We are just beginning to realise that exposure to asbestos is a hidden travel risk in Asia, particularly for those on a low budget who stay in cheap deteriorating buildings or next to demolition sites.
It’s a small but real risk.
Asbestos is a popular building material in many parts of Asia and given that it only takes a few fibres to cause a fatal cancer, tourists may unknowingly be facing a health risk.
While there is no safe level of exposure to asbestos, risk does increase with dose.
The longer and higher the level of exposure, the greater the dose. This explains why asbestos workers are at higher risk of developing disease. But others get it too and some are totally disbelieving when they get the diagnosis because they can’t recall ever being exposed.
Although asbestos may be locked into insulation, floor tiles and coating, walls and roofing material, as buildings decay fibres can be freed.
These fibres can be 1000 times thinner than a human hair and can be inhaled without detection.
Some travel blogs suggest opting for new hotels and avoiding construction or renovation sites where fibres may be in the air, the soil or on nearby surfaces.
Oblivious of danger
Australians who may be hyper-vigilant about exposure to asbestos at home, travel though Asia oblivious of the risks.
Professor Ken Takahashi, director of the Asbestos Diseases Research Institute (ADRI) says the travel risks have not previously been considered by researchers.
“But in the case of travel, one can assume that the exposure level is low and the duration of exposure is short. Therefore, the risk would be small,” he says.
“A practical recommendation would thus be to avoid going near places where asbestos may be obviously present, the most typical of which is asbestos factories or mines.
“Of course, presence of asbestos is not always obvious, such as in the case of exposure to buildings containing asbestos or exposure to asbestos-containing products.
“It then becomes a matter of practicality whether one should avoid travel in view of the small risk.
He strongly believes Australia has a responsibility to raise awareness of asbestos in Asia, provide education on protection against it and hopefully, help to get rid of it completely “for the sake of workers and residents of the country itself, much more than for the sake of travellers”.
He says more than 60 per cent of the world consumption of asbestos occurs in parts of Asia where commercial convenience and the need for development and housing outweigh public health concerns.
Causing persistent damage
While Japan and South Korea have banned it, China, India, Thailand, Indonesia and Vietnam are among the top 10 consumers in the world.
The small country of Laos has the highest per capita consumption of asbestos on the planet.
For almost 50 years, it has been known that inhaled asbestos fibres can cause cancer of the lungs or can pass through the lungs into a cell layer that surrounds all internal organs.
This layer is called the called the mesothelium and where malignant mesothelioma forms.
While the asbestos itself is chemically harmless, its long-pointed fibres lodge in the body and cause a series of micro-injuries.
As the body is unable to clear these fibres, they remain stuck and cause persistent damage to the tissue.
About 30 years ago, scientists observed that a single dose of asbestos fibres damages the mesothelium tissue.
It was proposed that persistent injury led to chronic inflammation and that cell proliferation somehow paved the way for fatal mesothelioma.
Asbestos can also cause asbestosis, a non-malignant disease that results in irreversible lung damage, difficulty breathing, a cough and, in severe cases, an enlarged heart.
Australia should ‘share knowledge’
Professor Takahashi says Australia is the only country in the world that has a dedicated federal agency to deal with the legacy of the asbestos industry.
In other countries, if it is managed at all, it is done so within health, labour or environmental ministries.
“Australia should be taking a lead in the global effort to ban asbestos in developing countries that continue to use it at a very high level because it is cheap, widely available and has many advantageous characteristics.”
He says Australia should share its knowledge and technology about substitutes for asbestos within the Asian neighbourhood.
“These countries are hesitant to make the transition because they prioritise economy over health and added to that is the fact that there are many pro-asbestos lobbies trying to maintain the global trade.
“And there is corruption among officials of ministries of developing countries, so they are not fully motivated to make the transition.
“I believe Australia should assist these counties in developing their own expertise to detect the disease and also develop systems so that workers and consumers are not exposed to asbestos while they are using it.
“Until these countries stop the manufacture and export of products containing asbestos, Australia will have to deal with illegal imports for a long time.”
Professor Takahashi says this as the epidemic of asbestos-related disease in Australia has begun peaking.
Although Australia implemented a complete asbestos ban in 2003, classic asbestos cancer – mesothelioma – can take up to 40 years to develop, which means new cases will continue to occur and people will be dying from it for many years to come.
In the 1950s and 1960s, Australia had the world’s highest per capita rate of asbestos consumption. Today it has among the highest rates of mesothelioma.
In 2016, about 700 people – the great majority male – were newly diagnosed with this fatal disease.
Apart from those involved in mining or manufacturing asbestos, many more people have been affected because vast numbers of houses built before 1990 had materials containing asbestos.
Tradesmen, such as plumbers and electricians, working in such residential properties had a high degree of occupational exposure.
Mesothelioma has been characterised by nihilism in the past but an international research effort is making some inroads into the disease.
Last month, Swiss researchers unmasked an underlying mechanism that helps explain why asbestos causes cancer.
Detecting disease earlier
They say that until now, this cancer was “a black box” and they are hopeful their discovery may lead to detecting the disease much earlier in its development.
This may then lead to a means of slowing it.
They say over time the immune system can’t cope with the changes induced by the presence of the fibres.
“The immune system goes out of balance and is no longer strong enough to combat tumour formation,” said lead researcher Dr Emanuela Felley-Bosco, of the Swiss National Science Foundation.
Published in the journal Oncogene, the study proposes that immunotherapy, a treatment that triggers the body’s own immune system to fight disease, may work in this cancer.
Using mice, the researchers showed that micro-injuries caused by asbestos triggered an immune reaction.
Tissue-repair pathways were activated that promote cell proliferation and favoured the growth of tumours
The team also found an accumulation of mutations in RNA (a kind of working copy of DNA), which they thought weakened the tissue-repair immune response.
As a result, tumour formation was no longer effectively combated and cancer developed.
An analysis of data from a human gene bank revealed that human mesothelioma tumours also produce large amounts of the enzyme that causes the mutations in the RNA.
It’s hoped this will be useful in recognising early signs of inflammation and in developing a specific immunotherapy against mesothelial cancer.
A clinical study of immunotherapy at the advanced stage of this disease is under way at hospitals in Switzerland, Spain and Britain.
Dr Yuen Cheng, a molecular biologist at ADRI, says the Swiss research has taken the science of mesothelioma a step forward.
While it was known an immune imbalance occurred, the importance and the potential triggers for it were not known.
The Swiss have shown immune imbalance plays a major role and have provided list of genes that were previously not considered.
While these genes were found in the animal model, they were also found in mesothelioma tumours in human gene banks.
The problem is that the banks have samples from fewer than 100 tumours and hundreds of thousands are needed to confirm the finding.
“They’ve clearly shown a link, something different to what other researchers have done, but we don’t know for certain until we have done a large sample,” Dr Cheng says.
The next step, which is not difficult, is to confirm this in humans. If proved correct, it could be useful in the clinical setting.
*Jill Margo is an adjunct associate professor at The University of NSW.
- Reported by the Australian Financial Review on 11 April 2018