontoxic and not classified as toxic as per the CLP classification criteria.

 

Thus based on the results of both the studies for test chemical, it can be concluded that EC 50 value of test chemical is expected to be range from 172.9 to 250 mg/l. By considering this range EC 50 value test chemical is considered to be non toxic and not classified as per the CLP classification criteria.  

Description of key information

After exposure of test chemical to aquatic algaefor 72 hrs the  EC 50 value of test chemical is expected to be in range from  172.9 to 250 mg/l. By considering this range EC 50 value test chemical is considered to be non toxic and not classified as per the CLP classification criteria.  

Key value for chemical safety assessment

EC50 for freshwater algae:
250 mg/L

Additional information

Short term toxicity of test chemical on the growth of aquatic algae was carried out on the basis of it structurally and functionally similar read across chemicals. The results of both the studies are as mentioned below:

 

Freshwater algal growth inhibition test was carried out according to OECD Guideline 201. The test organism used in this study was on Desmodesmus subspicatus .The stock solution (150 mg/L) of test chemical was prepared by dissolving test chemical in OECD growth medium. The solution was kept in ultrasonic bath for 20 min. Test solutions of required concentration were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture and tested at the concentrations 0, 30, 45, 67, 100 and 150 mg/L. Effects on the growth rate of the organism were studied. The median effective concentration (EC50) for the test chemical, in Desmodesmus subspicatus was determined to be 172.9 mg/L. This value indicates that the substance is likely to be non-hazardous to aquatic algae and can be considered as not classified as per the CLP criteria.

 

 In another study the Growth Inhibition of Alga (Pseudokirchneriella subcapitata) was determined by the exposing the test chemical for 72 hrs. Test conducted according to OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test). Test solutions were prepared by mixing a stock solution of the test substance, which was prepared by adding and stirring the substance under the water surface of the Erlenmeyer flask filled with medium. Test was conducted at the different concentrations 500, 160, 50, 16, 5.0 mg/L (geometric ratio; square root of 10), control. Analytical monitoring was also done using the GC were the Frequency of analysis was at the start of exposure, after 4 hours from start of exposure, and at the end of exposure. Based on the growth rate inhibition of test organism Pseudokirchneriella subcapitata due to exposure of test chemical for 72 hrs, the effect concentration EC50 and NOEC value was determined to be 250 mg/l and 16 mg/l respectively. Thus on the basis of EC50, test chemical was consider as nontoxic and not classified as toxic as per the CLP classification criteria.

 

Thus based on the results of both the studies for test chemical, it can be concluded that EC 50 value of test chemical is expected to be value range from 172.9 to 250 mg/l. By considering this range EC 50 value test chemical is considered to be nontoxic and not classified as per the CLP classification criteria.