Detection of graphite using laser microprobe mass analysis of a transbronchial biopsy from a foundry worker with...

Inhalation of dust containing graphite can cause lung disease in foundry workers and workers in graphite mines or mills. Mixed dust pneumoconiosis caused by long-term occupational exposure to graphite dust is a rare disease. Only a few cases of graphite pneumoconiosis have been reported in literature, and these were usually diagnosed post mortem. Our report is of an 80-year-old male patient who had worked in an iron foundry for 20 years and whose work had entailed regular contact with ground graphite and foundry vapors. Chest x-rays revealed both a reticular and nodular pattern in the lung, moderate apical distractions and pleural scarring, all of which were confirmed by high-resolution computed tomography. Bronchoalveolar lavage and transbronchial biopsies were also consistent with mixed dust pneumoconiosis, and due to the long-term dust exposure, graphite pneumoconiosis was strongly suspected. To confirm this diagnosis, the chemical composition of the dark granules in the semi-thin histological sections of the transbronchial biopsies were analyzed using laser microprobe mass spectroscopy. The mass spectra of these black particles were consistent with those of natural graphite powder. Comparative analyses of normal lung tissue did not produce similar spectral patterns. We conclude that histology and cytology does not always suffice to confirm a diagnosis of graphite pneumoconiosis, because black particles are also found in conditions resulting from other exposures, such as heavy smoking or coal mining. Analysis of the composition of particles deposited in the lung tissue offers more precise information, which can be used as evidence in occupational and forensic medicine. Laser microprobe mass spectroscopy can assess the mineral dust load in lung samples.