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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:
01 - 04 Dec 2014
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Remarks:
Staatliche Gewerbeaufsicht Hildesheim, Germany
Analytical monitoring:
yes
Details on sampling:
- Concentrations: control, 100 mg/L
- Sample storage conditions before analysis: All original samples were stored at room temperature until sample preparation, if necessary. Prepared samples were stored at room temperature until analysis.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A stock solution of nominal 100 mg/L was prepared in dilution water. The solution was treated 2 min with ultrasound at room temperature.
- Eluate: no
- Differential loading: no
- Controls: yes, test medium control
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: green algae
- Strain: SAG 61.81
- Source (laboratory, culture collection): Sammlung von Algenkulturen (SAG), Pflanzenphysiologisches Institut der Universität Göttingen, Göttingen, Germany
- Method of cultivation: Fresh stocks were prepared every month on Z-Agar. Light intensity: 35-70 µE m-2 s-1 for 24 h/d. Culture medium: Nutrient medium Z according to Lüttge et al. (1994).
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Test temperature:
21.5 - 23.0 °C
pH:
8.24 - 8.27 (0 h)
8.88 - 8.95 (72 h)
Nominal and measured concentrations:
Nominal: 0, 100 mg/L
Measured: < LOQ, 99.9 mg/L (0 h), 98.0 mg/L (72 h)
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Type (delete if not applicable): sealed with cotton wool plugs
- Material, size, headspace, fill volume: glass, size: 250 mL, headspace: 150 mL, fill volume: 100 mL
- Aeration: constantly shaken at 70 rpm at a rotary shaker
- Initial cells density: 7085 cells/mL
- Control end cells density: 1643447 cells/mL (mean of six replicates)
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: according to guideline

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: continuous illumination
- Light intensity and quality: 69.5 µE*m-2*s-1 (mean)

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: Cell density was measured daily via Chlorophyll-a-fluorescence, excitation at 436 nm, emission at 685 nm. Dilution water was used as background signal.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: none, limit test
- Range finding study
- Test concentrations: 0.01, 0.1, 1.0, 10.0, 100 mg/L
- Results used to determine the conditions for the definitive study: max. 2% inhibition of growth rate
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
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:
other: yield
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: yield
Details on results:
- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): no abnormalities observed
- Any stimulation of growth found in any treatment: no
Results with reference substance (positive control):
- Results with reference substance valid? yes
- EC50: ErC50 (72 h): 0.774 mg/L (95% CL: 0.711 - 1.08 mg/L, within the valid range of 0.678+/- 0.414 mg/L)
Reported statistics and error estimates:
A standard t-test was used to determine NOEC/LOEC. A normality test (Shapiro-Wilk) and an equal variance test (Levene median test) were done first.
The EC10-, EC20-, and EC50-values were estimated empirically based on the results of the only treatment level.
Validity criteria fulfilled:
yes
Conclusions:
No inhibition of growth of Pseudokirchneriella subcapitata was observed at the limit concentration of 100 mg/L in a guideline study according to OECD 201 (GLP). Hence, the ErC10/50 (72 h) was derived to be > 100 mg/L (nominal).
Executive summary:

The study was performed according to OECD 201 (GLP) with the freshwater algae Pseudokirchneriella subcapitata. A limit test concentration of 100 mg/L was tested. The actual test substance concentration was verified by HPLC-DAD analysis after 0 and 72 h. At both samplings the measured concentrations were within the range of 80-120% of nominal (99.9 mg/L after 0 h, 98.0 mg/L after 72 h). Thus, the effect concentrations were based on the nominal concentrations. Since no inhibition of growth was observed after 72 h the ErC10/50 (72 h) was derived to be > 100 mg/L. The respective NOErC (72 h) is ≥ 100 mg/L. All validity criteria were met.

Description of key information

No inhibition of growth of Pseudokirchneriella subcapitata was observed at the limit concentration of 100 mg/L in a guideline study according to OECD 201 (GLP). Hence, the ErC10/50 (72 h) was derived to be > 100 mg/L (nominal).

Key value for chemical safety assessment

EC50 for freshwater algae:
100 mg/L
EC10 or NOEC for freshwater algae:
100 mg/L

Additional information

One experimental study is available investigating the toxicity of the test substance to aquatic algae (2015). The study was performed according to OECD 201 (GLP) with the freshwater algae Pseudokirchneriella subcapitata. A limit test concentration of 100 mg/L was tested. The actual test substance concentration was verified by HPLC-DAD analysis after 0 and 72 h. At both samplings the measured concentrations were within the range of 80-120% of nominal (99.9 mg/L after 0 h, 98.0 mg/L after 72 h). Thus, the effect concentrations were based on the nominal concentrations. Since no inhibition of growth was observed after 72 h the ErC10/50 (72 h) was derived to be > 100 mg/L. The respective NOErC (72 h) is ≥ 100 mg/L. All validity criteria were met.