The present study has recorded a high prevalence of pDDIs in internal medicine wards. Patients with old age, longer hospital stay and increased number of prescribed medications were at higher risk.

This study aimed to quantify the accuracy and precision of a method for in vivo measurements of lead in bone using L-shell x-ray fluorescence (LXRF), the former via comparison with independent measurements of lead in bone obtained using electrothermal atomic absorption spectrometry (AAS) following acid digestion. Using LXRF. the lead content of adult human cadaver tibiae was measured, both as intact legs and as dissected tibiae with overlying tissue removed, the latter at several proximal-distal locations. After LXRF, each tibia was divided into nine cross-sectional segments, which were further separated into tibia core and surface samples for AAS measurement. The proximal-distal variability of AAS-measured core and surface tibia lead concentrations has been described elsewhere (the lead concentration was found to decrease towards both ends of the tibia). The subjects of this paper are the proximal-distal variability of the LXRF-measured lead concentrations, the measurement uncertainty and the statistical agreement between LXRF and AAS. There was no clear proximal-distal variability in the LXRF-measured concentrations; the degree of variability in actual tibia lead concentrations is far less than the LXRF measurement uncertainty. Measurement uncertainty was dominated by counting statistics and exceeded the estimate of lead concentration in most cases. The agreement between LXRF and AAS was reasonably good for bare bone measurements but poor for intact leg measurements. The variability of the LXRF measurements was large enough, for both bare bone and intact leg measurements, to yield grave concerns about the analytical use of the technique in vivo.

Twenty-five years of public health efforts produced a striking reduction in lead exposure; the blood lead average in the United States has decreased to less than 20% of levels measured in the 1970s. However, poor minority groups that live in large urban centers are still at high risk for elevated lead levels. In this study, our data showed that pregnant immigrants (n = 1,428) who live in South Central Los Angeles--one of the most economically depressed regions of California--have significantly higher (p < .0001) blood lead levels (geometric mean = 2.3 microg/dl [0.11 micromol/l]) than 504 pregnant nonimmigrants (geometric mean = 1.9 microg/dl [0.09 micromol/l]). The most important factors associated with lower blood lead levels in both groups were younger age; more-recent date of blood sampling (i.e., decreasing secular trend); and blood sampling in mid-autumn, instead of mid-spring (i.e., seasonal trend). Blood lead levels of immigrants were strongly dependent on time elapsed since immigration to the United States; each natural log increase in years of residence was associated with an approximately 19% decrease in blood lead levels. Although blood lead means for both groups were almost the same as the estimated national average, 25 of the 30 cases of elevated blood lead (i.e., > or = 10 microg/dl [0.48 micromol/l) occurred in the immigrant group. The odds ratio (95% confidence intervals within parentheses) for having elevated blood lead levels (a) was 9.3 (1.9, 45.8) if the immigrant engaged in pica; (b) was 3.8 (1.4, 10.5) if the immigrant had low dietary calcium intake during pregnancy; and (c) was .65 (.43, .98) for every natural log unit increase of years of residence in the United States. The control of pica and dietary calcium intake may offer a means of reducing lead exposure in immigrants.

No abstract

No abstract

A few studies have examined the variability in 109Cd-based K-shell x-ray fluorescence (KXRF) bone lead measurements from replicate measurements made either at the same time or over a period of time, and one of these studies has shown that the uncertainty in an individual measurement is an underestimate of the standard deviation of replicate measurements. Variability in KXRF tibia lead measurements was assessed from ten cadaver intact legs, from the bare tibiae dissected from nine of these legs, and from four in vivo volunteers. Cadaver legs underwent replicate measurements on multiple occasions. In vivo volunteers underwent single measurements of the left tibia monthly for one year. Average tibia lead levels in the cadaver legs and in vivo volunteers ranged from 6 to 50 and from 6 to 13 microg Pb per g of bone mineral respectively. The factors influencing the standard deviation of replicate measurements were investigated. Both cadaver and in vivo measurements confirmed that the uncertainty in an individual measurement is an underestimate of the standard deviation of replicate measurements, suggesting a methodological deficiency probably shared by most current 109Cd-based K-shell XRF lead measurement systems.

The aim of this study was to validate 109Cd-based K-shell x-ray fluorescence measurements against atomic absorption spectrometry (AAS) measurements of core and surface tibia lead. The lead content of nine adult human cadaver tibiae was measured using 109Cd-based K-shell x-ray fluorescence (XRF) spectrometry and the results compared to measurements obtained using electrothermal atomization atomic absorption spectrometry following acid digestion. Each tibia was divided into nine cross-sectional segments, which were further separated into tibia core and surface samples for the AAS analytical measurements. Proximal-distal variability in tibia lead concentration as determined by AAS was previously described for both surface and core segments and was found to decrease towards the ends of the tibia, in contrast to XRF in which lead was found to increase towards the tibia ends. The effect of this contrasting behaviour on the agreement between XRF and AAS measurements was examined. Lead concentrations determined by AAS ranged from 3 to 19 microg of lead per gram of dry weight bone (microg g(-1)) for tibia core and from 5 to 32 microg g(-1) for tibia surface. Lead concentrations determined by XRF ranged from 2 to 35 microg g(-1) dry weight. No statistically significant difference was found between mean XRF-measured concentrations and mean surface lead concentrations measured by AAS, but XRF significantly overestimated tibia core lead concentrations by between 5 and 8 microg g(-1).

The aims of this study were to determine whether the location on the tibia measured by 109Cd-based K-shell x-ray fluorescence (XRF) affected the measurement result and its uncertainty, and whether higher tibia lead levels at the extremities of the tibia and/or inhomogeneity in the distribution of lead in the tibia could be inferred therefrom. Replicate XRF measurements were performed at multiple locations on ten adult cadaver intact legs and on nine bare tibiae dissected from them. Mean lead levels in the bare tibiae ranged from 16 to 48 microg Pb per g of bone mineral. Bare tibia measurements showed that both the XRF result and its uncertainty increased towards the proximal and distal ends of the tibia. The XRF result decreased away from the medial-lateral mid-point of the tibia, but XRF uncertainty was not significantly affected. Intact leg measurements showed no effect of proximal distal location on XRF result but did show an effect on XRF uncertainty. We conclude that the XRF method used can determine the differences in bone lead level resulting from the more trabecular composition at the ends of the tibia, and we present limited evidence for localized regions of low tibia lead level.