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Diss Factsheets

Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

Link to relevant study record(s)

Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
guideline study (no analytics, no GLP)
Qualifier:
according to guideline
Guideline:
other: DIN 38412 L 9
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
Concentration of the stock solution was 100 mg/L.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Common name: Desmodesmus subspicatus (former name: Scenedesmus subspicatus)
- Strain: CHODAT SAG 86.81
- Source (laboratory, culture collection): Supplier: Sammlung für Algenkulturen der Universität Goettingen
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Test temperature:
23.2 °C
pH:
7.85-8.20
Nominal and measured concentrations:
0, 2.5, 5.0, 10.0, 25.0, 50.0 and 100.0 mg/L (nominal concentrations)
Details on test conditions:
- Initial cells density: 12000 to 13000 cells/mL
- Control end cells density: yes
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to DIN 38412/9

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: in vivo chlorophyll-a-fluorescence at 685 nm wavelength (as measure for cell number) after 0, 24, 48, 72, and 96 hours
- pH values: after 0 and 96 hours
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
70.6 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 49.3 - 101.0 mg/L
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
41.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: 30.6 - 56.1 mg/L
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
53.9 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 43.5 - 66.9 mg/L
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
26.5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: 20.9 - 33.5 mg/L
Details on results:
- Exponential growth in the control: yes
- Any stimulation of growth found in any treatment: no
- EC50 values were determined with appropriate statistical methods (Tallarida et al. 1979)
Conclusions:
72-hour EC50 (algae): 70.6 mg/L (growth rate)
72-hour EC50 (algae): 41.4 mg/L (ibomass)
96-hour EC50 (algae): 53.9 mg/L (growth rate)
96-hour EC50 (algae): 26.5 mg/L (biomass)
Executive summary:

The acute toxicity of the test substance to aquatic algae was studied in accordance with DIN 38412 L 9. Algae were exposed to the test substance at concentrations of 2.5, 5, 10, 25, 50, and 100 mg/L. The 72-hour EC50 for growth rate and biomass were 70.6 and 41.4 mg/L. The 96-hour EC50 for growth rate and biomass were 53.9 and 26.5 mg/L.

Description of key information

72-hour EC50 (Desmodesmus subspicatus): 70.6 mg/L; DIN 38412 L 9; Reliability = 2

Key value for chemical safety assessment

EC50 for freshwater algae:
70.6 mg/L

Additional information