Risk of leukaemia or cancer in the central nervous system among children living in an area with high indoor radon concentrations: results from a cohort study in Norway

BACKGROUND: Over the past few years, there has been growing interest in assessing the relationship between exposure to radon at home and the risk of childhood cancer. Previous studies have produced conflicting results, probably because of limitations assessing radon exposure, too few cancer cases and poorly documented health statistics. METHODS: We used a cohort approach of 0–15-year-old children to examine whether residential radon exposure was associated with childhood leukaemia and cancer in the central nervous system in the Oslo region. The study was based on Norwegian population registers and identified cancer cases from The Cancer Registry of Norway. The residence of every child was geo-coded and assigned a radon exposure. RESULTS: In all, 712 674 children were followed from 1967 to 2009 from birth to date of cancer diagnosis, death, emigration or 15 years of age. A total of 864 cancer cases were identified, 437 children got leukaemia and 427 got cancer in the central nervous system. CONCLUSIONS OR INTERPRETATION: No association was found for childhood leukaemia. An elevated nonsignificant risk for cancer in the central nervous system was observed. This association should be interpreted with caution owing to the crude exposure assessment and possibilities of confounding.