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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:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP-guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
Gas chromatography, measuring at start and end (72 h) of the test.
Vehicle:
no
Test organisms (species):
Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Green alga
- Strain: ATCC22662
- Source (laboratory, culture collection): ATCC
- Method of cultivation: Shaking at 100 rpm, OECD medium

Test type:
static
Water media type:
freshwater
Total exposure duration:
72 h
Test temperature:
23 ± 2 °C
pH:
pH = 7.7 - 10.4 at start and 8.0 - 8.8 at end of the test (72 h)
Nominal and measured concentrations:
Nominal: 0, 42, 76, 137, 247, 444 and 800 mg/L
Measured at start of the test (0 h); < 0.2, 40, 71, 130, 221, 400, 707 mg/L
Measured at end of the test (72 h); < 0.2, 44, 78, 144, 252, 477, 755 mg/L
Details on test conditions:
Test Conditions
- Growth/test medium: OECD medium.
- Shaking: 100 rpm
- Dilution water source: OECD medium.
- Exposure vessel type: A 100 mL OECD medium in a 300 mL Erlenmeyer flask with a silicon cap which allows ventilation.
- Stock solutions preparation : No stock solution was prepared. Test chemical was diluted to 2.0 wt.% with OECD medium and sterilised with filter before use.
- Light levels and quality during exposure: 4,000 - 5,000 Lux, continuous illumination.

Test design:
- Number of replicates: Triplicate
- Initial cell number in cells/mL: 1×104
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
107 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
76 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Results with reference substance (positive control):
EC50 of potassium dichromate was 0.41 mg/L.

(1) Growth inhibition (comparison of area under growth curve)

EC50 (72 h) 107 mg/L

NOEC 76 mg/L

(2) Growth inhibition (comparison of growth rates)

EC50 (24 - 48) 127 mg/L

EC50 (24 - 72) 155 mg/L

NOEC (24 - 72) 76mg/L

Validity criteria fulfilled:
yes
Conclusions:
The determined EC50 value for biomass (0 - 72 h) was 107 mg/L based on the nominal concentration. The NOEC value for biomass (0 - 72 h) was evaluated to be 76 mg/L. The EC5 for growth rate were 127 mg/L (24 - 48 h) and 155 mg/L (24 - 72 h). The NOEC’s for growth rate were 76 mg/L (24 - 48 h) and 76 mg/L (24 - 72 h).

Description of key information

The toxicity to aquatic algae was investigated by tests with selenastrum capricornutum and Scendedesmus subspicatus. In the key study with selenastrum capricornutum the acute EC 50 (72h) is 107 mg/L and the chronich NOEC (72h) value is 76 mg/L. In the supporting study with Scendedesmus subspicatus acute EC 50 (72h) is 158 mg/L and the chronich NOEC (72h) value is 10 mg/L. 

Key value for chemical safety assessment

EC50 for freshwater algae:
107 mg/L
EC10 or NOEC for freshwater algae:
76 mg/L

Additional information