Silica Health Advisory – 03/18/19

Worker exposure to silica dust during stone countertop fabrication
March 18, 2019

Situation Overview

In March 2019, the Texas Department of State Health Services (DSHS) received a report of an apparent cluster of multiple cases of silicosis among workers associated with occupational silica dust exposures that occurred during the manufacture, finishing, and installation of stone countertops. DSHS is currently investigating these cases. There are no reported silica exposures to consumers from countertops in their homes.

Silicosis is an incurable, disabling, and often-fatal lung disease caused by inhalation of very fine particles of crystalline silica dust over a long period of time, which primarily occurs in workplace settings.

Occupational Silicosis Among Countertop Fabricators

Occupational silicosis among workers in the engineered stone countertop industry is a rising concern in the United States and globally (1,2,3). The first case of silicosis associated with engineered stone countertop manufacturing in the United States was reported in Texas in 2014 (4). Crystalline silica is present in varying amounts in sand, sandstone, quartz, granite, engineered or artificial stone, and other types of rock. Highest silica levels are associated with engineered stone. Workers may be repeatedly exposed to dangerous levels of respirable silica dust when grinding, cutting, routing, drilling, chipping, or polishing engineered stone, granite, and other stone materials containing crystalline silica during the fabrication process.

The United States Occupational Safety and Health Administration (OSHA) has set a permissible exposure limit (PEL) of 50 µg/m3, averaged over an 8-hour work day, for respirable crystalline silica exposure among workers in fabrication shops and other construction job sites (5,6).

Preventing occupational exposure to silica dust

For employers:

• Conduct air monitoring to identify the amount of silica dust workers are exposed to, and continue to monitor air levels to make sure the exposure level is below the PEL.
• When possible, eliminate job tasks that can expose workers to silica dust above the PEL.
• Reduce exposure by using dust control methods or engineering controls such as wet methods for cutting or grinding, local exhaust ventilation, wet sweeping, or high efficiency particulate (HEPA)-filtered vacuuming.
• Use administrative controls and safe work practices such as a written exposure control plan and a designated competent person to implement it, and limit access to areas with exposure above the PEL.
• Provide workers with Personal Protective Equipment (PPE) such as respirators and washable clothing when exposure control does not sufficiently reduce the amount of airborne silica dust.
• Train all employees at the worksite on the health effects of silica exposure, workplace tasks that can expose them to silica dust, and how to control or prevent exposures.
• Offer medical screenings to all who may be exposed to silica dust as per OSHA standards (5,6). Keep records of workers’ exposure to silica and medical screening results.

For workers:

• Participate in trainings on silica exposure control and prevention including use of PPE.
• Follow procedures and protocols to safely work around silica and reduce or prevent exposures.
• Report any possible silica exposure to the employer, supervisor, or health care provider.

Disease Reporting

Texas law requires reporting of specific occupational diseases to DSHS. Texas Administrative Code, Title 25, Chapter 99 requires health care providers, hospitals, laboratories, and other designated professionals to report confirmed or suspected cases of asbestosis and silicosis to DSHS.

Additional Resources

• Silica Safe
• OSHA Silica Crystalline
• CDC Silica

References

1. Bang KM, Mazurek JM, Wood JM, White GE, Hendricks SA, Weston A. Silicosis mortality trends and new exposures to respirable crystalline silica - United States, 2001-2010. MMWR Morb Mortal Wkly Rep. 2015;64(5):117-20.
2. Mazurek JM, Wood JM, Schleiff PL, Weissman DN. Surveillance for Silicosis Deaths Among Persons Aged 15-44 Years - United States, 1999-2015. MMWR Morb Mortal Wkly Rep. 2017;66(28):747-752. doi:10.15585/mmwr.mm6628a2.
3. Hoy RF, Baird T, Hammerschlag G, Hart D, Johnson AR, King P, et al. Artificial stone-associated silicosis: a rapidly emerging occupational lung disease. Occup Environ Med 2018;75:3-5. doi:10.1136/oemed-2017-104428.
4. Friedman GK, Harrison R, Bojes H, Worthington K, Filios M. Centers for Disease Control and Prevention (CDC). Notes from the field: silicosis in a countertop fabricator - Texas, 2014. MMWR Morb Mortal Wkly Rep. 2015;64(5):129-30.
5. United States Occupational Safety and Health Administration. Silica, Crystalline – General Industry and Maritime. Washington D.C.: United States Department of Labor; 2019. https://www.osha.gov/dsg/topics/silicacrystalline/gi_maritime.html.
6. United States Occupational Safety and Health. Silica, Crystalline – Construction. Washington D.C.: United States Department of Labor; 2019. https://www.osha.gov/dsg/topics/silicacrystalline/gi_maritime.html.