The ongoing dangers of silica dust

More than half a million Australian workers are currently exposed to harmful silica dust, with as many as 10,000 now predicted to develop lung cancer in their lifetimes.

Crystalline silica (silica) is found in stone, sand and mortar, as well as many building and construction products. Engineered stone — used mainly for kitchen benchtops — is a particularly potent source of silica dust.

According to Safe Work Australia, when workers cut, crush, drill, polish, saw or grind products that contain silica, dust particles are generated that are small enough to lodge deep in the lungs and cause illness or disease including silicosis. The International Agency for Research on Cancer classified crystalline silica as a Group 1 (definite) carcinogen in 1997 and 2012.

Over the past 60 years, silicosis was a very rare occurrence in Australia, but the increased use of engineered stone in kitchen benchtops is driving a re-emergence of the disease. This prompted the Australian federal government to set up the National Dust Diseases Taskforce. Safe Work Australia also released a Consultation Regulation Impact Statement that proposed options for managing the risks of exposure.

As the result of a study commissioned by the Australian Council of Trade Unions (ACTU), Curtin University researchers used a unique method to predict how many Australians would develop lung cancer in their lifetime as the result of their exposure to silica dust in a specific year.

What does the modelling suggest?

Lead researcher Dr Renee Carey, from the Curtin School of Population Health, said the modelling provided the best available estimate of the future number of lung cancer and silicosis cases that would result from workplace exposure to silica.

“Our modelling predicts more than 10,000 Australians will develop lung cancer and up to 103,000 workers will be diagnosed with silicosis as the result of their current exposure to silica dust at work,” Carey said.

“We estimated that more than half a million Australian workers are currently exposed to silica dust across various industries, including construction, mining and quarrying, and manufacturing jobs.”

Banning engineered stone

The ACTU has called for the implementation of a full ban on high silica content engineered stone.

“At least 230 workers a year are being diagnosed with silicosis — many as young as 25. It’s 2022 and we’re seeing an increase in workers dying from entirely preventable occupational lung diseases,” said ACTU Assistant Secretary Liam O’Brien in April 2022.

“Every worker has the right to healthy, safe and secure work. That means a workplace free of mental and physical hazards and where workers can, without fear, raise concerns about unsafe practices.”

John Curtin Distinguished Professor Lin Fritschi — also from the Curtin School of Population Health — agreed that banning engineered stone would save lives, and said that almost 100 lung cancers and a thousand silicosis cases could be prevented.

“While a complete ban of engineered stone would be the best option, it is possible to reduce the health impacts of working with engineered stone by various methods such as mandatory wet-cutting or on-tool dust extraction, as long as these methods are combined with the consistent use of high-quality respiratory protection,” Fritschi said.

“The damage from other types of silica-containing materials could be reduced by using better dust suppression techniques on mine and construction sites, and using wet-cutting during concrete cutting and grinding.”

The rate of occupational cancer

By estimating how many of Australia’s adult population in 2016 were exposed to silica dust at work, and then modelling the number of lung cancer cases that would occur over their lifetime, the Curtin research team was able to predict that 1% — or 10,390 — of those lung cancer cases could be attributed to a person’s occupational exposure to silica dust. Carey said further research was needed and better estimates may be possible as new information becomes available.

Control measures to reduce the risks

According to Safe Work Australia, there are several control measures for reducing the risks associated with silica.

• Elimination: Completely removing the hazard from a workplace, where reasonably practicable.
• Substitution: Replacing silica and products containing silica with material that is less hazardous.
• Isolating workers and others from silica dust: Placing a barrier between workers and the hazard.
• Engineering controls: Physical methods to change the characteristics of a task, such as using automation when cutting, grinding or drilling.
• Ventilation: Using a ventilation system that best suits the workplace, such as tool dust extraction.
• Engineering controls for silica-containing products: Even when wet methods are used, silica dust is not always adequately controlled, and silica-contaminated mist generated by water on rotating tools must also be controlled.
• Administrative controls: These rely on worker behaviour and should only be used to provide additional protection after implementing substitution, isolation and engineering controls.
• Administrative controls when working with silica-containing products: Organisations need to develop and implement administrative controls to support the higher level control measures they have in place to protect workers.
• Training: Talking to workers about silica dust hazards, and providing the correct training.
• Housekeeping: Developing written rules and policies for the workplace is a good way to implement housekeeping as an administrative control.
• Decontamination: Dusty clothing and PPE can expose workers and others to silica dust, and it is important to minimise this exposure.
• Personal protective equipment: This should never be solely relied upon to protect workers from silica dust, and should only be considered after implementing substitution, isolation, engineering and administrative controls.
• Respiratory protective equipment: Workers should use a tight-fitting respirator with an effective face seal to protect against small silica particles.
• Fit testing respiratory protective equipment: Fit testing measures the effectiveness of the seal between the respirator and the wearer’s face, and workers should pass a respirator fit test before they first start wearing a tight-fitting respirator.
• PPE when working with silica-containing products: Respiratory protective equipment is not enough to protect workers from silica dust. A combination of controls is required to protect workers’ health, including engineering, isolation, work practices, personal protective equipment, worker training and consultation. Selected PPE must also be appropriate for other risks when working with silica, such as eye, hand or hearing protection.
   

Image credit: iStock.com/Nikolay Tsuguliev