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The general population is increasingly exposed to cerium (Ce), which is contained in industrial products or is present as nuclear Ce fission products. Some studies suggested a link between elevated Ce levels and endomyocardial fibrosis. Since breast milk is the optimal, and directly after birth, usually the sole nutrition for newborns, exposure of females to Ce and its transfer to infants by breast-feeding is of concern in neonate protection. Consequently, the transfer rate of Ce from blood to breast milk is of interest for elucidating the Ce exposure of infants. Biomonitoring of paired serum and breast milk samples provides such information about Ce transfer to human milk. Therefore, this study is aimed at clarification of the relationship between Ce in human milk and serum from respective mothers for elucidating Ce enrichment in human milk with possible nutritional risk for newborns. As a prerequisite a strictly quality-controlled Ce determination method applicable to very low Ce concentration was developed, and its figures of merit were determined and found to be sufficient for our purpose. It turned out that Ce concentration in milk from Munich (Germany) and Madrid (Spain) showed a median of 13 ng/L. Ce concentrations in serum were at limit of quantification (LOQ) 10 ng/L (Munich) or 21.6-70.3 ng/L (Madrid), suggesting a higher Ce intake in Madrid. No enrichment from blood to milk was seen, and no elevated nutritional risk for breast-fed babies from Ce was found. Ce in serum, but not in milk, could indicate environmental Ce. [ABSTRACT FROM AUTHOR]

An extensive study using stable isotopes of molybdenum as tracers was undertaken to investigate intestinal uptake, systemic kinetics and urinary excretion of molybdenum in healthy human volunteers. In total 63 experiments with 17 volunteers were performed administering the tracers in different chemical forms and measuring their concentrations in blood plasma and urine samples by means of activation analysis and mass spectrometry. Molybdenum was eliminated very rapidly from the circulation. The amount eliminated via the renal pathway was observed to be dependent on several factors, such as form and modality of administration and also the total amount of circulating molybdenum. The fact that the urinary excretion patterns diverged significantly from the current predictions of the International Commission on Radiological Protection model might be relevant when using the model for retrospective intake assessments in case of an accident. On the basis of the experimental data, a more realistic compartmental structure has been presented. [ABSTRACT FROM AUTHOR]

The article focuses on the nationwide survey on natural radionuclides in drinking water that displayed high concentrations of natural uranium in Finland. The concentrations of natural uranium in drinking water of the drilled wells were found out by radiochemical and alpha spectrometric methods in order to assess the radiation dose from the natural uranium to individuals. Uranium contents were assessed in the urinary samples of five members of a Finnish family through the substance of inductively coupled plasma-mass spectrometry. Similarly, theoretical biokinetic modeling of natural uranium integrated for the same persons was executed with the help of follow-up interviews.

Systemic kinetics and urinary excretion after intravenous injection of stable strontium 84Sr were evaluated in 42 investigations in human subjects. Tracer concentrations in plasma and urine were determined by thermal ionisation mass spectrometry. The initial strontium plasma clearance measured after tracer administration was found to be much faster than that predicted by the current model of the International Commission of Radiological Protection (ICRP). The biological half-life of the fast component plasma clearance (T(1/2)) was 0.25 h in comparison with 1.1 h of the ICRP value. This early clearance could be the consequence of a more rapid transfer from blood plasma to other compartments of the human body. In vitro blood tests have shown that strontium was not bound to red blood cells. Cumulative urinary excretion is considerably lower than the model prediction. The reason could be the reduced transfer rate of strontium from plasma to urine in the first 12 h after tracer administration. Plasma clearance and urinary excretion showed no dependency on the age or gender of the adult volunteers.