Registration Dossier

Ecotoxicological information

Toxicity to microorganisms

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
read-across based on grouping of substances (category approach)
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.
Justification for type of information:
1. HYPOTHESIS FOR THE CATEGORY APPROACH: The hypothesis is that properties are likely to be similar or follow a similar pattern because of the presence of a common metal ion, in this case tungstate.
2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES):
Source: Tungsten Carbide
Target: Fused tungsten carbide
3. CATEGORY APPROACH JUSTIFICATION: See Annex 3 in CSR
4. DATA MATRIX: See Annex 3 in CSR
Reason / purpose:
read-across: supporting information
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 ⁰C
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).
Key result
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.
Executive summary:

No toxicity to microorganisms data of sufficient quality are available for fused tungsten carbide (target substance). However, toxicity to microorganisms data are available for tungsten carbide (source substance), which will be used for read-across. Due to similar water solubility and lower toxicity for the target substance compared to the source substance, the resulting read-across from the source substance to the target substance is appropriate. In addition, read-across is appropriate because the classification and labelling is similar for the source substance than the target substance, the PBT/vPvB profile is the same, and the dose descriptors are, or are expected to be, lower for the source substance. For more details, refer to the read-across category approach included in the Category section of this IUCLID submission and/or as an Annex in the CSR.

Description of key information

Fused tungsten carbide was not tested for toxicity to soil micro-organisms and read-across to tungsten carbide (WC) was used for this endpoint. An EC50 of >1000 mg WC/L was derived from the test results (approximately 939 mg W/kg).

Key value for chemical safety assessment

EC50 for microorganisms:
939 mg/L

Additional information

No toxicity to microorganisms data of sufficient quality are available for fused tungsten carbide (target substance). However, toxicity to microorganisms data are available for tungsten carbide (source substance), which will be used for read-across. Due to similar water solubility and lower toxicity for the target substance compared to the source substance, the resulting read-across from the source substance to the target substance is appropriate. In addition, read-across is appropriate because the classification and labelling is similar for the source substance than the target substance, the PBT/vPvB profile is the same, and the dose descriptors are, or are expected to be, lower for the source substance. For more details, refer to the read-across category approach included in the Category section of this IUCLID submission and/or as an Annex in the CSR.