Ambient NO2 Exposure and Respiratory Cancer Risk in São Paulo, Brazil

Abstract

The International Agency for Research on Cancer (IARC) has classified outdoor air pollution as carcinogenic to humans (Group 1). This evidence has been based on predominantly studies from the global North. However, there is a dearth of evidence from low-middle income countries, including those within South America. We studied the association between exposure to ambient air pollution and mortality of respiratory cancers in the city of São Paulo, Brazil. Mortality data (between 2002 and 2013) for all individuals above the age of 20 years was derived from the Municipal Department of Health. Outcomes of interest were coded by the International Classification of Diseases (ICD-10). A total of 19,500 deaths attributable to respiratory cancers (12,826 in men, 6,674 in women) were geocoded by residential zip code. Annual estimates of NO2 (between 1997 and 2011) were obtained from the global NO2 land use regression model. Study population was divided in five exposure groups based on centiles of exposure: 0-25, 26-50, 51-75, 76-90 and > 90. Age-adjusted Binomial Negative Regression models were developed, stratifying by deprivation index and gender. We observed an increased risk of respiratory mortality in association with increased NO2 concentrations. The IRRs for all individuals ranged from 1.10 (95% CI 1.03-1.18), in the lower exposed group, to 1.30 (95% CI 1.20-1.41) in the highest exposed group. The IRRs among men ranged from 1.07 (95% CI 0.98-1.16) to 1.26 (95% CI 1.14-1.39) and women ranged from 1.16 (95% CI 1.04-1.30) to 1.36 (95% CI 1.20-1.55). Our results showed that exposure to ambient NO2 were associated with an increased risk of mortality of respiratory cancers in the city of São Paulo. These results strengthen the observation on air pollution and lung cancer risk by extending the evidence base to South-America aiding to a more refined estimate of the Global Burden of Disease of air pollution to health.