Systematic Review and Meta-Analysis of Inflammatory Biomarkers in Individuals Exposed to Radon

Background/Objectives: Radon is a significant carcinogen, particularly as a leading cause of lung cancer among non-smokers. While its carcinogenic effects are well documented, the relationship between radon exposure and inflammatory reactions remains underexplored. This systematic review investigates inflammatory biomarkers in individuals exposed to chronic radon exposure and conducts a meta-analysis on serum C-reactive protein (CRP) and tumor necrosis factor-alpha (TNF-α) levels. Methods: A systematic search was conducted in PubMed, Scopus, Web of Science, ScienceDirect, and Google Scholar using the keywords "radon" AND "inflammation biomarkers" following established guidelines. Studies reporting inflammatory biomarker levels in biological fluids of human participants exposed to residential or occupational radon were included. Statistical analyses, including pooled mean estimates, influence analysis, publication bias, and meta-regression, were performed in RStudio. Results: Ten studies involving 33,099 individuals met the inclusion criteria. Eight studies focused on residential radon exposure, and two examined occupational exposure among uranium miners. Inflammatory biomarkers were analyzed in serum, bronchoalveolar lavage fluid, and saliva. Among individuals exposed to high residential radon levels, serum CRP and TNF-α were the most frequently assessed biomarkers, with pooled mean levels of 2.11 mg/L (95% CI, 1.32-2.89) and 2.20 pg/mL (95% CI, 0.25-4.64), respectively. Conclusions: Serum CRP and TNF-α levels appear lower in adults with chronic radon exposure, suggesting potential anti-inflammatory effects despite radon's established carcinogenicity. Future longitudinal studies using standardized methods are crucial to elucidate the long-term health impacts of radon exposure.