An unusual case of mixed-dust exposure involving a "noncommercial" asbestos

Our health center evaluated an individual for suspected pneumoconiosis, which had resulted from exposures in a foundry/metal reclamation facility. Appropriate consent forms were obtained for the procedures. Historically, individuals who work in foundries have been exposed to various types of dusts. The clinical findings in this case were consistent with silicosis with a suspicion of asbestos-induced changes as well. A sample from this individual, analyzed by electron microscopy, showed both classical and atypical ferruginous bodies. The uncoated fiber burden in this individual indicated an appreciable number of anthophyllite asbestos fibers. This finding, coupled with analysis of cores from ferruginous bodies and the presence of ferruginous bodies in areas of interstitial fibrosis, pathologically supported the diagnosis of asbestos-related disease. The unique factor associated with this case is that unlike in some settings in Finland where anthophyllite was mined and used commercially, this mineral fiber is not commonly found in commercially used asbestos products in the United States. Although the actual source of the asbestos exposure in this case is still being sought, it should be recognized that anthophyllite is a contaminant of many other minerals used in workplace environments, including foundries. The fiber burden indicates a unique type of exposure, differing from that usually construed as typical in occupational settings in the United States.