File: 120396_sep96_decls12_0001.txt
Page: 0001
Total Pages: 3

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