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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2008
Reliability:
1 (reliable without restriction)
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2008
Report Date:
2008

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
ETAD method, to differ between light shading and toxic effects
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent

Sampling and analysis

Details on sampling:
- Concentrations: 0.388, 1.20, 4.00, 12.4, 38.9 mg/l

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: a saturated solution was prepared. A dispersion of 100 mg/l prepared in dilution water was shaken with 110 rpm for 24 h at room temperature. After 24 h particles were removed by centrigugation at 3000 rpm for 20 min. 5 dilution levels of the saturated solution were tested.

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
Strain: CHODAT SAG 86.81


Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
6 d

Test conditions

Hardness:
0.24 mmol Ca+Mg/l
Test temperature:
21-24 +/- 2°C
pH:
8.0 +/-0.2
Dissolved oxygen:
n.a.
Salinity:
*
Nominal and measured concentrations:
A saturated solution of 100 mg/l was prepared by shaking with 110 rpm for 24 h at room temp. and centrifugation at 3000 rpm for 20 min. . 5 dilution levels were tested, corresponding to 0.288, 1.20, 4,00, 12.4 and 38.9 mg/l
Details on test conditions:

- Initial cells density: 2-5E3 cells/ml
- Control end cells density: 177333 cells/ml

- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes


- Light intensity and quality: 35-70 µE x mE-2 x sE-1 for 24 h per day


- Determination of cell concentrations: counted with an inverse microscope

Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 38.9 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
cell number
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 38.9 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 38.9 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
biomass
Results with reference substance (positive control):
- Results with reference substance valid? y
- EC50: rate-related inhibition: 0.74

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The difference of the rate-related inhibition and Yield inhibition measured for group A (test item dissolved in the test medium) and group B (test item solution above the algae cultures) is below 10%. Therefore the observed inhibition is caused by lack of light and not by direct intoxitation.
The test substance has no effect to the Yield inhibition and the Specific Growth Rate Inhibition of green algea until the limit of the solubility of 38.9 mg/l of the substance