The toxicity of TiO₂ (titanium dioxide) nanoparticles (TiO₂-NP) in rodents has been reported. Many authors studied the serum biochemical parameters, pathology changes, and the biodistribution of TiO₂-NP in the liver, kidneys, lung, spleen, and brain tissue by facilitating a variety of methods including blood biomarker assays, histopathological examination, etc. The dependence of experiment results on the intake (inhalation, oral administration, intraperitioneal/intravenous injection), dosages, and different sizes of nanoparticles was also discussed.

In two studies regarding the pulmonary response of rodents to subchronic inhalation of TiO₂-NP, Bermudez et al. reported a dose-dependent expression of lung burdens in mice, rats, and hamsters in exposure to a wide range of TiO₂ (titanium dioxide) pigment. Rats also developed a unique progressive fibro-proliferative lesions alveolar epithelial metaplasia in response to high dose of TiO₂-NP. Warheit et al. also reported the species-specific keratin cysts in rats under the overload exposure condition.

The acute toxicity and biodistribution were discussed in Wang et al., Chen et al., and Fabian et al. studies. Wang et al. reported the injury in the liver (hydropic degeneration around the central vein in the liver and spotty necrosis of the hepatocyte) and kidneys (the BUN level was increased with pathologic renal changes) after oral administration with large dose (5 g/kg body) of different sizes of TiO₂ (titanium dioxide) particles (25, 80, and 155 nm). The biodistribution examinations also showed predominant accumulation in the liver, kidney, spleen, and lungs of TiO₂, which indicated the ability of TiO₂ be transported to other organs after oral intake. Following this report, Chen et al. also reported the pathological changes of the spleen, heart, liver, lung, and kidneys caused by acute toxicity in rats injected with TiO₂-NP. The influence of TiO₂ on the central nervous system (CNS) is gaining attention recently.