8 min dust&disease

8 min dust&disease - Exposure to mineral dust can lead...

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Unformatted text preview: Exposure to mineral dust can lead to serious lung diseases Two classes of respiratory disease are caused by mineral dusts Fibrogenic diseases (emphysema-like) silicosis–quartz black lung–coal dust asbestosis–asbestos minerals Malignant neoplasms– lung cancer–asbestos & quartz(?) mesothieloma–crocidolite asbestos & erionite (a fibrous zeolite) Much exposure occurs in the workplace Construction of the Hawk’s Nest Tunnel near Gauley Bridge, WV caused one of the worst industrial disasters in US history Tunnel construction occurred in the early 1930’s A 3.75 mi tunnel was driven through quartz sandstone with no regard for the workers’ exposure to quartz dust An estimated 1500 of 2000 workers died of acute silicosis Our lungs are protected from dust and microbes by Mucocilliary escalator––trapped by mucus & removed by action of cillia Phagocytization––engulfed and isolated by macrophages then translocated to lymph glands Dissolution––enhanced by low pH in macrophages Exposure to quartz dust causes Chronic silicosis––(long term exposure, moderate levels) development of fibrotic (scar) tissue, nodules visible on x-rays Acute silicosis––(intense exposure) linings of airways damaged lipid-rich protein fills air sacs superinfection (tuberculosis) & massive fibrosis Accelerated silicosis––(5–10 years of heavy exposure, e.g. sandblasting)–intermediate progression Silicotuberculosis––M. tuberculosis infection promoted by silica damage Silicotic nodules are collagen rich areas caused by mineral damage to tissue They show up as bright (dense) areas on chest x-rays Asbestos is a broad commercial term for a group of naturally occurring hydrated silicate minerals that crystallize in a fibrous habit Asbestos Use 1974 Use Serpentine Amphibole (tons) (tons) 250, 070 38, 100 Cement pipe and sheet Roofing and floor 206, 170 products Gaskets & 36, 910 insulation Brake linings 72, 200 Coatings & fillers 125, 440 Other (filters, 33, 020 etc. ) TOTAL 723, 810 1540 1720 180 360 810 43, 350 Serpentine asbestos was the most widely used type in the US Chrysotile (White asbestos)Mg6Si4O10(OH)6 Amphibole asbestos was used mostly for filters Thought to be more dangerous than serpentine asbestos Crocidolite (Blue asbestos)Na2(FeIII)2(FeII)3Si8O22(OH)2 Amosite/Anthophyllite(Fe,Mg)7Si8O22(OH)2 Tremolite-Ca2Mg5Si8O22(OH)2 ActinoliteCa2(Fe,Mg)5Si8O22(OH)2 Asbestosis Collagen deposition caused by chronic inflammation reduces the flexibility of lung tissue Risk enhanced by smoking Lung Cancer Malignant tumor growth in lung tissue Risk enhanced by smoking Mesothelioma Malignant tumor growth in lining of chest and abdominal cavity Smoking does not increase risk Stages of Cancer Development Initiation––mutations that make the cell immortal and resistant to normal growth controls Promotion––death of nearby cells that allow the mutated cell to begin growing Malignant Progression––formation of a tumor and spread of cancerous cells by metastization Hypotheses about how asbestos exposure causes cancer Stanton fibers––(diameter 0.25 m, length>8 m) penetrate cells and their nuclei and cause physical and chemical transformations Active oxygen species––(free radicals) produced by chemical reactions of Fe released from minerals transform DNA Persistent inflamation––promotes cell growth and transformation Cause Comparison of risks of asbestosis exposure in public schools with other hazards Asbestos exposure in schoo l s Whooping cough vaccination Annual death rate per million exposed 0.005 to 0.093 1 to 6 Aircraft accid e n t s 6 High school footbal l 10 Drowning (ages 5 to 1 5 ) 27 Motor vehicle accident, pedestrian (ages 5 to 14 ) 32 Home accidents (ages 1 to 1 4 ) 60 Long term smoking 1200 ...
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This note was uploaded on 08/09/2011 for the course GEOS 1004 at Virginia Tech.

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