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Surface composition of respirable silica particles in a set of U.S. Anthracite and Bituminous coal mine dusts.

Authors
Harrison-JC; Brower-PS; Attfield-MD; Doak-CB; Keane-MJ; Grayson-RL; Wallace-WE
Source
J Aerosol Sci 1997 Jun; 28(4):689-696
NIOSHTIC No.
20024748
Abstract
Respirable particles of high-percentage silica content from anthracite and bituminous coal mine dust samples were analyzed for aluminosilicate clay surface coating, by measuring silicon and aluminum X-ray spectra using scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDS). Silicon and aluminum elemental ratios were determined with incident electron energies of 20 and 5 keV to reveal whether surface occlusion was present. Some 20 respirable-sized, non-agglomerated particles with silicon fraction of signal of 75% or more (for elements above sodium) were analyzed for each of 12 coal mine dust samples. Mine dust samples were from U.S. anthracite and bituminous coal mining regions involved in epidemiological studies of the U.S. National Study of Coal Workers' Pneumoconiosis. Some particles of high-percentage silica content exhibited a decrease in the ratio of silicon-to-aluminum K-alpha line intensities with decreasing electron beam accelerating voltage, consistent with aluminosilicate clay surface contamination or occlusion of a silica particle. Significantly lower frequencies of particles manifesting occluded behavior were found for anthracite dusts versus all bituminous dusts. It is suggested that such occlusion alters the biological availability of the surface of those particles. This may be a factor in the results of attempts to correlate disease prevalence with conventionally measured dust composition, as in the classical failure of coal workers' pneumoconiosis disease prevalence to correlate with silica exposure while being correlated with cumulative total respirable dust exposure and with coal rank.
Keywords
Silica-dusts; Silicates; Respirable-dust; Coal-mining; Bitumens; Aluminum-compounds; Coal-miners; Respiratory-system-disorders; Pulmonary-system-disorders
Contact
National Institute for Occupational Safety and Health, U.S. Centers for Disease Control and Prevention, Morgantown, WV 26505, U.S.A
CODEN
JALSB7
CAS No.
14808-60-7
Publication Date
19970601
Document Type
Journal Article
Fiscal Year
1997
NTIS Accession No.
NTIS Price
Issue of Publication
4
ISSN
0021-8502
NIOSH Division
DRDS; EID
Source Name
Journal of Aerosol Science
State
WV; OH
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