Is There an Association Between Ambient Air Pollution and Bladder Cancer Incidence? Analysis of 15 European Cohorts

Abstract Background Ambient air pollution contains low concentrations of carcinogens implicated in the etiology of urinary bladder cancer (BC). Little is known about whether exposure to air pollution influences BC in the general population. Objective To evaluate the association between long-term exposure to ambient air pollution and BC incidence. Design, setting, and participants We obtained data from 15 population-based cohorts enrolled between 1985 and 2005 in eight European countries ( N =303431; mean follow-up 14.1 yr). We estimated exposure to nitrogen oxides (NO 2 and NO x ), particulate matter (PM) with diameter 10 ), 2.5 ), between 2.5 and 10μm (PM 2.5–10 ), PM 2.5 absorbance (soot), elemental constituents of PM, organic carbon, and traffic density at baseline home addresses using standardized land-use regression models from the European Study of Cohorts for Air Pollution Effects project. Outcome measurements and statistical analysis We used Cox proportional-hazards models with adjustment for potential confounders for cohort-specific analyses and meta-analyses to estimate summary hazard ratios (HRs) for BC incidence. Results and limitations During follow-up, 943 incident BC cases were diagnosed. In the meta-analysis, none of the exposures were associated with BC risk. The summary HRs associated with a 10-μg/m 3 increase in NO 2 and 5-μg/m 3 increase in PM 2.5 were 0.98 (95% confidence interval [CI] 0.89–1.08) and 0.86 (95% CI 0.63–1.18), respectively. Limitations include the lack of information about lifetime exposure. Conclusions There was no evidence of an association between exposure to outdoor air pollution levels at place of residence and risk of BC. Patient summary We assessed the link between outdoor air pollution at place of residence and bladder cancer using the largest study population to date and extensive assessment of exposure and comprehensive data on personal risk factors such as smoking. We found no association between the levels of outdoor air pollution at place of residence and bladder cancer risk.