Background gamma radiation and childhood cancer in Germany: an ecological study
The relationship of low-dose background gamma radiation and childhood leukaemia was investigated in a number of studies. Results from these studies are inconclusive. Therefore, in the present study 25 years of German childhood cancer data were analyzed using interpolated background annual gamma dose rate per community in an ecological study. The main question was leukaemia; as exploratory questions we investigate central nervous system (CNS) tumours, thyroid carcinomas and diagnoses less likely to be related to radiation. A Poisson regression model was applied and a fractional polynomial model building procedure. As the main sensitivity analysis a community deprivation index was included as a potential confounder. It was found that outdoor background gamma annual dose rates in Germany range roughly from 0.5–1.5 mSv/a with an average of 0.817 mSv/a. No association of annual ambient gamma dose rates with leukaemia incidence was found. Amongst the exploratory analyses, a strong association was found with CNS tumour incidence [rate ratio for 1.5 vs 0.5 mSv/a: 1.35; 95% confidence interval (1.17, 1.57)]. The community level deprivation index was not a confounder. It is concluded that the present study did not confirm an association of annual outdoor ambient gamma dose rate and childhood leukaemia, corresponding to some studies and contrasting others. An association with CNS incidence was found in the exploratory analyses. As this is an ecological study no causal interpretation is possible.
KeywordsChild Neoplasm Background radiation Gamma radiation Ecological study Leukaemia Central nervous system tumours (CNS)
The authors thank Dr. Werner Maier, MPH, EMPH, Dipl.-Geogr., Institute of Health Economics and Health Care Management, Helmholtz Zentrum München—German Research Center for Environmental Health (GmbH), Neuherberg, Germany, for providing the data of the German Index of Multiple Deprivation (GIMD). Thanks also to Mr. Thomas Ziegler for the preparation of the data, especially for the handling of the different community definitions, and to Mrs. Irene Jung for help with the maps.
Compliance with ethical standards
Role of the funding source
This paper was not funded by a specific funding source. The childhood cancer data were provided by the Childhood Cancer Registry at the Institute for Medical Biometry, Epidemiology and Informatics in the University Medical Center Mainz, Germany; the registry is funded by the German government. The radiation data were provided by the Federal Office for Radiation Protection, an agency of the Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety. The deprivation data were provided by the Institute of Health Economics and Health Care Management, Helmholtz Zentrum München, a research institution funded by the German government.
Conflict of interest
All authors declare they have no actual or potential conflicts of interest.
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