Titanium dioxide, (TiO2), a whitening agent, is used in food products, toothpastes, and pharmaceutical tablets. Its use as a food additive (E171 in EU) has raised concerns for human health. However, oral transmucosal passage of TiO2 particles has not been documented.
This study analyzed E171 particle translocation in vivo through pig buccal mucosa and in vitro on human buccal TR146 cells, revealing high absorption capacities. The study found that all TiO2 samples were cytotoxic in proliferating cells but not after differentiation.
Genotoxicity and slight oxidative stress were reported for E171 and 115 nm TiO2 particles. The study suggests that buccal exposure should be considered during toxicokinetic studies and risk assessment of TiO2 in humans when used as food additives, including toothpastes and pharmaceutical formulations.