Ferruginous body formation on a nonasbestos mineral.

Tissue from a lung biopsy specimen was submitted for electron microscopy and x-ray energy-dispersive analysis of ferruginous bodies. The presence of these entities had been used as a factor in concluding an asbestos-related tissue response. A 62-year-old man had worked for over 25 years in an iron reclamation and manufacturing facility that had no known sources of asbestos in the work environment. He had no history of recurrent respiratory problems. Combined studies in tissue sections as well as on digested specimens revealed that the core of a majority of the ferruginous bodies was an iron-rich fiber. The source of the fibers was traced to a material used in packing and insulation of the metal during the tempering process. While there is a widespread regional potential for exposure in both environmental and occupational settings, the question as to whether the dust is actually a health hazard or more of a nuisance pollutant remains unanswered. It is evident, however, that the fibrous mineral should be recognized as a stimulus for ferruginous body formation in humans.