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Short-term toxicity to fish

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Endpoint:
short-term toxicity to fish
Type of information:
experimental study
Adequacy of study:
key study
Study period:
from 30 oct 2000 to 29 nov 2000
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to the OECD internationally recognised guideline, but the GLP are not stated, and no analytics were performed.
Qualifier:
according to
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
Deviations:
no
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The substance, practically insoluble in water, was introduced in the test medium by weighed adequate quantity and was dispersed by stirring. The dissolution was continued during a period of 168 hours to be sure that the equilibrium was reached and "soluble fraction" stable during the test. After correction of evaporation by addition of deionised water, stirring was stopped and the different suspensions were decanted for a resting period of 4 hours.
- Controls: yes, test water without test item
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no

Test organisms (species):
Danio rerio (previous name: Brachydanio rerio)
Details on test organisms:
TEST ORGANISM
- Common name: Zebra fish
- Source: Pisciculture Exotique - Dourdan, 91, France
- Size/weight: 30.4 mm, 0.3 g
- Method of breeding: The fish were bred in reconstituted water (ISO 7346) with continuous aeration and filtering device
- Food: TetraMin Tetra during breeding (no feeding during the test)

ACCLIMATION
- Acclimation period: 2 weeks
- Acclimation conditions: same as test
- Health during acclimation: mortality less than 1% within the adaptation period
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
96 h
Post exposure observation period:
none
Hardness:
250 mg/L +/- 25 mg/L as CaCO3.
Test temperature:
24°C +/- 1°C
pH:
7.17-7.83
Dissolved oxygen:
4.5-8.2 mg/L
Salinity:
not applicable
Nominal and measured concentrations:
100 mg/L (nominal loading rate)
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type: 5-L glass beakers
- Fill volume: 4 L of reconstituted water
- Aeration: none during the test, but dilution water was previously saturated with oxygen before the start of the test
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- Biomass loading rate: 0.76 g/L

WATER PARAMETERS
- Source: reconstituted water-ISO 7346
- Conductivity: < 5 µs/cm
- Intervals of water quality measurement: pH and dissolved oxygen were measured after 0, 24, 48, 72 and 96 h of exposure
- No further data

OTHER TEST CONDITIONS
- Photoperiod: about 12 h light daily
- Light intensity: natural diffused lighting

EFFECT PARAMETERS MEASURED : Immobility and absence of respiration motion observed after 3, 24, 48, 72 and 96 h of exposure
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
No mortality was observed during the test, either in control or test groups.
No abnormal response of the fish was observed during the test period.
Results with reference substance (positive control):
- Results with reference substance valid? yes
- Mortality: no data
- 24h LC50: 226 mg/L (K2Cr2O7). This calculated value was between the interval (200-400 mg/L) formerly defined by the method, and was used to validate the selected fish batch.

Validity criteria fulfilled:
yes
Conclusions:
Using a limit test at 100 mg/L, zirconium dioxide had no acute toxic effect on the fish Danio rerio.
Executive summary:

The 96-h acute toxicity of zirconium dioxide to Brachydanio rerio was studied under static conditions, according to OECD Guideline 203. Fish were exposed to control and test chemical at a nominal concentration of 100 mg/L. Mortality/immobilisation were observed daily. No mortality was observed during the test, neither in the control nor in the group exposed to the test item. The 96-h LC50 was thus > 100 mg/L.

Endpoint:
short-term toxicity to fish
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
Read across from a study performed with zirconium dioxide. The read across justification document is attached to IUCLID Section 13.
Reason / purpose:
read-across source
Key result
Remarks on result:
other: Tungsten zirconium oxide is not considered to be toxic or harmful to fish.
Remarks:
This conclusion was based on the results of the study from Bazzon (2000) with zirconium dioxide.

Description of key information

No data for tungsten zirconium oxide were added to the dossier because the assumption of the read across approach (i.e. the addition of tungsten (oxide) to the crystal lattice of zirconium dioxide does not affect the unhazardous properties of zirconium dioxide) was already validated by comparison of key data for zirconium dioxide and tungsten zirconium oxide for the basic endpoints acute toxicity to aquatic invertebrates and toxicity to aquatic algae. Therefore, the endpoint is covered using the study of Bazzon (2000), in which the acute toxicity of zirconium dioxide was investigated in Brachydanio rerio and in which no mortality was observed up to the limit concentration of 100 mg/L (nominal loading rate). Based on the results of this study and the conclusions of the read across approach, it can be safely concluded that tungsten zirconium oxide is equally unharmful to fish as pure zirconium dioxide. 

Key value for chemical safety assessment

Additional information

1. Information on zirconium dioxide

The 96-h acute toxicity of zirconium dioxide to Brachydanio rerio was studied (Bazzon, 2000) under static conditions, according to OECD Guideline 203. Fish were exposed to control and test chemical at a nominal concentration of 100 mg/L. Mortality/immobilisation were monitored daily. No mortality was observed during the test, neither in the control nor in the group exposed to the test item. The 96-h LC50 was thus > 100 mg/L.

2. Conclusion on tungsten zirconium oxide

Tungsten zirconium oxide is zirconium dioxide with tungsten partly replacing zirconium in the crystal lattice. Zirconium dioxide has been demonstrated not to cause any adverse effects in fish (Bazzon, 2000). Based on comparison of key data for zirconium dioxide and tungsten zirconium oxide for basic ecotoxicological endpoints such as acute toxicity to aquatic invertebrates and toxicity to aquatic algae, it was concluded that the addition of tungsten (oxide) to the crystal lattice of zirconium dioxide is not expected to alter the unhazardous character of zirconium dioxide. Therefore the study of Bazzon (2000) can be considered as representative for tungsten zirconium oxide.