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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:
For 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: Refer principle below
Principles of method if other than guideline:
WoE report is prepared based on tixicity to alage and cyanobacteria studies namely WoE-2 and WoE- 3
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
WoE-2:
PREPARATION AND APPLICATION OF TEST SOLUTION
The stock solution 200 mg/L was prepared by dissolving test chemical in OECD growth medium. The stock solution was kept 5 min in ultrasonic bath. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture.

- Controls: OECD medium as specified in OECD 201, used as a control and for dilution of the stock solution.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
WoE-2:
TEST ORGANISM
- Strain: 86.81 SAG
- Source (laboratory, culture collection): Institute of botany of the ASCR
- Age of inoculum (at test initiation): 5x103 cells/ml

WoE-3:
TEST ORGANISM:Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capr
icornutum)
- Common name: Green algae
- Strain: ATCC 22662
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
WoE-2: 23°C ± 2°C
pH:
WoE-2:The sample at concentration 200 mg/L : pH = 8.0 changed to pH = 7.8 during the test,
Control 1: pH = 8.0 changed to pH = 7.6 during the test
Control 2: pH = 8.2 changed to pH = 7.8 during the test
Nominal and measured concentrations:
WoE-2:12.5, 25, 50, 100 and 200 mg/L nominal concentrations were used in the study

WoE-3: 13 nominal concentrations (1.0-1000 mg/l).
Details on test conditions:
WoE-2: TEST SYSTEM
- Test vessel: 50ml glass vessel
- Type : closed (with air-permeable stopper)
- Material, size, headspace, fill volume: 7.5 ml
- Aeration: No data
- Type of flow-through (e.g. peristaltic or proportional diluter): No data
- Renewal rate of test solution (frequency/flow rate): No data
- Initial cells density: 5x10E3 cells/mL
- Control end cells density: No data
- No. of organisms per vessel: No data
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): No data
- No. of vessels per vehicle control (replicates): No data

GROWTH MEDIUM
- Standard medium used: Yes

OTHER TEST CONDITIONS
- Adjustment of pH: Without adjustment
- Photoperiod: Continuous
- Light intensity and quality: 6000 lx - 8000 lx

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell counting: Microscope with counting chamber Cyrus I or electronic particle counter.
- Chlorophyll measurement: No
- Other: ErC50 was calculated using non-linear regression by the software Prism 4.0

WoE-3: - Type (open / closed): Open system
Reference substance (positive control):
yes
Remarks:
Potassium dichromate (K2Cr2O7)
Key result
Duration:
72 h
Dose descriptor:
other: ErC50
Effect conc.:
276.1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CL: 149.8 – 508.9 mg/L
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
190 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
5.8 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: No effect was observed(p < 0.05)
Results with reference substance (positive control):
WoE-2:
- Results with reference substance valid
- ErC50: 0.69 mg/L K2Cr2O7

WoE-2: Control Solution: OECD growth medium without the sample, the coefficient of variation of average growth rate in replicates during the whole test period was 1.0 % in control 1 and 0.6 % in control 2.

Validity criteria fulfilled:
not specified
Conclusions:
By applying weight of evidence approach the EC50 value of test chemical was determined to be in range from 190 mg/L to 276.1 mg/l after exposure of test chemical for 72 hrs. The range EC50 value indcates that the substance is likely to be nonhazardous to fish and cannot be classified as per the CLP classification criteria.
Executive summary:

Data available for the structurally and functionally read across chemicals has been reviewed to determine the toxicity to aquatic algae. The studies are as mentioned below:

In first study the freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the test chemical according to OECD Guideline 201 (Alga, Growth Inhibition Test). The stock solution 200 mg/L was prepared by dissolving test chemical in OECD growth medium. The stock solution was kept 5 min in ultrasonic bath. Test solutions of required concentrations were prepared by mixing the stock solution of the test chemical with OECD growth medium. The nominal concentration used in this study was 12.5, 25, 50, 100 and 200 mg/L. Static system was used in this study and test chemical was exposed to green algae for 72 hrs. The test vessel used was 50 ml glass vessel. Effects on the growth rate of the Desmodesmus subspicatus were studied. ErC50 calculated using nonlinear regression by the software Prism 4.0. The median effective concentration (ErC50) for the test chemical on a freshwater green algae Desmodesmus subspicatus was determined to be 276.1 mg/L. On the basis ErC50 value after 72 hour exposure of test chemical to green algae test chemical is considered to be non- toxic and cannot be classified as per the CLP classification criteria.

Another study was reviewed from secondary was performed to determine the toxicity of test chemical, to algae according to the standard OECD Guideline 201 (Alga, Growth Inhibition Test). Test organism used was Selenastrum capricornutum ATCC 22662. 13 nominal concentrations of test chemical were used in this study in range of 1.0-1000 mg/l. The test was performed in static open system by following the OECD guideline. Selenastrum

capricornutum were exposed to the chemical for 72hrs.

Based on the biomass inhibition of algae by the test chemical, the EC50 value and NOEC value was determined to be 190 mg/L and 5.8 mg/L, respectively. Thus, based on the EC50 value it was concluded that the test chemical was nontoxic and can be considered to be not classified as per the CLP classification criteria.

By considering results of both the studies mentioned above and applying weight of evidence approach the EC50 value of test chemical was determined to be in range from 190 mg/L to 276.1 mg/l after exposure of test chemical for 72 hrs. The range EC50 value indcates that the substance is likely to be nonhazardous to fish and cannot be classified as per the CLP classification criteria.

Description of key information

By applying weight of evidence approach the EC50 value of test chemical was determined to be in range from 190 mg/L to 276.1 mg/l after exposure of test chemical for 72 hrs. The range EC50 value indcates that the substance is likely to be nonhazardous to aquatic algae and cannot be classified as per the CLP classification criteria.

Key value for chemical safety assessment

Additional information

Data available for the structurally and functionally read across chemicals has been reviewed to determine the toxicity to aquatic algae. The studies are as mentioned below:

In first study the freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the test chemical according to OECD Guideline 201 (Alga, Growth Inhibition Test). The stock solution 200 mg/L was prepared by dissolving test chemical in OECD growth medium. The stock solution was kept 5 min in ultrasonic bath. Test solutions of required concentrations were prepared by mixing the stock solution of the test chemical with OECD growth medium. The nominal concentration used in this study was 12.5, 25, 50, 100 and 200 mg/L. Static system was used in this study and test chemical was exposed to green algae for 72 hrs. The test vessel used was 50 ml glass vessel. Effects on the growth rate of the Desmodesmus subspicatus were studied. ErC50 calculated using nonlinear regression by the software Prism 4.0. The median effective concentration (ErC50) for the test chemical on a freshwater green algae Desmodesmus subspicatus was determined to be 276.1 mg/L. On the basis ErC50 value after 72 hour exposure of test chemical to green algae test chemical is considered to be non- toxic and cannot be classified as per the CLP classification criteria.

Another study was reviewed from secondary was performed to determine the toxicity of test chemical, to algae according to the standard OECD Guideline 201 (Alga, Growth Inhibition Test). Test organism used was Selenastrum capricornutum ATCC 22662. 13 nominal concentrations of test chemical were used in this study in range of 1.0-1000 mg/l. The test was performed in static open system by following the OECD guideline. Selenastrum

capricornutum were exposed to the chemical for 72hrs.

Based on the biomass inhibition of algae by the test chemical, the EC50 value and NOEC value was determined to be 190 mg/L and 5.8 mg/L, respectively. Thus, based on the EC50 value it was concluded that the test chemical was nontoxic and can be considered to be not classified as per the CLP classification criteria.

By considering results of both the studies mentioned above and applying weight of evidence approach the EC50 value of test chemical was determined to be in range from 190 mg/L to 276.1 mg/l after exposure of test chemical for 72 hrs. The range EC50 value indcates that the substance is likely to be nonhazardous to aquatic algae and cannot be classified as per the CLP classification criteria.