A study published in the Medical Journal of Australia todays says the increase in the number of malignant mesothelioma cases in Western Australia over the past decade is the result of home renovation and do-it-yourself (DIY) projects involving building products containing asbestos. This domestic exposure has been described as part of the "third wave" of asbestos-related diseases, the first being in miners, millers and transport workers, and the second in workers who used asbestos products. Clinical Professor of Respiratory Medicine and senior author of the paper, Bill Musk, discusses the risks to human health posed by asbestos.
When did we first find out about the harmful effect asbestos has on health?
We’ve known about it all for quite a while but it took a painfully long time for action to be taken. Asbestos was finally banned in Australia in 2003. The problem is the stuff that’s still out there.
Tell me about the study you’ve published today.
The West Australian Mesothelioma Registry has recorded every case of mesothelioma that has occurred in the state ever since the start of the epidemic in the early 1960s.
What we’ve been looking at is where asbestos exposure comes from. In the early period, the greatest proportion of the cases was people who were mining asbestos in the Wittenoom Gorge in Western Australia’s Pilbara Region.
With time, the number of cases from Wittenoom has stayed fairly level because the mines in Wittenoom were closed in 1966. They‘re still happening but the number of people at risk is reducing.
The second wave of cases of mesothelioma was in people who’d been using asbestos, such as carpenters and mechanics. Anybody who used asbestos as part of their trade was at risk and those cases have been getting proportionally greater.
Now we’ve got a growing number of people who’ve been exposed through doing-it-yourself jobs at home. Like the others, the risk for people renovating or undertaking DIY projects is proportional to the amount of asbestos they’re exposed to.
But it’s very important to remember there’s no level of exposure at which there’s no risk.
There are lots of people out there who do their own little jobs at home and their individual risks are small but because of the large number of people doing this kind of thing, the number of cases has been increasing.
The study reports that the proportion of women developing mesothelioma is much higher than men – a rise from 5% of all cases in the 1990s to 35% for the period 2005 to 2008. Why is this?
Mesothelioma is very uncommon in women because their exposure to asbestos in occupational settings is so much less than men. So, as a proportion of all new cases, the percentage of women getting mesothelioma is higher but the number of cases overall is smaller.
Where is this exposure coming from?
Asbestos was used a lot in the 1950s and 1960s as building material. And there’s nothing wrong with it as a building material, it’s just the health problems that we’re worried about.
So there were lots of asbestos roofs on houses, especially during this time but it reduced soon after because better materials came on board and the health risks started to be recognized. It’s those older houses that are most likely to contain asbestos.
If people think there’s asbestos in their house, they shouldn’t touch it, they should get it identified and if there’re going to remove it, they should take all the recommended precautions for removal.
This is a preventable disease and avoiding exposure to asbestos is the best way to avoid it.
How can we avoid exposure?
There are regulations about how asbestos should be handled at home or anywhere else for that matter. People doing home renovations often don’t abide by those sort of rules – wearing protection, closing the job they’re doing, wetting it down and preventing exposure to the airborne fibres.
Really you shouldn’t be removing asbestos without observing proper precautions and there’s no great rush to remove asbestos – it’s often safer being left where it is than it is being disturbed.
There’s a degree of ignorance in the general community about the risk and the fact that asbestos might be present in various places and we’re hoping this study will increase people’s awareness of the risk and their care in handling it.
How else can we be exposed to asbestos?
Asbestos is around us all the time and it has been for years as a result of people using it. There’s asbestos in brake lining, for instance, which may get released into the atmosphere.
Motor mechanics and people working on engines where the exhaust had been covered by asbestos were a significant part of the second wave of people to be diagnosed with mesothelioma.
Between all these sorts of activities, there’s asbestos being released into the atmosphere in urban environments so we all have a few asbestos fibres in our lungs. The risk is related to how much there is.
This sort of environmental exposure doesn’t have a big impact on the individual’s risk but over the whole of the population, a few people getting mesothelioma mounts up and that’s the effect we’re seeing.
What exactly is meosthelioma?
Mesothelioma is a form of cancer arising in the tissue that covers the surface of the lung and lines the inside of the chest wall. It also covers the surface of the bowel and lines the abdominal cavity. The same sort of the tissue covers the heart and lines the pericardial cavity.
It’s a cancer of those cells and the main problem that it gives people initially is where it arose, either around the lung or around the bowel.
What are the treatment options for people who develop this illness?
That’s the problem with mesothelioma – we don’t have a treatment for it. Because it’s a surface cancer, it already involves all the tissues around the lung, including the lung surface itself. So it’s not really feasible to surgically remove it. It’s been tried but it doesn’t appear, at least at this stage, to have any useful effect.
And again because it’s distributed over the whole surface, it makes it impossible to give adequate amount of radiotherapy to the cancer. It’s also very resistant to chemotherapy, which is the other form of treatment for cancer. There’s one regime of chemotherapy that shrinks the tumour and may keep people alive for a little longer but this cancer is 100% fatal.
What is its progression?
Mesothelioma doesn’t occur within ten years of first exposure to asbestos, it’s very uncommon within the first 15 years but after that period the rate rises exponentially. Half of the people die within nine and 12 months
There’s no level of exposure below which there’s no risk but the risk is also related to what sort of asbestos the exposure was to. But the more exposure a person has, the greater the risk of getting mesothelioma.
Blue asbestos is the worst while white asbestos is the least potent – we don’t know if pure white asbestos exposure has ever actually caused mesothelioma.
So some asbestos is worse than others – could you elaborate?
The most commonly used asbestos around the world has been white asbestos and that’s relatively innocuous in causing mesothelioma – it can cause chrysotile cancer and asbestosis but it’s a much less potent cause of mesothelioma.
But amosite or brown asbestos, which is what we got from South Africa, is a different variety of asbestos and it’s much more likely to cause mesothelioma.
Blue asbestos, or crocidolite, is the most potent cause of mesothelioma. And that’s why we believe Western Australia has more mesothelioma per head of population than pretty much elsewhere in the world.
We’ve been taking mainly about malignant mesothelioma but asbestos causes a number of other illnesses. What other diseases result from asbestos exposure?
Asbestos can cause a number of diseases but one doesn’t cause another – they’re all pretty much independent effects of asbestos. If you’ve been exposed to it, you can get plural plaques and mesothelioma, or plural plaques and lung cancer or plural plaques and asbestosis. Plural plaques are benign so they tend to be around for a long time.
Asbestosis is an inflammation of the lung tissues that causes fibrosis in the walls and the air spaces of the lungs. It impairs their function but its not cancer while mesothelioma and lung cancer are forms of cancer.
Asbestosis was the first asbestos-related disease to be described and that was early last century. Lung cancer was described as an effect of asbestos exposure in the 1950s and mesothelioma as described as a result of blue asbestos exposure in South Africa in 1960.