Translocation of inhaled TiO₂ nanoparticles along olfactory nervous system to brain studied by synchrotron radiation X-ray fluorescence

Nanosized TiO₂ is widely used for cleaning air, antibacterial and decomposing organic in wastewater for its highly photocatalytic function. TiO2 inhalation via respiratory tracts is the most common route of its exposure in industry and environment. After inhalation by human or rodents, TiO₂ can induce inflammation and pulmonary lesions, which was reported to even cause lung cancer by long-term exposure. In this paper, Synchrotron Radiation X-ray Fluorescence was employed to investigate the distribution of TiO₂ in the olfactory bulb and brain of mice after inhalation of TiO₂ particles suspension. The results showed that TiO₂ could enter the olfactory nerve layer (ON), granular cell layer of olfactory bulb (Gro), and olfactory ventricle (OV) and further the hippocampus, thalamus, and CA3 area of the brain through the olfactory nervous system. The distribution area of microsized TiO2 was wider than that of nanosized TiO₂.