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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:
2001-11-20, 2002-03-08
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
-Source and lot.batch No. of test material: 16031/01
-Purity test date: >98%
Analytical monitoring:
yes
Vehicle:
no
Details on test solutions:
Stock Solution: The solution (100 mg/L test item were weighed out) was applied to 1 L test medium
Dispersion Treatment: The stock solution was shaken with 20 upm for 24 h on a magnetic stirrer and filtrated with 0.45 um
Limit Concentration: 1:1 Saturated Solution (saturated concentration)
Test organisms (species):
Scenedesmus sp.
Details on test organisms:
TEST ORGANISM
- Common name: Scenedesmus subspicatus
- Strain/clone: CHODAT SAG 86.81
- Origin: Sammlung von Algenkulturen (SAG), Pflanzenphysiologisches Institut der Universitat Gottingen, Nikolausberger Weg 18, D-37073 Gottingen
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
Microscopic evaluation of the cells at the start and end of exposure
Test temperature:
23.0 +/- 2.0 degrees
Nominal and measured concentrations:
The mean measured concentration was 245 ug Tungsten/L
Details on test conditions:
TEST SYSTEM
- Test vessel: Plastic curvettes, transparant, with top, volume: 20mL
- No. of vessels per concentration (replicates): Three
- No. of vessels per control (replicates): Six

RANGE-FINDING STUDY
A preliminary range finding test was conducted under static conditions. 100 mg/L were weighed out, stirred 24 h and fitered with 0.45 before using. THree dilutions (1:1, 1:10, 1:100) of the stock solutions were carried out and used for the preliminary test.
Reference substance (positive control):
yes
Remarks:
Potassium Dichromate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
> 245 µg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
ca. 245 µg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Results with reference substance (positive control):
The EC 50 Values of the reference item potassium dichromate after 72 h met the validity criteria according to EEC Method C.3 Annex 2
Validity criteria fulfilled:
yes
Conclusions:
In this study tungsten disulphide was not found to inhibit the biomass growth of the freshwater green algae Scenedesmus subspicatus at the saturated solution level corresponding to the concentraton of 245 ug tungsten/L
Executive summary:

There is toxicity to aquatic algae and cyanobacteria data currently available for tungsten disulphide. The acute toxicity of tungsten disulphide to the unicellular freshwater green alga Scenedesmus subspicatus was determined according to the principles of OECD-Guideline 201 and EEC Directive 92/69/EEC Method C.3. The study was conducted under static conditions over the duration of 72 hours with an initial cell density of nominally 10e4 cell/mL. A saturated stock solution as limit concentration of the test item was tested. Three replicates were tested but the limit concentration and six replicates for control. Microscopic evaluation of the cells at the start and end of the incubation period revealed no morphological abnormalities. The mean concentration for tungsten was 245 ug/L at the saturated solution.

Results based on 95% confidence interval are: EbC50 at 72h: >245 ug/L; NOEC at 72h: 245 ug/L, and ErC50 at 72: >245 ug/L In this study tungsten disulphide was not found to inhibit the biomass growth of the freshwater green algae Scenedesmus subspicatus at the saturated solution level corresponding to the concentration of 245 ug tungsten/L.

Description of key information

There is toxicity to aquatic algae and cyanobacteria data currently available for tungsten on disulphide which will be used for read-across purposes. The acute toxicity of tungsten disulphide to the unicellular freshwater green alga Scenedesmus subspicatus was determined according to the principles of OECD-Guideline 201 and EEC Directive 92/69/EEC Method C.3. The study was conducted under static conditions over the duration of 72 hours with an initial cell density of nominally 10* cell/mL. A saturated stock solution as limit concentration of the test item was tested. Three replicates were tested but the limit concentration and six replicates for control. Microscopic evaluation of the cells at the start and end of the incubation period revealed no morphological abnormalities. The mean concentration for tungsten was 245 ug/L at the saturated solution.

Results based on 95% confidence interval are: EbC50 at 72h: >245 ug/L, NOEC at 72h: 245 ug/L, and ErC50 at 72: >245 ug/L

In this study tungsten disulphide was not found to inhibit the biomass growth of the freshwater green algae Scenedesmus subspicatus at the saturated solution level corresponding to the concentration of 245 ug Tungsten/L

Key value for chemical safety assessment

EC50 for freshwater algae:
245 µg/L
EC10 or NOEC for freshwater algae:
245 µg/L

Additional information