Tungsten carbide

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

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.

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 °C

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

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Duration:

96 h

Dose descriptor:

LC0

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

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.

Description of key information

The toxicity of tungsten carbide (WC) to fish was tested following OECD 203. A 96 hour LC50 of >1000 mg/L, and 96 hour LC0 of >1000 mg WC/L were derived from the test results.

 

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

1 000 mg/L

Additional information

Due to lower transformation/dissolution results for tungsten carbide (the target substance) than sodium tungstate (the source substance), the resulting toxicity potential would also be expected to be lower, so read-across is appropriate. In addition, read-across is justified because the classification and labelling is less severe for the target substance and the PBT/vPvB profile is the same. Finally, the dose descriptor for the target substance is expected to be sufficiently lower than the source chemical, and read-across to the source chemical is adequately protective. For more details refer to the attached description of the read-across approach or see Annex 3 of the CSR.