The material on this website is for your information only. Whilst we have taken all reasonable steps to ensure the accuracy and completeness of contents of this website, to the extent permitted by applicable law, the author accepts no responsibility for loss suffered as a result of any reliance on any part of its contents. Any medical information on this website is not intended as a substitute for informed medical advice. Prof. Roger Allen is not responsible for the content of any linked site, changes or updates. Links are provided for your convenience inclusion does not imply endorsement.
The unique properties of asbestos were first recognized by Finnish potters around 2500B.C. During Greek and Roman times asbestos was woven into cloth due to its fire resistant properties. Asbestos is a compound composed of magnesium and iron silicates, there are six varieties and although they all share a delicate fibrillar character, flexibility and crystalline nature they all show distinct characteristics (acid resistance, insulating properties, fibre formation). Due to its unique properties, asbestos has been incorporated into insulation and building materials.
Asbestos air sampler
Asbestos sampler seen under an Electron microscope
Asbestos under rope maker
Asbetos in bags
Asbestos related diseases
Lesions resulting from asbestos exposure are separated into the following groups:
- Benign asbestos pleural disease
- Pleural plaques
- Pleural thickening
- Pleural effusions
- Mesothelioma (often presents with a malignant effusion)
- Lung cancer.
The risk of developing asbestosis, lung cancer and mesothelioma is linked to the degree and type of asbestos exposure. The risk of developing lung cancer increases greatly when the person is or has been a heavy smoker and has asbestosis rather than just asbestos pleural disease.
Asbestos bodies - Asbestos fibres in lung tissue, which have been coated by inflammatory cells with an iron-protein complex. They are also called ferruginous bodies because of their iron content. Benign asbestos pleural disease
Benign asbestos pleural disease
Plaques are localized thickenings of the parietal (i.e. the pleura on the chest wall and not on the lung itself) pleura; they vary between 1 to 2cm and may even be as large as 10cm. They are due to chronic irritation to the pleural surface. These plaques do not contain asbestos bodies. They rarely arise if there is no asbestos exposure history. The presence of pleural plaques is the hallmark of previous asbestos exposure.
Pleural thickening is defined as a smooth, non- interrupted sheet of pleural thickening more than 5cm wide, more than 8cm craniocaudal (up-down) extent and more than 3mm thick. Extensive diffuse pleural thickening can lead to restrictive lung disease.
Pleural disease may lead to pleural effusions (collection of fluid or blood in the pleural space). Recurrent pleural effusions may lead to diffuse pleural thickening.
Asbestosis leads to a reduction in lung size, the ability of the lung to exchange gas and increased lung stiffness. One of the most characteristic symptoms of asbestosis is breathlessness on effort and a dry cough.
Asbestosis is a scarring or fibrotic process that involves the lung itself and is sometimes loosely and incorrectly used to mean asbestos pleural disease. Asbestosis may take between 20 - 25 years to develop. Asbestosis may increase the risk of developing lung cancer or mesothelioma.
Mesothelioma was once considered a rare malignant tumour of mesothelial tissue, but is now relatively common. It occurs in approximately 15 per 1 million men and 2 per million women. This disease may take up to 30 years to develop. A prominent symptom of malignant mesothelioma is nagging chest pain.
Surgery in the form of extra pleural pneumonectomy has been recently used for attempted cure of mesothelioma. However the long term effects and survival rate is very minimal.
Recent studies have shown that the use of chemotherapy drugs (gemcitabine and cisplatinum) may have some effect in shrinking mesothelioma. Increased survival and improvements in quality of life are encouraging.
Expert Witness in Lung Diseases
Dr Allen has been involved as an expert witness in numerous medico-legal cases of a wide range of occupational lung diseases and particularly, asbestos-related diseases. He sees many patients with this condition on a weekly basis and has appeared in the Federal Court (Queensland) on numerous occasions as an Expert Witness over recent years. In addition, he also manages many patients with occupational lung disease, particularly mesothelioma, asbestosis and asbestos pleural disease, both as inpatients and outpatients.