Silicosis

by

Kenneth Rosenman

• LAST REVIEWED: 26 May 2023
• LAST MODIFIED: 26 May 2023
• DOI: 10.1093/obo/9780199756797-0153

Introduction

The element silicon (Si) is the second most common element in the Earth’s crust. Silicon in combination with oxygen is silica (SiO₂). Silicosis, an interstitial lung disease, is produced by the inhalation of silica-containing dust. Silicosis is the most common of the pneumoconioses (lung disease caused by inhalation of mineral dusts). Silicosis is an ancient disease, and its pathology was first described in the 1600s. The association of silica exposure with an increased risk of lung cancer, chronic obstructive pulmonary disease, connective tissue disease, renal disease, and tuberculosis was recognized in the 1900s. These conditions can occur after silica exposure in the absence of silicosis. Workers in many types of industry can be at risk of exposure to silica. Given it’s abundance in the Earth’s crust, workers in all parts of the mining industry, including quarry workers, have the potential for exposure to silica, which is commonly used in foundries and the manufacture of brick, cement, glass, pottery, sinks, and toilet bowls. Construction workers such as jackhammer operators, masons, and abrasive blasters are an additional high-risk group for silica exposure. New exposures to silica continue to be reported, such as in the manufacture or installation of artificial stone countertops, abrasive blasting of denim clothes, dental laboratories, and hydraulic fracturing (fracking). Cristobalite is a polymorph of silica—it has the same chemical formula, SiO₂, but a different chemical structure. Cristobalite can be found in volcanic rock and when silica is heated, such as in foundries or diatomaceous earth production facilities. In animal models it is more fibrogenic than silica. The occurrence of silica exposure is worldwide. World production is estimated to be 291 million metric tons per year. The largest number of cases of silicosis are currently being recognized in rapidly growing economies such as China and Brazil.

General Overviews

General overviews on the topic of silicosis include Leung, et al. 2012; Li, et al. 2022; National Institute for Occupational Safety and Health 2002; Occupational Safety and Health Administration 2010; Steenland 2005; and World Health Organization 2000.

• Hoy, R. F., M. F. Jeebhay, C. Cavalin, et al. 2022. Current global perspectives on silicosis—convergence of old and newly emergent hazards. Respirology 27:387–398.

  DOI: 10.1111/resp.14242

  A summary of more recent issues related to the ongoing worldwide occurrence of silicosis.

• Leung, C. C., I. T. S. Yu, and W. Chen. 2012. Silicosis. Lancet 379:2008–2018.

  DOI: 10.1016/S0140-6736(12)60235-9

  A summary on silica that covers the epidemiology, pathophysiology, adverse health effects, clinical management, and prevention of silicosis.

• Li, J., P. Yin, H. Wang, et al. 2022. The burden of pneumoconiosis in China: An analysis from the Global Burden of Disease Study 2019. BMC Public Health 22:1114.

  DOI: 10.1186/s12889-022-13541-x

  An estimate of incident cases, deaths, and disability of pneumoconiosis in China in 2019.

• National Institute for Occupational Safety and Health. 2002. Health effects of occupational exposure to respirable crystalline silica. DHHS (NIOSH) Publication 2002–129. Cincinnati: National Institute for Occupational Safety and Health.

  A review of literature of effects of silica exposure with particular emphasis on the respiratory effects.

• Occupational Safety and Health Administration. 2010. Occupational exposure to respirable crystalline silica—Review of health effects literature and preliminary quantitative risk assessment. Docket OSHA-2010-0034. Washington, DC: Occupational Safety and Health Administration.

  The US Occupational Safety and Health Administration (OSHA), in conjunction with a proposal to update the US silica standard, conducted an extensive literature review and written a comprehensive report (483 pages) that includes quantitative exposure-risk assessments.

• Steenland, K. 2005. One agent, many diseases: Exposure-response data and comparative risks of different outcomes following silica exposure. American Journal of Industrial Medicine 48:16–23.

  DOI: 10.1002/ajim.20181

  Review of exposure-response data for silica and the development of three conditions: chronic renal disease; lung cancer; and silicosis. This paper calculates the quantitative risk for these three conditions based on the results of multiple studies.

• World Health Organization. May 2000. Silicosis. WHO Fact Sheet 238. Geneva, Switzerland: World Health Organization.

  The International Labor Organization and the World Health Organization in 1995 began the International Programme on the Global Elimination of Silicosis, the goal of which is the global reduction and eventual elimination of silicosis.