July 27, 2023

Cal/OSHA Emergency Standard to Address Silicosis among Engineered Stone Fabrication Workers

On July 20, the California Occupational Safety and Health Standards Board granted the petition of a medical association for Cal/OSHA to develop an emergency temporary standard (ETS) to address increasing cases of advanced silicosis among workers in engineered stone fabrication shops. According to the petitioner, the Western Occupational and Environmental Medical Association, “irreversible end-stage lung disease has now been shown to develop in fabrication workers after only a few years of poorly controlled occupational exposure” to respirable crystalline silica. WOEMA, a regional component of the American College of Occupational and Environmental Medicine, expressed concern that the current silica standard is insufficiently protective for these workers. The association’s petition recommended that an ETS cover the use of engineered stone with high silica content, require controlled access to areas where artificial stone is fabricated, prohibit dry fabrication work practices, and address inadequate respiratory protection.

When Cal/OSHA evaluated WOEMA’s petition in May, the agency found that an ETS would be easier for employers—particularly smaller stone fabrication shops, which comprise much of the industry—to implement than its existing silica regulation. The existing standard is based on performance and requires employers to conduct “sophisticated exposure assessments as the basis for implementing silica exposure controls,” the agency says. Larger employers with more resources can more easily meet this type of standard than smaller businesses, which Cal/OSHA has found to be more likely to be unable or unwilling to install engineering and work practice controls. The agency agreed with WOEMA that an ETS with a prescriptive approach would be more effective in protecting the health of workers in this industry.

“[A more prescriptive] approach makes it clear that implementing effective exposure controls is integral to the business of operating an engineered stone fabrication shop,” the agency’s adopted decision (PDF) reads. “Cal/OSHA suggests that for all businesses, the use of engineered stone material itself should trigger specific engineering, work practice and respiratory protection requirements.”

The petition called for an ETS to cover workplaces using engineered stone with silica content greater than 50 percent, but because of the “unique hazards associated with engineered stone” Cal/OSHA instead proposes that the ETS apply to all workplaces that use engineered stone consisting of more than 1 percent silica.

If employers move quickly to implement the ETS, workplace inspections show exposures across the engineered stone fabrication industry to be below the action level (25 µg/m3 as an 8-hour time-weighted average), and silicosis cases drop to zero in the coming months, Cal/OSHA will recommend that the ETS and related enforcement activities continue. But if inspections instead show continued widespread noncompliance, Cal/OSHA says it will recommend an advisory committee be convened to develop plans to prohibit the use of engineered stone products in California, effective July 1, 2024.

Increasing cases of silicosis among engineered stone fabrication workers have been on researchers’ radar for years. A study published this week in JAMA Internal Medicine details a case series of 52 California workers—primarily young Latino immigrant men—diagnosed with silicosis associated with exposure to engineered stone. Previously, a report published by CDC in 2019 identified 18 cases of silicosis, including two fatalities, among stone fabrication workers in the states of California, Colorado, Texas, and Washington during the years 2017–2019. Before that time, only one case of silicosis had been reported among engineered stone fabrication workers in the U.S., according to CDC.

Information about the recent regulatory developments related to engineered stone in California can be found on the website of the California Department of Industrial Relations. An article published on July 22 by northern California’s KQED provides additional details about this topic.

Related: A SynergistNOW blog post from May 2023 discusses engineered stone, silica, and the precautionary principle.