Ferrosilicon - reaction mass of iron and iron disilicide and iron silicide and silicon

Endpoint summary

Description of key information

Acute toxicity studies on synthetic amorphous silicas (oral and inhalation) and acute oral toxicity studies on Ca-silicates and Na-Al-silicate all suggest low toxicity. Also some dermal acute toxicity data is available on silica.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

5 000 mg/kg bw

Quality of whole database:

Robust study available, read-across justified.

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

OECD review. Read-across justified.

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

5 000 mg/kg bw

Additional information

Acute toxicity studies have not been performed with ferrosilicon, and read-across to synthetic amorphous silica and silicates has been performed. A detailed description of the justifications for read-across is available in Section 13 of the Iuclid dossier.

According to the available data, the acute oral toxicity of synthetic amorphous silica is very low: no signs of toxicity were observed at doses of up to 5,000 mg SiO₂/kg bw. Silicates like calcium and aluminium sodium silicates also have very low acute oral toxicity supporting the low toxicity of ferrosilicon. Moreover, available evidence shows that amorphous silica is not acutely toxic via dermal or inhalation exposure routes.

Strontium and barium may be present in ferrosilicon at levels up to 1-5% and 12%, respectively, and have been shown to be released at low levels from the FeSi matrix. Data on acute toxicity is available only on their slightly soluble compounds, but based on that, at the concentration levels occurring in FeSi, they are not likely to have any impact on the acute toxicity classification of ferrosilicon (oral LD₅₀of strontium compounds is >2,000 mg/m³and, e.g., barium carbonate is 400-800 mg/kg).

Based on weight of evidence, ferrosilicon is not acutely toxic via the oral, inhalation or dermal exposure routes.

Justification for selection of acute toxicity – oral endpoint
Read-across to guideline study performed with synthetic amorphous silica. No acute effects observed, LD50 > 5000 mg/kg.

Justification for selection of acute toxicity – inhalation endpoint
Read-across to synthetic amorphous silica. No lethal effects observed at the maximum concentrations tested (140-2000 mg/m3).

Justification for selection of acute toxicity – dermal endpoint
Read-across to studies performed with synthetic amorphous silica. No acute effects observed, LD50 > 5000 mg/kg.

Justification for classification or non-classification

The acute oral toxicity of synthetic amorphous silica is very low. Silicates such as calcium silicate and aluminium sodium silicate also have very low acute oral toxicity, supporting the low toxicity of ferrosilicon. Moreover, available evidence shows that synthetic amorphous silica is not acutely toxic via the dermal or inhalation routes, either.

Strontium and barium may be present in ferrosilicon at levels up to 1.5% and 12%, respectively, and have been shown to be released at low levels from a FeSi matrix. Data on acute toxicity is available only on their slightly soluble compounds, but based on that, at the concentration levels occurring in FeSi, they are not likely to have any impact on the acute toxicity classification of ferrosilicon. Thus, based on weight of evidence, ferrosilicon is not acutely toxic via the oral, inhalation or dermal routes.