File: 120396_sep96_decls12_0001.txt
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Subject: SILICOSIS AND OPERATIONAL EXPOSURES TO DUST AND SAND Unit: VAR. BUMED Parent Organization: BUMED Box ID: BX303811 Folder Title: VARIOUS NAVAL MESSAGES FOLDER 1 Document Number: 21 Folder SEQ #: 2 UNCLASSIFIED NEHC-36 14 Nov 1990 BILICOSIS AND OPERATIONAL EXPOSURES TO DUST AND SAND (Interim Report) Issue Are military personnel at risk for silicosis or other pulmo- nary diseases due to exposure to sand and dust during operation Desert Shield? Background silicosis is a diffuse, nodular, interstitial pulmonary fibrosis caused by inhalation of crystalline silica.1,2 SiliCoSiS is a chronic disease which may progress for decades before significant respiratory symptoms develop. Exposure to silica may occur in a variety of occupations, including foundry workers, granite workers, miners and tunnelers, ceramic industry workers and diatomaceous earth workers. Airborne particles of silica that measure five microns or less in diameter are capable of reaching the alveoli, and those measuring one micron have the highest probability of being deposited in the alveoli.3 The alveolar clearance mechanism is highly efficient and capable of completely eliminating all particles smaller than five microns if the airborne concentration does not exceed 10 particles/cu cm, however only 90 percent of the particles may be eliminated if the airborne concentration approaches 1000 particles/cu cm. Alveolar macrophages ingest deposited silica particles. Silica induces lung fibrosis by causing lysosomal rupture within the macrophage, macrophage death and the release of fibrogenic substances. Discussion Sand grains which range in diameter from 200 to 2000 microns are not respirable. In a desert environment, however, the wear silica ingredients have and continue to produce sand or siliceous dust particles which are carried by desert winds, especially sandstorms.4-5 These particles are less than three microns in diameter, and thus are respirable. Silica forms accounted for 60 percent of wind-carried dust in the Negev and 88 percent in the Sahara.5 Calcium carbonate or oxide, ferric oxide and aluminum oxide are found in smaller quantities. Deposition of siliceous dust in the lungs has been reported among inhabitants of the Saharan, Libyan, Negev and Arabian deserts. 4,6 In the Negev reports, radiographs and pathologic specimens (biopsy and autopsy) demonstrated a simple pneumoconio- sis without the marked fibrosis seen in classical silicosis. No symptoms were attributable to these findings.4,5 Dust accumu- lation became more pronounced with increasing age, and was more| First Page | Prev Page | Next Page | Back to Text |