Indoor radon concentration and risk and severity of inflammatory bowel diseases: a case-control study.

BACKGROUND

Inflammatory bowel disease (IBD) develops from a dysregulated immune response influenced by environmental exposures. Radon, a radioactive gas, has known biological effects, but its role in IBD remains unexplored.

OBJECTIVES

To examine the association between residential radon exposure and the risk and clinical course of IBD.

DESIGN

A case-control study with 1-year prospective follow-up of cases.

METHODS

We included 178 newly diagnosed IBD patients and 178 age- and sex-matched controls in Santiago de Compostela, Spain, from June 2020 to September 2023. Residential radon levels were measured using passive detectors for 3 months. Outcomes included IBD diagnosis, disease extent, hospitalizations, and flares. Logistic regression was used to estimate odds ratios adjusted for age and sex.

RESULTS

Median residential radon was 144.5 Bq/m in IBD cases and 189.5 Bq/m in controls. Higher radon levels were associated with reduced odds of IBD (OR 0.5 for 100-299 and >299 Bq/m vs 0-99 Bq/m). No significant association was found between radon levels and hospitalizations or flares. Among ulcerative colitis patients, higher radon was linked to more extensive disease.

CONCLUSION

Higher residential radon exposure might be inversely associated with IBD risk. However, it does not appear to influence disease progression. Further studies are needed to confirm these findings, since this is the first study on this topic, and chance or selection bias might be present.