Exposure to Ambient Air Pollution and the Risk of Inflammatory Bowel Disease: A European Nested Case-Control Study.

Abstract

Background Industrialization has been linked to the etiology of inflammatory bowel disease (IBD).AimWe investigated the association between air pollution exposure and IBD.MethodsThe European Prospective Investigation into Cancer and Nutrition cohort was used to identify cases with Crohn’s disease (CD) (n = 38) and ulcerative colitis (UC) (n = 104) and controls (n = 568) from Denmark, France, the Netherlands, and the UK, matched for center, gender, age, and date of recruitment. Air pollution data were obtained from the European Study of Cohorts for Air Pollution Effects. Residential exposure was assessed with land-use regression models for particulate matter with diameters of <10 μm (PM10), <2.5 μm (PM2.5), and between 2.5 and 10 μm (PMcoarse), soot (PM2.5 absorbance), nitrogen oxides, and two traffic indicators. Conditional logistic regression analyses were performed to calculate odds ratios (ORs) with 95 % confidence intervals (CIs).ResultsAlthough air pollution was not significantly associated with CD or UC separately, the associations were mostly similar. Individuals with IBD were less likely to have higher exposure levels of PM2.5 and PM10, with ORs of 0.24 (95 % CI 0.07–0.81) per 5 μg/m3 and 0.25 (95 % CI 0.08–0.78) per 10 μg/m3, respectively. There was an inverse but nonsignificant association for PMcoarse. A higher nearby traffic load was positively associated with IBD [OR 1.60 (95 % CI 1.04–2.46) per 4,000,000 motor vehicles × m per day]. Other air pollutants were positively but not significantly associated with IBD.ConclusionExposure to air pollution was not found to be consistently associated with IBD.Electronic supplementary materialThe online version of this article (doi:10.1007/s10620-016-4249-4) contains supplementary material, which is available to authorized users.