Risk of death from bladder cancer in relation to long-term exposure to fine particulate air pollution in Taiwan

The International Agency for Research on Cancer (IARC) has classified fine particulate matter (PM2.5) from outdoor air pollution as carcinogenic to humans. However, few studies have examined the association between residential ambient PM2.5 exposure with the occurrence of bladder cancer (BC). It is noteworthy that available findings remain inconclusive. Several Taiwanese investigators reported a significant positive association between long-term exposure to PM2.5 and various non-lung cancers. Building upon this evidence, the aim of the present study was to examine the relationship between long-term exposure to ambient PM2.5 and BC-attributed mortality across 66 municipal areas in Taiwan. Annual PM2.5 concentrations were compared with age-standardized BC mortality rates among male and female residents from 2012 to 2023. Municipal annual PM2.5 levels were categorized into tertiles, and adjusted risk ratio (RRs) were estimated using multiple-regression models controlling for the following factors: municipal lung cancer mortality, urbanization level, annual household income, and physician density. Among men, adjusted RRs for municipalities in the intermediate (19.34–25.11 ug/m3) and the highest PM2.5 tertiles (25.12–30.82 ug/m3) were 1.07 (95% CI = 0.98–1.18) and 1.31 (95% CI = 1.19–1.44), respectively, compared with those in the lowest tertile. Among women, corresponding adjusted RRs were 1.05 (95% CI = 0.91–1.21) and 1.29 (95% CI = 1.12–1.48). These findings indicate that long-term exposure to elevated ambient PM2.5 concentrations may increase the risk of mortality attributed to BC among both men and women in Taiwan.