Uncertainties in committed equivalent doses to the thyroid after ingestion or inhalation of different chemical forms of 125-129-131I

The aim of this study is to re-analyse uncertainties in committed equivalent doses to the thyroid after ingestion of 125-129-131I using the last variability reported for anatomical and physiological parameters of the different ICRP age groups, and to estimate uncertainties after inhalation exposure to different chemical forms of iodine (elemental and organic iodine vapours, iodine loaded particles (study limited to workers for activity median aerodynamic diameters of 1 and 5 mm)). The 95% confidence interval appears in the range of 7-18 (ratio of 97.5 versus 2.5 percentile values of the log-normal distribution: GSD4). The largest uncertainties are observed for 129I which is due to its long half-life. Because of the small range of beta rays of 125-129I when compared with that of 131I, and the preferential location of iodine within the colloid of the thyroid follicles, the use of calculated doses for a realistic risk assessment is discussed. (author)