Impacts after inhalation of nano- and fine-sized titanium dioxide particles: morphological changes, translocation within the rat lung, and evaluation of particle deposition using the relative deposition index

Abstract

A 3-week inhalation study with nano- and fine-sized titanium dioxide (TiO₂) with 3, 28, and 90 days recovery time was performed in female Wistar rats. Lung volume measurements, histology, electron microscopy, hematology, and bronchoalveolar lavage (BAL) fluid analyses were conducted and the relative deposition index (RDI) was calculated. Minimal inflammatory changes in the lungs, leucopenia, and a decrease in β-glucuronidase were observed. Particles were mainly deposited in alveolar macrophages and, to a lesser extent, in type-I pneumocytes, and this was quantified using the RDI. Rarely, particle-laden cells were observed inside capillaries. Therefore, minimal translocation of particles into the bloodstream has to be considered. Significant changes, e.g. in elicited effects or translocation behavior, between nano- and fine-particle-treated groups were not observed.

Keywords::

• Titanium dioxide
• nano particles
• particle inhalation
• stereology
• relative deposition index
• electron microscopy
• rat lung

Acknowledgements

The authors would like to thank U. Heinrich for the possibility to take a doctoral degree at the Fraunhofer ITEM and for fruitful discussions, M. Ochs for his help with stereological methods, C. Dasenbrock and G. Pohlmann for study design and performance, M. Schleiss, K. Serwatzki, I. Bleeker, A. Schulze, C. Blum, G. Geide and K. Rohn for their excellent technical assistance and K. Schlemminger for correcting the manuscript.

Declaration of interest

The authors report no declarations of interest.