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Ecotoxicological Summary

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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:
PNEC STP
PNEC value:
5.86 mg/L
Assessment factor:
100
Extrapolation method:
assessment factor

Sediment (freshwater)

Hazard assessment conclusion:
PNEC sediment (freshwater)
PNEC value:
960 mg/kg sediment dw
Assessment factor:
10
Extrapolation method:
equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:
PNEC sediment (marine water)
PNEC value:
96 mg/kg sediment dw
Assessment factor:
10
Extrapolation method:
equilibrium partitioning method

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:
PNEC oral
PNEC value:
0.011 g/kg food
Assessment factor:
90

Additional information

No definitive results were available from tests performed with tungsten metal. Therefore, the most reliable studies identified for sodium tungstate were used in for read-across in the PNEC derivations. This approach is considered to be appropriate since sodium tungstate has been shown to undergo more dissolution in water solutions mimicking natural water conditions than tungsten metal. Hence, sodium tungstate is likely to be more bioavailable than tungsten metal and adequately protective for estimating potential toxicity. Furthermore, neither tungsten metal or sodium tungstate are classified for aquatic toxicity and their PBT profile is the same. For further details regarding the appropriateness of read-across, see the attached read-across document.

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 53. 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