Asbestos exposure can cause lung cancer years later


  • Wellness
  • Thursday, 19 Mar 2020

A local resident explains to a foreign worker that he should not dry foodstuffs on the asbestos sheet in this filepic, as the fibres are known to cause cancer.

The term asbestos refers to a family of fibrous minerals that have been used extensively in domestic and engineering applications since the Industrial Revolution.

High resistance to chemical, electrical and heat damage made asbestos ideal for use as an insulation material in machinery, and as fire-resistant building material.

In fact, the use of asbestos in textiles goes back much further in our history: it was incorporated into the burial wrappings of Egyptian pharaohs and in stain-resistant table cloths used by the ancient Romans.

However, as useful as asbestos is, it also poses a threat to our health.

As early as the 1890s, doctors became aware that asbestos workers sometimes developed life-threatening lung conditions as a result of their contact with these minerals.

But it was not until the 1970s that countries began banning the use of asbestos.

In 2005, the European Union banned the use of asbestos completely on health grounds.

Occupational hazard

In the mind of the public, lung cancers are most closely associated with smoking.

However, pleural mesothelioma is a very rare form of lung cancer that develops in the pleura – the tissues that surround the lungs. This cancer is not associated with smoking.

In fact, occupational exposure to asbestos has been established as the greatest risk factor in the development of mesothelioma.

This is why this cancer occurs the most among men who have worked in the construction industry or with heavy machinery.

Mesothelioma is much rarer in women due to a reduced risk of occupational exposure to asbestos.

Those cases that do occur in women are most likely due to exposure to asbestos fibres released into the environment from deteriorating buildings.

Asbestos was extensively used in Europe in the post-World War II construction of public buildings such as schools and hospitals, leaving significant legacy issues as these buildings get older.

Poor outcome

Mesothelioma often develops over many years, and even decades, after asbestos exposure.Workers fix the asbestos roof on a house in this filepic. Construction workers are most at risk of developing mesothelioma as they are constantly exposed to asbestos materials.Workers fix the asbestos roof on a house in this filepic. Construction workers are most at risk of developing mesothelioma as they are constantly exposed to asbestos materials.

This is linked to the extended time the inhaled fibres can remain in the lungs, causing damage.

Most diagnoses are made in men of older age, long after they have stopped working with asbestos.

Once symptoms such as chest pain or breathing difficulty develop, the outcome for the patient is poor.

Survival after a mesothelioma diagnosis is typically six to 18 months, and the diagnosis is essentially a death sentence.

The therapies currently available for treating mesothelioma, such as chemotherapy, radiotherapy and surgery, have very limited benefit in terms of prolonging life.

Instead, most mesothelioma treatment is focused on enhancing the quality of life for patients through pain control and making breathing easier.

An ongoing issue

The health risks posed by blue (crocidolite) and brown (amosite) asbestos are very widely accepted, even by the asbestos industry.

But there remains some uncertainty over the health risks associated with white (chrysotile) asbestos.

White asbestos use is not banned in all countries; it is still mined in countries like Canada and exported to countries such as India and Malaysia, mainly for use in construction.

However, the use of asbestos in the construction of public buildings in Malaysia was banned in 2005.

In the United States, settling the legal claims from workers who developed mesothelioma as a consequence of workplace exposure to asbestos has morphed into a litigation industry, which does not always support the best interests of victims who may only have a short life expectancy.

A genetic element

Over the decades, a huge number of people were exposed to high levels of asbestos fibres in their working environments, but mesothelioma remains a very rare form of cancer.

This begs the question of why do only a fraction of workers exposed to asbestos develop mesothelioma?

Other factors must contribute to the risk of mesothelioma development – a point that was tackled by a 2001 study in Turkey by Professor Michele Carbone.

A small cluster of villages in the Cappadocia region had an abnormally high rate of mesothelioma.

In fact, this normally rare cancer was causing half of all the deaths in these villages, including in children.

The study found that the natural stone from which the houses in these villages was constructed, contained erionite, an asbestos-like fibrous mineral.

The unusually high rate of mesothelioma was due to mutations in a critical gene called BAP-1, which made those who had the mutation more vulnerable to developing mesothelioma, following erionite exposure.

The Turkish families affected by this mesothelioma mini-epidemic were all found to carry the mutated form of the BAP-1 gene.

While the use of asbestos is declining globally, it is likely that the incidence of mesothelioma will decline only slowly, due to asbestos exposure in previous decades and detection of the cancer only at an advanced stage.

Recent studies in the US have highlighted the issues around erionite exposure causing mesothelioma in road workers, where the gravel used in road construction in some parts of the country contains this mineral at high concentrations.

Assoc Prof Dr Warren Thomas is the Academic Lead in Physiology at Perdana University–Royal College of Surgeons in Ireland School of Medicine. This article is courtesy of Perdana University. For more information, email starhealth@thestar.com.my. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.

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Cancer , lung cancer , asbestos , construction

   

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