Reaction mass of ditungsten carbide and tungsten carbide

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

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:

GLP guideline study. Reliability assigned by a secondary source (OECD SIDS Initial Assessment Report). Only secondary source reviewed, as primary study was not available. However details provided were sufficient for assessment.

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 for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

GLP compliance:

yes

Analytical monitoring:

yes

Details on test solutions:

The test substance was separately weighed for each concentration, added to the test media, and dispersed by ultrasonic for 30 minutes. Afeter these treatments, undissolved test substance remained in the test beakers and was dispersed twice daily with an ultraturrax 20500 rpm for 5 minutes. Although recoveries were 52-89%, the nominal concentrations were used because loss of the test substance occurred during the sampling procedure. These recovery rates are attributed to the solubility and sedimentation of the test substance in the test medium during sampling.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM:
-Origin: Zoo-Stumpe, 31134 Hildesheim (Germany)
-Length: 29 mm (n=7)
-Weight: 1.6 g (n=7)
-Medical pre-treatment: none
-Mortality while kept: < 5 %

Test type:

static

Water media type:

freshwater

Total exposure duration:

96 h

Hardness:

Hardness 82.6 CaCO3 mg/L

Test temperature:

Temperature 18.6 -21.2 ⁰C

pH:

6.92 - 8.29

Dissolved oxygen:

Oxygen saturation: 93 - 99 %
The oxygen saturation was >= 60 % at the end of testing.

Nominal and measured concentrations:

-Test concentrations: 100, 180, 320, 580, 1000 mg/L

Details on test conditions:

-Test medium: dechlorinated drinking water, filtered and aerated for at least 24 h
-Test vessel: aquarium with a volume of 15 L, containing 10 L test medium
-Natural photoperiod, light intensity 10 umol/mE+2s
-Number of fish per dose: 7
-Preliminary testing: range finding with 2 concentrations
-Application of test substance: mixed using an ultraturrax 20500 rpm for 5 min.
-Replicate: 1 and 1 control
-Solubilizer: none
-Daily recording of non lethal and/or lethal effects

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Key result

Duration:

96 h

Dose descriptor:

LC0

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Key result

Duration:

96 h

Dose descriptor:

LC100

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Details on results:

Sedimentation of the test substance was observed in all test vessels. The sedimentated test substance was dispersed twice daily with an ultraturrax.

The recovery rates of the active ingredient at the end of the test were > 77 %. For that reason effect level concentrations are given as nominal concentrations.

A concentration-effect relationship for 24, 48, 72 and 96h was not calculated as no mortality was observed after 96h. Neither probit analysis nor graphical presentation is made. A LC50 of >1000 mg/l was derived from the test results.

Reported statistics and error estimates:

no data

Conclusions:

A 96 hour LC50 of >1000 mg/L, and 96 hour LC0 of >1000 mg/L were derived from the test results.

Executive summary:

No fish short-term toxicity data of sufficient quality are available for fused tungsten carbide (target substance). However, fish short-term toxicity 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

A 96 hour LC50 of >1000 mg/L, and 96 hour  LC0 of >1000 mg WC/L were derived from the test results.

The following information is taken into account for long-term fish toxicity for the derivation of PNEC:

Fused tungsten carbide was not tested for chronic toxicity to fish, and read-across to sodium tungstate was used for this endpoint. In a flow-through, early-life stage test using zebrafish and testing sodium tungstate, the NOEC was found to be greater than or equal to the highest concentration tested (≥9.8 mg sodium tungstate/L or approximately 5.74 mg W /L). The mean calculated concentrations in the test solutions represented recoveries of 92 to 103% of the nominal concentrations.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

1 000 mg/L

Additional information

No short-term toxicity to fish data of sufficient quality are available for fused tugsten carbide (target substance). However, short-term toxicity 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.