Toxicokinetics of titanium dioxide (TiO2) nanoparticles after inhalation in rats

Abstract This study focused on the generation of aerosols of titanium dioxide (TiO 2 ) nanoparticles (NPs) and their disposition kinetics in rats. Male Sprague-Dawley rats were exposed by inhalation to 15 mg/m 3 of anatase TiO 2 NPs (∼20 nm) during 6 h. Rats were sacrificed at different time points over 14 days following the onset of inhalation. Ti levels were quantified by ICP-MS in blood, tissues, and excreta. Oxidative damages were also monitored (MDA). Highest tissue levels of Ti were found in lungs; peak values were reached only at 48 h followed by a progressive decrease over 14 days, suggesting a persistence of NPs at the site-of-entry. Levels reached in blood, lymph nodes and other internal organs (including liver, kidney, spleen) were circa one order of magnitude lower than in lungs, but the profiles were indicative of a certain translocation to the systemic circulation. Large amounts were recovered in feces compared to urine, suggesting that inhaled NPs were eliminated mainly by mucociliary clearance and ingested. TiO 2 NPs also appeared to be partly transferred to olfactory bulbs and brain. MDA levels indicative of oxidative damage were significantly increased in lungs and blood at 24 h but this was not clearly reflected at later times. Translocation and clearance rates of inhaled NPs under different realistic exposure conditions should be further documented.