A recent study conducted in Japan with the intent of assessing the risk of developing an asbestos-related disease, such as mesothelioma, from general environmental exposure to asbestos, suggests that even incidental exposure to low levels of the carcinogen can be potentially harmful.

Mesothelioma is a cancer which is usually associated with high levels of occupational asbestos exposure. Yet there has been some evidence of people developing this disease, as well as others such as asbestosis and asbestos-related lung cancer, after only low levels of ambient asbestos exposure. In sites such as Libby, Montana, where asbestos-contaminated vermiculite was mined for years, the rate of mesothelioma cases even in non-asbestos workers is high. Furthermore, the Japanese study looked at one area in France, where cumulative asbestos exposure at levels lower than in many other countries nevertheless led to an above average rate of mesothelioma.

The researchers concluded that general exposure to asbestos from the environment may have contributed to a higher number of mesothelioma diagnoses than previously believed. In fact, the data collected by the study’s authors suggests that of 100,000 mesothelioma deaths that are predicted to occur in Japan between 2000 and 2039, as many as 30,000 of those may result from general environmental exposure to asbestos.

General environmental asbestos exposure can occur either in areas where asbestos or asbestiform minerals are mined, or where asbestos-containing materials have been used in building and construction. Previously aggregated data in Japan showed that urban dwellers who did not have any occupational contact with asbestos still had asbestos fibers within their lungs, further supporting the hypothesis that ambient exposure can be hazardous.

Mesothelioma affects the thin membrane which both surrounds the lungs, heart and stomach, and lines the inside of the chest and stomach cavities. It kills approximately 20,000 people across the world each year.

(Asbestos.net, 19/02/2010)