Dihydrogen wolframate

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.338 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.31 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.034 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

no hazard identified

Sediment (freshwater)

Hazard assessment conclusion:

insufficient hazard data available (further information necessary)

Sediment (marine water)

Hazard assessment conclusion:

insufficient hazard data available (further information necessary)

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

2.17 mg/kg soil dw

Assessment factor:

10

Extrapolation method:

assessment factor

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

All PNECs presented herein are expressed in terms of the concentration of tungsten ion, as toxicity is expected to occur from the metal ion. The dissolution of tungsten from tungsten trioxide (read across source substance) of 18.1% obtained from transformation/dissolution 100 mg/L loading (pH 8.5) at 24 hours studies was used to estimate the equivalent tungsten concentration contributed from sodium tungstate and to determine if a PNEC needs to be estimated. A PNEC was developed when the tungsten equivalent dose was lower than the recommended limit dose (on a tungsten basis) of the respective ecotoxicity study. 

Conclusion on classification

Inorganic metals and metal compounds are classified for aquatic toxicity by comparing T/D data, generated using the standard protocol (UN GHS, Annex 10) with toxicity data for a highly soluble metal substance as described in the CLP technical guidance (Section IV. 5 Application of classification criteria to metals and metal compounds) (EU, 2008). The T/D data are ideally obtained at the pH at which the highest dissolution is expected, within the range defined by the test protocol (pH 5.5-8.5).

In Section 1.3 provides the T/D results for WO₃, which are relevant to tungstic acid by read across. Since inorganic tungsten substances have been demonstrated to have a higher T/D rate at pH 8.5 than pH 6, the data used for aquatic toxicity classification of tungstic acid were derived at pH 8.5 (CANMET-MMSL, 2010). At pH 8.5 and a loading rate of 100 mg/L, the T/D test generated an aqueous concentration of 62.4 mg/L as W. This T/D value was compared to the corresponding acute (31 mg W/L, based on the ErC50) and chronic (3.38 mg W/L, based on the ErC10) aquatic toxicity reference values derived from sodium tungstate testing of algae, as the most sensitive standard aquatic species for sodium tungstate. The comparison indicates that tungstic acid does not classify for aquatic toxicity.

The CLP classification scheme for evaluating the aquatic toxicity of metals and metal compounds is the same as that used to classify metals and metal compounds under the Dangerous Substances Directive, with the exception of the name of the classifications (eg, DSD cites R phases, and CLP uses acute and chronic categories). Although the DSD does not specifically cite the classification scheme for metals and metal compounds, the scheme was outlined in the ECB documents used in the classification of nickel metal (massive and powder). In addition, this classification scheme was used to evaluate aquatic toxicity of nickel metal and some copper compounds (ECB, 2001; ECB, 2005).