Silicon

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

Silicon has not been tested for its skin-sensitising properties. Neither has synthetic amorphous silica has been tested for skin sensitisation. The surface of silicon is composed of a thin oxidized silicon layer resembling the surface of amorphous silicon dioxide. Both silicon and amorphous silica release silicon from particles. Thein vitrodata on the dissolution kinetics of silicon in different artificial biological fluids shows that the solubility of silicon in biological media is similar or lower than that of amorphous silicon dioxideand it is justified to use read-across from amorphous silicon dioxide to silicon. A detailed description of the justifications for read-across is available in Section 13 of the Iuclid dossier.

Long and widespread use of synthetic amorphous silica without any cases of sensitisation supports silicon’s lack of sensitising properties. The lack of skin sensitising properties of silicon and amorphous silica is also supported by a lack of case reports from the industry producing or using ferrosilicon and silicon. It should be noted that silicon in different forms is ubiquitous in the environment and exposure to different forms of silicon is very widespread.

The elemental impurities of silicon whose bulk concentration exceeds the classification cut-off limit of 0.1% (iron, aluminium and calcium) do not exert skin sensitising properties. In addition, the dissolution of these elements from the silicon matrix is likely to be very restricted because of the protective silicon oxide layer. This has been shown not to significantly differ from the release of these elements from pyrogenic amorphous silica (see Chapter Toxicokinetics).

No cases of respiratory tract sensitisation caused by amorphous silica or silicon have been reported in the literature.

Conclusion: Silicon is not sensitising to the skin or respiratory system. No further tests are suggested.

Migrated from Short description of key information:
No cases of skin sensitisation caused by silicon or amorphous silica have been reported in the literature.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

No cases of respiratory tract sensitisation caused by amorphous silica or silicon have been reported in the literature.

Migrated from Short description of key information:
No cases of respiratory tract sensitisation caused by amorphous silica or silicon have been reported in the literature.

Justification for classification or non-classification

Long and widespread use of synthetic amorphous silica without any cases of silica sensitisation supports silicon’s lack of sensitising properties. The lack of skin sensitising properties of amorphous silica and silicon is also supported by a lack of case reports from the industry producing or using ferrosilicon and silicon. Silicon in different forms is ubiquitous in the environment and exposure to different forms of silicon is very widespread. No cases of respiratory tract sensitisation caused by amorphous silica or silicon have been reported in the literature.