Tungsten carbide

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

LP guideline study. Reliability assigned by a secondary source (OECD SIDS Initial Assessment Report). Only secondary source reviewed, as primary study was not available.

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
no data

Analytical monitoring:

no

Vehicle:

not specified

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

TEST ORGANISM:
-Mixed population of aquatic micro-organisms of a waste water treatment plant treating predominantly domestic sewage (Hildesheim, Germany); pre-treatment: washed twice with autoclaved tap water and diluted 1:3.
-Nutrient solution: synthetic waste water, pH 7.1, dry sludge concentration; 2.7 g/L.

Test type:

static

Water media type:

not specified

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

no data

Hardness:

no data

Test temperature:

19 °C

pH:

no data

Dissolved oxygen:

no data

Salinity:

no data

Nominal and measured concentrations:

Test concentration: 6 (58, 100, 180, 320, 580, 10000 mg/L)

Details on test conditions:

Type: aquatic

TEST CONDITIONS:
-Static test system
-Dry sludge concentration: 2700 mg/L
-Test vessels: 500 ml Erlenmeyer flasks
-Stirring period before start of incubation time: 16.5 h
-Dispersion treatment of test substance: 15 min ultrasonic bath at 30 °C
-Replicates: 1 per concentration and control
-Test parameter: respiration rate
-Aeration: permanent

Reference substance (positive control):

yes

Remarks:

copper (II) sulfate pentahydrate (58, 100, 180 mg/L).

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

not specified

Basis for effect:

growth inhibition

Details on results:

The test substance was not soluble in water in a concentration of 1000 mg/L.
The test substance was deposited on the ground. Effects of the test concentration leading to an inhibition >20 % after 3h were not observed. The EC-values were not determinable. An EC50 of >1000 mg/L was derived from the test results.

Results with reference substance (positive control):

The two control respiration rates differ not more than 15 %
The EC50 of the reference substance was in the accepted range (67 - 134 mg/L).

Reported statistics and error estimates:

No data

Validity criteria fulfilled:

yes

Conclusions:

An EC50 of >1000 mg/L was derived from the test results.

Description of key information

The toxicity of tungsten carbide on activated sludge, respiration inhibition was assessed. The 3h EC50 was found to be >1000 mg/L (938.7 mg W/L).

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L