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Administrative data

Link to relevant study record(s)

Description of key information

No reliable results are available for basic toxicokinetics of synthetic rutile. Therefore, read-across is proposed to available data on TiO2. No substantial accumulation of titanium was observed in tissues following oral administration of titanium dioxide.

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential

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 repeated dose oral toxicity 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).

In a toxicokinetic study rats were exposed with diets reinforced with different forms of titanium dioxide at approx. 200 ppm (equivalent to ca. 30 mg/kg bw) for 7 days. The main route of excretion was via the faeces accounting for means of 39 – 63% daily dose. For each collection interval (0 - 24, 24 – 48, 48 – 72 hours) there was no statistical evidence to suggest differences in patterns of excretion between different forms of titanium dioxide. The results suggest that there is no substantial accumulation of titanium in tissues following administration of diets with different forms of titanium dioxide.

In vitro bioaccessibility data on titanium released from titanium dioxide were determined when exposed to synthetic biological media of varying pH and composition. Only a small fraction of titanium was released/dissolved from the titanium dioxide powder during exposure to any of the media matrices of varying acidity and composition. A trend with somewhat higher release rates with increasing acidity and exposure period was evident. The test results suggest that there is no substantial accumulation of titanium in tissues following administration of diets with different forms of titanium dioxide.