Silicosis and silicotuberculosis

Silicosis and silicotuberculosis - Silicosis and...

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Silicosis and Silicotuberculosis Dr. Basanta Hazarika Department of pulmonary Medicine PGIMER, Chandigarh
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Introduction • Silicosis, major occupational lung disease • Problem in both industrialized and developing countries • Due to inhalation of crystalline silica, quartz • Tuberculosis contributes significantly morbidity and mortality
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Etiology • Caused by inhalation of tiny particles of silicon quartz, silicon dioxide • Workers at greatest risk, who blast rock and sand (miners, quarry workers, stonecutters) • who use silica-containing rock or sand abrasives (sand blasters; glass makers; foundry, gemstone, and ceramic workers; potters). • Coal miners are at risk of mixed silicosis and coal workers' pneumoconiosis
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Physical and Chemical Properties Description Transparent crystals Molecular formula SiO2 Molecular weight 60.09 g/mol Density 2.65 g/cm3 Melting point 1610 °C Boiling point 2230 °C Solubility Practically insoluble in water or acids, except hydrofluoric acid; very slightly sol. in alkali.
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Factors that influence the likelihood of progression to silicosis • Duration and intensity of exposure, • Form of silicon (exposure to crystalline form poses greater risk than bound form), • Surface characteristics (exposure to uncoated form poses greater risk than coated form), • Rapidity of inhalation after the dust is fractured and becomes airborne • The current limit for free silica in the industrial atmosphere is 100 μ g/m3
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Prevalence and risks • Prevalence: 22/1000 miners (1917-20) to <8/1000 miners currently • Risk: 24 years vs 36 years exposure to: low dust levels: 5% 10% high dust levels: 15% 40%
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Forms of silicosis • Chronic (or Classic) Silicosis • Accelerated Silicosis • Acute Silicosis
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Chronic (or Classic) Silicosis • Most common form of the disease • Usually follows one or more decades • Respirable dust containing < 30% quartz • Pathological hallmark- silicotic nodule • Usually bilateral upper zones, visceral pleura, regional lymph nodes
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Accelerated silicosis • Results from heavier exposures • Duration of 5 to 10 years • More cellular than fibrotic in nature • More diffuse interstitial pulmonary fibrosis • Develop superimposed mycobacterial infection • Scleroderma more frequent in this stage
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Acute silicosis (Silicoproteinosis) • Follows intense exposure to fine dust of high silica content • Develops within a few months up to 5 years • Shows all the features of PAP • Rapid progression to severe HRF • Radiographic finding –diffuse alveolar filling, lower lung zone
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Pathology Macroscopic: • Hard gray-black nodules upper lobes and
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This note was uploaded on 12/03/2011 for the course MEDICINE 350 taught by Professor Dr.aslam during the Winter '07 term at Medical College.

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Silicosis and silicotuberculosis - Silicosis and...

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