Silica is not the only component of engineered stone that may be harmful for lung health, a new study has found.

As governments around Australia consider a ban on engineered stone products, a new study has shed greater light on how lung health is impacted by the dust which is generated by cutting engineered stone – a product which is commonly used in kitchen benchtops.

The study was undertaken by researchers from the University of Adelaide and the University of Tasmania.

Not surprisingly, it found that silica was an important contributor to the effect of the engineered stone products on lung health.

However, the study also found that other components of engineered stone also contribute to lung health impacts.

In particular, relatively high concentrations of metals such as cobalt and aluminium were also linked with the toxicity of the dust.

The latest study comes amid growing concern about health risks associated with the manufacture and use of engineered stone products in Australia and elsewhere.

Engineered stone is essentially a composite slab of stone that is generally made up of crushed stone which is bound together by an adhesive to create a solid surface.

Over recent decades, the product has become popular in terms of use in kitchen benchtops on account of its low cost, durability, ease of cleaning and resistance to scratching and staining.

However, concern has been growing that manufacture and use of the product may be leading to silicosis and other lung diseases among workers who are involved in its manufacture and installation.

This occurs as workers are exposed to dust over time as a result of cutting, grinding, trimming, drilling, sanding and polishing.

In Queensland, a 2018 health screening program of workers from the engineered stone bench-top fabrication industry found that 11 percent had confirmed cases of silicosis.

Further, researchers believe that the true prevalence of silicosis in engineered stone workers could be as high as 20 or 30 percent (refer link).

As a result, there has been an intensive campaign by unions and public health organisations for an outright ban on use of engineered stone products.

In its final report in mid-2021, the National Dust Disease Taskforce did not back an immediate ban on use of engineered stone but encouraged governments to prepare for a potential ban within three years should other measures to protect workers fail to deliver sufficient outcomes.

In August, Safe Work Australia went further and recommended a complete ban on the product.

The latest study is particularly important as it highlights concern that even products which contain only low-silica content or no silica at all may still be hazardous.

As noted in the Safe Work Australia report referred to above, a significant concern associated with engineered stone products revolves around their particularly high silica content – as high as 90 or even 97 percent for some products.

This has led some manufacturers to switch toward products with either have no silica or have a lower silica content.

However, there is also concern that hazards associated with engineered stone may extend beyond the actual silica concentration.

As noted in the Safe Work Australia report, these include:

• the ease with which stone can be processed relative to natural stone (leading to higher levels of dust exposure as a greater quantity of stone can be processed in one shift);
• different physical properties of engineered stone compared with natural stone, including a greater portion of very small particles which can penetrate deeper into the lungs; and
• concerns that apart from silica, other components of engineered stone may further contribute to the toxic nature of engineered stone dust – either alone or by exacerbating the impacts of the silica. These other components include metals, amorphous silica and pigments.

In the latest study, the research team used 50 engineered stone products as well as products made out of natural stone and other building materials.

These were cut and analysed for particle size and 26 different chemical characteristics.

The researchers then exposed lung cells to the dust that was produced by cutting the products in order to measure the response.

As expected, the results showed that higher silica content was associated with greater inflammation of the lungs.

However, the results also showed that the higher metal content associated with engineered stone products such as cobalt and aluminium was also linked with the cell toxicity of the dust.

Professor Graeme Zosky, Associate Dean Research Performance in the College of Health and Medicine at the University of Tasmania, said the results were concerning in light of the emergence of low or no silica engineered stone products.

“The study has highlighted that while silica is important, it is not the only component of engineered stone that is of concern for lung health,” Professor Zosky said.

“This is important given the emergence of low or no silica products on the market.”

The study was published in the journal Respirology.

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