[Environmental air pollutants and the risk of cancer].

The increased combustion of fossil fuels is one of the main reasons for the hazardous changes in the atmospheric composition. The sources of air pollution in urban areas include diesel motor vehicles, residential wood burning, and certain industrial processes. The types of air pollution include gases(eg, carbon monoxide, sulfur dioxide, nitrogen oxides, ozone)and suspended particulate matter(PM)such as PM2.5 and PM10 in diesel exhaust particles. PM2.5 refers to particles less than 2.5 micrometers in diameter. Long-term exposure to PM2.5 can increase the cardiovascular disease risk and lung cancer mortality. Although the role of PM2.5 in the etiology of lung cancer is not very clear, some researchers have shown evidence of increases in lung cancer mortality associated with exposure to PM2.5. Asbestos is also an important cause of cancer of the respiratory tract, particularly lung cancer and mesothelioma. The oncogenic hazards of asbestos fiber have been noted in cases of lowdose environmental exposure, as well in cases of high-dose occupational exposure. The use of asbestos has been strictly prohibited in Japan since 2006. However, large-scale natural disasters such as earthquakes, tsunamis, and typhoons can destroy many buildings and houses that were constructed before the ban on asbestos was initiated, thus resulting in the exposure of human beings to asbestos fibers. In the Cappadocian villages of Tuzkoy, Karain, and Sarihidir in Turkey, 50% of all deaths among villagers are caused by mesothelioma. This condition has been attributed to exposure to erionite, which is a type of fibrous zeolite mineral commonly found in this area of Turkey. However, pedigree studies of these villages showed that mesothelioma was prevalent in certain families but not in others, and that erionite exposure typically causes mesothelioma in those with a genetic predisposition to this disease. Recently, the germline BAP1 mutation was demonstrated in 2 different familial clusters of mesothelioma in the US.