1. bone marrow cells because the clearance of comparable to that of Cd or silica in vitro.
2. RE from the bone is known to be very slow. These discrepancies in lethal toxicity Inhalational or intratracheal exposure between in vivo and in vitro studies seem to
3. of animals to RE has been proven to cause be due to chemical forms of RE in the
4. acute pneumonitis with neutrophil infiltra- experimental system because those cytotox
5. tion in the Iung; long-term exposure to RE icity studies were carried out in culture