Oral exposure to titanium dioxide (TiO₂) nanoparticles: from translocation through oral and intestinal epithelia to fate and effects in the organism

Abstract

As we are faced with the exponential use of nanomaterials in consumer products, including food, the consequences of daily exposure to nanoparticles at low doses set public health issues for humans. Among the different routes of exposure, the oral route remains the less documented, although nanomaterials are commonly used as food additives, or incorporated into packaging in contact with food or water, to provide their texturing and anti-microbial properties, or as simple colorant agents. The oral and gastrointestinal mucosa are the first regions in contact with the ingested nanoparticles. The latter cross these biological barriers, and distribute to the systemic compartment. Although differences exist between categories of nanoparticles, given differences in their physico-chemical properties, primary particle size and solubility, the example given in this review with titanium dioxide (TiO₂) is intended to illustrate oral toxicity studies conducted in vivo and in vitro in order to contribute to the risk assessment in humans.