IARC 60th Anniversary - 19-21 May 2026
Session : 20/05/26 - Posters
Domestic radiation and risk of childhood leukemia and brain tumors: An individual participant data meta-analysis of nationwide studies
ALIMAM W. 1, CHALKOU K. 2, ABUHAMED J. 1, AAMODT G. 3, GIUSSANI A. 4, HVIDTFELDT U. 5, KREIS C. 2, RAASCHOU-NIELSEN O. 5, SPIELMANN V. 4, AUVINEN A. 1, SPYCHER B. 2, BONAVENTURE A. 6, DIARRA T. 6, GOUJON S. 6, LAINE J. 2, OUGHTON D. 7
1 Health Sciences Unit, Faculty of Social Sciences, Tampere University, Tampere, Finland; 2 Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland; 3 Department of Public Health Sciences, Faculty of Landscape and Society, Norwegian University of Life Sciences, Ås, Norway; 4 Department of Medical and Occupational Radiation Protection, Federal Office for Radiation Protection, Oberschleißheim, Germany; 5 Danish Cancer Society Research Center, Copenhagen, Denmark; 6 Université Paris Cité and Université Sorbonne Paris Nord, Inserm, INRAE, Centre for Research in Epidemiology and Statistics, Obstetric, Perinatal and Paediatric Life Course Epidemiology (OPPaLE) team, Paris, ; 7 Centre of Environmental Radioactivity (CERAD), MINA, Norwegian University of Life Sciences, Ås, Norway, Norway
Background
Growing evidence indicates an excess cancer risk associated with ionizing radiation at doses <100 mGy, with heightened susceptibility in children. However, the contribution from exposure to natural sources such as background gamma radiation (BGR) and domestic radon remains inconclusive.
Objectives
As part of RadoNorm project, risks of childhood leukemia and central nervous system (CNS) tumors were investigated in relation to cumulative doses to the red bone marrow (RBM) and brain from BGR and radon.
Methods
A meta-analysis was conducted across six nationwide, register-based case-control studies from Denmark, Finland, France, Norway, and Switzerland. Cases of leukemia (N=5,943) and CNS tumors (N=3,625) diagnosed at <16 years were identified, with age-matched population controls (N=101,165 & N=76,723). Using residential histories and country-specific exposure models, indoor gamma dose rates and radon levels were predicted for all homes from birth to diagnosis. Novel dosimetric models estimated cumulative organ doses up to diagnosis using age-specific coefficients at fine age intervals. Odds ratios (ORs) and 95% confidence intervals (CIs) for cancer per 1mSv increase in organ dose were estimated using unconditional logistic regression and pooled using random-effects meta-analysis.
Results
Radon accounted for only a small share of the combined cumulative RBM (6–16%) and brain doses (2–5%) from radon and BGR. Combined organ doses were associated with increased risks of leukemia (OR: 1.02 per mSv; 95% CI: 1.00–1.04) and CNS tumors (ORs 1.02; 95% CI: 0.99–1.06). Associations were similar for organ doses from BGR, whereas radon estimates were subject to lage uncertainty. Findings were robust to country-specific counfounder adjustment and a range of sensitivity analyses
Conclusions/Implications
The findings indicate substantial excess relative risks associated with low-dose natural radiation, consistent with standard radiation risk models. Remaining uncertainty highlights the need for larger, well-harmonized studies and further efforts to improve exposure assessment.