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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:
2006-01-20 to 2006-05-04
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
Identity: TIC2782 (T002907)
Batch No.: 00467090 (= charge 05C0836)
Expiration date: May 04, 2006
Purity: 99.9%
Solubility in water: 32 g/L
Aggregate state/physical form
at room temperature: Solid
Color: White
Storage conditions: At room temperature
Analytical monitoring:
yes
Details on sampling:
- Sampling method: duplicate samples were taken before the start of the test and after 72 hours from each test medium and from the control (all without algae).
- Sample storage conditions before analysis: the samples were deep-frozen (~-20°C) immediately after sampling.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test medium of the highest nominal test item concentration of 100 mg/L was prepared by dissolving 50.83 mg T002907 in 500 mL of test water by ultrasonic treatment (10 minutes) and intense stirring for 10 minutes at room temperature. The lower test item concentrations were prepared by dilution.
- Controls: yes

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Strain:n° 86.81 SAG
- Source (laboratory, culture collection): SAG, Institute for Plant Physiology, University of Göttingen, D-37073 Göttingen, Germany)
- Method of cultivation: in the RCC laboratories under standardized conditions according to the test guideline (OECD 201)

ACCLIMATION
- Acclimation period: 4 days
- Culturing media and conditions (same as test or not): same as the test
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Hardness:
24 mg CaCO3/L
Test temperature:
23-24°C
pH:
At the start of the test: 8.0-8.3
At the end of the test: 6.2 - 8.3
Dissolved oxygen:
not reported
Salinity:
not applicable
Nominal and measured concentrations:
nominal test concentrations (mg/L) : 0.32, 1.0, 3.2, 10, 32, 100
arithmetic mean measured concentrations (mg/L) : 2.52, 8.00, 28.8, 87.0

The mean measured concentrations (calculated as the average over all measurements per test concentration) ranged from 56 to 79% of nominal.
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Type (delete if not applicable): covered with glass dishes
- Material, size, headspace, fill volume: 50 mL Erlenmeyer flasks filled with 15 mL algal suspension
- Initial cells density: 10,000 cells/mL
- Control end cells density: 91.98 x 10,000 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes (OECD 201)

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: synthetic test water
- Culture medium different from test medium: no
- Intervals of water quality measurement:
* temperature: daily
* pH: at the begin and the end of the test

OTHER TEST CONDITIONS
- Sterile test conditions: no information
- Adjustment of pH: no
- Photoperiod: continuous illumination
- Light intensity and quality: mean of 8000 lux (range: 7230-8570 lux) by fluorescent tubes (Philips TLD 36W/840)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter
- effect calculated parameters: specific growth rate and biomass (area under the growth curve)

TEST CONCENTRATIONS
- Spacing factor for test concentrations: x3.2
- Range finding study
- Test concentrations:data not shown
- Results used to determine the conditions for the definitive study: yes, test concentrations were based on the results of a range-finding test and the results of the pre-experiment to determine the solubility of the test item in test water.
Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 87 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: not determined
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 87 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
- Exponential growth in the control (for algal test): yes
- Any stimulation of growth found in any treatment: no
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: clear test medium
- EC50 (biomass) > 87mg T002907 /L.
- EC10 (growth rate) > 87 mg T002907 /L.
- EC10 (biomass) < 0.25 mg T002907 / L.
- LOEC (biomass) = 2.5 mg T002907 / L.
- NOEC (biomass) = 2.5 mg T002907 / L.
Reported statistics and error estimates:
The 72-h EbC10 value was calculated by Probit Analysis.
The 72-h ErC value could not be calculated because none of the response exceeded 10%.
NOEC and LOEC values were compared to the control using a Dunnett-test.
Validity criteria fulfilled:
yes
Conclusions:
A 72-h growth inhibition test with the unicellular green alga Scenedesmus subspicatus was performed according to the OECD 201 guideline. The results were based on mean measured test item concentrations. The 72-h EC50 (growth rate) was determined to be > 87 mg T002907/L. The 72-h NOEC (gowth rate) was determined to be >= 87 mg T002907/L. The results of the test can be considered reliable without restrictions.

Description of key information

The study of Peither (2006), investigating the acute toxicity of T002907 to algae according to OECD guideline 201, was considered as the key study for endpoint coverage. The 72-h NOEC and 72-h EC50 for growth rate were determined to be >= 87 mg/L and >87 mg/L respectively. The substance can be considered as not harmful to algae.

Key value for chemical safety assessment

Additional information