Environmental pollution, racial segregation, and lung cancer incidence

There are wide racial disparities in lung cancer incidence, treatment, and outcomes. Previous studies have shown the impact of structural racism and the built environment on lung cancer outcomes in Black communities. The current study sought to understand the mediation of airborne pollutants between racial segregation and lung cancer incidence in the United States. Lung cancer incidence data for Black/white populations from 2014 to 2018 were obtained from the CDC. We assessed the impact of segregation on lung cancer incidence and the mediating effects of pollutants SO₂, NO₂, PM_2.5, O₃, and CO in the pathway. We estimated the indirect effect of each pollutant on the interaction between segregation and cancer outcomes. We found that segregation was associated with an 11% increase in lung cancer incidence among Black individuals (IRR 1.11, 95%CI 1.08,1.14) and a 7% increase in white lung cancer incidence (IRR 1.07, 95%CI 1.05,1.09). For Black lung cancer rates, this effect was mediated by SO₂/ NO₂ (23%), PM_2.5 (9.2%), and smoking (36%). For white lung cancer rate, the effect was mediated through SO₂/ NO₂ (25%), PM_2.5 (15%), O₃/CO (4%), and smoking (37.4%). Air pollution is an important mediating factor on lung cancer incidence in more segregated areas, suggesting that the increased pollution in more segregated areas likely also affects white residents, leading to higher levels of lung cancer compared to their counterparts in less segregated areas. Policies targeting polluting sources in segregated areas will be important in reducing lung cancer incidence and disparities therein.