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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:
April 12, 2020 to July 10, 2020
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Version / remarks:
2015
Deviations:
no
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)
Version / remarks:
2011
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
- Concentrations: 0 and 100 mg/L
- Sampling method: samples were taken directly after preparation of the test solutions and after 24 h. Since no test item was detected after 24 h, no further measurements were conducted after 48 and 72 hours.
- Sample storage conditions before analysis: one replicate was directly anaylsed, the other replicate was deep-frozen as backup
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: green algae
- Source: Pflanzenphysiologisches Institut der Universität Göttingen, Germany
- Age of inoculum (at test initiation): 2-4 days
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Test temperature:
21.4-23.4 °C
pH:
pH was not adjusted and ranged from 7.8 to 8.89
(measurements of freshly prepared test solution and after 24 h)
Nominal and measured concentrations:
nominal: 0, 10, 17.8, 31.6, 56.3 and 100 mg/L
measured: recovery rate 4.5 % for the test substances concentrations at 0 hours. At 24 h, the measured concentration was
Details on test conditions:
TEST SYSTEM
- Test vessel: flasks containing 100 mL
- Type: open
- Initial cells density: 10000 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: continuous light
- Light intensity and quality: 7112 Lux +/- 4 %

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: particle counter
- Other: microscopical analysis of the cell morphology
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 0.05 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat. (dissolved fraction)
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
A small significant effect on growth rate and yield of the algae was observed at a nominal concentration of 100 mg/L, i.e. up to the maximum water solubility, but the EC10, EC20 and EC50 values were >0.05 mg/L (nominal 100 mg/L).
Validity criteria fulfilled:
yes
Conclusions:
The EC10, EC20 and EC50 values were >0.05 mg/L (=LOQ), correspondingto a nominal concentration of >100 mg/L.
Executive summary:

The toxicity of the test item to the unicellular freshwater green alga Pseudokirchneriella subcapitata was determined according to the principles of OECD 201 and Council Regulation (EC) No. 266/2016/Method C.3. The aim of the study was the determination of the effects on growth rate and yield over a period of 72 hours. The study was conducted under static conditions with an initial cell density of 10000 cells/mL. The following nominal test concentrations were prepared: 0, 10, 17.8, 31.6, 56.3 and 100 mg/L. HPLC analysis resulted in a recovery rate of 4.5 % for the test substances concentrations at 0 hours. At 24 h, the measured concentration was <LOQ for all concentrations. No further measurements were performed. A small significant effect on growth rate and yield of the algae was observed at a nominal concentration of 100 mg/L, i.e. up to the maximum water solubility, but the EC10, EC20 and EC50 values were >0.05 mg/L (nominal 100 mg/L). The NOEC was determined to be 56.3 mg/L (nominal).

Description of key information

The EC10, EC20 and EC50 values were >0.05 mg/L (=LOQ), corresponding to a nominal concentration of >100 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:
56.3 mg/L

Additional information

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