Cell type specificity of female lung cancer associated with sulfur dioxide from air pollutants in Taiwan: An ecological study

BACKGROUND: Many studies have examined the association between air pollutants (including sulfur dioxide [SO(2)], carbon monoxide [CO], nitrogen dioxide [NO(2)], nitric oxide [NO], ozone [O(3)], and particulate matter < 10 μm [PM(10)]) and lung cancer. However, data from previous studies on pathological cell types were limited, especially for SO(2 )exposure. We aimed to explore the association between SO(2 )exposure from outdoor air pollutants and female lung cancer incidence by cell type specificity. METHODS: We conducted an ecological study and calculated annual average concentration of 6 air pollutants (SO(2), CO, NO(2), NO, O(3), and PM(10)) using data from Taiwan Environmental Protection Administration air quality monitoring stations. The Poisson regression models were used to evaluate the association between SO(2 )and age-standardized incidence rate of female lung cancer by two major pathological types (adenocarcinoma [AC] and squamous cell carcinoma [SCC]). In order to understand whether there is a dose-response relationship between SO(2 )and two major pathological types, we analyzed 4 levels of exposure based on quartiles of concentration of SO(2). RESULTS: The Poisson regression results showed that with the first quartile of SO(2 )concentration as the baseline, the relative risks for AC/SCC type cancer among females were 1.20 (95% confidence interval [CI], 1.04-1.37)/1.39 (95% CI, 0.96-2.01) for the second, 1.22 (95% CI, 1.04-1.43)/1.58 (95% CI, 1.06-2.37) for the third, and 1.27 (95% CI, 1.06-1.52)/1.80 (95% CI, 1.15-2.84) for the fourth quartile of SO(2 )concentration. The tests for trend were statistically significant for both AC and SCC at P = 0.0272 and 0.0145, respectively. CONCLUSION: The current study suggests that SO(2 )exposure as an air pollutant may increase female lung cancer incidence and the associations with female lung cancer is much stronger for SCC than for AC. The findings of this study warrant further investigation on the role of SO(2 )in the etiology of SCC.