Health effects of structural specialization of silica surface.
Demchuk-E; Murashov-V; Harper-M
American Industrial Hygiene Conference and Exposition, May 8-13, 2004, Atlanta, Georgia. Fairfax, VA: American Industrial Hygiene Association, 2004 May; :77
Inhaled crystalline silica is commonly viewed as an increased risk factor for pulmonary fibrosis, pneumoconiosis, silicosis, and lung cancer, although the mechanisms involved in silica-dependent lung injury are poorly understood. Based on the structural analysis of crystals and computational modeling, a new association between the structural specificity of silanol sites on silica surface and health effects of respirable silica is proposed. Silica surface accommodates two types of silanol sites. They are the Si-OH (single) and Si=(OH)2 (geminal) sites. It is found that unlike natural grown quartz or kaolinite, the surface of cleaved quartz is enriched with geminal silanol sites. An estimated concentration of 0.067 Angstrom-2 silanol sites on the conchoidal fracture of pure a-quartz is obtained. About 25% of these sites are geminal. In contrast, surfaces of pristine quartz crystals and kaolinite are found to be virtually free of geminal sites. Because of the higher calculated surface energy of geminal sites, it is proposed that the concentration of geminal sites on respirable particulate matter may be associated with the increased fibrogenic potential of crystalline silica. It is suggested that structural specificity of silanol sites on silica surface may be a factor deserving consideration in occupational risk assessment.
Silica-dusts; Pulmonary-system-disorders; Risk-factors; Pneumoconiosis; Silicosis; Lung-cancer; Respiratory-system-disorders; Structural-analysis; Models; Quartz-dust
American Industrial Hygiene Conference and Exposition, May 8-13, 2004, Atlanta, Georgia