Silicosis screenings ‘failing’ stone countertop workers in Australia, researchers say

Melbourne, Australia — A recent study of stone countertop industry workers reveals an “alarmingly high” occurrence of silicosis, indicating that government-mandated screening tests may be inadequate to diagnose the disease.

The Centers for Disease Control and Prevention defines silicosis as “a severe chronic lung disease caused by inhaling crystalline silica. Occurring in crystalline and non-crystalline form, silica is a mineral found in sand, sandstone, shale and granite.” When workers drill, crush, chip or break materials that contain crystalline silica, large amounts of respirable crystalline silica can form as dust, CDC says.

Employers in Australia’s stone countertop industry (called “benchtops” in that country) are required to screen workers who are at risk for silica exposure. A team led by researchers from Monash University’s School of Public Health and Preventive Medicine in Australia examined 544 workers in the industry to determine how many of them had silicosis. They also looked at the accuracy of current mandated screening methods – including respiratory function testing and chest X-rays.

The vast majority of the workers (95%) worked with artificial stone, while 86% were exposed to dry processing of stone. Some artificial stone products can contain up to 95% silica, a Monash press release states.

The researchers found that, in addition to the required respiratory function testing and X-rays, 414 of the workers (76%) needed a secondary screening that included high-resolution CT scans of the chest and a respiratory physician assessment. Of those workers, 117 were diagnosed with silicosis. They were all male, between 35 and 50 years old, and had worked an average of 12 years in the industry. In one case, the worker had been in the industry for only three years.

The researchers say the mandated respiratory function testing and chest X-rays have limited value and are “failing to diagnose those with the disease.” Among the 117 workers diagnosed with silicosis after a secondary screening, 72% had normal respiratory function tests. In addition, 40% of them had normal chest X-rays.

The researchers call for “urgent action” to enhance occupational health and safety measures in the industry, including eliminating high-silica artificial stone and mandating more sensitive chest imaging for workers.

“Poor dust control measures have been widely reported in the industry, in particular the practice of ‘dry processing,’ where water dust suppression has not been used during cutting, grinding or polishing of stone,” study co-author Malcolm Sim, emeritus professor at Monash, said in the release. “Despite these health concerns, the use of artificial stone has grown at a rapid rate since its introduction to Australia in the early 2000s.”

The study was published online in the journal Occupational and Environmental Medicine.