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Ecotoxicological information

Toxicity to microorganisms

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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

Additional information