Particulate matter exposure may increase the risk of irritable bowel syndrome: a large-scale prospective study based on the UK Biobank

Background: irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders and considerably contributes to the global disease burden. Ambient air pollution, especially particulate matter (PM), could be a risk factor for IBS. However, limited evidence has linked PM exposure to IBS. Methods: we conducted a large-scale prospective cohort study based on the UK Biobank. The annual average concentrations of PM₁₀, PM_2.5-10, and PM_2.5 were obtained from the ESCAPE study using the land-use regression (LUR) model. The Cox proportional hazard model was used to calculate hazard ratios (HRs) at 95% confidence intervals (95% CIs) of PM with IBS incidence. We further explored the exposure-response relationship curve and performed several stratified analyses based on sex, age, BMI, and other factors. Results: during a follow-up period of 13.7 years, 5796 individuals diagnosed with IBS were identified. We estimated that the HRs of IBS associated with a 10 μg m⁻³ increase in PM₁₀, PM_2.5-10, and PM_2.5 were 1.14 (95% CI: 1.01, 1.29), 1.16 (95% CI: 0.90, 1.50), and 1.33 (95% CI: 1.04, 1.68), respectively. We estimated an almost linear exposure-response relationship between PM₁₀ and PM_2.5 exposure and IBS. Individuals under 60 years old were more vulnerable to PM exposure. Conclusions: our study provided robust evidence on the association between long-term PM₁₀ and PM_2.5 exposure and IBS; and the impact of PM_2.5 was higher than that of PM₁₀. We further suggest restricting the ambient PM standards to reduce the impact of PM exposure on IBS.