Abstract Background Inflammatory bowel disease (IBD), comprising Crohn’s disease (CD) and ulcerative colitis (UC), has shown a rising incidence worldwide, particularly in rapidly urbanizing regions. While genetic susceptibility contributes to disease pathogenesis, the sharp increase in IBD incidence highlights a predominant role of environmental factors. As one of the major environmental factors, pollution has been implicated in the pathogenesis of IBD through mechanisms involving immune dysregulation and disruption of the intestinal barrier. However, large-scale prospective evidence capturing the effects of a comprehensive range of pollutants remains limited. Methods We used data from the UK Biobank and estimated individual level pollutant exposures according to participants’ residential addresses (Figure 1A). Pollution datasets included air, soil and water pollutants from national monitoring programs in the United Kingdom and Europe, together with night-time light exposure derived from satellite observations. To comprehensively evaluate the effects of pollution, we included 34 pollutants across diverse environmental media, which were broadly grouped into eight categories based on their physicochemical characteristics (Figure 1B). Cox proportional hazards regression models were then applied to evaluate the associations between pollutant exposure levels and incident IBD. Results A total of 39 out of 51 pollutant indicators were significantly positively associated with IBD risk (Figure 2). Significant associations were observed for 37 pollutant indicators with UC risk, which was higher than the 18 associated with CD risk. For air pollutants, the greatest increases in IBD risk were observed for NO2 (HR per SD = 1.09, 95% CI: 1.06-1.13, P 0.001) and NOx (HR per SD = 1.09, 95% CI: 1.05-1.12, P 0.001) based on outdoor ambient levels, while Cd (HR per SD = 1.08, 95% CI: 1.05-1.11, P 0.001) and polychlorinated biphenyls (HR per SD = 1.08, 95% CI: 1.05-1.12, P 0.001) showed the largest risk increases when assessed by emission levels. For water pollutants, heavy metals, especially Cd (HR per SD = 1.30, 95% CI: 1.19-1.41, P 0.001) and Hg (HR per SD = 1.24, 95% CI: 1.15-1.33, P 0.001), were associated with substantially higher IBD risks than those in air or soil. Conclusion A broad range of pollutants were associated with increased IBD risk, with more pollutant indicators reaching significance for UC than for CD. Among all pollutants, Cd and Hg originating from water exhibited the greatest risk of IBD. These findings underscore the importance of environmental pollution monitoring, particularly waterborne heavy metals such as Cd and Hg, for guiding preventive strategies. Conflict of interest: Dan, Lintao: I have no COI related to submitted program Guo, Yang: I have no conflicts of interest to declare. Chen, Xuejie: No conflict of interest Deng, Minzi: No conflict of interest Dr. Chen, Jie: No conflict of interest Wang, Xiaoyan: I have no conflict of interest to disclosure.
Dan et al. (Thu,) studied this question.