Settling the Dust: Silica Past, Present & Future

• Published in: Professional safety 2014-04, Vol.59 (4), p.38-43
• Main Authors: Cyrs, William D., Le, Matthew H., Hollins, Dana M., Henshaw, John L.
• Format: Article
• Language: English
• Subjects: Construction companies; Dust; Epidemiology; Health Hazards: Peer-Reviewed; Hydraulic fracturing; Lung diseases; Lungs; Occupational health; Occupational safety; Quartz; Silica; Silicosis; Tuberculosis; Workers
• ISSN: 0099-0027; 2163-6176

Crystalline silica has been one of the most widely studied substances in the history of occupational disease and industrial hygiene. It is the most toxic form of silica, and estimates suggest that approximately 1.7 million workers are ex-posed to respirable crystalline silica in the U.S. Free silica is a term commonly used to describe quartz, a form of silica that is most prevalent in the environment and, therefore, in the workplace. Less common forms, or polymorphs, include cristobalite and tridymite, which differ from quartz only in structure (Madl, Donovan, Gaffney, et al., 2008; OSHA, 2013). High exposures to crystalline silica can occur during construction activities such as abrasive blasting, jackhammering and tuck-pointing, as well as in other industries such as mining, foundry work, concrete product, paint and coating manufacturing (OSHA, 2013). In addition, NIOSH has found high exposures to respirable crystalline silica in hydraulic fracturing operations (OSHA & NIOSH, 2012). NIOSH (2005) estimates that more than 15,000 silicosis deaths occurred over the past 3 decades. Between 1995 and 2004, the number of U.S. deaths from silicosis de-creased slightly, with NIOSH (2008) reporting approximately 150 to 250 deaths annually. However, the number of workers exposed to crystalline silica could rise with the increasing prevalence of hydraulic fracturing (fracking), in the U.S.