Objective: We present pulmonary disorders of four employees who were exposed to high concentration of pure mica dust in a muscovite milling unit.
Method: All cases underwent traditional examinations with a dual-energy chest computed tomographic scan. An analysis of exhaled breath condensate by Raman microspectrometry and of mineralogical content of a lung biopsy was performed for one case.
Results: All cases showed bilateral micronodular ground glass opacities and mediastinal and hilar hyperdense lymph nodes consistent with the nodal sequestration of mineral particles. Histological analysis showed giant cell granulomas without typical silicotic nodule with high concentration of birefringent particles consistent with mica. Mica particles found in the exhaled breath condensate were identical to particles in ambient air at the company.
Conclusion: Occupational exposure to mica dust is responsible for diffuse infiltrative lung disease by overload processes.