The impact of the weakly-fibrogenic bauxite dust on lungs in mine workers

Introduction. New cases of pneumoconiosis are detected annually at the bauxite mining enterprises of the Sverdlovsk Region. Differential diagnosis of bauxite pneumoconiosis with other interstitial lung diseases using only lung radiography can be difficult.

The aim of the work was to clarify the nature of changes in the lungs of workers exposed to weakly fibrogenic dust of bauxite, and the relationship of changes in the lungs with working conditions in cases of difficulty in making the final diagnosis of pneumoconiosis.

Material and methods. Underground miners of a working face and underground drifters with a work experience of at least ten years in conditions of exposure to bauxite dust were examined. All patients underwent a plain chest x-ray and high-resolution computed tomography (HRCT), bodyplethysmography, bronchoscopic examination with trans-bronchial biopsy, and subsequent histological examination of the biopsy. To determine the elemental composition of micro- and nanoparticles in biological tissue samples, scanning electron microscopy with X-ray spectral microanalysis was used.

Results. During the histopathological examination of lung tissue biopsy materials by a bright-field method and polarized filter and using electron microscopy, the composition of dust in the lung tissue complied with the composition of industrial aerosol. It is formed during bauxite mining (aluminum, iron, and quartz compounds). High-resolution computed tomography (HRCT) and bronchoscopy can detect signs of exposure to industrial aerosol of complex composition represented by early interstitial parenchymal fibrosis and changes in bronchial mucosa. This is typical for individuals at risk of occupational respiratory diseases development without radiological features specific to pneumoconiosis. Before X-ray pattern formation, typical for pneumoconiosis, bronchitis syndrome and atrophic changes in the bronchial mucosa are developed. This happens in workers exposed to weakly-fibrogenic dust of a complex composition formed during the mining of bauxite.

The changes are permanently observed long after the exposure to the dust factor has ceased.