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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:
2003-06-18 to 2003-07-25
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Remarks:
: There were no circumstances that may have affected the quality or integrity of the data.
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
Remarks:
: There were no circumstances that may have affected the quality or integrity of the data.
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Name of test material (as cited in study report): T002615
- Substance type: not applicable
- Physical state: solid white
- Analytical purity: > 98%
- Purity test date: no data
- Lot/batch No.: 00403487
- Expiration date of the lot/batch: December 2003 (retest date)

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Stability under test conditions: Determined in RCC study No. 847007
- Storage condition of test material: at room temperature at about 20 °C, away from direct sunlight
- Solubility in water: Determined in RCC study No. 846983
Analytical monitoring:
yes
Details on sampling:
- Sampling method: Just before test start and after 72 hours: duplicate samples from the test medium and control (without algae).
- Sample storage conditions before analysis: no, analyzed immediately after sampling.
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A filtrate of a saturated dispersion of the test item was prepared. The undiluted filtrate was tested as the only test concentration. Before the start of the test, a supersaturated dispersion with a loading rate of 100 mg/L was prepared by mixing 250.3 mg of the test item into 2500 mL of test water. The test item was mixed into the test water as homogeneously as possible using ultrasonic treatment for 15 minutes and by intense stirring for 24 hours at room temperature in the dark. No auxiliary solvent or emulsifier was used. the supersaturated dispersion of the test item was filtered through a membrane filter (Schleicher & Schuell, Type NC45, pore size 0.45 µm) just before the start of the test (= addition of algae).
- Controls: yes
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no remarkable observations, clear test substance solutions
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Scenedesmus subspicatus CHODAT
- Strain: No. 86.81 SAG
- Source (laboratory, culture collection): Supplied by the Collection of Algal Cultures (SAG, Institute for Plant Physiology, University of Gottingen, D-37073 Göttingen, Germany). The alga had been grown in the RCC laboratories under standardized conditions according to the test guidelines.
- Age of inoculum (at test initiation): 4 days
- Method of cultivation: in synthetic test water prepared according to the guidelines


ACCLIMATION
- Acclimation period: 4 days
- Culturing media and conditions (same as test or not): yes
- Any deformed or abnormal cells observed: no
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Hardness:
0.24 mmol/L (24 mg/L) as CaCO3
Test temperature:
23°C
pH:
Control: 8.2 (begining of the test) -9.1 (end of the test)
100 mg/L: 8.0 (begining of the test) - 8.8 (end of the test)
Dissolved oxygen:
not applicable
Salinity:
not relevant
Conductivity:
not relevant
Nominal and measured concentrations:
Nominal: 100 mg/L (one concentration, limit test)
Measured: 1.4 µg/L (one concentration, limit test)
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmayer flasks
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 50 mL
- Aeration: no
- Initial cells density: 10000 algal cells/mL test medium
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes
- Detailed composition if non-standard medium was used: not applicable

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: synthetic test water
- Alkalinity: 0.08 mmol/L
- Culture medium different from test medium: no
- Intervals of water quality measurement: The pH was measured and recorded in the single test concentration and the control at the start and at the end of the test. The water temperature was measured and recorded daily in an Erlenmeyer flask filled with water and incubated under the same conditions as the test flasks. The appearance of the test media was also recorded daily.

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: continuously
- Light intensity and quality: 8230-9560 Lux (average 9000 Lux). Light produced from Philips TLD 36W-1/840 fluorescent tubes.
- Salinity (for marine algae): not applicable

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: counting with an electronic particle counter (Coulter Counter Model ZM) with at least two measurements per sample

TEST CONCENTRATIONS
- Spacing factor for test concentrations: not applicable
- Justification for using less concentrations than requested by guideline: pre-test results and guideline
- Range finding study: Yes
- Test concentrations: no data
- Results used to determine the conditions for the definitive study: yes
Reference substance (positive control):
yes
Remarks:
potassium dichromate (historical data)
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: The test substance had no staistically significant inhibitory effect on the growth (cell densities) of Scenedesmus subspicatus after the exposure period of 72h at a loading rate of 100 mg/L (nominal values)
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 1.4 µg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: The test substance had no staistically significant inhibitory effect on the growth (cell densities) of Scenedesmus subspicatus after the exposure period of 72h at a loading rate of 1.4 ug/L (measured).
Details on results:
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): yes microscopic observations
- Unusual cell shape: no
- Colour differences: no
- Flocculation: no
- Adherence to test vessels: no
- Aggregation of algal cells: no
- Any stimulation of growth found in any treatment: no
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: the test medium remained clear throughout the entire test period.
- Effect concentrations exceeding solubility of substance in test medium: no
Results with reference substance (positive control):
No data
Reported statistics and error estimates:
The test cocnentrations corresponding to 10 and 50% inhibition of the algal biomass or of the growth rate could not be calculated due to the absence of a toxic effect of the test item.
The LOEC and the NOEC were determined directly from the counted algal cell densities. The mean cell densities were tested on significant differences to the control values by a t-test (alpha=0.05, one-sided smaller).
Validity criteria fulfilled:
yes
Conclusions:
A 72-h growth inhibition limit test with the unicellular alga Scenedesmus subspicatus was performed with the test substance T002615 according to OECD guideline 201 (GLP conditions). It can be concluded that the test item had no significant significant inhibitory effect on the growth (cell densities) of Scenedesmus subspicatus after the exposure period of 72h at a loading rate of 1.4 µg/L (mean measured) or 100 mg/L (nominal). The results of the test can be considered reliable without restrictions.

Description of key information

The study of Seyfried (2003), investigating the acute toxicity of T002615 to algae according to OECD guideline 201, was considered as the key study for endpoint coverage. The 72-h EC50 for growth rate was determined to be > 100 mg/L. The substance can be considered as not harmful to algae.

Key value for chemical safety assessment

Additional information