Ambient Air Pollution and Bladder Cancer Incidence in 15 European Cohorts Within the ESCAPE Project.

Abstract

Background: Ambient air pollution includes a mix of carcinogens implicated in the etiology of urinary bladder cancer. Methods: We aimed to evaluate the association between long-term exposure to ambient air pollution and bladder cancer incidence. We obtained data from fifteen population-based cohorts with enrollment during 1985-2005 in eight European countries. Exposure to nitrogen oxides (NO2 and NOX), particulate matter (PM) with diameter of less than 10 μm (PM10), less than 2.5 μm (PM2.5), between 2.5 and 10 μm (PM2.5-10), PM2.5 absorbance, eight elemental constituents of PM and organic carbon at baseline home addresses were estimated using standardized land-use regression models from the ESCAPE project. We also investigated traffic density on the nearest road. We used Cox proportional-hazards models with adjustment for potential confounders for cohort-specific analyses and meta-analyses to estimate summary hazard ratios (HRs). Results: Out of 303,431 participants 943 primary bladder cancer cases were diagnosed during the follow-up (mean 14.1 years). In the meta-analysis, none of the exposures were associated with elevated HRs. The summary HRs associated with a 10-g/m3 increase in NO2 and 5-g/m3 increase in PM2.5 were 0.98 (95% confidence interval (CI): 0.89, 1.08) and 0.86 (95%CI: 0.63, 1.18), respectively. Strengths of our study relate to the long prospective follow-up of a large study population from a large geographic area with different air quality and the standardized, extensive exposure assessment, which enable us to assess fine-scale, address-specific, spatial variation in concentrations of a more comprehensive number of air pollutants than previous studies. Limitations include lack of information about lifetime exposure, time-activity patterns or personal measures of exposure. Conclusion: There was no evidence of an association between long-term exposure to ambient air pollution and bladder cancer incidence in this European prospective cohort study.