Registration Dossier
Registration Dossier
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EC number: 241-022-2 | CAS number: 16949-65-8
Ecotoxicological Summary
Administrative data
Hazard for aquatic organisms
Freshwater
- Hazard assessment conclusion:
- PNEC aqua (freshwater)
- PNEC value:
- 0.9 mg/L
- Assessment factor:
- 10
- Extrapolation method:
- assessment factor
Marine water
- Hazard assessment conclusion:
- PNEC aqua (marine water)
- PNEC value:
- 0.9 mg/L
- Assessment factor:
- 10
- Extrapolation method:
- assessment factor
STP
- Hazard assessment conclusion:
- PNEC STP
- PNEC value:
- 51 mg/L
- Assessment factor:
- 10
- Extrapolation method:
- assessment factor
Hazard for air
Hazard for terrestrial organisms
Soil
- Hazard assessment conclusion:
- PNEC soil
- PNEC value:
- 11 mg/kg soil dw
- Assessment factor:
- 10
Hazard for predators
Additional information
Short term toxicity tests have been performed on disodium hexafluorosilicate. Toxicity to fish, algae and microorganism has been determined. However, there are no available data on long term toxicity to the aquatic environment, which are preferred to derive PNECs. Due to the presence of hydrolysable groups on its chemical structure, fluorosilicate anions are not expected to remain in solution long under environmental conditions. Instead, fluoride anions will be formed. Thus, the performance of such tests is unjustified, since there are reliable studies on sodium fluoride or hydrogen fluoride. Read-across to sodium fluoride is appropriate. Thus, PNECs will be derived based on long term studies on NaF.
Conclusion on classification
Aquatic toxicity values experimentally obtained for disodium hexafluorosilicate are the following: 96h EC50 (fish)= 37.5 mg/l 48h EC50 (daphnia)= 35.4 mg/l 72h ErC50 (alga)= 18 mg/l. The three of them are between 10 and 100 mg/l.
The substance readily dissociates in water and undergoes further hydrolysis is hydrolisable at environmental conditions, providing fluoride. Thus, the substance is unstable in water and therefore rapidly degradable. Moreover, as its bioaccumulation potential cannot be assessed, it is then justified to use biodegradation and bioaccumulation results on fluorides for assessment.
As indicated in endpoint 5.3.1, BCF for fluorides is lower than the threshold of 2000, meaning that the substance is considered not bioaccumulative.
Considering all data together, disodium hexafluorosilicate shall not be classified for aquatic toxicity.
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