Ammonium hexafluorosilicate

Endpoint summary

Description of key information

The LD50 of ammonium hexafluorosilicate was considered to be 70 mg/kg bw.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Study completion date - 01 January 1988.

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

not specified

GLP compliance:

not specified

Test type:

standard acute method

Species:

mouse

Strain:

not specified

Sex:

not specified

Route of administration:

oral: drinking water

Vehicle:

water

Control animals:

not specified

Key result

Sex:

not specified

Dose descriptor:

LD50

Effect level:

70 mg/kg bw

Based on:

test mat.

Mortality:

Details not available

Clinical signs:

other: - PERIPHERAL NERVE AND SENSATION: Flaccid paralysis without anesthesia (usually neuromuscular blockage); - BEHAVIORAL: Ataxia; - BEHAVIORAL: Muscle contraction or spasticity

Interpretation of results:

Category 3 based on GHS criteria

Conclusions:

LD50 for sodium hexafluorosilicate was found to be 70 mg/kg bw.

Executive summary:

The acute oral toxicity of sodium hexafluorosilicate was evaluated in this study conducted with mice. The test substance was administered via drinking water. Flaccid paralysis resulting from neuromuscular blockage, ataxia and muscle contraction or spasticity were the clinical signs observed in this study. The study concluded that the LD50 for sodium hexafluorosilicate was 70 mg/kg bw.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

70 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The hexafluorosilicates disassociate into hexafluorosilicate ion and corresponding cation when dissolved in water. Further the hexafluorosilicate ion dissociates to fluoride ions and hydrated silica and the disassociation is essentially complete at the pH of drinking water (6.5–8.5) (NTP, 2001; NICNAS, 2017). The monovalent cations and hydrated silica are known to have low toxicity. Hence, the fluoride ion is considered to be the driver of toxicity. Taking this into consideration, in addition to limited details available about acute toxicity of ammonium hexafluorosilicate or sodium hexafluorosilicate, data available for sodium fluoride (CAS No. 7681-49-4) has been used for in this summary, to support the conclusion. Currently, no study is available on Ammonium hexafluorosilicate. However, a similar substance, Sodium hexafluorosilicate was evaluated in this study conducted with mice. The test substance was administered via drinking water. Flaccid paralysis resulting from neuromuscular blockage, ataxia and muscle contraction or spasticity were the clinical signs observed in this study. The study concluded that the LD50 for sodium hexafluorosilicate was 70 mg/kg bw. Further, references discuss the LD50 of sodium hexaflurorosilicate to be 125 mg/kg bw in rats as well as rabbits, though further details about the study conditions are not available (RTECS: sodim hexafluorosilicate, as available on 17 July, 2017). Ammonium hexafluorosilicate has been described to have the LD50 of 100 mg/kg bw (NICNAS, 2017). However, no further details are available. Sodium fluoride has been reported to have LD50 of 31–101 mg fluoride/kg bw in rats, while in mice it was 44.3 and 58 mg fluoride/kg bw (Fluorides: Environmental Health Criteria 227, World Health Organization Geneva, 2002). Hence, the data on sodium fluorides also supports the conclusion that ammonium hexafluorosilicate is highly toxic, and should be classified as acute toxicity category 3 according to the CLP.

Justification for classification or non-classification

Based on the available data, ammonium hexafluorosilicate should be classified as acute toxicity category 3 according to the CLP (Regulation EC No. 1272/2008) criteria.