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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:
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 degree 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

Tungsten carbide was not tested for toxicity to soil micro-organisms and read-across to sodium tungstate was used for this endpoint. In both a carbon and a nitrogen transformation test using sodium tungstate the 28-day EC50 was found to be > 1000 mg/kg soil d.w. (sodium tungstate concentration) (nominal) (approximately 586 mg W/kg). Read across to sodium tungstate is appropriate as sodium tungstate is of higher solubility under simulated environmental conditions and has the same classification and PBT profile as WC.

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L

Additional information

Tungsten carbide was not tested for toxicity to soil micro-organisms and read-across to sodium tungstate was used for this endpoint. In both a carbon and a nitrogen transformation test using sodium tungstate the 28-day EC50 was found to be > 1000 mg/kg soil d.w. (sodium tungstate concentration) (nominal) (approximately 586 mg W/kg). Read-across to sodium tungstate is appropriate as sodium tungstate is of higher solubility under simulated environmental conditions and has the same classification and PBT profile as WC.