Abstract
Tritium (3H) is a radioactive isotope of hydrogen that is ubiquitous in environmental and biologicalsystems. Following debate on the human health risk from exposure to tritium, there havebeen claims that the current biokinetic model recommended by the InternationalCommission on Radiological Protection (ICRP) may underestimate tritium doses. Anew generic model for tritium in mammals, based on energy metabolism andbody composition, together with all its input data, has been described in a recentpaper and successfully tested for farm and laboratory mammals. That modelconsiders only dietary intake of tritium and was extended to humans. This paperpresents the latest development of the human model with explicit considerationof brain energy metabolism. Model testing with human experimental data onorganically bound tritium (OBT) in urine after tritiated water (HTO) or OBTintakes is presented. Predicted absorbed doses show a moderate increase for OBTintakes compared with doses recommended by the ICRP. Infants have highertritium retention—a factor of 2 longer than the ICRP estimate. The highest tritiumconcentration is in adipose tissue, which has a very low radiobiological sensitivity. Theranges of uncertainty in retention and doses are investigated. The advantage ofthe new model is its ability to be applied to the interpretation of bioassay data.
Published Version
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