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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study according to OECD 201

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes (incl. certificate)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
- Physical state: Red powder
- Stability under test conditions: Not specified, assumed to be stable.
- Storage condition of test material: Room temperature, protected from light, in original container.

Sampling and analysis

Analytical monitoring:
no

Test solutions

Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
The water accommodated fraction (WAF) was prepared with a nominal loading of the test item of 100 mg/L.
100 mg/L of the test item was weighed out and transferred with an appropriate amount of dilution water into a brown glass flask. This dispersion was shaken for 24 hours with 20 rpm at room temperature. After a separation phase of 1 hour, the water accommodated fraction was taken from the homogenous liquid phase. The aqueous phase or WAF was removed by siphoning (from the approximate centre of the glass flask) to give the 100 mg/L loading rate WAF to be used as a stock WAF.

Test organisms

Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM
- Strain: Desmodesmus subspicatus CHODAT SAG 86.81
- Source (laboratory, culture collection): Sammlung von Algenkulturen (SAG), Pflanzenphysiologisches lnstitut der Universitat Gottingen, Nikolausberger Weg 18, D-37073 Gottingen.
- Age of inoculum (at test initiation): A four day old preculture, prepared in dilution water, was used as inoculum.
- Method of cultivation: Fresh stocks are prepared every month on Z-Agar. Light intensity amounts to 35-70 µE · mE-2 * s^-1 for 24 h per day.
- Culture medium: Nutrient medium Z according to LOTTGE et al. (1994)
- Age of inoculum (at test initiation):

Study design

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

Test conditions

Test temperature:
21 - 24 °C, controlled at± 2 °C.
pH:
7.99 to 8.40
Nominal and measured concentrations:
WAF: 100 mg/L (loading rate)
Details on test conditions:
TEST SYSTEM
- Test vessel: Sterile Erlenmeyer flasks (vol. 250 ml) with cotton wool plugs.
- Aeration: No
- Initial cells density:
Nominal: approximately 2- 5 x 10E3 cells/ml
Actual: 4.332 x 10E3 cells/ml
- No. of organisms per vessel:
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Sterile test conditions: yes/no
- Adjustment of pH:
- Photoperiod: 24 hours/day light
- Light intensity and quality: 60 - 120 µE * m^-2 * s^-1
- Light source: Fluorescent tubes, OS RAM L 36 W /11-865, cool daylight

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Cell density was measured daily via Chlorophyll-a- fluorescence, excitation at 436 nm, emission at 685 nm. Dilution water was used as background signal.
The pH-value at the beginning of the exposure was measured in one additional replicate of the limit loading and the control. At the end of the exposure, it was measured in a pooled sample of the limit loading and the control. The room temperature was measured continuously. Light intensity was measured prior to the start of the test.
Algae cells were evaluated microscopically at the start and the end of the incubation period. The cells were checked for unusual cell shapes, colour differences, differences in chloroplast morphology, flocculation, adherence of algae to test containers and agglutination of algal cells.
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:
other: loading rate
Basis for effect:
growth rate
Remarks on result:
other: No acute toxic effects at the range of solubility.
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
other: loading rate
Basis for effect:
growth rate
Remarks on result:
other: No acute toxic effects at the range of solubility.
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
other: loading rate
Basis for effect:
biomass
Remarks on result:
other: No acute toxic effects at the range of solubility.
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
other: loading rate
Basis for effect:
biomass
Remarks on result:
other: No acute toxic effects at the range of solubility.
Results with reference substance (positive control):
see "Any other information on results incl. tables"

Any other information on results incl. tables

EC50 Values of the Reference Item (based on nominal concentrations [mg/L], (0-72 hours))

   Actual Study  Valid Range (average ± 3 x SD)
 

Rate-related inhibition

 ErC50  0.631 0.682 ± 0.452    
 95 % confidence interval  0.583- 0.687
 

Yield inhibition

 EyC50 0.256  0. 314 ± 0.144    
 95 % confidence interval 0.247- 0.265 

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
No acute effects occur within the range of solubility. The test substance is with high probability acutely not harmful to aquatic algae.