Registration Dossier

Physical & Chemical properties

Water solubility

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
transformation / dissolution of metals and inorganic metal compounds
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Well documented, scientifically sound study that determined the dissolution of the test substance according to the UN Guidance on transformation/dissolution (T/D) of metals and metal compounds (UN GHS Annex 10).
Qualifier:
according to
Guideline:
other: UN Guidance on transformation/dissolution (T/D) of metals and metal compounds (UN GHS Annex 10)
Principles of method if other than guideline:
Standardized amounts of powdered solids are added to specified simulated aquatic media and amounts of the relevant soluble metal ion are measured after defined timepoints.
GLP compliance:
not specified
Type of method:
other: Guidance on transformation/dissolution (T/D) of metals and metal compounds (UN GHS Annex 10)
Key result
Type of test:
screening transformation/dissolution test - sparingly soluble metal compounds
Mean dissolved conc.:
18.154 mg/L
Element analysed:
Dissolved tungsten
Loading of aqueous phase:
100 mg/L
Incubation duration:
24 h
Test conditions:
pH=8.5, 20-23 deg C
Key result
Type of test:
screening transformation/dissolution test - sparingly soluble metal compounds
Mean dissolved conc.:
20.225 mg/L
Element analysed:
Tungstate anion
Loading of aqueous phase:
100 mg/L
Incubation duration:
24 h
Test conditions:
pH=8.5, 20-23 deg C
Key result
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
0.607 mg/L
Element analysed:
Dissolved tungsten
Loading of aqueous phase:
1 mg/L
Incubation duration:
7 d
Test conditions:
pH=8.5, 20-23 deg C
Key result
Type of test:
screening transformation/dissolution test - sparingly soluble metal compounds
Mean dissolved conc.:
0.814 mg/L
Element analysed:
Dissolved tungsten
Loading of aqueous phase:
1 mg/L
Incubation duration:
7 d
Test conditions:
pH=8.5, 20-23 deg C
Key result
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
6.03 mg/L
Element analysed:
Dissolved tungsten
Loading of aqueous phase:
10 mg/L
Incubation duration:
7 d
Test conditions:
pH=8.5, 20-23 deg C
Key result
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
8.156 mg/L
Element analysed:
Tungstate anion
Loading of aqueous phase:
10 mg/L
Incubation duration:
7 d
Test conditions:
pH=8.5, 20-23 deg C
Key result
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
62.47 mg/L
Element analysed:
Dissolved tungsten
Loading of aqueous phase:
100 mg/L
Incubation duration:
7 d
Test conditions:
pH=8.5, 20-23 deg C
Key result
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
83.516 mg/L
Element analysed:
Tungstate anion
Loading of aqueous phase:
100 mg/L
Incubation duration:
7 d
Test conditions:
pH=8.5, 20-23 deg C
Key result
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
0.627 mg/L
Element analysed:
Dissolved tungsten
Loading of aqueous phase:
1 mg/L
Incubation duration:
28 d
Test conditions:
pH=8.5, 20-23 deg C
Key result
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
0.831 mg/L
Element analysed:
Tungstate anion
Loading of aqueous phase:
1 mg/L
Incubation duration:
28 d
Test conditions:
pH=8.5, 20-23 deg C
Details on results:
Screening tests at pH 8.5:
The screening test data for the test substance revealed that the measured concentrations of total dissolved W and WO4-- speciation at 24 hr were 18.154 mg/L (σ% = 3) and 19.884 mg/L (σ% = 2), respectively, representing 23% and 19% dissolution of the 100 mg/L loadings of the test substance. For these data, the ratio y = [W]/[WO42-] was 0.898, and was higher than the value of 0.742 calculated from the molecular weights.

Definitive 28- and seven- day tests at pH 8.5, respectively:
The net average concentrations of both total dissolved W and the WO4-- species attained maximum values of 0.607 mg/L (σ% = 7) and 0.814 mg/L (σ% = 7), respectively, at 168 hr (7 days), thereafter increasing slightly to 627 ug/L (σ% = 7) and 831 ug/L (σ% = 8), at 672 hr (28 days). Over the 672 hr, the average value of y was 0.752, which compares favorably with the calculated value of 0.742, and is reflected in the quite good agreement between the values of W and WO4-- calculated from the corresponding measured concentrations over the 672 hr. Values of y close to 0.742 mean that all the W existed in solution as the WO4-- anion.
Both the 10 and 100 mg/L loadings initially exhibit near-linear increases in net W and WO4-- concentrations, followed by reduced rates of concentration change with the suggestion of an approach to limiting values by the end of 168 hr. For the 10 mg/L loadings, the 168 hr values of W and WO4-- were 6.03 mg/L (σ% = 1) and 8.156 mg/L (σ% = 2), respectively, with an attendant y value of 0.739. For the 100 mg/L loadings, W and WO4-- were 62.4 mg/L (σ% = 5) and 83.5 mg/L (σ% = 4), respectively, at 168 hr and y was 0.747. There was good agreement between the calculated and measured concentrations of W and WO4--. The W and WO4-- concentrations for the 100 mg/L loadings represent about 79% and 78% dissolution of the test substance.

The average temperature among all seven- and 28-day tests varied in the range 21.0-21.6 deg C, with 19.9 deg C as the single value below 20.0 deg C, which was not expected to affect the reaction kinetics. With the maximum temperature of 22.0 deg C, essentially all temperatures fell within the 20-23 deg C proposed for the T/DP. The average D.O. readings met or exceeded the >70% saturation criterion.

All target 8.5 pH levels in the W-series for the test substance lay in the range 8.3-8.7, which is the variability proposed from the T/DP. Similarly, all but 21 of the 480 target 6 pHs were less than the proposed upper limit of 6.25, and it was not expected that these variations would have had a significant effect on the T/D kinetics of the tested substances. The pH levels less than the lower limit of 5.85, since the variability appears to have been random, are not expected to have affected the substances’ reaction kinetics.

Conclusions:
Interpretation of results (migrated information): slightly soluble (0.1-100 mg/L)
The test substance was found to be more soluble at a pH of 8.5 than 6. The respective W and WO4-- concentrations of about 62 and 84 mg/L for the 7 day, 100 mg/L loadings at pH 8.5 corresponding to about 79% dissolution. The seven-day y value of 0.747, which indicated that all W dissolved as the WO4-- anion.

Description of key information

The test substance was found to be more soluble at a pH of 8.5 than 6. The respective W and WO4 concentrations of about 62 and 84 mg/L for the 7 day, 100 mg/L loadings at pH 8.5 corresponding to about 79% dissolution. The seven-day y value of 0.747, which indicated that all W dissolved as the WO4-anion.

Key value for chemical safety assessment

Water solubility:
84 mg/L
at the temperature of:
21 °C

Additional information