Effects on Dose Coefficients for Workers of Recent Changes in Internal Dosimetry

Dose coefficients for the embryo and foetus following intakes of radionuclides by the mother

“…There are, however, substantial differences between the different lung absorption types. The differing absorption rates (types F, M and S) mean that significantly different amounts of activity reach the maternal blood [44]. Thus, dose coefficients for the offspring for intakes of type F materials tend to be higher than those for type M materials, which in turn are usually higher than those for type S. Comparisons with the dose coefficients for reference adults are complicated by the fact that the less soluble absorption types tend to give higher doses to the adult (due to protracted retention in lung).…”

Deposition in the respiratory tract

“…(197) As part of an investigation of the effects on worker dose coefficients of recent changes in ICRP biokinetic models, Silk et al (1997) derived simple functions giving the percentage of inhaled activity reaching blood, allowing for uptake in the GI tract from material transferred to it from the respiratory tract, for the Publication 30 lung model (1 mm AMAD) and HRTM (1 and 5 mm AMAD). These functions are in the form A + B*f 1 , where A is the amount absorbed directly from the respiratory tract to blood (Fig.…”

“…Values of A and B are given in Table 8.1. The amounts Table 8.1 Total deposition, and amounts eventually transferred from respiratory tract to blood or to the GI tract (in the absence of radioactive decay) as percentages of inhaled activity (Silk et al, 1997) ICRP A Absorbed directly into the blood from respiratory tract B Transferred to GI tract from respiratory tract A + B*f 1 Absorbed into the blood directly from respiratory tract and via GI tract * For the HRTM the total transferred to blood and GI tract (A+B) is lower than the total deposition because it is assumed that material deposited in ET 1 is removed from the body to the environment.…”