Elemental analysis of inorganic dusts in lung tissues of interstitial pneumonias

People have the opportunity to inhale inorganic dusts under various environments. Inorganic dust exposures as a result of occupational exposure may induce or modulate pulmonary fibrosis. We analyzed the deposition of elements in lung tissues of patients with idiopathic pulmonary fibrosis (IPF) and compared element deposition with chronic hypersensitivity pneumonitis (chronic HP) and collagen vascular diseases (CVD). Thirty-five patients (18 men and 17 women with the mean age of 64.3) were studied, including 15 IPF, 8 chronic HP, 6 CVD, and 6 control patients. Four IPF patients have occupational dust exposures. Inorganic particles were counted by polarizing light microscopy and scanning electron microscopy. Energy dispersive X-ray spectroscopy was performed to analyze an elemental deposition. The number of birefringent particles was greater in IPF, even in IPF without occupational exposure, than in controls. The silicon (Si)/sulfur (S) ratio and aluminium (AI)/S ratio were increased in IPF independent of occupational exposure. A point elemental analysis showed that the major compound of the particles was aluminium-silicate in IPF. These results suggest that unrecognized dust exposures are relatively common in some IPF patients and aluminium-silicate could be associated with the disease process of IPF.