Cause of Malignant Mesothelioma – The types of Exposure to Asbestos

The major risk factor for mesothelioma is when one is working with asbestos. Asbestos is undeniably the major cause of malignant mesothelioma which can be considered indisputably associated with the development of mesothelioma. The connection between asbestos and mesothelioma is so strong that so many people see mesothelioma as a signal tumor. In most cases, there exists a history of types of exposure to asbestos. However, there have been reports of mesothelioma in some individuals without any known exposure to asbestos. In rare situations, mesothelioma has also been associated with intrapleural thorium dioxide (thorotrast), inhalation of other fibrous silicates, such as erionite and irradiation. There have also been studies that suggest that simian virus 40 (SV40) may act as a cofactor in the development of mesothelioma.

Records have shown that asbestos was known in antiquity, but it was not mined and widely used commercially until the late 1800s. It was greatly used during the World War II. Since the early 1940s, millions of workers have been exposed to asbestos dust. At first, the risks associated with asbestos exposure were not known publicly. However, a high risk of developing mesothelioma was later observed among people who work in asbestos mines and mills, shipyard workers, workers in the heating and construction industries, producers of asbestos products, and other trades people.

The duration of exposure to asbestos causing mesothelioma may be short. For instance, cases of mesothelioma have been documented with only one to three months of exposure.  It is advisable to wear personal protective equipment to lower their risk of exposure. Latency, the time from first exposure to manifestation of disease, is prolonged in the case of mesothelioma. It is virtually never less than 15 years and peaks at 30–40 years or even more. According to a review, the instances of occupationally related mesothelioma cases, the median latency were 32 years.

Some of The Types of Exposure to Asbestos are:
Occupational Exposure
Since the early 1900s, exposure to asbestos fibers has been known to be an occupational health hazard. There have been various epidemiological studies which associate occupational exposure to asbestos with the development of diffuse pleural thickening, pleural plaques, carcinoma of the lung and larynx, asbestosis, peritoneum, diffuse malignant mesothelioma of the pleura and gastrointestinal tumors. Asbestos has been widely used in several industrial products such as insulation, cement, gaskets, brake linings, roof shingles, textiles and flooring products.

Paraoccupational Secondary Exposure
Family members and others who live with asbestos workers have a high risk of developing mesothelioma, and possibly other related diseases. This very risk may be due to exposure to asbestos dust unknowingly brought home on the hair and clothing of asbestos workers. To reduce the risks of exposing family members and others to asbestos fibers, asbestos workers are advised to always shower and change their clothing before they leave their workplace.

Environmental Exposures
Incidence of mesothelioma was found to be higher in people living near naturally occurring asbestos. For instance, in central Cappadocia, a place in Turkey, mesothelioma was causing about 50% of all deaths in three small villages which are Sarıhıdır, Karain and Tuzköy. At first, this was attributed to erionite, this is a zeolite mineral with similar properties to asbestos. However, a newly detailed epidemiological investigation proved that erionite causes mesothelioma mostly in families with a genetic predisposition. There is a documented presence of asbestos fibers in food products and water supply has fostered concerns about the possible impact of long term and, as yet unknown exposure of the general population to these fibers.

Asbestos in Buildings
There is a number of building materials used in both public and domestic premises prior to the banning of asbestos may contain asbestos. Also, those performing renovation works or Do It Yourself activities may expose themselves to asbestos dust.