Radon exposure and potential health effects other than lung cancer: a systematic review and meta-analysis

Abstract

Context and objective: To date, lung cancer is the only well-established health effect associated with radon exposure in humans. To summarize available evidence on other potential health effects of radon exposure, we performed a comprehensive qualitative and quantitative synthesis of the available literature on radon exposure and health effects other than lung cancer, in both occupational and general populations.

Method: Eligible studies published from January 1990 to March 2023, in English and French languages, were identified in PubMed, ScienceDirect, Scopus, ScieLo and HAL. In the meta-analysis, we estimated average weighted standardized incidence ratios (metaSIR), standardized mortality ratios (metaSMR), and risk ratio (metaRR) per 100 unit (Bq/m³ or Working level Month) increase in radon exposure concentration by combining estimates from the eligible studies using the random-effect inverse variance method. DerSimonian & Laird estimator was used to estimate the between-study variance. For each health outcome, analyses were performed separately for mine workers, children, and adults in the general population.

Results: A total of 129 studies were included in the systematic review and 40 distinct studies in the meta-analysis. For most of these health outcomes, the results of the meta-analyses showed no statistically significant association, and heterogeneity was only present among occupational studies, especially between those included in the metaSIR or metaSMR analyses. However, the estimated exposure-risk associations were positive and close to the statistical significance threshold for: lymphohematological cancer incidence in children (metaRR = 1.01; 95%CI: 1.00-1.03; p = 0.08); malignant melanoma mortality among adults in the general population (metaRR = 1.10; 95%CI: 0.99-1.21; p = 0.07); liver cancer mortality among mine workers (metaRR = 1.04; 95%CI: 1.00-1.10; p = 0.06); intestine and rectal cancer mortality combined among mine workers (metaRR = 1.02; 95%CI: 1.00-1.04; p = 0.06).

Conclusion: Although none of the exposure-risk associations estimated in the meta-analyses reached statistical significance, the hypothesis that radon may have other health effects apart from lung cancer could not be ruled-out and call for additional research. Larger and well-designed studies are needed to further investigate this question.

Systematic review registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023474542, ID: CRD42023474542.

Keywords: cancer; cardiovascular disease; meta-analysis; neurodegenerative disease; non-malignant disease; occupational exposure; radon; residential exposure.

Figure 1

PRISMA flow diagram for the systematic review and meta-analysis.

Figure 2

Repartition of studies included in the systematic review and meta-analysis by exposure type and design. *“Two-design in one” studies: ecological study & case-control study; Ecological study & case-only study; Ecological study & cohort study.