Tungsten

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

no hazard identified

Marine water

Hazard assessment conclusion:

no hazard identified

STP

Hazard assessment conclusion:

no hazard identified

Sediment (freshwater)

Hazard assessment conclusion:

no hazard identified

Sediment (marine water)

Hazard assessment conclusion:

no hazard identified

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

no hazard identified

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Conclusion on classification

Aquatic toxicity classification of inorganic metals and metal compounds is conducted by comparing transformation/dissolution (T/D) data for the substance, generated using the standard protocol (UN GHS, 2007, Annex 10) [see Table 3 in Section 1.3 for results] with toxicity data for the most soluble metal substance as described in the CLP technical guidance (section IV. 5 Application of classification criteria to metals and metal compounds) (EU, 2008). In the case of tungsten metal, T/D data for tungsten metal is compared to the aquatic toxicity reference values derived from read-across to sodium tungstate. The T/D data is ideally tested at the pH at which the highest dissolution is expected, within the range defined by the test protocol (pH 5.5-8.5). 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 tungsten metal was derived at pH 8.5 (7- and 28- day T/D testing) (CANMET-MMSL, 2010). These T/D values were compared to the corresponding acute (31000 ug W/L, based on the ErC50) and chronic (3380 ug W/L, based on the ErC10) aquatic toxicity reference values derived from sodium tungstate testing of algae, as the most sensitive standard aquatic species. The results of this comparison demonstrate that tungsten metal does not classify for aquatic toxicity.

Table 7.12. Classification of tungsten metal using T/D data comparison to toxicity data according to CLP 

 

Test type/ duration	T/D loading amount as W (mg/L)	T/D results (μg W/L)	Toxicity reference value          (μg W/L)	Comparison of T/D and toxicity values (μg W/L)	Aquatic toxicity classification result
Acute full test/ 7 days	1	52	Acute= 31000	52<31000	No Acute 1 classification
Acute full test/ 7 days	10	988	Acute= 31000	988<31000	No Acute 2 classification
Acute full test/ 7 days	100	16509	Acute= 31000	16509<31000	No Acute 3 classification
Chronic full test/ 28 days	1	188	Chronic=3380	188<3380	No Chronic 4 classification
CLASSIFICATION CONCLUSION	No aquatic toxicity classification

 

General discussion

 

The dissolution of tungsten of tungsten metal of 2.20% obtained from transformation/dissolution studies was used to estimate the equivalent tungsten concentration contributed from tungsten metal 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 study.