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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:
2012-03-09 - 2012-05-15
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
The Department of Health of the Government of the United Kingdom
Analytical monitoring:
yes
Details on sampling:
- Concentrations: All concentrations at 0 and 72 hr.
- Sample storage conditions before analysis: Stored at -20 degrees C until analysed.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Serial dilution of stock solution directly in culture medium
- Controls: Culture medium without test substance added
- Evidence of undissolved material (e.g. precipitate, surface film, etc): None noted
Test organisms (species):
Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Strain: CCAP 278/4
- Source (laboratory, culture collection): Culture Collection of Algae and Protozoa, SAMS Research Services Ltd, Scottish Marine Institute, Oban, Argyll, Scotland.
- Method of cultivation: Periodic replenishment of culture medium

ACCLIMATION
- Acclimation period: None
- Culturing media and conditions (same as test or not): Same as test
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
24 +/- 1 degree C
pH:
Range 7.7-8.0
Nominal and measured concentrations:
Nominal concentrations: 0, 0.010, 0.032, 0.10, 0.32 and 1.0 mg/L.
Measured concentrations were 58-92%, with a concentration dependant decline. It was considered that the decline was caused by adsorbtion to the algal cells; therefore near nominal exposure was assumed.
Details on test conditions:
TEST SYSTEM
- Test vessel: Flask
- Type (delete if not applicable): closed with polyurethane foam bungs
- Material, size, headspace, fill volume: glass, 250 mL, 100 mL test volume
- Aeration: orbital shaker only
- Control end cells density: 10^4-10^5 cells/mL
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: RO purified deionized water
- Culture medium different from test medium: No
- Intervals of water quality measurement:

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: medium adjusted to 7.5 +/- 0.1 with 0.1N NaOH or HCl
- Photoperiod: Constant 24 hr
- Light intensity and quality: Warm white 7000 lux


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : cell density, 72 hr
- Determination of cell concentrations: electronic particle counter


TEST CONCENTRATIONS
- Spacing factor for test concentrations: approximately 3
- Range finding study
- Test concentrations: 0.0010, 0.010, 0.10 and 1.0 mg/L
- Results used to determine the conditions for the definitive study: yes
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.16 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95 % CL- 0.14-0.19 mg/L
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.032 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.:
0.071 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
- Exponential growth in the control (for algal test): yes
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: None noted
- Effect concentrations exceeding solubility of substance in test medium: None
Results with reference substance (positive control):
- Results with reference substance valid? Yes
- EC50: 1.4 mg/L; 95 % CL 1.2-1.7 mg/L based on rate. 0.59 mg/L; 95% CL 0.53-0.65 mg/L based on yield.
- Other: Results within normal ranges
Reported statistics and error estimates:
Statistical analysis was conducted via ANOVA, incorporating Bartlett's test for homogeneity, as well as Dunnett's multiple comparison test. (P>/= 0.05.
Validity criteria fulfilled:
yes
Conclusions:
The 72 hour EC50 of the test substance to P. subcapitata was found to be 0.16 mg/L (95% CL 0.14-0.19 mg/L) based on growth rate, and 0.084 mg/L (95% CL 0.077-0.092 mg/L) based on yield.

Description of key information

In this study, the acute toxicity of the test substance to Pseudokirchneriella was investigated in a 72-h static study (nominal concentrations between 0-1 mg/L). This results in a 72-h ErC50 of 0.16 mg/L and a 72 -h ErC10 of 0.071 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:
0.16 mg/L
EC10 or NOEC for freshwater algae:
0.071 mg/L

Additional information

The algae growth inhibition study of Vrijenhoef (2012) was used as key study for PNEC derivation. The 72-h test was conducted according to OECD guideline 201. The nominal test concentrations were between 0 -1 mg/L. A 72-h ErC50 of 0.16 mg/L for Pseudokirchnerialla subcapitata was obtained in this study. The 72-h ErC10 was 0.071 mg/L. This indicates that the test substance is very toxic to aquatic algae.