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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
November 26 - 28, 2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study has been performed according to OECD and EC guidelines and according to GLP principles.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2008
Report Date:
2008

Materials and methods

Test guidelineopen allclose all
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
Qualifier:
equivalent or similar to
Guideline:
ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Corsair Clear #34
- Substance type: Clear white lumpy solid
- Physical state: Solid
- Stability under test conditions: Stable
- Storage condition of test material: At room temperature in the dark

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
- Concentrations: control and highest concentration
- Sampling method: 40 ml at t=0 and t=48h
- Sample storage conditions before analysis: refrigerator

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test substance was ground before weighing. Preparation of test solutions started with loading rates of 10 and 100 mg/l. The aqueous mixtures were treated with ultrasonic waves for 15 minutes, followed by a 24-hour magnetic stirring period and a 2½ hour stabilisation period. The resulting mixtures were clear and colourless but contained a floating layer, precipitate and undissolved particles in the solution. Therefore, the mixtures were passed over glass wool, after which they were clear and colourless.
After preparation, volumes of 50 ml were added to each replicate of the respective test concentration. Subsequently, 1 ml of an algal suspension was added to each replicate providing a cell density of 10^4 cells/ml.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: NIVA CHL 1
- Source (laboratory, culture collection): In-house laboratory culture
- Age of inoculum (at test initiation): not indicated
- Method of cultivation: Algae stock cultures were started by inoculating growth medium with algal cells from a pure culture on agar. The suspensions were continuously aerated and exposed to light in a climate room at a temperature of 21-24°C.

ACCLIMATION
- Acclimation period: 3 days
- Culturing media and conditions (same as test or not): stock culture medium is M1 (according to the NPR 6505, formulated using Milli-Ro water); test medium and pre-culture medium is M2 (according to the OECD 201 Guideline, formulated using Milli-Q water (tap water purified by reverse osmosis and subsequently passed over activated carbon and ion-exchange cartridges) preventing precipitation.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Post exposure observation period:
No post exposure observations.

Test conditions

Hardness:
0.24 mmol/l (24 mg CaCO3/l)
Test temperature:
20.8 - 23.7°C
pH:
8.0 - 8.2
Nominal and measured concentrations:
Loading rate 0 mg/l t=0h: TOC = 0.3488 mg/l
Loading rate 0 mg/l t=48h: TOC = 0.6064 mg/l
Loading rate 100 mg/l t=0h: TOC = 0.8062 mg/l
Loading rate 100 mg/l t=48h: TOC = 0.3288 mg/l
The TOC contents in treated samples were comparable or only slightly higher than those in control samples, indicating that the actual test substance concentration was very low. This is not unexpected considering the presence of undissolved test substance and a floating layer in the solution, which were left behind after separation of the water accommodated fraction.
Details on test conditions:
TEST SYSTEM
- Test vessel: 100 ml, all-glass, containing 50 ml of test solution
- Initial cells density: 10000 cells/ml
- Control end cells density: 260000 cells/ml
- No. of vessels per concentration (replicates): 6 replicates of the highest test concentration, 3 replicates of the lower concentration, 5 replicates of the highest test concentration without algae, 1 replicate of the lower test concentration without algae
- No. of vessels per control (replicates): 6 replicates of the control and 4 replicates of the control without algae

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: continuous
- Light intensity and quality: 86 to 92 µE.m-2.s-1 using TLD-lamps of the type ‘Cool-white’ of 30 Watt.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : 0, 24 and 48 h
- Determination of cell concentrations: spectrophotometer

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10 (0, 10 and 100 mg/l)
- Range finding study: the study is a combined limit/range finding study
Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
loading rate
Basis for effect:
growth rate
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
100 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
- 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: The EC50 for growth rate reduction (ERC50: 0-72h) was 2.1 mg/l with a 95 % confidence interval ranging from 1.5 to 3.0 mg/l.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
Under the conditions of the present study with Pseudokirchneriella subcapitata, no reduction of growth rate or inhibition of yield was recorded at any of the concentrations of Corsair Clear #34 tested. The NOEC for growth rate reduction and yield inhibition was 100 mg/l based on loading rates.
Due to the very low solubility of Corsair Clear #34 in water, concentration levels that might be toxic for algae could not be reached. Hence the 48h-EC50 for both growth rate reduction and yield inhibition was above a loading rate of 100 mg/l.