Instilled Ferric Oxide Nanoparticles in Rats and the Potential Health

Exposure to nanoparticles has presented potential risks to human cardiorespiratory systems. Pulmonary retention and extrapulmonary redistribution of inhaled nanoparticles have been considered to be important contributing factors of cardiorespira-tory diseases. In the present work, 22-nm 59Fe2O3 nanoparticles (radioactive isotope 59Fe-labeled ferric oxide nanoparticles) were intratracheally instilled into the male Sprague-Dawley rats at a dose of 4 mg/rat. Extrapulmonary distribution of 59Fe2O3 in organs and its metabolism in lung, blood, urine, and feces were measured for 50 days of exposure. Phagocytosis and clearance of agglomerated nano-Fe2O3 by monocytes/macrophages were ob-served by histopathology and inductively coupled plasma-mass spectrometry examination. Our results showed intratracheal-instilled nano-59Fe2O3 could pass through the alveolar-capillary barrier into systemic circulation within 10 min that consisted wit