Reliability of the ICRP's Dose Coefficient for Members of the Public. 1. Sources of Uncertainty in the Biokinetic Models

Abstract

During the decade following the Chernobyl accident, the International Commission on Radiological Protection (ICRP) developed dose coefficients (doses per unit intake) for ingestion or inhalation of radionuclides by members of the public. The level of uncertainty in those coefficients varies considerably from one radionuclide to another, due largely to differences in the level of understanding of the biological behaviour of different elements in the human body. This paper is the first in a series that examines the sources and extent of uncertainties in the ICRP's biokinetic and dosimetric models for members of the public and the dose coefficients derived from those models. The present paper describes the different types of information generally used to develop biokinetic models for radionuclides, the main sources of uncertainty associated with each type of information, and the approach used in subsequent papers in this series to quantify the uncertainties in biokinetic and dosimetric estimates.

Life-long accumulation of 137Cs and 40K in the vertebral column of a cow

“…The collection of small or non-representative samples can contribute to the uncertainties in developing biokinetic models (Leggett, 2001). We have assessed the uncertainty by using the 137 Cs-activity concentration of a single vertebral body to predict the activity concentration in the whole vertebral column and skeleton.…”

“…Durbin and Schmidt (1985) assumed in their analysis of 241 Amcontent in the skeleton of a donor, that vertebral bodies and arches may be assigned to trabecular and cortical bone, respectively. The importance of representative samples is addressed by Leggett (2001) and Howard et al (2009).…”

Les méthodes et les limites de la dosimétrie après contamination interne

“…En particulier, la précision de l'évaluation dosimétrique est limitée par la sensibilité des techniques de mesure, une activité inférieure à la limite de détection pouvant parfois être associée à une dose significative, et par la fiabilité des modèles dosimétriques. Des lacunes dans la connaissance des suites de certains types d'exposition doivent être comblées par extrapolation à partir d'expositions similaires : de l'expérimentation animale vers le métabolisme humain, d'un élément chimique vers ses analogues, de situations simples comme l'incorporation aiguë vers des scénarios plus complexes comme la contamination chronique (Leggett, 2001). Il s'ensuit que les modèles utilisés comme référence peuvent être plus ou moins réalistes, indépendamment de la variabilité inter et intraindividuelle par rapport à cette référence.…”

Modeling Dose Deposition and DNA Damage Due to Low-Energy β–Emitters

“…In 55 Uncertainties in biokinetic model assumptions principally arise from the quality and uncertain applicability of the experimental data on which they are based and on the complexity of behaviour of the radionuclide (Leggett, 2001(Leggett, , 2003. In some cases, good human data are available and uncertainties are small (eg tritium as HTO in adults).…”

“…In the context of using dose coefficients to estimate equivalent dose to organs and tissues, which would be done if more detailed information were required for specific purposes, knowledge of uncertainties may be crucial in applying the results. The importance of recognising and attempting to quantify uncertainties in dose estimates for internal emitters is recognised by those contributing to ICRP work, and by others, as attested by recent publications on this subject Leggett, 2001Leggett, , 2003.…”