Tissue distribution and clearance of intravenously administered titanium dioxide (TiO₂) nanoparticles

Abstract

The organ-tissue distribution and clearance of Degussa P25 TiO₂ nanoparticles were determined after intravenous administration to rats (0.95 mg/kg bodyweight) using an inductively coupled plasma sector field mass spectrometer. The detection limits of Ti analysis, 0.54 and 1.4 ng/mL for blood and urine and 0.35–2.0 ng/g tissue for several organ tissues, enabled determination of tissue distribution and clearance for organs in which Ti content could not be previously determined due to low concentrations. Blood concentrations of TiO₂ were 420 and 19 ng/mL at 5 and 15 min after administration, which were equivalent of only 2.8% and 0.13% of the administration dose, respectively. At 6 h, 94%, 2.0%, 0.17%, 0.023%, 0.014% and 0.026% of administered TiO₂ was found in the liver, spleen, lung, kidney, heart and blood, respectively. Liver and spleen TiO₂ burden was significantly higher in the administration than control group (p < 0.01) and did not decrease up to 30 days after administration, while TiO₂ burden in the lung, kidney, heart and blood decreased over time. A two-step decay model was more suitable than a one-step decay model for the decay curves of pulmonary TiO₂ burden but did not improve fitting to the decay curves of kidney TiO₂ burden. No translocation to the brain was confirmed at a lower detection limit than was applied in previous studies. Ti content in faeces and urine in the TiO₂ administration group did not differ from that in the control group.

Keywords::

• nanomaterial
• distribution
• clearance
• toxicokinetics
• excretion