Dose, dimension, durability and biopersistence of chrysotile asbestos

Chrysotile asbestos is cleared more rapidly than riebeckite ("crocidolite") or grunerite ("amosite") asbestos from the lung following inhalation. This enhanced clearance of chrysotile appears to be due to the greater solubili ty in lung fluid and tissues compared to riebeckite ("crocidolite"). Magnes ium is readily leached from chrysotile fibers under acid conditions such as those found in the phagolysosomes of alveolar macrophages. Removal of magn esium can be expected to make the remaining silica-dominant framework fragi le and susceptible to breakage and removal by macrophages. The breakage of a fiber may be accelerated by alternating pH conditions found between phago somes and extracellular fluids. The time frame of chrysotile dissolution is longer than the typical irt vitro study and the short-term inhalation stud y. This makes the study of the mechanism of chrysotile-induced lung damage difficult without the use of long-term exposure studies.