Figure 1.

Intracellular and extracellular dissolution of 1.5 and 0.5 μm ⁵⁹Fe₂O₃ particles in alveolar macrophages (in vitro study). Rat alveolar macrophages (AM) or incubation media without AM were incubated in vitro with ⁵⁹Fe-labeled 0.5 μm Fe₂O₃ particles and 1.5 μm Fe₂O₃ particles, respectively. The intracellular particle dissolution (IPD) rate for cells of 4 different animals (n = 4) and the extracellular dissolution for 4 different incubations without cells (n = 4) were determined over a period of 7 days. The small 0.5 μm particles exhibited a higher IPD rate (0.0037 ± 0.0014 d-1; n = 4) than the large 1.5 μm particles (0.0016 ± 0.0012 d-1; n = 4); both rates were corrected for extracellular particle dissolution see equation 3. The extracellular dissolution rate for both types of particles was negligible small.