A CT scan of a silicosis victim’s lungs. The whitish areas show severe scarring and destruction of normal lung tissue. Healthy lungs appear black. Credit: Trevor Stamp

The number of artificial-stone countertop fabricators in California with confirmed cases of silicosis, a fatal lung disease, has risen to 77.

In December, Public Health Watch, LAist and Univision reported on a cluster of the disease – caused by the inhalation of ultrafine silica particles – in the Los Angeles area. The toxic powder is unleashed when the countertop slabs are cut or ground.

At the time, the number of confirmed cases among fabricators in and around Los Angeles stood at 30, with 52 cases documented statewide between 2019 and 2022. By May, when Public Health Watch reported that California workplace regulators were drafting an emergency silica rule, the statewide tally was 69.

At a hearing last week before the California Occupational Safety and Health Standards Board — which voted unanimously to proceed with an emergency temporary standard — Dr. Robert Harrison, representing the California Department of Public Health, said eight cases had been added to the count.

Harrison, an occupational physician on the faculty at the University of California, San Francisco, co-authored a study published today in JAMA Internal Medicine. The paper provides new details on the initial 52 cases in California. For example:

  • The median age at diagnosis was 45
  • All but one of the 52 victims were Latino immigrants
  • The median work tenure was 15 years
  • Thirty, or 58 percent, of the workers initially were misdiagnosed with bacterial pneumonia or tuberculosis, delaying care
  • Twenty workers had an advanced form of the disease, known as progressive massive fibrosis, at diagnosis; 10 died, with a median age of 46

Dr. Jane Fazio, a pulmonary physician at Olive View-UCLA Medical Center in the San Fernando Valley and another of the study’s co-authors, told Public Health Watch she has acquired four silicosis patients since May. She estimated that she’s treated a total of 40 patients, some of whom have died.

Asked if she believed progress had been made toward quelling the epidemic, Fazio said, “Yes and no.” The continued emergence of cases, she said, indicates the need for more aggressive outreach to workers and employers about the dangers of silica dust. An outreach program, which is being led by the Los Angeles County Department of Public Health and includes community organizations, has begun with the training of “people who will go and find workers,” Fazio said.

In June, the Los Angeles County Board of Supervisors took preliminary steps toward a countywide ban on artificial-stone products.

Also known as engineered stone, artificial stone consists of crushed, silica-rich quartz bound by an adhesive to create a solid slab or block.

“Driven by new construction, consumer taste, and imported slabs of engineered stone that are less expensive than other countertop materials, demand has increased 23% annually over the last decade,” according to the JAMA Internal Medicine article. “At present, engineered stone is the most popular countertop material in the US, with a global market value of more than $20 billion in 2020.”