Biokinetic modelling of natural thorium in humans by ingestion

Abstract

The retention of naturally occurring thorium (228Th, 230Th, 232Th) in model compartments and its daily urinary and faecal excretion after acute and chronic injections and ingestions were calculated for male and female subjects of six age groups based on the current age-dependent biokinetic model for thorium (Th) recommended by the International Commission on Radiological Protection (ICRP). The results are tabulated in a database. The calculated contents of 228,230,232Th in organs or tissues using their reference concentrations in foodstuffs for the European population are compared with autopsy data. The model prediction of 232Th in whole body for a 50-year-old unexposed person is 22 mBq, 86% of that in skeleton, 9.7% in other soft tissues, 3.4% in liver, 0.7% in kidneys and 0.01% in blood. The modelling predicts lower contents of the natural Th isotopes in whole body, especially in blood compared with measured data for the unexposed public. Modelled 232Th daily urinary excretions are 5 to 10 times less than bio-assay data from the authors' own laboratory.

Complex Formation of the Cerium(IV) Ion with Glycyl-Glycine at Different Ionic Strengths

“…Thus, the separation, analysis of peptides and peptide hormones, and determination of their stability constants with metal ion complexes has become increasingly important for an ever-widening range of research disciplines. On the other hand, research results have clearly demonstrated that certain transition and actinide metal ions play a basic role in directing a number of biochemical processes. − …”

Complex Formation of Thorium(IV) Ion with Glycyl−Glycine and Glycyl−Valine

“…The interaction between amino acids, peptides, and proteins with metal ions plays an important role in biochemistry and biology and has been studied extensively during the last three decades. Complexes of amino acids and oligopeptides are involved in the exchange and transport mechanism of some trace metal ions in the human body. − Oligopeptides have proved to be the most useful model compounds for such studies since they are able to mimic to a great extent the metal ion binding site of much more complicated protein molecules. , …”

“…Thorium is the most abundant radioactive element in nature [(0.001 to 0.002) % weight of the earth’s crust] and is distributed widely at up to 15 ppm in soils. , The half-life of 232 Th is about three times longer than the age of the earth (1.4·10 10 years), but 228 Th has a half-life of 1.9 years. 230 Th with a half-life of 7.5·10 4 years is the parent of 226 Ra and 232 Ra . Thorium is used in industry for many purposes including ceramics, gas mantles, nuclear fuel, flame spraying, crucibles, medicine, nonsilica optical glass, catalyst, etc. , This element and its derivatives have been known as a toxic element for many years .…”

“…Complexes of amino acids and oligopeptides are involved in the exchange and transport mechanism of some trace metal ions in the human body. [1][2][3][4] Oligopeptides have proved to be the most useful model compounds for such studies since they are able to mimic to a great extent the metal ion binding site of much more complicated protein molecules. 5,6 Thorium is the most abundant radioactive element in nature [(0.001 to 0.002) % weight of the earth's crust] and is distributed widely at up to 15 ppm in soils.…”

Dissolution Factors of Ta, Th, and U Oxides Present in Pyrochlore

“…Biokinetic behavior of several compounds of Th and U are well known (International Commission on Radiological Protection (ICRP) 1959, publication no. 2), but there is little data about the biokinetic behavior of Th and U associated to mineral crystal lattice (Dias da Cunha et al 2002;Wan et al 2006;Stradling et al 2003;Sutton and Burastero 2004;Chen et al 2005;Li et al 2007). While there are available several data about the effects of Th and U in the human body, there is very few data about Ta toxicity and these few studies are not conclusive.…”