Tungsten trioxide

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:

2002-07-01 to: 2002-07-12

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: Commission Directive 88/302/EEC

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes

Analytical monitoring:

no

Details on sampling:

no data

Vehicle:

no

Details on test solutions:

The test substance was added to about 130 mL of deionized water and stirred overnight before testing (equilibration phase)

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

no data

Test type:

not specified

Water media type:

not specified

Limit test:

no

Total exposure duration:

3 h

Remarks on exposure duration:

permanent aeration

Post exposure observation period:

no data

Hardness:

no data

Test temperature:

20 +/- 2 °C

pH:

pH of the suspension before application : 6.1
pH of the various test substance concentratoins: 7.2 - 7.4

Dissolved oxygen:

no data

Salinity:

N/A

Nominal and measured concentrations:

Nominal test concentrations (mg/L): 1000, 1800, 3200, 5600, 10000

Details on test conditions:

TEST SYSTEM
- Test vessel: aeration tank of waste water treatment plant treating predominately domestic sewage (Wupper area water authority)
- Test concentration of the activated sludge : 480 mg/L suspended solids

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol (purity of 97%)

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 10 000 mg/L

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

- Tungsten trioxide showed 3.1 % respiration inhibition of activated sludge at a test substance concentration of 10,000 mg/L.

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- Relevant effect levels: EC50 = 6.1 mg/L

Reported statistics and error estimates:

- The EC values were determined by statistical methods (probit analysis)

Test concentration: 1000 mg/L - Inhibition: 0.0% Test Concentration: 1800 mg/L - Inhibition: 15.4% Test Concentration: 3200 mg/L - Inhibition: 7.7% Test Concentration: 5600 mg/L - Inhibition: 7.7% Test Concentration: 10000 mg/L - Inhibition: 3.1% Physical-Chemical oxygen consumption was 0 mg/L-h for all test concentrations. The Respiratory rate-phsical-chemical oxygen consumption ranged from 22.0 mg/L-h to 27.0 mg/L-h

Conclusions:

Tungsten trioxide showed 3.1% respiration inhibition of activated sludge at the test substance concentration of 10,000 mg/L. The EC50 > 10,000 mg/L

Description of key information

Tungsten trioxide was tested for toxicity to microorganisms. Tungsten trioxide showed 3.1% respiration inhibition of activated sludge at the test substance concentration of 10,000 mg/L. The EC50 > 10,000 mg/L

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

10 000 mg/L