Association between long-term exposure to fine particulate air pollution and risk of death attributed to esophageal cancer in Taiwan

The International Agency for Research on Cancer (IARC) classifies exposure to fine particulate matter (PM_2.5) air pollution as carcinogenic to humans (Group I), most frequently associated with lung cancer. Airborne air pollutants may be associated with other sites of cancer, although few studies have examined this avenue of research. Esophageal cancer mortality rates vary substantially across townships in Taiwan, a fact that suggests environment influence. Therefore, the aim of this study was to investigate the association between long-term exposure to ambient PM_2.5 and deaths attributed to esophageal cancer in 66 municipal areas across Taiwan. To conduct this study, annual PM_2.5 levels were determined taking into account age-standardized esophageal cancer mortality rates in male and female residents of these municipalities from 2012 to 2021. The annual PM_2.5 levels of each municipality were divided into tertiles and computed adjusted risk ratio (RR) using weighted-multiple regression analyses controlling for municipal lung cancer deaths, urbanization level, and physician density. Men residing in those areas with intermediate PM_2.5 tertile levels (18.96-25.19 ug/m³) were found to have an adjusted RR of 1.22 (1.15-1.30) and those of residing areas with the highest tertiles levels (25.20-29.48 ug/m³) exhibited an RR of 1.11 (1.051.18). However, in women in the same municipalities, a significant inverse association was found between PM_2.5 levels and mortality attributed to esophageal cancer, 0.82 (95% CI = 0.65-1.04) and 0.61 (95% CI = 0.47-0.79), respectively. These findings suggest that long-term exposure to PM_2.5 increases the risk of developing esophageal cancer in men in Taiwan.