Calculation of internal dose from ingested soil-derived uranium in humans: Application of a new method

Abstract

The aim of the present study was to determine the internal dose in humans after the ingestion of soil highly contaminated with uranium. Therefore, an in vitro solubility assay was performed to estimate the bioaccessibility of uranium for two types of soil. Based on the results, the corresponding bioavailabilities were assessed by using a recently published method. Finally, these bioavailability data were used together with the biokinetic model of uranium to assess the internal doses for a hypothetical but realistic scenario characterized by a daily ingestion of 10 mg of soil over 1 year. The investigated soil samples were from two former uranium mining sites of Germany with (238)U concentrations of about 460 and 550 mg/kg. For these soils, the bioavailabilities of (238)U were quantified as 0.18 and 0.28 % (geometric mean) with 2.5th percentiles of 0.02 and 0.03 % and 97.5th percentiles of 1.48 and 2.34 %, respectively. The corresponding calculated annual committed effective doses for the assumed scenario were 0.4 and 0.6 µSv (GM) with 2.5th percentiles of 0.2 and 0.3 µSv and 97.5th percentiles of 1.6 and 3.0 µSv, respectively. These annual committed effective doses are similar to those from natural uranium intake by food and drinking water, which is estimated to be 0.5 µSv. Based on the present experimental data and the selected ingestion scenario, the investigated soils-although highly contaminated with uranium-are not expected to pose any major health risk to humans related to radiation.

Environmental Geochemistry of Uranium in Recent Sediments of Alkhasa Valley in Kirkuk City / Northern Iraq

“…The result of correlation for recent sediment in Kirkuk city (table 2) and (appendix1) are summarized in (table 1) The very high positive correlation between Uwith (Ta and K 2 O) byr value (0.904 and 0.896) respectively, then high positive correlation of Uwith (TiO 2 , Y and Nb) byr value (0.822, 0.793 and 0.753) respectively and The good correlation of U with Na 2 Owith value (0.673) (figure 2) because according to Goldschmidtthis elementsare found in one group (Lithophile elements)of classification elements (Goldschmidt, 1954) while the good correlation of Uwith (p and P 2 o 5 ) by value (0.74 and 0.68) respectively because one of the main sources of Uare from fertilizers that's have high values of phosphor (Träber et al, 2015). The good negative correlation of U with (Ni and Co) by value (-0.79 and -0.783) respectively because the source of this element is different with source of U in the environments.…”

“…There are three isotopes for U with percentages by mole fraction and half-lives of 234 U 0.0054% (245,500 Years), 235 U 0.72% (704,000,000 Years) and 238 U 99.27 % (4,468,000,000 Years) (Berglund and Wieser, 2011;Träber et al, 2015). This element has a very high density (18.95 g /cm 3 , 1.7 times higher than lead density of 11.35 g /cm 3 ).…”

“…The source of U in environment are leaching from natural deposits, release in mill tailings, emissions from nuclear industry and the combustion of coal and other fuels (Dresenet al 1982;Cothern and Lappenbusch 1983, Essien et al,1985, Tadmor 1986, however the soil contamination with U is due to addition of phosphate fertilizers (Träber et al, 2015). On the other hand, large amounts of U contents are produced by the modern industry: metallurgy, oil refinery, nuclear industry, nuclear weapon tests, the use of U ammunition, ore mining, phosphogypsum waste heap as well as the manufacture and processing of fuel rods (Boryło, 2012).…”

Internal dose assessment of 238U contaminated soils based on in-vitro gastrointestinal protocol

“…The experiments were repeated for each types of soil. The solutions were stored frozen until measured with inductively coupled plasma mass spectrometer (ICP-MS) [14][11][15] [9]. Table 2 represents the measured chemicals and enzymes used for 0.5 g of soil [15].…”

“…Meanwhile study by Stanek and Calabrese [7] summarised the soil ingestion in the range of 0.013 -0.138 g/day for children and estimation of 0.01 g/day for adults [8]. Dose assessment conducted by Traber et al [9] in order to estimate the exposure risk for 238 U after soil ingestion, an intake of 0.01 g/day was assumed. Through deliberate or involuntary ingestion of soils, the chemical and biological components of soils can either be beneficial or detrimental to human health.…”