Particulate matter as a possible risk factor for eosinophilic esophagitis

Background Air pollution, including particulate matter smaller than 10 (PM 10 ) and 2.5 (PM 2.5 ) µm, increases the risk for heart and lung diseases, including asthma, but has not been extensively studied as a possible etiology in eosinophilic esophagitis (EoE). We aimed to estimate the associations between exposure to PM 2.5 or PM 10 and EoE. Methods In this case-control study, using a large national pathology database of esophageal biopsies, EoE cases were defined by having biopsies with ≥15 eosinophils per high-powered field in the absence of other histopathologic causes. Controls were all other patients with esophageal biopsies. Patient residential addresses were geocoded and exposure to PM 2.5 and PM 10 were estimated using National Emissions Inventory data at the county level for a 5-year period including the biopsy. We estimated the odds ratios (OR) for EoE as a function of PM 2.5 or PM 10 exposure in tons emitted per year air using mixed logistic regression models adjusted for individual- and census tract-level characteristics. Results Among 12,062 EoE cases and 229,397 non-EoE controls, the unadjusted OR for PM 2.5 was 1.12 (0.99–1.25) and the adjusted OR was 1.10 (95% CI, 0.99–1.23). The unadjusted OR for PM 10 was 1.04 (1.00–1.07) and the adjusted odds ratio was 1.02 (95% CI, 0.99–1.06). Discussion Exposure to higher levels of PM 25 and PM 10 was modestly associated with EoE case status but the association was attenuated by adjusting for potential confounders. The findings suggest any etiologic role for these particulates in EoE would be of small magnitude.