Silicosis is a group of lung diseases caused by exposure to respirable crystalline silica, a biologically active dust that can accumulate in the lungs and, depending on the level of exposure, can cause terminal damage.
The severity of silicosis is defined by three clinical categories:
- chronic/classic silicosis, which can occur after 10-30 years of low levels of exposure
- accelerated silicosis, which can occur within 10 years of high levels of exposure – this type of silicosis is being most commonly diagnosed in this new generation of cases
- acute silicosis, which can occur after a few weeks of extremely high levels of exposure.
There is no effective treatment and it usually presents asymptomatic until the level of exposure has caused significant damage. Often people with silicosis don’t know they have it until it is too late.
The silicosis cases in Australia have mostly come from occupational exposure, particularly in the stone masonry sector, where stonemasons are working with products containing silica, such as sandstone, tiles, bricks, concrete, granite and, most significantly, engineered stone.
Workers who are exposed to crystalline silica dust particles tend to polish, cut, sand, drill or blast silica-based materials. Some of the highest risk workers are those working with engineered stone products commonly installed as household benchtops. Those who are working on site and dry cutting without vacuum extraction are especially at risk.
The most concerning product is engineered stone which can have a silica concentration of up to 90% or higher. This material features a small percentage of stone bonded by adhesives. Natural stone products have a silica concentration of about 40%.
It has been estimated that 6.6% of Australians are being exposed to occupational respirable crystalline silica dust, with 3.7% being highly exposed.
Medical Forum spoke with Owen Whittle, the assistant secretary of Unions WA, who said the spike in silicosis cases was not unexpected.
“We’ve long held concerns about dust management in the industry. There seems to have been a loss of focus in regards to dust. We have been agitating for action around monitoring and regulation,” he said.
The first cases in this new wave of silicosis occurred in the eastern states of Australia, in particular Queensland, which has so far recorded the most cases of the disease.
“That sent shockwaves through the union movement, with our concerns around dust management coming to bare in the unique circumstances of manufactured stone industry,” he said.
In WA, Owen places some of the blame on the defunding of the occupational health and safety regulator, WorkSafe.
“Successive governments have reduced the resources available to WorkSafe to do proactive inspections, not just on silica and dust, but on any other occupational safety issue,” he said.
“Worksafe has begun an inspection regime for artificial stone benchtops, which is encouraging but I think there are still a lot of elements of the industry that are yet to be touched by the regulator. And my understanding of their processes is that while they have had a range of inspections in workshops, there hasn’t been much, if any, on-site installations in people’s homes.”
It is in these uncontrolled environments, says Owen, that pose the greatest exposure risks.
“In a workshop it’s easier to control dust management, even though I think it has been done really badly in a range of places. Normally the workers who are sent out to install the artificial stone aren’t given the appropriate tools or time to install it in a way that it is safe.”
“Silica, or dust, is not a new occupational hazard. This is an issue that has been around for a very long time and there is no excuse. The importers of artificial stone know that it has anywhere between 90-95% silica content. There is no excuse for ignorance here, it merely comes down to cost cutting.”
Another sobering fact is that existing regulations are in place with employers obligated to ensure employees are operating in safe working environments. However, these regulations have not been enforced and there has been little in the way of employee education.
“Talking to workers in the industry, some have been diagnosed or have precursor conditions to silicosis and are still working. It’s their trade, it’s their livelihood, they just can’t afford to walk out and be unemployed,” said Owen.
“What’s concerning for us, industry is not moving fast enough to protect their workers; workers are being left in the lurch and are going through mental stress fearing their future health.”
Although it may be easy to draw parallels with the asbestos disaster, Owen sees a clear point of difference.
“The regulations to prevent silicosis are there, it’s just a matter of the appropriate compliance. That’s the main difference between now and when asbestos was emerging as an issue,” he said.
“There is power for the regulator to act and there are also very strict requirements on employers to conduct health surveillance on their workers when they are exposed to silica. It was just never done.”
Sally North, Director of WorkSafe Service Industries and Specialists Directorate, said although the danger of crystalline silica dust particles was known to WorkSafe, the regulator was caught blindsided like the rest of the industry.
“We have had information about silica hazards on our website for years because silica has been known as a respiratory hazard. It was quite a problem in mining many years ago. Those industries which had problems introduced controls and there were very few cases of silicosis after that time,” Sally said.
When silicosis cases appeared in Queensland in 2017, WorkSafe began enforcing safe working standards in specific industries.
“Anecdotally we knew these benchtops and similar products were becoming increasingly popular, so we started to take regulatory action across the last financial year. We began visiting targeted workplaces to see how compliant they were with the existing OHS legislation.”
“There were and are regulations around silica substances with requirements to pick up on hazards, do risk assessments and conduct air monitoring, where the need is identified.”
Yet, without enforcement, the industry has been operating too long with too little oversight and the result has been the rise in individuals with silicosis.
“If the regulator isn’t proactive in doing its own monitoring of silica dust and not carrying out ongoing inspection campaigns, we will continue to see cases of silicosis and still see workers exposed to 90-95% silica dust without any personal protective equipment.”
WorkSafe has visited around 30 workplaces and found many to be non-compliant, according to Sally.
“We have undertaken a fair amount of compliance enforcement and do hold some concerns that the compliance in the industry isn’t as good as we would like to see it, which is why we are continuing and expanding the project.”
“Employers should be providing health surveillance medicals with an appointed doctor for these employees. Not all employers might be doing this, so if someone presents to their GP and they have a concern about silica exposure, the GP can contact Worksafe to get some further information regarding medical screening.”
Indexed case redux
To understand just when and how silicosis re-emerged as a health problem, Medical Forum spoke to A/Prof Deborah Yates, a respiratory physician at St Vincent’s Hospital and University of NSW.
“The re-emergence of such an old group of diseases is a lesson to us in terms of complacency because wherever there is silica exposure there is likely to be disease. Australia has quite a lot of industries such as mining that exposes workers to silica.”
“We described the first indexed case in a patient in NSW. It was about 2016 when I first saw him. And he was referred to me by some colleagues in Bankstown and I was shocked, I have to say. I saw a lot of cases of silicosis in England but not with bad disease. This man had terrible disease, the sort of disease I hadn’t ever seen.”
Conferring with her colleagues, Deborah discovered they all had silicosis cases.
“It was at that stage we thought we should write them all up and put our cases together. That was pretty frightening because when did that, we found that all the cases were from exposure to artificial stone. It was evidence that these people were getting much worse, more quickly, than we would expect from classical silicosis.”
To date, Queensland has the most reported cases of silicosis, which Deborah attributes to that state’s health department having the systems in place from dealing with the re-emergence of pneumoconiosis (black lung) from the increase in coal mining activity.
Message for GPs
Although silicosis can present asymptomatically, one of the key indicators in identifying an at-risk patient is the relationship with their GP who has a working knowledge of their patient’s employment history.
“The GP is the key player in preventative health and that’s the most important thing really. Catch it early. Look for any history of silica exposure, working in the mines or with artificial stone benchtops – any industry exposed to silica and there a so many of them, concreting, tunnelling, road making,” Deborah said.
“Those are the traditional industries; artificial stone is one of the newer ones. Any industry that involves cutting of stone or moving sand or using silica in industrial processes is potentially a risk.”
The Morrison government went to the last election with a promise of action to tackle the issue of occupational dust diseases and in July the Taskforce to Tackle Silicosis and Other Dust Diseases was launched with a $5 million commitment to developed a national strategy to prevent, identify early, control and manage dust diseases, in particular silicosis.
With the formation of the taskforce, numerous specialists have become involved on a national policy level. WA respiratory physician A/Prof Fraser Brims, Deputy Director of the Institute for Respiratory Health and chairs the Western Australian Mesothelioma Registry, is on the taskforce.
Fraser says the taskforce will examine the issues at a national level, both from an occupational health and safety perspective to reduce exposure and also from a clinicians’ response perspective. “How do we screen and case find, and what do we do with people down the line,” he said.
The taskforce was an opportunity for the medical community to work together in addressing silicosis by using a national register which would identify trends in diagnosis.
“Seeing trends emerging, means faster response and, of course, identifying occupational groups,” he said.
Fraser has, himself, seen one silicosis case in WA – a stonemason, but said WA hasn’t quite got up and running yet with a formal screening program to case find.
“I hope this will be happening in the next couple of months, in partnership with WA WorkSafe.”
Difficulty in diagnosis
Fraser said the real challenge of silicosis was that patients could be asymptomatic.
“They can have normal lung function but still have radiological signs of disease. Common sense would be chronic cough and breathlessness on exertion. Lung function can be variable but there could be an obstructive ratio, so reduced FEV1 (forced expiratory volume),” he said.
“Many of these people are relatively young – often in their 20s and 30s. So, it’s starting when symptoms don’t really fit in – it’s too early potentially for COPD and smokers.”
Again, the relationship with the GP is so important.
“It’s actually more about identifying what their occupation and exposures are, considering many might not have symptoms but they could be exposed and could have early signs of disease.”
“The frustrating and honest truth about silicosis is there is no treatment. We need to stop exposure, and stop any tobacco smoke exposure. We have to find it early so vigilance of chronic symptoms that can’t be explained is required.”
“I urge GPs to ask their patients ‘what’s your job? Do you breathe in any of these chemicals or dust?’ and if they are stonemasons and have been exposed to silica dust, to adopt a very low threshold for investigation.”
Testing risk in court
A legal class action has been mounted to test if the suppliers of engineered stone are responsible for occupational exposure to respirable crystalline silica in plaintiffs suffering from silicosis.
The previous national exposure standard for crystalline silica was 0.1mg of airborne particles per cubic metre, which was considered to be dangerously high. A new national standard has been agreed to lowering the exposure level to 0.05mg/m3.
Owen Whittle said the new standard was a step in the right direction though even at that level, some workers still risked silicosis.
“What we need is a standard that is based on the science which says quite clearly that 0.02 is preferable even though there is no safe level of silica exposure. We need to get it down to the lowest possible level of exposure to protect workers.”