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Toxicological information

Carcinogenicity

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Description of key information

No reliable results are available for carcinogenicity of synthetic rutile. Therefore, read-across is proposed to available data on TiO2. The available data in rats and mice clearly suggest that ingested titanium dioxide is neither toxic nor carcinogenic to both species. Based on the histopathological examination in a 103 week feeding study, titanium dioxide was considered to be neither toxic nor carcinogenic to rats and mice. Thus, the highest dietary concentration of 50000 ppm titanium dioxide is representing the NOAEL which corresponds to a dose of 3500 mg titanium dioxide/kg bw/d for rats.

Key value for chemical safety assessment

Additional information

Read across concept

Synthetic rutile consists primarily of a titanate phase (solid solution) most of which is titanium in an oxidised form. Upon ingestion, a low rate of dissolution in the GI tract is assumed, based on the experimental verified inertness of the material. Any material being released from Synthetic rutile under physiological conditions will be in the form of ionic titanium, which is similarly the case for titanium dioxide, thus read-across from carcinogenicity: oral data on titanium dioxide is considered feasible without any restrictions.

Furthermore, transformation/dissolution testing according to “OECD 29 Environmental Health and Safety Publications, Series on testing and assessment, Guidance document on transformation/ dissolution of metals and metal compounds in Aqueous media” has shown that synthetic rutile compared to titanium dioxide has a similar release rate of titanium ions (please refer to the respective entry under the endpoint water solubility).

The available data in rats and mice clearly suggest that ingested titanium dioxide is neither toxic nor carcinogenic to both species. Based on the histopathological examination in a 103 week feeding study, titanium dioxide was considered to be neither toxic nor carcinogenic to rats and mice. Thus, the highest dietary concentration of 50000 ppm titanium dioxide is representing the NOAEL which corresponds to a dose of 3500 mg titanium dioxide/kg bw/d for rats.

Justification for classification or non-classification

Based on the weight of evidence from the available long-term toxicity/carcinogenicity studies in rodents and the relevant information on the toxicokinetic behaviour in rats, it is concluded that synthetic rutile does not present a carcinogenicity hazard via oral application. There is evidence from the animal chronic toxicity/carcinogenicity studies in rats and mice that the intake of high amounts of titanium dioxide was not associated with adverse effects.

For the reasons presented above, no classification for carcinogenicity is required. It is considered that these conclusions can be read across to Synthetic Rutile.