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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
Study period:
05.02.2018 - 08.03.2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Version / remarks:
2006
GLP compliance:
yes (incl. certificate)
Test material information:
Composition 1
Analytical monitoring:
yes
Details on sampling:
The test samples of the test item were analyzed for test item concentration at the start (0 hours) and for stability at the end of the treatment (72 hours) both during range finding study and limit test.
Vehicle:
no
Details on test solutions:
Stock solution was prepared in the OECD alga medium. Stock solution was prepared by weighing required quantity of test item in a beaker, to this small volume of OECD alga media was added and stirred well using a glass rod, after complete solubility, test formulation was transferred to measuring cylinder, the beaker was rinsed with OECD alga media and transferred again to measuring cylinder, rinsing process was repeated until the complete transfer of test contents. The required test concentrations were prepared by adding appropriate amount of stock solutions and make up to required volume using OECD alga medium. A homogeneous distribution of the test item within the stock solution was achieved by means of vortexing shortly before preparation of the test vessels.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Strain: ATCC 22662
- Source: American Type Culture Collection
- Method of cultivation: in OECD alga medium

ACCLIMATION
- Acclimation period:no
- Culturing media and conditions: same as test
- Any deformed or abnormal cells observed: no
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Test temperature:
22.1 to 22.9°C
pH:
8.08 to 8.18
Nominal and measured concentrations:
Nominal concentration: 100 mg/L
Measured concentration: 116.71 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Material, fill volume: glass, 250 mL
- Initial cells density: 41025 cells/mL
- Control end cells density: 869000 cells/mL
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes, OECD algae medium

TEST MEDIUM PARAMETERS
- Preparation of dilution water: OECD algae medium as described in OECD guideline 201

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Light intensity and quality: 5190 to 5651 Lux

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: with counting chamber after 24, 48 and 72 h

TEST CONCENTRATIONS
- Range finding study: yes
- Test concentrations: 1, 10, 50 and 100 mg/L
- Results used to determine the conditions for the definitive study: yes
Reference substance (positive control):
not required
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Details on results:
- Exponential growth in the control: yes
- Observation of abnormalities: no
- Any stimulation of growth found in any treatment: no
- Any observations that might cause a difference between measured and nominal values: no
Validity criteria fulfilled:
yes
Conclusions:
The 72 hour EC50 and ErC10 of the test item on Raphidocelis subcapitata is >100 mg/L. The 72 hours NOEC is 100 mg/L and the Lowest observed effect concentration (LOEC) is >100 mg/L.
Executive summary:

The test item was assessed on Raphidocelis subcapitata for Growth Inhibition Test as per the OECD Guidelines for Testing of Chemicals Guideline No. 201.  A range finding study was conducted with six concentrations of 0.01, 0.1, 1.0, 10.0, 50.0 and 100.0 mg/L along with control, each concentration contains 2 replicates except control possessing 3 replicates. The algal growth (cell density) was assessed at 24, 48 and 72 hours of post-exposure during the test. During the range finding study, exponentially growing cells were exposed to range of selected concentrations. The growth rate inhibition of maximal 0.53% was observed in the tested concentrations. Based on the results of range finding study, a limit test was conducted at the concentration of 100 mg/L along with control (each 6 replicates). The algal growth (cell density) was assessed at 24, 48 and 72 hours post-exposure. Exponentially growing alga cells were exposed to the limit concentration. A growth rate inhibition of 0.71% was observed in the tested concentration of 100 mg/L respectively as compared with the control. Similarly, inhibition in yield of 3.5% was observed in the tested concentration of 100 mg/L. The present alga growth inhibition study fulfills the validity criteria of the test. The test samples were analyzed for test item concentration at the start (0 hours) and for stability at the end of the treatment (72 hours) both during range finding study and limit test, and were found to be within the acceptable range of ± 20% recovery to the nominal concentrations. Therefore, the results are based on the nominal concentrations. From the experiment conducted under standard experimental conditions, the 72 hour ErC50 and ErC10 (growth rate) and EyC50 and EyC10 (yield) of the test item on Raphidocelis subcapitata is >100 mg/L. The 72 hours No Observed Effect Concentration (NOEC) is 100 mg/L and the Lowest observed effect concentration (LOEC) is >100 mg/L.

Description of key information

The 72 hour EC50 and ErC10 of the test item on Raphidocelis subcapitata is >100 mg/L. The 72 hours NOEC is 100 mg/L and the Lowest observed effect concentration (LOEC) is >100 mg/L.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater algae:
100 mg/L

Additional information

The test item was assessed on Raphidocelis subcapitata for Growth Inhibition Test as per the OECD Guidelines for Testing of Chemicals Guideline No. 201.  A range finding study was conducted with six concentrations of 0.01, 0.1, 1.0, 10.0, 50.0 and 100.0 mg/L along with control, each concentration contains 2 replicates except control possessing 3 replicates. The algal growth (cell density) was assessed at 24, 48 and 72 hours of post-exposure during the test. During the range finding study, exponentially growing cells were exposed to range of selected concentrations. The growth rate inhibition of maximal 0.53% was observed in the tested concentrations. Based on the results of range finding study, a limit test was conducted at the concentration of 100 mg/L along with control (each 6 replicates). The algal growth (cell density) was assessed at 24, 48 and 72 hours post-exposure. Exponentially growing alga cells were exposed to the limit concentration. A growth rate inhibition of 0.71% was observed in the tested concentration of 100 mg/L respectively as compared with the control. Similarly, inhibition in yield of 3.5% was observed in the tested concentration of 100 mg/L. The present alga growth inhibition study fulfills the validity criteria of the test. The test samples were analyzed for test item concentration at the start (0 hours) and for stability at the end of the treatment (72 hours) both during range finding study and limit test, and were found to be within the acceptable range of ± 20% recovery to the nominal concentrations. Therefore, the results are based on the nominal concentrations. From the experiment conducted under standard experimental conditions, the 72 hour ErC50 and ErC10 (growth rate) and EyC50 and EyC10 (yield) of the test item on Raphidocelis subcapitata is >100 mg/L. The 72 hours No Observed Effect Concentration (NOEC) is 100 mg/L and the Lowest observed effect concentration (LOEC) is >100 mg/L.