Long-term fine particulate air pollution exposure and risk of gastric cancer mortality in Taiwan

Although long-term exposure to fine particulate matter (PM_2.5) has been linked to lung cancer, its association with non-lung cancers remains underexplored. The aim of this study was to examine the association between PM_2.5 exposure and development of gastric cancer (GC), which ranks as the eighth leading cause of cancer-related deaths in Taiwanese men and sixth in women. The mortality rates of GC vary considerably across townships in Taiwan, suggesting potential environmental influence. Thus, whether there was an association between long-term exposure to PM_2.5 and deaths attributed to GC was investigated across 66 municipalities in Taiwan. To determine this relationship, age-standardized GC mortality data were collected for the years 2012-2021 and correlated with PM_2.5 levels divided into tertiles. Adjusted risk ratio (RR) attributed to GC death was calculated by multiple regression analyses. For men, adjusted RRs were 1.04 (95% CI = 0.97-1.11) and 0.89 (95% CI = 0.82-0.95) in municipalities in the middle tertile (18.96-25.19 μg/m³) and highest (25.2-29.46 μg/m³), respectively, compared to the lowest (9.44-18.95 μg/m³). For women, the corresponding adjusted RRs were 1.04 (95% CI = 0.94-1.13) and 0.85 (95% CI = 0.77-0.94), respectively. Surprisingly, trend analyses noted a significant inverse association between PM_2.5 levels and GC-related mortality in both men and women. This counterintuitive finding may be a chance finding. Further investigation is needed to study the possible adverse effects of long-term exposure to PM_2.5 on GC-associated mortality.