Tungsten disulphide

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

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