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Toxicological information

Carcinogenicity

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Description of key information

Based on available information CaSi is not carcinogen. 
Silicon is released from CaSi at similar or somewhat lower levels than from amorphous silicon dioxide. The release of iron from silicocalcium is very restricted. The calcium released fron CaSi does not affect the physiological levels present in the tissues. Thus, amorphous silica, which is not classified as carcinogen, is used for read-across in the assessment of CaSi.

Key value for chemical safety assessment

Additional information

There are no non-human or experimental data on carcinogenicity of silicocalcium. Therefore, weight of evidence approach is utilised. This means the use of information on the carcinogenicity of the released consituents (e.g. silicon and calcium) and related compounds - such as calcium silicate, which has similar order of water solubility releasing both silicon and calcium (OECD 2004).

The surface of silicocalcium is composed mainly of oxides of silicon and calcium . Silicon is released from CaSi at similar or somewhat lower levels than from amorphous silicon dioxide. The release of iron from silicocalcium is very restricted. The calcium released fron CaSi does not affect the physiological levels present in the tissues. Thus, amorphous silica is used for read-across in the assessment of the carcinogenicity of CaSi.

Also small amounts of aluminium are released from silicocalcium matrix in synthetic biological fluidsin vitro. Many epidemiological studies with kaolin, which is a Al-silicate mineral, and in this respect related to CaSi containing aluminium, do not show carcinogenic potential unless the material is contaminated with quartz.

The iron from CaSi mass is not released in significant amounts to contribute the normal physiological contents. 

Some carcinogenicity studies on synthetic amorphous silica exist. A two‑year rat and mouse feeding study with silica gel did not show increased incidence of tumours. This result is supported by negativein vitro and in vivo mutagenicity data and intrapleural implantation of amorphous silica and sodium aluminium silicate, which did not induce tumours.

Based on available information CaSi is not carcinogen.

Justification for classification or non-classification

Conclusion: Silicocalcium is unlikely to possess carcinogenic properties.