An ecological analysis of associations between ambient air pollution and cancer incidence rates in Taiwan

Air pollution is deemed a human carcinogen and can be linked to certain types of cancer other than lung cancer. The present study aimed to investigate the pollutant-cancer associations in a population-level cohort. We obtained the annual age-standardized incidence rates of 28 different cancer types between 2015 to 2019 from the Taiwan Cancer Registry. Outdoor concentrations of particulate matter with a diameter of 10 μm or less (PM₁₀), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), ground-level ozone (O₃), and carbon monoxide (CO) between 2001 to 2010 were retrieved from the Taiwan Air Quality Monitoring Network. Weighted quantile sum (WQS) regression models were used to determine the combined effects of five air pollutants on the relationship to cancer incidence rates after controlling for sex ratio, age, average disposable income per household, overweight/obesity prevalence, current smoking rate, and drinking rate. Trend analyses showed that NO₂ and CO concentrations tended to decrease, while SO₂ concentrations increased in some counties. WQS regression analyses revealed significantly positive correlations between air pollutants and liver cancer, lung and tracheal cancer, colorectal cancer, thyroid cancer, kidney cancer, and small intestine cancer. Altogether, the results from this ecological study unravel that exposure to ambient air pollution is associated with the incidence of several non-lung cancer types.