How Does Asbestos Cause Lung Disease?
Inhalation Can Lead to Cancer and Other Serious Illnesses
Sep 17, 2009
The insulating properties of asbestos are useful in a wide range of products, but prolonged exposure to asbestos fibres carries a risk of lung disease.
What is Asbestos?
‘Asbestos’ refers to a group of several minerals, all of which have a soft, fibrous structure. Most of the world’s production comes from Canada and Russia.
There are three main types of asbestos – white (chrysotile), blue (crocidolite) and brown (amosite). All are highly resistant to heat, chemicals and electricity, and because of this they have been used widely in the construction and manufacturing industries. Asbestos may be found in products as diverse as ceiling, floor and roof tiles, pipe insulation, brake pads, fire retardants and even ironing board covers.
Asbestos and Lung Disease
It is important to note that undamaged asbestos is not harmful. Risk occurs only when asbestos is chipped or broken. This can release a fine dust of microscopic asbestos fibres into the air, which may cause disease in people who inhale them.
The risk is related to the amount of asbestos inhaled and the duration of the exposure. Heavy asbestos exposure over many years is generally needed to cause serious illnesses such as asbestosis and malignant mesothelioma. For this reason, asbestos-related lung diseases are most commonly seen in people who have had prolonged contact with asbestos at work.
Asbestosis – a Chronic Inflammatory Condition
When asbestos fibres are inhaled, many are removed by the body’s natural defences against intruders. Some fibres may escape this process, however, and these may migrate out of the airways and become lodged within the tissues of the lung. The needle-shaped fibres of blue and brown asbestos are most likely to be trapped, while the curly, flexible fibres of white asbestos are more likely to be removed. Crocidolite and amosite are therefore the most hazardous types of asbestos.
The trapped fibres cause irritation of the surrounding lung tissue, which stimulates the body to produce excessive amounts of thickened, fibrous tissue in a reaction called ‘fibrosis’. The tiny air sacs in the lungs are gradually replaced by this fibrotic tissue, and breathing becomes increasingly difficult as a result. This is a slow process; decades may pass between the initial exposure to asbestos and the first symptoms of illness.
Benign Pleural Disease
The pleura is a membrane, or mesothelium, that covers the outside of the lungs and the inside of the chest wall. Asbestos exposure can cause thickening of the pleura, leading to breathlessness and pain, or pleurisy (inflammation and fibrosis of the pleura).
Malignant Mesothelioma
Malignant mesothelioma is a cancer of the pleura that is usually caused by exposure to asbestos. It occurs when asbestos fibres trapped in the lung migrate outwards into the pleura. How asbestos causes cancer is not completely understood. It is thought that fibres that are engulfed by cells of the body’s immune system may interact with the DNA of these cells, causing changes in the genes that trigger the development of a tumour.
Asbestos-related Lung Cancer
Lung cancer may also be caused by asbestos. The risk of developing lung cancer may be greater in people who already have asbestosis.
Asbestos-related Lung Disease – an Increasing Problem
Use of asbestos is now banned in the EU, while other countries have implemented strict regulations. However, the long delay between exposure to asbestos and the development of symptoms means that the number of people with asbestos-related lung disease will continue to increase for years to come.
References
IndustryWeek. France Calls for Worldwide Asbestos Ban. Accessed 17-09-09
NHS Choices. Asbestosis. Accessed 17-09-09
Rudd R. Asbestos and the Lung. Medicine 2004; 32(1): 111–13.
Disclaimer
The information contained in this article is for educational purposes only and should not be used for diagnosis or to guide treatment without the opinion of a health professional. Any reader who is concerned about his or her health should contact a doctor for advice.
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