Silicosis in manufacture of electric cable: report of four cases.

Free silica (silicon dioxide) is naturally found in amorphous and crystalline forms in many rocks in the Earth . Inhaled silicon dioxide is usually crystalline and most often quartz which is the most important form. Silicosis is an irreversible disease that results from workrelated exposures to dusts containing silica crystals, and is characterized by fibrotic tissue reaction caused by the presence of silica in the lungs. Crystalline silica exposure and silicosis have been associated with work in mining, quarrying, tunneling, sandblasting, masonry, foundry work, glass manufacture, ceramic and pottery production, cement and concrete production, and work with certain materials in dental laboratories. The diagnosis of silicosis is based on history of exposure to silica dust and multiple, bilateral pulmonary nodules and large opacities on chest radiography. Several studies have demonstrated that high resolution computed tomography (HRCT) is superior to conventional radiography for detection of silicotic lesions, confluence of nodules, and presence of emphysema. Most pneumoconiosis evolves slowly and changes in radiological findings take a long time, usually years, to occur. However, in rare instances, such as acute silicosis associated with exposure to a very large quantity of very fine silicaceous dust, radiological changes can show up within months . We present clinical and radiological findings of four cases working in the same department producing ‘silicone paste’ by mixing quartz dust (a synonym for silicon dioxide (SiO 2 ), silica or silicon) with silicone (polysiloxane ([R 2 SiO] n , a class-name for various synthetic plastic substances made of silicon, oxygen, carbon, germanium, and hydrogen), in an electric cable factory, for 5 to 8 yr. Up to now, this branch of industry has not been reported in the English literature as a cause of silicosis.