Long-term ambient hydrocarbon exposure and incidence of urinary bladder cancer

Abstract

AbstractBackgroundParticulate matter and volatile organic compounds, including total hydrocarbons (THCs), are major ambient air pollutants. The primary nonmethane hydrocarbons (NMHCs) originate from vehicle emissions. Studies on the association between air pollution and urinary bladder cancer (UBC) have revealed contradictory results.ObjectivesThe present study investigated whether long-term exposure to ambient hydrocarbons increases UBC risk among people aged ≥20 years in Taiwan.MethodsLinkage dataset research with longitudinal design was conducted on 600,666 cancer-free individuals from 2000–2013; 12 airborne pollutants were determined. Several Cox models considering potential confounders were employed. The study outcomes were invasive or in situ UBC incidence over time. The targeted pollutant concentration was divided into three tertiles: T1/T2/T3.ResultsThe mean age of the individuals at risk was 42.8 (SD, 15.7), and 50.2% were men. The mean daily average over 10-years of airborne THC concentration was 2.24 ppm (SD, 0.14), and NMHC was 0.29 ppm (SD, 0.09). There was a dose-dependent increase in UBC at follow-up. The incidence of UBC cases per 100,000 people by T1/T2/T3 exposure to THC was 60.3, 203.7, and 450.8, respectively; it was 180.2/202.4/453.8 per 100,000, corresponding to T1/T2/T3 exposure to NMHC, respectively. Without controlling for confounding air pollutants, the adjusted hazard ratio (adj.HR) was 1.77 (95% CI, 1.69–1.87) per 0.14 ppm increase of THC; after controlling for PM2.5, adj.HR was even higher at 2.10 (95% CI, 1.99– 2.22). The adj.HR was 1.38 (95% CI, 1.31–1.44) per 0.09 ppm increase in ambient NMHC concentration. After controlling for SO2 and CH4, the adj.HR was 1.16 (95% CI, 1.11–1.21). Sensitivity analyses showed that the UBC development risk was not sex-specific or influenced by diabetes status.DiscussionLong-term exposure to THC and NMHC may be a risk factor for UBC development. Acknowledging the pollutant sources can inform risk management strategies.