Incidence and mortality for respiratory cancer and traffic-related air pollution in Sao Paulo, Brazil

Background: Multiple lines of evidence have associated exposure to ambient air pollution with an increased risk of respiratory malignancies. However, there is a dearth of evidence from low-middle income countries, including those within South America, where the social inequalities are more marked. Objectives: To quantify the association between exposures to traffic related air pollution and respiratory cancer incidence and mortality within Sao Paulo, Brazil. Further, we aim to investigate the role of socioeconomic status (SES) upon these outcomes. Methods: Cancer incidence between 2002 and 2011 was derived from the population-based cancer registry. Mortality data (between 2002 and 2013) was derived from the Municipal Health Department. A traffic density database and an annual nitrogen dioxide (NO2) land use regression model were used as markers of exposure. Age-adjusted Binomial Negative Regression models were developed, stratifying by SES and gender. Results: We observed an increased rate of respiratory cancer incidence and mortality in association with increased traffic density and NO2 concentrations, which was higher among those regions with the lowest SES. For cancer mortality and traffic exposure, those in the most deprived region, had an incidence rate ratio (IRR) of 2.19 (95% CI: 1.70, 2.82) when comparing the highest exposure centile (top 90%) to the lowest (lowest 25%). By contrast, in the least deprived area, the IRR for the same exposure contrast was.1.07 (95% CI: 0.95, 1.20). For NO2 in the most deprived regions, the IRR for cancer mortality in the highest exposed group was 1.44 (95% CI: 1.10, 1.88) while in the least deprived area, the IRR for the highest exposed group was 1.11 (95% CI: 1.01, 1.23). Conclusions: Traffic density and NO2 were associated with an increased rate of respiratory cancer incidence and mortality in Sao Paulo. Residents from poor regions may suffer more from the impact of traffic air pollution.