Internal Dose Assessment of Natural Uranium From Drinking Water Based on Biokinetic Modeling and Individual Bioassay Monitoring: A Study of a Finnish Family

Abstract

Since the later 1960's, a nationwide survey on natural radionuclides in drinking water showed high concentrations of natural uranium (U) in Finland, especially in uraniferous granite areas. In order to assess the radiation dose from the natural uranium to individuals, the concentrations of natural uranium in drinking water of the drilled wells were determined by radiochemical and alpha spectrometric methods. Uranium contents were measured in the urinary samples of five members of a Finnish family by means of inductively coupled plasma-mass spectrometry. Correspondingly, theoretical biokinetic modeling of natural uranium incorporated for the same persons were performed with the aid of follow-up interviews. The ICRP biokinetic compartmental model and the age-dependent transfer rates for uranium were used to model the intake, transfer, distribution, retention, and excretion of (234)U and (238)U, respectively, from the drinking water for each person of the family. The organ absorbed dose, equivalent dose, and effective dose were evaluated for each family member at time intervals using specific effective energy values calculated by the SEECAL program and compared with recommended values. The modeled urinary excretion rates were found to be mostly higher than the measured values by a factor of three. The mean annual effective dose for this family is 8 muSv y(-1). By comparing the measured and calculated data, estimation of retrospective radiation exposure based on biokinetic modeling and bioassay method is enhanced and, vice versa, the biokinetic and dosimetric models are tested and verified.

Uranium and thorium in soils, mineral sands, water and food samples in a tin mining area in Nigeria with elevated activity

“…The measured concentrations of 238 U exceed the UNSCEAR reference only in the Bisichi river and in the well waters of Bisichi and Jos City. However, also in these cases, the activities are well below the ranges observed in many works published about the content of uranium in drinking waters: in bottled mineral waters for example, 238 U activity can exceed 100 mBq l À1 (Martin Sanchez et al, 1999;Werner et al, 1999;Bagatti et al, 2003), and in private drilled wells it is not uncommon to find concentrations above 1 Bq l À1 , even up to 150 Bq l À1 (Limson Zamora et al, 1998;Hakonson-Hayes et al, 2002;Li et al, 2006). Also for 232 Th, the concentrations were definitely below the UNSCEAR reference values, with the exception of the two surface water samples in Bisichi.…”

Internal Dosimetry

“…These estimated dose coef cients can be used to make decisions if some measures should be taken for protection of people from radiation. 66,117)…”

Radiation dose assessment of exposure to depleted uranium

“…The organ equivalent dose, H T , for each U isotope, that is, 234 U, 235 U, 236 U and 238 U, is calculated by summing the product of U S (nuclear transformations) and the specific effective energy (SEE(T'S)) over all source organs, S (ICRP, 1995a, b;Li et al, 2006). In the values of the SEEs each type of radiation is weighted by a given radiation weighting factor, w R , which accounts for the different biological effectiveness in inducing late effects.…”