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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:
2008
Reliability:
1 (reliable without restriction)

Data source

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

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Physical state: solid, red powder
- Analytical purity: approx 98 %

- Lot/batch No.: RG 367 REG
- Expiration date of the lot/batch: 2015-01-01
- Stability under test conditions: stable at room temperaturev
- Storage condition of test material: At room temperature at about 20 °C, away from direct sunlight.

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
For measurement of the actual concentrations of the test item, duplicate samples were taken from the single test concentration at the start of the test (without algae) and at the end of the test (containing algae). At the same sampling times, duplicate samples were also taken from the control.
For the 72-hour stability samples, additional flasks containing the test medium with algae were incubated under the test conditions. This was necessary as the volume of test solution of the treatment replicates (3 x 15 mL) was too small to perform the analyses. A volume of 500 mL per sample was necessary for analytical purposes.
The samples were analyzed immediately after sampling.
The concentrations of the test item were determined in the duplicate test medium samples from the undiluted filtrate. From the control samples, one of the duplicate samples was analyzed from the corresponding sampling times. The analytical procedure and results are described in the attached analytical part report.

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: a dispersion of the test item was prepared in the test water and stirred for 96 hours in order to dissolve a maximum amount of the test item. After the stirring period, the dispersion was filtered through a membrane filter and the undiluted filtrate (saturated solution) was used as test medium.
- Controls: test water without addition of the test item

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Selenastrum capricornutum
- Strain: No. 61.81 SAG
- Source (laboratory, culture collection): Collection of Algal Cultures (SAG, Institute for Plant Physiology, University of Göttingen, Göttingen / Germany).
- Method of cultivation: under standardized conditions according to the test guidelines.


ACCLIMATION
- Acclimation period: An inoculum culture was set up three days before the start of the test. The algae were cultivated under the test conditions and were kept in the exponential growth phase until inoculation of the test solutions.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h

Test conditions

Hardness:
0.24 mmol/L (= 24 mg/L as CaCO3)
Test temperature:
22°C
pH:
8.0
Dissolved oxygen:
No data
Nominal and measured concentrations:
Nominal (loading) concentration: 100 mg/L
Measured concentrations: 2.8 microgram/L (at the start of the test), 0.70 microgram/L (after 72 hrs)
Mean measured concentration: 1.4 microgram/L
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): open
- Material, size, fill volume: glas, 50mL Erlenmeyer flasks, 15 mL of test solution
- Initial cells density: 10000 cells/mL
- Control end cells density: 152.9 x 10E4 cells/mL
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: sterile purified water
- Composition: according to the test guidelines


OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: continuous illumination
- Light intensity and quality: 7700 Lux (range 7150 to 8340 Lux); illuminated by fluorescent tubes



EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter (Coulter Counter, Model ZM)


TEST CONCENTRATIONS
- Test concentrations: 100 mg/L loeading rate
Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrationsopen allclose all
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:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC90
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
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks:
(yield)
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks:
(yield)
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks:
(yield)
Duration:
72 h
Dose descriptor:
LOEC
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks:
(yield)
Results with reference substance (positive control):
- Results with reference substance valid? yes
- EC50: 1.20 mg/L (72 h)

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The substance had no toxic effect on the growth of Pseudokirchneriella subcapitata, up to its water solubility limit at a loading rate of 100 mg/L.
Executive summary:

The influence of the substance on the growth of the freshwater green algal species Pseudokirchneriella subcapitata (formerly Selenastrum capricornutum) was investigated in a 72‑hour static test according to the OECD Guideline 201 (2006) and the Commission Regulation (EC) No 440/2008, C.3.

A limit test was performed in accordance with the test guidelines to demonstrate that the test item has no toxic effect on the algae up to its limit of solubility in the test water.

Due to the limited water solubility of the test item a dispersion of the test item was prepared in the test water and stirred for 96 hours in order to dissolve a maximum amount of the test item. After the stirring period, the dispersion was filtered through a membrane filter and the undiluted filtrate (saturated solution) was used as test medium. The undiluted filtrate was tested in parallel to a control.

At the start of the test, the analytically determined concentration of the test item in the undiluted filtrate was 2.8 µg/L. During the test period of 72 hours, a decrease of test item concentration in the test medium was determined. At the end of the test, 0.70 µg/L were found. The biological results were related to the loading rate of the test item of 100 mg/L.

The test item had no statistically significant inhibitory effect on the growth of the algae (growth rate and yield) during the test period of 72 hours at the loading rate of 100 mg/L (results of Student t-tests). The loading rate of 100 mg/L was, therefore, determined to be the 72‑hour NOEC. This value might even be higher, but loading rates of the test item exceeding 100 mg/L were not tested, in accordance with the test guidelines. The 72‑hour LOEC was higher than the loading rate of 100 mg/L.