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Short-term toxicity to aquatic invertebrates

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Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
This information is used in a read-across approach in the assessment of the target substance.

Reason / purpose for cross-reference:
read-across source
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
> 163 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Remarks:
sodium tungstate
Basis for effect:
other: immobilization
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 163 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Remarks:
sodium tungstate
Basis for effect:
other: immobilization
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
90.8 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Remarks:
sodium tungstate
Basis for effect:
other: immobilization
Details on results:
After 48 hours of exposure, immobility was 0, 0, 0, 0, 5 and 15 % in the control and 11.9, 21.5, 41.5, 90.8, and 163 mg/L treatments, respectively. There were no sublethal effects noted in any of the control or test substance treatments. Based on mean measured concentrations, the 48 hour EC50 was > 163 mg/L, the highest concentration tested. Immobility was significantly increased at only the highest test concentration level. The 48 hour NO Observed Effect Concentration (NOEC) was determined to be 90.8 mg/L, based on the lack of statistically significant (p=0.05) immobility and sublethal effects at this test substance treatment.
Results with reference substance (positive control):
n/a
Reported statistics and error estimates:
All statistical analyses were performed with SAS software. Estimates of LC50 values and their 95 % confidence limits were calculated using the probit method and trimmed Spearman-Karber method. When the p value for goodness of fit was > 0.05 and there was no other evidence of questionable convergence, the probit method was selected for reporting. When this criterion was not achieved, the trimmed Spearman-Karber method was selected for reporting. The NOEC was determined by using a one-tailed Dunnett’s test.
Validity criteria fulfilled:
not specified
Conclusions:
The 48 hour EC50 value was estimated to be >163 mg/L. The 48 hour NOEC was 90.8 mg/L based on the lack of statistically significant (p=0.05) immobility and sublethal effects at this and lower test substance treatments.

Executive summary:

The 48 h acute toxicity of tungsten trioxide to Daphnia magna was studied under static conditions. Daphnids were exposed to control, and test chemical at mean measured concentrations of sodium tungstate dihydrate of 0 (control), 11.9, 21.5, 41.5, 90.8, and 163 mg/L. Mortality and immobilization were observed daily. The 48–hour EC50was > 163 mg sodium tungstate dihydrate/L. The 48-hour NOEC based on immobilization was 90.8 mg Na2WO4/L (56.8 mg W/L).

 

This study is classified as supplementary and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

 

Results Synopsis

 

Test Organism Age: 1stinstar

Test Type: Static

 

EC50:  > 163 mg Na2WO4/L (102 mg W/L)

NOEC (immobility): 90.8 mg Na2WO4/L (56.8 mg W/L)

Endpoint(s) Effected: mortality, immobility

This information is used in a read-across approach in the assessment of the target substance.

For details and justification of read-across please refer to the attached report in section 13 of IUCLID.

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
This information is used in a read-across approach in the assessment of the target substance.
Reason / purpose for cross-reference:
read-across source
Duration:
48 h
Dose descriptor:
EC0
Effect conc.:
>= 5 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
WO3
Basis for effect:
mortality
Duration:
48 h
Dose descriptor:
EC0
Effect conc.:
>= 3.3 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Remarks:
WO3
Basis for effect:
mortality
Duration:
48 h
Dose descriptor:
EC0
Effect conc.:
>= 2.6 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
other: W
Basis for effect:
mortality
Details on results:
The results are expressed in terms of mean measured concentrations (at 48 h). Measured concentrations correspond to 66 % of nominal (tungsten trioxide - WO3) at 0 hours and at 48 hours.
Results with reference substance (positive control):
n/a
Reported statistics and error estimates:
no data
Validity criteria fulfilled:
not specified
Conclusions:
48 hour EC0 ≥ 2.6 mg/L (W); ≥ 3.3 mg/L (WO3)
Executive summary:

The 48-h acute toxicity of tungsten trioxide to Daphnia magna was studied under static conditions.  Daphnids were exposed to control, and test chemical at nominal concentration of 5 mg a.i./L and measured concentration of 3.3 mg WO3/L for 48 h (according to 2.6 mg W/L).  Mortality and immobilization were observed daily.  The 48-h LC50was > 2.6 mg W/L.  The 48-h NOEC based on mortality and immobilization was 2.6 mg W/L. Investigations on the following sublethal effects were included in the study design: alteration of the normal mobility behaviour and the loss of locomotory actions. 

 

This study is classified as supplementary and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

 

Results Synopsis

 

Test Organism Age (e.g. 1stinstar): 1stinstar

Test Type (Flowthrough, Static, Static Renewal): Static, Limit test

 

EC50:  > 2.6 mg W/L (meas.)

NOEC:  2.6 mg W/L (meas.)

Endpoint(s) Effected: mortality, alteration of the normal mobility behaviour and the loss of locomotory actions

This information is used in a read-across approach in the assessment of the target substance.

For details and justification of read-across please refer to the attached report in section 13 of IUCLID.

Description of key information

The acute toxicity to aquatic invertebrates was tested using sodium tungstate dihydrate and tungsten trioxide.

Tungsten trioxide was applied at a single nominal concentration of 5 mg/L, corresponding to a measured concentration of 2.6 mg W/L. No immobilisation was observed; therefore, a definitive EC50 could not be determined.

In the test on Daphnia employing sodium tungstate dihydrate as test substance the EC50 was found to be above the highest concentration tested (> 163 mg Na2WO4/L, corresponding to 102 mg W/L).The 48-hour NOEC based on immobilization was 90.8 mg Na2WO4/L (56.8 mg W/L).

This information is used in a read-across approach in the assessment of the target substance.

For details and justification of read-across please refer to the attached report in section 13 of IUCLID.

Recalculation of these values to corresponding concentrations of tungsten hexachloride result in theoretic values of:

- NOEC = 122.5 mg WCl6/L

- EC50 > 220 mg WCl6/L

However, these values considerably exceed the water solubility of the substance which is in the range of 20- 42.1 µg/L and 44.8 µg/L after adjustment to pH 7 (Golz, 2017). Therefore, no adverse effects in aquatic invertebrates are expected through the amount of soluble tungsten ions released from tungsten hexachloride in water.

Key value for chemical safety assessment

Additional information