Stone fabrication workers at risk for silicosis

Eighteen cases of silicosis in stone fabrication workers have highlighted the occupational risk faced by those who work with engineered stone, according to findings published in Morbidity and Mortality Weekly Report.

“Clinicians should be on the lookout for cases of silicosis and other diseases associated with silica dust exposure in stone fabrication workers, and should always make sure to take an occupational history,” Amy Heinzerling, MD, MPH, epidemic intelligence service officer with the CDC, wrote in an email to Healio Pulmonology. “Under federal or state occupational regulations, employers are required to control and monitor worker exposures to silica dust. Despite this, workers in this industry are still getting sick and dying of silicosis.”

Heinzerling and colleagues examined 18 cases of silicosis among stone fabrication workers, including six patients from California, seven from Colorado, four from Texas and one from Washington. Cases from each state were identified via independent investigation and confirmed based on lung biopsy findings or CT scan.
All six California patients were Hispanic and shared the same employer, with two of the patients dying as a result of silicosis. Both fatal cases had an associated autoimmune condition other than silicosis, including scleroderma and rheumatoid arthritis.

The seven Colorado patients were identified via a single lung disease physician’s systematic review of patients from June 2017 to December 2018. All Colorado patients were also Hispanic, two of whom were women and five of whom were men. Two of the patients reported bystander exposure to engineered stone dust, with the remaining five reporting exposure from cutting, grinding and polishing mainly engineered stone.

Of the four Texas patients, two were Hispanic and two were black. All four patients were men aged 40 to 59 years, with three working as fabricators and one working in engineered stone casting and stripping. Two patients had abnormal pulmonary function testing that showed moderate to severe restriction.

The single patient identified in Washington, a Hispanic man aged 38 years working in stone countertop fabrication, had reduced diffusion capacity as well as a severe restrictive defect on pulmonary function testing.

Of the total patients identified, 11 were younger than 50 years and were diagnosed with severe, progressive disease. Latent tuberculosis infection was also found in two of the patients, and five had concurrent autoimmune disease in addition to silicosis. Engineered stone contains more than 90% silica, whereas granite, for instance, contains less than 45%. This suggests that workers who interact with engineered stone are exposed to higher levels of silica dust.

“Because there is no registry of cases of silicosis in most states or nationally, and because there is no systematic medical surveillance for the disease, there are probably thousands of cases that we don’t know about and haven’t diagnosed,” Cecile Rose, MD, MPH, professor of medicine with National Jewish Health and the University of Colorado, wrote in an email to Healio Pulmonology. “It would be vital to have a national emphasis program on silicosis, both through the Occupational Safety and Health Administration to improve primary prevention efforts (controlling dust levels at the worksite through ventilation, work practices and respiratory protection along with employer/employee training on the hazard) and through creation of a national register of silicosis cases.” – by Eamon Dreisbach

Disclosures: Heinzerling and Rose report no relevant financial disclosures.