Authored By:
Demoury C, Marquant F, Ielsch G, Goujon S, Debayle C, Faure L, Coste A, Laurent O, Guillevic J, Laurier D, Hémon D, Clavel JSummary:
This is a case-control study which investigated the link between exposure to ionising radiation from natural sources and childhood leukaemia. A total of 2,700 cases (diagnosed during the period 2002-2007) and 30,000 controls were included in the study. The exposure to radon, gamma, and total radiation were estimated using environmental exposure data, based on the child’s municipality at time of diagnosis. Overall, the study did not find any association between childhood leukaemia and exposure to natural background radiation, hence providing no support to the hypothesis that residential exposure to natural background radiation increases the risk of childhood leukaemia.
Published In:
Environ Health Perspect. 2017 Apr;125(4):714-720Commentary by ARPANSA:
This study by Demoury et al did not find an association between childhood leukaemia and exposure to natural background radiation, whereas two older studies by Kendall et al in Switzerland and Spycher et al in the UK both found an increased risk of childhood leukaemia at a dose of 1 millisievert per year over 10 years or so. It should be noted that the study by Demoury et al did not rule out a slight association with gamma radiation at the time of birth – which is in line with the findings in the Swiss and UK studies.
All of these three studies are well conducted and are large enough to provide a statistically significant result however differences in the methodology are likely accounting for the difference in results. The two biggest methodological issues in all three studies were (a) the assessment of exposure which was based on residence estimation and not individual dosimetry, and was estimated differently in all three and (b) all three studies used retrospective registry information.
Since all three studies used registry information, other lifestyle, genetic or environmental factors (requiring interview to be determined) were not accounted for. Nevertheless the registry information eliminates the potential for recall bias. Bias due to unknown confounding factors is very unlikely to explain the entire observed effect.
In conclusion, there is currently mixed results on whether background radiation is associated with childhood leukaemia and further research is needed in this area.
