MCQ MAHE 2000 PSM Answer 06

The Correct Answer is A

Mesothelioma is the most serious of a number of diseases that can arise from exposure to asbestos dust. It is an aggressive form of cancer that affects the pleura, the thin membrane that surrounds the lungs and internal organs of the chest. Once diagnosed, the conditions is essentially untreatable and is invariably fatal with attendant distress to the families of the victims.


The disease has a very long ‘latency’ period, in that there may be a gap of up to 50 years between the victim being exposed to asbestos dust and development of the disease. It is thought that the first cell mutations in the pleura may start to take place some 10 years before the first proper symptoms of the disease become apparent and a diagnosis is made.

Unlike other chest diseases, where it is usually necessary for the victim to be exposed to dust for a long period of time to enable a disease to develop, mesothelioma does not appear to have a minimum level of exposure. It is believed that a single asbestos fibre may be capable of initiating the development of the disease, albeit many years after inhalation by the victim.

Asbestos is the fibrous form of mineral silicates belonging to the serpentine and amphibole groups of minerals. Loose fibre broken down from the mined rock material is used in the manufacture of numerous products. Asbestos is invariably mixed with another material and is rarely encountered in its raw form making identification based on visual examination unreliable. Inhalation of asbestos fibres has been shown to pose a potentially fatal health risk.

The main diseases associated with the inhalation or ingestion of asbestos fibres are: asbestosis, lung cancer and mesothelioma. Inhalation of high concentrations of all forms of asbestos may result in asbestosis, a progressive fibrosis of lung tissue. The development of scar tissue (fibrosis) may occur after exposure to asbestos ends or may continue after exposure has ceased.

The two forms of cancer associated with the inhalation of asbestos are lung cancer and mesothelioma. It is generally accepted that fibres below 3 micrometers in diameter and greater than 5 micrometers in length are potentially carcinogenic, the risk of cancer increases as fibre diameter decreases. The risk of cancer also increases with the exposure level. There is a long latency period, which, in the majority of cases, ranges from fifteen to fifty years between exposure and the development of mesothelioma, asbestosis and lung cancer.

Children exposed to asbestos have a greater susceptibility to disease. Asbestos related disease, therefore, has the potential to continue to occur long after the exposure to asbestos has been controlled. Every effort should be made to reduce exposure to the lowest practicable level. All forms of asbestos have been found to cause lung cancer.

Mesothelioma is a specific cancer of the lining of the chest cavity (the pleura) or, less commonly, the lining of the abdominal cavity (the peritoneum). Asbestos exposure is considered to account for at least 80% of mesothelioma that develop with crocidolite (blue asbestos) and amosite (brown asbestos) providing the greatest hazard. Pleural changes in the form of pleural plaques or pleural thickening may also be associated with inhalation of asbestos fibres. Smoking increases the health risk associated with exposure to asbestos.

Category: MAHE 2000 MCQs