A recent Japanese risk assessment found that the dangers to health of a general environmental exposure to asbestos, leading to mesothelioma, had not been taken into account.

By comparing historical exposure data attributed to environmental exposure, it was found that general environmental asbestos exposure occurs in industrial areas where asbestos had been used, especially urban environments which show many buildings, homes and streets contain levels of asbestos fibres present in the atmosphere.

A key difficulty with collating data was that little evidence is available that developing asbestosis symptoms occurs as a direct consequence of general environmental exposure to asbestos. Moreover, there is no evidence of a threshold level, below which the risk of contracting asbestos-related disease actually disappears.

Increasing asbestos awareness, which has led to the suggestion that asbestosis might result due to exposure to a low level of asbestos in the general environment,  has also given rise to questions being asked of the significant rates of mesothelioma observed in France for cumulative asbestos exposure levels, which were probably far below the limits adopted in most industrialised countries.

Analysing previously collected data from different areas, showed  that citizens throughout urban areas of Japan did contain traces of asbestos fibres in their lungs leading researchers to conclude that general environmental asbestos exposure may be responsible for more mesothelioma cases than previously thought.

Estimates for future asbestos-related disease caused by both occupational and non-occupational asbestos exposure, predicts 100,000 deaths in Japan between 2000 and 2039. Results from the data for general environmental exposure also indicate the probability that out of those 100,000 deaths, anywhere between 13,000 and 30,000 would be the result of general environmental exposure.

Researchers stated that the results might suggest the need for developing increased social and medical support, and circulation of asbestos advice for general populations.

In addition, the findings of the risk assessment may be of considerable interest to other countries that have produced asbestos in the past.