Article by Thomas Baggs
Two decades after the complete ban of asbestos in Australia, the dangers of respirable crystalline silica are now in the spotlight. With a ban on engineered stone being considered by national policymakers, further options for regulating its use and processing are needed. But does natural stone also pose a risk?
Update November 2023
A Safe Work Australia report has called for a complete ban on engineered stone products, saying regulators had failed to protect workers from the deadly disease, an ABC News article states. The report states that continued work with engineered stone poses an unacceptable risk to workers, and that there was “no evidence” that lower levels of crystalline silica could be safe for workers cutting and grinding engineered stone. “The only way to ensure that another generation of Australian workers do not contract silicosis from such work is to prohibit its use, regardless of its silica content,” the report says.
The state and federal governments will meet to decide on next steps. Meanwhile, stores such as Bunnings and IKEA have moved to remove engineered stone products from their range. Stone Initiatives will continue to monitor developments on this issue.
Almost 20 years ago, asbestos was banned in Australia due to the harmful respirable mineral fibers generated by the processing of asbestos products. Now, similarly harmful respirable mineral particles – namely respirable crystalline silica – are increasingly becoming a focus of attention due to health and safety concerns in workplaces involved in the processing of stone. The main risk associated with the generation of respirable crystalline silica in the workplace is the uncontrolled, dry-cutting of products with high crystalline silica content (for example, some engineered stone).
From the 1 September 2023, new regulations were introduced in South Australia (where the Stone Initiatives laboratory is located) to prohibit any uncontrolled processing of engineered stone products. All workers involved in cutting, grinding, trimming, sanding, or drilling engineered stone products must be provided with respiratory protective equipment and use a dust control system such as a water suppressant and/or exhaust ventilation. Similar regulations have been adopted at a national level.
Does natural stone pose a crystalline silica risk?
However, the danger of crystalline silica is not isolated to engineered stone – it can also be an issue with natural stone products. Safe Work Australia identifies typical crystalline silica amount (percentage) of common stone types and similar products:
| Product type | Amount of silica (%) |
| Marble | 2 |
| Limestone | 2 |
| Slate | 25 to 40 |
| Shale | 22 |
| Granite | 20 to 45 (typically 30) |
| Natural sandstone | 70 to 95 |
| Engineered stone | Up to 97 |
| Aggregates, mortar and concrete | various |
According to Safe Work Australia, engineered stone products contain a very high percentage of crystalline silica when compared to most natural stone types. However, some manufacturers and suppliers of engineered stone have recently worked to reduce the total crystalline silica content in their products, with the development of new ‘low silica’ engineered stone products. The aim of these new products is to reduce the total quantity of crystalline silica to levels in line with some common natural stone products such as granite, which is widely used in built environment projects. The development of low-silica engineered stone products can see the total crystalline silica percentage of some engineered stone products drop to below 40%.
Workplace health and safety ministers from across the country are planning to meet toward the end of 2023 to consider expert advice around further options for regulating engineered stone at a national level. It is expected this will precipitate a national action on the processing and use of engineered stone.
Current workplace exposure standards apply to the quantity of respirable crystalline silica in a body of air over a weighted time exposure (the limit that must not be exceeded is 0.05mg/m3 eight-hour time weighted average). However, at the time of writing this article, no such standard exists for the total quantity of crystalline silica in the finished product to be considered acceptable to process.
What does the industry want?
When reviewing the industry body submissions and responses to Safe Work Australia’s ‘Prohibition on the use of engineered stone’ consultation, some common themes are evident: It is hoped that one of the outcomes of the meeting of workplace health and safety ministers in late 2023 will be guidance on the quantity limits of crystalline silica in any given stone product, including engineered stone. It is also hoped that guidance will be provided for the associated processing safety or licensing requirements based on the tested crystalline silica quantity in the product. This would allow suppliers and importers to have their product tested and determine the processing requirements and license requirements for the specific product.
Compared to historical typical engineered stone products, many natural stone products typically contain lower amounts of crystalline silica. And in many cases, engineered stone products tend to be comprised of a higher percentage of tiny particles of crystalline silica (which may produce crystalline silica particles that are more respirable), compared to natural stone. However, given the variation in crystalline silica content between different stone types, along with recent advances in reducing the total crystalline silica content in manufactured engineered stone products and the substitution of crystalline silica with recycled glass (amorphous silica) in some? engineered stone products, natural stone products should also be considered in discussions about crystalline silica safety in the workplace. A ‘blanket’ ban on either type seems unnecessary. It is worth noting in regards to Australia’s asbestos ban, that there is no known safe level of exposure to asbestos.
The development of regulations around safety and processing requirement levels, based on the tested quantity of crystalline silica in a finished stone product (natural or engineered), would allow all parties involved in stone processing and supply to know exactly what their workplace safety requirements are for any given product. In this system, the inclusion of licensing requirements for different levels of crystalline silica should also be considered. This method of control would be a simple method for identifying the processing requirements of a given product and would encourage manufacturers to further reduce the quantity of crystalline silica in their engineered products. This information could be easily gathered by testing on a per product basis and stored in a safety data sheet associated with the product.