Occupational Exposure to Crystalline Silica and Autoimmune Disease

Abstract

Occupational exposure to silica dust has been examined as a possible risk factor with respect to several systemic autoimmune diseases, including scleroderma, rheumatoid arthritis, systemic lupus erythematosus, and some of the small vessel vasculitidies with renal involvement (e.g., Wegener granulomatosis). Crystalline silica, or quartz, is an abundant mineral found in sand, rock, and soil. High-level exposure to respirable silica dust can cause chronic inflammation and fibrosis in the lung and other organs. Studies of specific occupational groups with high-level silica exposure (e.g., miners) have shown increased rates of autoimmune diseases compared to the expected rates in the general population. However, some clinic- and population-based studies have not demonstrated an association between silica exposure and risk of autoimmune diseases. This lack of effect may be due to the limited statistical power of these studies to examine this association or because the lower- or moderate-level exposures that may be more common in the general population were not considered. Experimental studies demonstrate that silica can act as an adjuvant to nonspecifically enhance the immune response. This is one mechanism by which silica might be involved in the development of autoimmune diseases. Given that several different autoimmune diseases may be associated with silica dust exposure, silica dust may act to promote or accelerate disease development, requiring some other factor to break immune tolerance or initiate autoimmunity. The specific manifestation of this effect may depend on underlying differences in genetic susceptibility or other environmental exposures.

Pathological Study of Chronic Pulmonary Toxicity Induced by Intratracheally Instilled Asian Sand Dust (Kosa)

“…Occupational exposure to crystalline silica leads to silicosis, which is characterized by a progressive granulomatous and fibrogenic response in the lung (Ishihara et al 2001). Another well-known health outcome associated with silica exposure is an increase in the incidence of autoimmune disorders Parks, Conrad, and Cooper 1999) including rheumatoid arthritis (Rosenman, Moore-Fuller, and Reilly 1999), scleroderma (Martin et al 1999), systemic lupus erythematosus (Parks and Cooper 2006), and antineutrophilic cytoplasmic antibody-related nephritis (Tervaert, Stegeman, and Kallenberg 1998). Experimental exposure of crystalline silica is known to cause granuloma formation (Huang et al 2001;Kumar 1989;Langley et al 2004Langley et al , 2010Saffiotti and Stinson 1988) and/or fibrosis (Porter et al 2004) in the lungs of rats.…”

“…Occupational exposure to crystalline silica is associated with silicosis, lung cancer, pulmonary tuberculosis, and chronic obstructive pulmonary disease (Calvert et al 2003). In addition, silicosis patients often develop autoimmune diseases Parks, Conrad, and Cooper 1999). It has been reported that experimental chronic exposure to crystalline silica caused granuloma formation (Huang et al 2001;Kumar 1989;Langley et al 2004Langley et al , 2010Saffiotti and Stinson 1988) and/or fibrosis (Porter et al 2004) in rats.…”

Cell markers, cytokines, and immune parameters in cement mason apprentices

“…At high levels, silica results in silicosis, a condition characterized by radiographic changes, impaired pulmonary function, and increased risk of other respiratory diseases (4). Increased risks of autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, and scleroderma, have also been observed among occupational groups highly exposed to silica (5)(6)(7).…”

Does the Harvard/U.S. Environmental Protection Agency Ambient Particle Concentrator Change the Toxic Potential of Particles?

“…13 Crystalline SiO 2 , occurring in several forms characterized by three-dimensional repeating patterns, is the cause of the pulmonary disease silicosis. 14,15 In contrast, amorphous SiO 2 , which has no significantly repeatable pattern, has minimal health risks to people.…”