Transport of inhaled dust to extrapulmonary sites.

A histological study of the lungs of guinea-pigs that inhaled carbon, chrysotile asbestos or crocidolite asbestos dust indicated that dust particles in macrophages move through alveolar walls towards the pleura. After some weeks accumulations of dust-filled macrophages were found near to pulmonary blood vessels. Macrophages that ingested carbon appeared to be much less mobile than those that ingested carbon appeared to be such less mobile than those that ingested asbestos. In sections from the animals that inhaled asbestos, macrophages were found that were penetrating the wall of blood vessels, dust is transferred to extrapulmonary sites by macrophages in the blood