Validation of a spatial model of background radiation using personal measurements in children

Limited knowledge about the prediction accuracy of exposure models hinders the interpretation of results from epidemiological studies on childhood cancer risks associated with exposure to background gamma-radiation. We aimed to validate a spatial exposure model that we recently developed for Switzerland. We used individual exposure measurements conducted with D-Shuttle dosimeters by 149 children throughout the country. We ran linear regression models fitting the measured exposure against predictions from the newly developed model, and compared results with the predictions from an earlier model. We further used variograms to investigate the spatial correlation of estimation errors. The prediction accuracy of the newly developed exposure model was modest (R2 = 0.2), but better than the earlier model (R2 = 0.13). Prediction errors revealed weak spatial correlation. Although the new exposure model marks an improvement, the modest prediction accuracy and the remaining spatial correlation of errors show room for further improvement. Our study highlights the need for validation of exposure models for background gamma-radiation used in epidemiological studies. •Exposure models are key to assess childhood cancer risk from background radiation.•A recently developed exposure model poorly predicted measured doses in children.•Existing models lack data on crucial determinants of ambient dose rates of exposure.•Improved exposure models of background radiation are needed.