Polluted Urban Air and Related Environmental Factors in the Pathogenesis of Pulmonary Cancer

¹ National Cancer Institute, National Institutes of Health

Data from several spheres of laboratory investigation lend support to the belief that the epidemiologic association between urban residence and lung cancer is of pathogenetic significance. Admittedly, the identification of carcinogenic agents in pollutant sources and in the atmosphere does not inevitably connote an adverse biologic effect. Nevertheless, despite significant omissions in our data and despite the limitations imposed by the absence of or deficiencies in certain analytic and biologic techniques, our chemical, physical, and biologic data unite to form a constellation that strongly implicates the atmosphere as one dominant factor in the pathogenesis of lung cancer. The data are accorded additional significance by virtue of their congruity with the epidemiologic pattern of lung cancer.

Epidemiologically, a reduction in lung cancer incidence may be properly anticipated as a result of reducing or eliminating the concentration of any of the environmental factors discussed. It is our belief, however, that predictions as to the extent of reduction when but one of the factors is eliminated are meaningless in light of the multiplicity of factors described. It is wholly unwarranted to anticipate a quantitative reduction in lung cancer rates equal in number to the percentage showing a statistical association with any environmental source or specific carcinogenic agent. While atmospheric pollution is advanced as but one potential source of agents carcinogenic to the lung, proper evaluation of its contribution to the pathogenesis of lung cancer will be possible only in terms of its relation to the action of other significant environmental sources.