摘要：We have shown that barium [from BaSO 4 nanoparticles (NPs)] was cleared from the lungs faster than other poorly soluble NPs and translocated mostly to bone. We now studied barium biokinetics in rats during Study 1: two-year inhalation exposure to 50 mg/m 3 BaSO 4 NP aerosols, and Study 2: single intratracheal (IT) instillation of increasing doses of BaSO 4 NPs or BaCl 2 . Study 1 showed that lung barium content measured by inductively coupled plasma mass spectrometry increased during 360 days of BaSO 4 NP aerosol exposures. An equilibrium was established from that time until 2 years. Barium concentrations in BaSO 4 -exposed animals were in the order (lungs > lymph nodes > hard bone > bone marrow > liver). In Study 2, there was an increase in lung barium post-IT instillation of BaSO 4 NPs while barium from BaCl 2 was mostly cleared by day 28. Transmission electron microscopy showed intact BaSO 4 NPs in alveolar macrophages and type II epithelial cells, and in tracheobronchial lymph nodes. Using stimulated Raman scattering microscopy, specific BaSO 4 Raman spectra were detected in BaSO 4 NP-instilled lungs and not in other organs. Thus, we posit that barium from BaSO 4 NPs translocates from the lungs mainly after dissolution. Barium ions are then incorporated mostly into the bone and other organs.
