ASTHMA AND LUNG-CANCER BY DIESEL EXHAUST

Recently, diesel engine powered cars has been increasing steadily in Japan, because diesel engine is powerful and the fuel is less expensive. Diesel exhausts emit some 2 to 20 times more nitrogen dioxide and some 30 to 100 times more particles than do gasoline engine cars. The exhausts are main cause of air pollutants in urban area, and people are anxious about that the exhausts may cause lung diseases such as asthma and lung cancers. There are clinical and epidemiological studies on relationship between asthma and diesel exhausts. However, it is not yet confirmed with experimental study. Here, I will introduce recent experimental data that essential features of asthma such as chronic inflammation with eosinophil-infiltration, mucus hypersecretion and airway hyperresponsiveness has been caused by diesel exhaust particles, and that the active oxygens generated from diesel exhaust particles may play an important role to cause asthmatic symptoms. The other hand, it is well established that diesel exhausts can cause lung tumors experimentally using F-344 rats. In this case, it is considered that carcinogens contained in benzene extract-fraction of the diesel exhaust particles are important. However, it has been found that diesel exhaust particles washed out sufficiently with organic solvent can also cause lung tumors. Therefore, the significance of carcinogens in diesel exhaust particles on the actual carcinogenesis is also introduced.