A Public Health Alerts report today highlights almost 600 cases of silicosis—an incurable lung disease caused by inhaling silica particles—in workers making stone countertops in California over a span of more than seven years.
In the report, researchers from the California Department of Public Health (CDPH) and their partners note that 65 of the 592 patients needed a lung transplant, and 31 of them died.
Public Health Alerts, a collaboration between NEJM Evidence and CIDRAP, fills a gap in reliable data, offering expert-reviewed reports that translate frontline observations into actionable public health evidence. An NEJM Evidence editorial explains the initiative further. Read all Public Health Alerts reports here.
Short exposure, severe disease, rapid progression
The authors write, “Over the past two decades, a growing risk has been recognized among workers fabricating crystalline silica-containing engineered stone counter tops (also known as artificial stone or “quartz”). Engineered stone slabs are manufactured by crushing natural quartz into fine powder then binding it with polyester resins and pigments; the material contains high levels of crystalline silica (typically >90%).
“Fabrication workers who cut, grind, and polish these slabs into countertops can be exposed to hazardous levels of respirable crystalline silica, along with volatile organic compounds and metals.”
The CDPH identified the index case in January 2019. It involved a 32-year-old countertop worker who died of respiratory failure at age 38. After identifying this first case, investigators confirmed two additional cases at the same company, one of which also proved fatal. Screening of the company’s 43 employees found five additional silicosis cases.
Through June 2026, the authors confirmed 592 cases related to working with engineered stone, including the 31 fatalities and 65 lung transplants.
“These cases are notable for the patients’ young age at diagnosis, short duration of exposure, severity and rapid progression of disease, and frequent co-occurrence of other silica-associated conditions, including autoimmune disease and tuberculosis,” the authors write.
The median age at diagnosis was 46, with a mean age at death of 52.
These cases are notable for the patients’ young age at diagnosis, short duration of exposure, severity and rapid progression of disease, and frequent co-occurrence of other silica-associated conditions.
This documentation of cases prompted the state in 2023 to strengthen its silica regulations. But, the authors report, stone-countertop workers remain at risk.
“Although silicosis is preventable with reduction or elimination of silica dust exposure, the water- based tools and ventilation systems required to control silica dust are costly to install and maintain, and overexposures can occur even with recommended controls in place,” they say. “In addition, enforcement of existing regulations is challenging.”