Ecological association between residential natural background radiation exposure and the incidence rate of childhood central nervous system tumors in France, 2000–2012

Abstract

High-dose ionizing radiation is an established risk factor for childhood central nervous system tumors (CNST) but the role of low doses remains debated. In particular, there are few studies of natural background radiation (NBR, gamma radiation and radon) and childhood CNST, and their results are inconclusive. This study aimed to investigate the association between NBR exposure and childhood CNST in France, over the period 2000-2012, based on data from the French national registry of childhood cancers. 5,471 childhood CNST cases, and their municipality of residence at diagnosis, were recorded, and municipality NBR exposures were estimated by cockriging models, using NBR measurements and additional geographic data. The standardized incidence ratios (SIR) per unit variation of exposure were estimated with Poisson log-linear regression models. NBR exposures were considered at the time of diagnosis, and cumulatively from birth to diagnosis. In an exploratory analysis, the cumulative brain dose due to NBR was used. Overall, there was no significant association between NBR exposure and childhood CNST, but an association was suggested for pilocytic astrocytomas with NBR levels at diagnosis: SIR = 1.12 (1.00,1.25) per 50 nSv/h for gamma radiation, and SIR = 1.15 (1.01,1.32) per 100 Bq/m3 for radon). Upward trends for this subtype were also suggested with the cumulative exposures to gamma radiation and radon separately. The results for the total brain dose were similar to those for the cumulative exposure to gamma radiation. Adjustment for socio-demographic factors did not change the findings. Conclusions: Our study was based on high quality incidence data, large numbers of CNST cases, and validated models of assessment of NBR exposures. However, we could not disentangle the possible role of each type of radiation in the association with pilocytic astrocytomas, even though gamma radiation may be more implicated than radon, given its physical properties.

Brain cancer incidence rates and the presence of nuclear reactors in US states: a hypothesis-generating study

“…These variables were positively associated with brain cancer in our data but were not statistically significant. Similarly, in ecologic studies of brain cancer and residential radon levels, both positive ( Ruano-Ravina et al 2017 ) and null results ( Berlivet et al 2020 ) were reported at the municipality level in Spain and in France (respectively). A significant association between radon and brain cancer incidence was reported for a Danish cohort that used radon levels that were estimated based on housing and geologic characteristics ( Brauner et al 2013 ).…”

“…Additionally, the potential role of radionuclides in brain cancer etiology could be tested via molecular epidemiology. Tritium and uranium can be measured in blood and urine (Belloni et al 1983) as well as in solid tissues, including the brain (Hisamatsu et al 1992;Ujeno et al 1986). Thus, a case-control study of radionuclides in biological samples from individuals with and without brain cancer may be feasible.…”

Environmental/Occupational Exposure to Radon and Non-Pulmonary Neoplasm Risk: A Review of Epidemiologic Evidence

“…Again, in a Norway cohort of 712,674 children with a total of 864 cancer cases 427 of them related to the CNS, an elevated non-significant risk for cancer was observed [ 56 ]. An ecological study related to a cohort of 5471 children with CNS tumors demonstrated that there was no association between Rn exposure and childhood CNS tumors incidence (IRR: 1.07; CI: 0.95–1.20 per 100 Bq/m 3 ) [ 57 ]. Finally, the results of a review performed on 18 studies (8 on miners, 3 on the general population, and 7 on children) are inconclusive because the available studies are extremely heterogeneous in terms of design and populations [ 60 ].…”

Summary of Radiation Research Society Online 66th Annual Meeting, Symposium on “Epidemiology: Updates on epidemiological low dose studies,” including discussion

“…These have been reviewed by Mazzei-Abba et al (Mazzei-Abba et al 2020). Since that review further studies have been published by Berlivet et al (Berlivet et al 2020) and Nikkilä et al (Nikkilä et al 2020). Results from these studies have been mixed.…”