Silicosis is a potentially fatal but preventable occupational lung disease caused by inhaling respirable particles containing crystalline silicon dioxide (silica). Quartz, a type of crystalline silica, is the second most abundant mineral in the earth’s crust and workers across a wide range of occupations and industries are exposed to silica-containing dusts. The risks, causes, and prevention of this avoidable disease have been known for decades. There is no cure for silicosis and only symptomatic treatment is available, including lung transplantation for the most severe cases. New national data have become available since a prior report on silicosis surveillance was published earlier this year. The new data show that silicosis continues to cause or contribute to the deaths of about 100 Americans each year. There were 88, 103, and 111 such deaths in 2011, 2012, and 2013 respectively.
The most common form of silicosis, chronic silicosis, takes at least 10 years from first exposure to develop and death does not typically occur until many years after that. Onset of silicosis can be faster and the severity of disease worse in the setting of high level exposures, which can cause accelerated or acute silicosis. From 2011-2013, 12 people younger than 45 years of age had silicosis listed as causing or contributing to death. Although we do not know the details of their cases, this is concerning because silicosis deaths in these young adults may reflect higher exposures than those causing chronic silicosis mortality in older individuals.
Examples of occupations with known high silica exposure include: mining, quarrying, sandblasting, rock drilling, road construction, pottery making, stone masonry, and tunneling operations. New settings for occupational exposure to respirable crystalline silica continue to emerge. For example, hazardous silica exposures have been newly documented in the United States during hydraulic fracturing of gas and oil wells (see related blog) and during fabrication and installation of engineered stone countertops (see related blog).
While silicosis mortality in the U.S. has declined over time, the continuing occurrence of silicosis deaths in young adults and reports of new occupations and tasks that place workers at risk for silicosis underscore the need for strengthening efforts to limit workplace exposure to respirable crystalline silica. Effective silicosis prevention strategies for employers are available from the Occupational Safety and Health Administration (OSHA) and NIOSH.
Healthcare providers should consider reporting silicosis cases to their health departments. In 2010, silicosis was a reportable condition in 25 states (click here for more information). State health departments can help strengthen silicosis prevention efforts by identifying silicosis cases through review of state morbidity and mortality data and investigating the circumstances surrounding silicosis cases.
Jacek Mazurek, MD, MS, PhD and David Weissman, MD
Dr. Mazurek is the Lead Research Epidemiologist in the NIOSH Division of Respiratory Disease Studies.
Dr. Weissman is Director of the NIOSH Division of Respiratory Disease Studies.