Found naturally all over the world, asbestos was heavily mined and used in thousands of products throughout the 20th century. A number of industries, such as the construction, shipyard and automotive industries, are particularly known as hotspots for occupational asbestos exposure. Workers from these industries are known to be at risk for asbestos-related disease because it usually takes repeated exposure to substantial amounts of asbestos to cause disease later in life. The most common asbestos-related diseases include asbestosis, lung cancer and malignant mesothelioma.
Researchers report that “Peak use of asbestos occurred around 1977, when about 25 countries were producing approximately 4.8 million metric tons per year, and about 85 countries were manufacturing asbestos products. Europe and the United States were the largest users of asbestos during the first two-thirds of the 20th century.” Because of the latency period associated with asbestos-related disease, incidence of these conditions is expected to peak over the next decade.
The authors of the study note that “Although asbestos has been widely distributed in the environment, health risks due to general environmental exposure to asbestos have not be estimated. Future mesothelioma risk from environmental exposure to asbestos in Japan was estimated by comparing historical exposure data and morality attributed to environmental exposure.” General environmental asbestos exposure occurs in areas where asbestos has been used, such as in urban settings where many buildings, homes and streets contain levels of asbestos fibers in the ambient air.
A challenge was faced in obtaining data because there is little evidence that ambient asbestos exposure can cause mesothelioma. Researchers commented, “General environmental exposure has also been investigated, although little evidence is available on mesothelioma that occurs as a direct consequence of general environmental exposure to asbestos. However, there is no evidence of a threshold level below which the risk of mesothelioma disappears. A significant excess of rate of mesothelioma has been observed in France for cumulative asbestos exposure levels that were probably far below the limits adopted in most industrialized countries. It is suggested that mesothelioma might occur due to exposure to low level of asbestos in the general environment.”
Previously collected data proved that citizens throughout urban areas of Japan did harbor asbestos fibers in their lungs, thus supporting that general environmental asbestos exposure does result in the accumulation of asbestos fibers (which has been established in a number of studies throughout the globe). Upon analyzing the data from multiple sources, the researchers found that general environmental asbestos exposure may be responsible for more mesothelioma cases than previously thought.
Estimates for future mesotheliomas caused by both occupational and non-occupational asbestos exposure predict 100,000 deaths in Japan between 2000 and 2039. Results from the data for general environmental exposure predict that out of those 100,000 deaths, anywhere between 13,000 and 30,000 would be the result of general environmental exposure.
Researchers stated, “In conclusion, limited available estimates reveal past and future trends for mesothelioma risk due to general environmental exposure to asbestos in Japan. Results might suggest the need for social and medical support for general populations. These findings may be of considerable interest to other countries that have used asbestos in the past.”
Additional information about mesothelioma and asbestos exposure may be found through the Mesothelioma Center.