CDC: Work to limit occupational silica exposure must continue

While silicosis-related deaths have declined, it remains a serious occupational health risk and one that requires continued public health attention, according to recent data from the Centers for Disease Control and Prevention.

In the Feb. 13 issue of CDC’s Morbidity and Mortality Weekly Report (MMWR), researchers noted that while annual silicosis deaths have dropped from 164 in 2001 to 101 in 2010, dangerous silica exposure has been newly documented in occupations related to hydraulic fracturing (fracking) and the installation of engineered stone countertops. Overall during the 2001-2010 time period, the report documented a total of 1,437 U.S. deaths with silicosis as an underlying or contributing cause. Preventable when workers are provided with adequate personal protective equipment, tools and training, silicosis is an occupational lung disease caused by inhaling respirable crystalline silica dust.

In analyzing the 2001-2010 mortality data for which silicosis was reported as an underlying or contributing cause, researchers found that 28 of the 1,437 deaths were among people ages 15 to 44 and men accounted for more than 95 percent of the deaths. Whites accounted for more than 1,200, or 86 percent, of the deaths; however, the rate of silicosis deaths among blacks was significantly higher than for white and other races. The researchers wrote that the disparities in sex and race “reflect differences in the composition of the workforces in the industries and occupations placing workers at risk for exposure to crystalline silica dust.”

The report notes that workplace exposure to crystalline silica dust has long been documented in sectors such as mining, quarrying, sandblasting, pottery making, rock drilling, road construction, stone masonry and tunneling construction. However, such exposure is being documented in additional occupations as well, such as among technicians responsible for sandblasting in dental labs, workers involved in the fabrication and installation of certain kitchen and bathroom countertops, and those employed in the fracking industry. Report authors Ki Moon Bang, Jacek Mazurek, John Wood, Gretchen White, Scott Hendricks and Ainsley Weston write:

Because of the serious health and socioeconomic consequences of silicosis, new operations and tasks placing workers at risk for silicosis, and the continuing occurrence of silicosis deaths among young workers, effective primary prevention through elimination of exposure to respirable crystalline silica is critical. At the same time, because of the sometimes long latency of silicosis, with cases diagnosed years after exposure and often in retirement, ongoing silicosis surveillance is needed to track its prevalence in the United States.

The authors did caution that the MMWR report is subject to some limitations. For instance, work history is not reported on death certificates and so it’s not possible to report in which occupational industries the deceased were exposed to crystalline silica. Also, exposure to crystalline silica can cause diseases other than silicosis, such as lung cancer and chronic obstructive pulmonary disease. This MMWR report only focused on silicosis deaths.

In 2013, OSHA proposed lowering the allowable silica exposure limit — the Pump Handle’s Celeste Monforton wrote about that proposal here and here. It’s estimated that about 2 million U.S. workers continue to be exposed to the dangerous dust.

To read the full MMWR report, click here. Visit OSHA for more on the agency's new silica proposal.

Kim Krisberg is a freelance public health writer living in Austin, Texas, and has been writing about public health for more than a decade.

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