Air pollution and lung cancer.

Epidemiological evidence proves conclusively that lung cancer correlates with air pollution. However, data on lung cancer death rates and smoking show that mankind accepts the risk of long-term and low-level exposure to carcinogens. As a rule, immediate benefits are sought and remote hazards ignored. Fear of atmospheric contamination by radioactive fallout seems to be the main factor for awareness of air pollution. Experimental works help us to understand physics of particle deposition in the lungs (inertial impactation, sedimentation, Brownian movement), shed light on carcinogenesis (eg, bay region theory in case of polycyclic aromatic hydrocarbons and surface charge changes regarding asbestos), show that atmospheric particulates accepted as harmless may act as co-carcinogens (eg, iron and benzo(a)pyrene) and stress the importance of in vitro researches (bacterial mutation tests, organ cultures, sister chromatid exchange system) to screen pollutants for their malignant potential and study their pathogenesis.