Autopsy samples from eight former shipyard workers were collected from lung parenchyma, tracheal lymph nodes, and pleural plaques. The tissue from each respective area was prepared by a modified bleach digestion technique, and the residue was collected on a 0.2-μm pore polycarbonate or 0.22-μm mixed cellulose ester filter.
Quantitation of ferruginous bodies and uncoated fibers was done by light and transmission electron microscopy, respectively. Differences in the asbestos burden were noted for each site. Ferruginous bodies were observed in both parenchyma and nodes but not in plaques. Three subjects were found to have more ferruginous bodies per gram dry weight in their lymph nodes than in their lung parenchyma. Likewise, all subjects were found to have more uncoated fibers per gram in the nodes than in the parenchyma. Amphibole and chrysotile fibers were noted in the lung and extrapulmonary sites, with chrysotile being the predominant asbestiform in plaques. The majority of the uncoated fibers in both the nodes and the plaques were ≤ 5 μm in length. However, some fibers with dimensions conforming to the “Stanton hypothesis” reached both areas.
These residual patterns most likely reflect the impact of clearance on lung burden as opposed to the eventual accumulation and stasis in the extrapulmonary areas.