Tungsten disulphide

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011-09-20 to 2001-11-14

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

yes

Remarks:

In contrast to the guideline, it was decided to use copper (II) sulphate pentahydrate instead of the prescribed 3,5-dichorophenol.

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: Batch No. 16031/01
- Expiration date of the lot/batch: 2002-04-01

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Non-adapted activated sludge fro sewage plant at Hildesheim is well suited as it comprimses mosthly household sewage and hardly industrial waste water.
- Municipal sewage treatment plant of D-31137 Hildesheim
- The sludge was washed with autoclavd tap water and diluted corresponding to a dry weight of 4.0 g/L +/- 10%
- 200 mL of inoculum, 16 ml synthetic waste water, 284 ml demineralised watr

Test type:

static

Limit test:

no

Total exposure duration:

3 h

Remarks on exposure duration:

One replicate per concentration and two per control

Test temperature:

- 18-22 C
- The room temperature during the test was recorded continuously by a hygrothermograph

Dissolved oxygen:

Th oxygen depletion of the control, reference and test item was measured after 3-hours incubation by means of oxmeter and recorded for at least 3 minutes on a flat baed recorder.

Nominal and measured concentrations:

Test Concentrations: 1000, 1800, 3200, 5800 and 10,000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 500 ml Erlenmeyer flasks
- Aeration: Permanent
- No. of vessels per concentration (replicates): One per concentration
- No. of vessels per control (replicates): Two per control
- Sludge concentration (weight of dry solids per volume): 4.01 g/L

OTHER TEST CONDITIONS
- Adjustment of pH: The pH value of the activated sludge was measured prior to testing.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
TEST CONCENTRATIONS
- Spacing factor for test concentrations: Dilution factor 1.8
- Range finding study: A range finding study was carried oit with three concentrations: 10-1000 mg/L
- Test concentrations: 1000 to 10,000 mg/L

Reference substance (positive control):

yes

Remarks:

Copper (ii) sulfate pentahydrate

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

ca. 8 972 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

EC50

Remarks:

95% Confidence Interval

Effect conc.:

> 8 574 - < 9 389 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

7 381 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

> 10 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Results with reference substance (positive control):

- Results with reference substance valid? Yes. The EC50-value of the reference item copper(II)-sulphate-pentahydrate was 143 mg/L which is in the confidence range of 54-146 mg/L

Validity criteria fulfilled:

yes

Remarks:

The EC50-value of the reference item copper(II)-sulphate-pentahydrate was 143 mg/L which is in the confidence range of 54-146 mg/L

Conclusions:

The test item Tungsten Disulphide is not toxic in concentratons of less or equal than 7381 mg/L to activated sludge of a muncipal sewage treatment plant.

Executive summary:

There is Toxicity to microorganisms data available for Tungsten Disulphide which will be used for Read-Across purposes.

A Respiration Inhibition Test with activated sludge according to OECD Guideline No. 209 and GLP principles was performed for 3 hours with the test item Tungsten Disulphide batch-no. 16031/01. The test system was activated sludge of a predominantly domestic sewage at a concentration of 4.01g/L. The test method was static and the nominal concentrations of the test item were 1000, 1800, 3200, 5800, 10000 mg/L. The respiration rates of control, reference and test item were measured after a contact time of three hours, and the inhibitory effects of the test and reference concentrations were determined in comparison to the control respiration rates. To check activity of test system and test conditions, a reference test was carried out once every 7 days with copper-(II)-sulphate-pentahydrate to determine the reference toxicity. Validity criteria of the test guideline were fulfilled.

Results:
EC50 for reference item: 143 mg/L
EC50 for test material: 8972.0 mg/L
EC 50 at 95% confidence level: >8574.0-<9389.0 mg/L
EC 20 for test material: 7381 mg/L
EC80 for test material: >10000 mg/L
The test item Tungsten Disulphide is not toxic in concentrations less than or equal to 7381 mg/L to activated sludge of a municipal sewage treatment plant.

Description of key information

The test item tungsten disulphide is not toxic in concentrations of less or equal than 7381 mg/L (EC20) to activated sludge of a municipal sewage treatment plant.

Key value for chemical safety assessment

EC50 for microorganisms:

8 972 mg/L

Additional information

There is toxicity to microorganisms data available for tungsten disulphide. A Respiration Inhibition Test with activated sludge according to OECD Guideline No. 209 and GLP principles was performed for 3 hours with the test item tungsten disulphide. The test system was activated sludge of a predominantly domestic sewage at a concentration of 4.01 g/L. The test method was static and the nominal concentrations of the test item were 1000, 1800, 3200, 5800, 10000 mg/L. The respiration rates of control, reference and test item were measured after a contact time of three hours, and the inhibitory effects of the test and reference concentrations were determined in comparison to the control respiration rates. To check activity of test system and test conditions, a reference test was carried out once every 7 days with copper-(II)-sulphate-pentahydrate to determine the reference toxicity. Validity criteria of the test guideline were fulfilled.

The EC50 for test material: 8972.0 mg/L, EC 50 at 95% confidence level: >8574.0-<9389.0 mg/L EC 20 for test material: 7381 mg/L, and EC80 for test material: >10000 mg/L. The test item tungsten disulphide is not toxic in concentrations less than or equal to 7381 mg/L to activated sludge of a municipal sewage treatment plant.