Tungsten dioxide

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

4 to 8 November 2002

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Well documented, scientifically sound study conducted in accordance to GLP and EU Method C.1 (Acute Toxicity for Fish) with no deviation from the protocol. The reliability of this study for the substance tested is 1, but in application of read-across to a different substance ECHA’s guidance specifies that the score can be a maximum of 2. Due to similar or lower transformation/dissolution results for tungsten dioxide (the target substance) than tungsten trioxide (the source substance), the resulting toxicity potential would also be expected to be similar or lower, so read-across is appropriate. Therefore, the dose descriptors are expected to be sufficiently similar or higher for the target substance, and read-across to the source chemical is adequately protective. For more details refer to the attached description of the read-across approach.

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 Trioxide
Target: Tungsten Dioxide
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:

EU Method C.1 (Acute Toxicity for Fish)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
PHYSICO-CHEMICAL PROPERTIES
- Water solubility: <10 mg/L WO3 at 20 °C

Analytical monitoring:

yes

Details on sampling:

no data

Vehicle:

no

Details on test solutions:

no data

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: Zebra fish
- Source: Di Mamma (Netherlands)
- Length at study initiation (length definition, mean, range and SD): mean 3.5 cm (S.D. = 0.33 cm)

ACCLIMATION
- Acclimation period: Stock held since September 2, 2002 and acclimatised to the test conditions since then.
- Acclimation conditions (same as test or not): same
- Type and amount of food: Commerical fish food
- Feeding frequency: daily; discontinued 24 hours prior to the test
- Health during acclimation (any mortality observed): < 5% mortalities

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Post exposure observation period:

no data

Hardness:

173.1 mg/L CaCO3

Test temperature:

20.8-22.0 °C (in the temperature range of 20-24 °C)

pH:

7.5-7.7

Dissolved oxygen:

8.2-8.4 mg/L (92-97 % saturation)

Salinity:

n/a

Nominal and measured concentrations:

Nominal: 2.5 mg/L (WO3)
Measured: 5.2-5.3 mg/L (WO3)
Measured: 4.15-4.20 mg/L (W)

Details on test conditions:

TEST SYSTEM
- Test vessels: Glass aquaria holding 5 L of test media
- Aeration: gentle aeration via narrow glass tubes
- Experimental design: 1 test concentration (2.5 mg/L) plus 1 control, no feeding during the exposure period, static system
- Renewal rate of test solution (frequency/flow rate): None
- No. of organisms per vessel: 10 animals per test concentration
- Photoperiod: 16 hours light, 8 hours dark
- Biomass loading rate: 0.88 g body weight (wet weight) per litre

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted water prepared according to the recommendations of ISO 7346. This freshly prepared standard dilution water is used for both the maintenance of the test animals under flow-through conditions and the preparation of stock and test solutions of the test substance.

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

LC0

Effect conc.:

>= 5.25 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

WO3

Basis for effect:

mortality (fish)

Duration:

48 h

Dose descriptor:

LC0

Effect conc.:

>= 4.16 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

act. ingr.

Remarks:

Tungsten (W)

Basis for effect:

mortality (fish)

Duration:

72 h

Dose descriptor:

LC0

Effect conc.:

>= 5.26 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

WO3

Basis for effect:

mortality (fish)

Duration:

72 h

Dose descriptor:

LC0

Effect conc.:

>= 4.18 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

act. ingr.

Remarks:

Tungsten (W)

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC0

Effect conc.:

>= 5.25 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

WO3

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC0

Effect conc.:

>= 4.16 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

act. ingr.

Remarks:

Tungsten (W)

Basis for effect:

mortality (fish)

Details on results:

All results are expressed in terms of mean measured concentrations. Measured concentrations correspond to 212 % of nominal values of tungsten trioxide at 0 hours, to 208 % of nominal values of tungsten trioxide at 24 hours, to 212% of nominal values of tungsten trioxide at 48 hours, to 212 % of tungsten trioxide at 72 hours, and to 208 % of nominal values of tungsten trioxide at 96 hours, respectively.

Results with reference substance (positive control):

n/a

Reported statistics and error estimates:

no data

Conclusions:

The acute toxicity of tungsten trioxide to zebrafish (Danio rerio) was assessed according to EU method C.1. Water quality parameters (temperature, dissolved oxygen and pH) were within acceptable limits. The study was conducted at the following nominal concentration of tungsten trioxide:

- Nominal: 2.5 mg/L (WO3)
- Measured: 5.2–5.3 mg/L (WO3)
- Measured: 4.15-4.20 mg/L (W)

Observations on mortality as well as subjective assessments on the type and incidence of sub-lethal effects compared with control fish were made at 2, 24, 48, 72, and 96 hours.
The results of the four day static fish toxicity study using tungsten trioxide are summarized below. Also the 24- and 48-hour LC50values were determined.
 
96-hour LC50 > 4.16 mg W/L (corresponding to 5.25 mg WO3/L; measured concentrations).

Furthermore, the results support a 96-hour no-observed effect concentration (LC0) of 4.16 mg W/L (5.25 mg WO3/L), which is based on the lack of both mortality and abnormal effects at the highest concentration tested. Highest test concentration resulting in 0 % mortality (LC0, 96h): >= 5.25 mg/L test substance.

Executive summary:

No short toxicity to fish data of sufficient quality are available for tungten dioxide (target substance). However, short toxicity to fish data are available for tungsten trioxide (source substance), which will be used for read-across. Due to similar water solubility and toxicity for the target substance compared to the source substance, the resulting read-across from the source substance to the target substance is appropriate as a conservative estimate of potential toxicity for this endpoint. For more details, refer to the read-across category approach included in the Category section of this IUCLID submission and/or as Annex 3 in the CSR.

Reference 2

Endpoint:

short-term toxicity to fish

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

2008-09-25 to 2009-03-13

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Well documented, scientifically sound study conducted in accordance to GLP and OECD guideline 203 with no deviation to the protocol. The reliability of this study for the substance tested is 1, but in application of read-across to a different substance ECHA’s guidance specifies that the score can be a maximum of 2. Due to similar or lower transformation/dissolution results for tungsten dioxide (the target substance) than sodium tungstate (the source substance), the resulting toxicity potential would also be expected to be similar or lower, so read-across is appropriate. Therefore, the dose descriptors are expected to be sufficiently similar or higher for the target substance, and read-across to the source chemical is adequately protective. For more details refer to the attached description of the read-across approach.

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: Sodium Tungstate
Target: Tungsten Dioxide
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)

Deviations:

no

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:

yes

Details on sampling:

- Concentrations: 0 (control), 13, 25, 50, 100, and 200 mg/L; a volume of 10 mL was collected from each control and test substance replicate at 0 and 96 hours and transferred to a culture tube.
- Sampling method: 0.05 mL aliquot of each sample was taken, diluted if necessary with 2 % HNO3, capped and shaken to mix.
- Sample storage conditions before analysis: Room temperature

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 7.5075 g of sodium tungstate dihydrate was added to a 21-L glass jar and bringing the jar to a volume of 15,000 mL with blended freshwater. Appropriate aliquots of the primary standard were diluted with 15 L of dilution water to prepare final test concentrations of 13, 25, 50, 100, and 200 mg total product/L. The control solution consisted only of dilution water.

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: Zebrafish
- Source: Osage Catfisheries, Osage Beach, Missouri
- Age at study initiation (mean and range, SD): Not specified
- Length at study termination: 28–31 mm; mean 30 (± SD 1.2) mm (controls only)
- Weight at study termination: 0.194-0.408 g; mean 0.276 ± 0.0664 g (controls only)
- Feeding during test
- Frequency: Not fed during test, or one day prior

ACCLIMATION
- Acclimation period: 5 days
- Acclimation conditions (same as test or not): Temperature adjusted for test
- Type and amount of food: Salmon starter, flake food, and brine shrimp
- Feeding frequency: Daily
- Health during acclimation (any mortality observed): No mortality observed in 14 days prior to testing.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

None

Hardness:

140 mg/L CaCO3

Test temperature:

23 ± 1 °C

pH:

8.0-8.3

Dissolved oxygen:

6.7-8.3 mg/L (82 to 101 % saturation)

Salinity:

Not applicable

Nominal and measured concentrations:

Nominal: 0 (control), 13, 25, 50, 100, and 200 mg/L.
Mean calculated:

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 21 L glass jars, covered with plastic Petri dishes; 15 L test solution.
- Aeration: None
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- Biomass loading rate: 0.18 g fish tissue/L test solution

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Moderately hard freshwater made with naturally hard well water blended with well water demineralized by reverse osmosis, total hardness of 130-160 mg/L CaCO, passed through a sediment filter prior to use.
- Metals: B (0.415 mg/L), Ca (83.1 mg/L), Mg (33.1 mg/L), K (7.93 mg/L), Na (32.2 mg/L); all others below DL.
- Pesticides: Below DL
- Alkalinity: 150 mg/L CaCO3
- Conductivity: 328 µS/cm
- Intervals of water quality measurement: Daily

OTHER TEST CONDITIONS
- Adjustment of pH: None
- Photoperiod: 16 h light/8 h dark, with 30 min simulated dawn and dusk periods
- Light intensity: 542 lux at initiation of the definitive test as measured with a LI COR Model LI-189 light meter equipped with a photometric sensor.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Mortality, 24 h

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study: Other studies indicated a low potential for toxicity to aquatic organisms; therefore, a range finding study was not performed. Definitive testing was performed at a level that exceeds the guideline-compliant maximum, 100 mg/L for this test.

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Remarks on result:

other: No mortality in any control or test solution

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 181 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Remarks:

based on mean calculated concentrations of sodium tungstate

Basis for effect:

mortality (fish)

Remarks on result:

other: No mortality in any control or test solution

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

behaviour

Remarks on result:

other: Lack of mortality and sublethal effects

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 181 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Remarks:

based on mean calculated concentrations of sodium tungstate

Basis for effect:

behaviour

Remarks on result:

other: Lack of mortality and sublethal effects

Details on results:

Biological Results:
After 96 hours of exposure, there was no mortality in the control or any of the test substance treatments. There were no sublethal observations during the exposure. The estimated 24-, 48-, 72-, and 96-hour LC50 values for zebrafish exposed to sodium tungstate dihydrate were >200 mg/L, the highest concentration tested. Since there was no partial response, the 96-hour slope of the concentrations-response line could not be calculated from the probit analysis. The 96 hour no-observed-effect concentration (NOEC) was 200 mg/L based on the lack of mortality and sublethal effects atthis and lower test substance concentrations.

Reported statistics and error estimates:

Both the EC50 and the no observed-effect concentration (NOEC) was determined based on the absence of any mortality or sublethal effects.

Conclusions:

The acute toxicity of sodium tungstate to zebrafish (Danio rerio) was assessed in accordance with OECD guideline 203. Water quality parameters (temperature, dissolved oxygen and pH) were within acceptable limits.The study was conducted at the following nominal concentrations of sodium tungstate dihydrate:

- Nominal conentrations: 0 (control), 13, 25, 50, 100, and 200 mg/L
- Mean calculated concentrations: < LOQ (Control), 12.0, 23.1, 46.1, 89.2, and 181 mg/L (89–92 % of nominal).

Observations for mortality and sublethal responses were made every 24 hours (±1 hour) throughout the test.

The results of the four day static fish toxicity study using sodium tungsten are summarized below:
 
96-hour LC50 > 181 sodium tungstate/L.
 
Also, the results indicated a 96-hour, no-observed effect concentration could be estimated at 181 mg sodium tungstate/L, which is based on the lack of both mortality and sub-lethal effects at the highest concentration tested

Based on nominal concentrations, the estimated 96 hour LC50 value for zebrafish exposed to sodium tungstate dihydrate was >200 mg/L, the highest concentration tested. Accordingly, derivation of a concentration-response relationship is not appropriate. The 96-hour no-observed-effect concentration (NOEC) was 200 mg/L, based on the lack of mortality and sublethal effects at this and the lower concentrations.

Executive summary:

No short toxicity to fish data of sufficient quality are available for tungsten dioxide (target substance). However, short toxicity to fish data are available for sodium tungstate (source substance), which will be used for read-across. Due to lower 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 as a conservative estimate of potential toxicity for this endpoint. In addition, read-across is appropriate because the classification and labelling is more protective 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 Annex 3 in the CSR.

Description of key information

Tungsten dioxide was not tested for acute and chronic aquatic toxicity and read-across to tungsten trioxide and/or sodium tungstate was used for these endpoints. No deaths were observed at saturation concentration under exposure conditions in an acute toxicity test with tungsten trioxide; therefore, a definitive LC50 could not be determined and read-across to sodium tungstate is used for this endpoint. In a flow-through test using zebrafish and testing another soluble tungsten compound with the same classification and PBT profile (sodium tungstate) the LC50 observed was found to be greater than the highest concentration tested (>181 mg sodium tungstate/L or approximately 106 mg W/L).

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

106 mg/L

Additional information

Due to similar or lower transformation/dissolution results for tungsten dioxide (the target substance) than tungsten trioxide/sodium tungstate (the source substances), the resulting toxicity potential would also be expected to be similar or lower, so read-across is appropriate. Therefore, the dose descriptors are expected to be sufficiently similar or higher for the target substance, and read-across to the source chemical is adequately protective. For more details refer to the description of the read-across category approach.