The distribution of lead in human hemopoietic tissue and spongy bone after lead poisoning and Ca-EDTA chelation therapy. Observations made by atomic absorption spectroscopy, laser microbeam mass analysis and electron microbeam X-ray analysis

Effects of various Fe compounds on the bioavailability of Pb contained in orally ingested soils in mice: Mechanistic insights and health implications

Reducing lead (Pb) exposure via oral ingestion of contaminated soils is highly relevant for child health. Elevating dietary micronutrient iron (Fe) intake can reduce Pb oral bioavailability while being beneficial for child nutritional health. However, the practical performance of various Fe compounds was not assessed. Here, based on mouse bioassays, ten Fe compounds applied to diets (100-800 mg Fe kg^-1) reduced Pb oral relative bioavailability (RBA) in two soils variedly depending on Fe forms. EDTA-FeNa was most efficient, which reduced Pb-RBA in a soil from 79.5 ± 14.7 % to 23.1 ± 2.72 % (71 % lower) at 100 mg Fe kg^-1 in diet, more effective than other 9 compounds at equivalent or higher doses (3.6-68 % lower). When EDTA-FeNa, ferrous gluconate, ferric citrate, and ferrous bisglycinate were supplemented, Fe-Pb co-precipitation was not observed in the intestinal tract. EDTA-FeNa, ferrous gluconate, ferric citrate, and ferrous sulfate suppressed duodenal divalent metal transporter 1 (DMT1)mRNA relative expression similarly (27-68 % lower). In comparison, among ten compounds, EDTA-FeNa elevated Fe concentrations in mouse liver, kidney, and blood (1.50-2.69-fold higher) most efficiently, suggesting the most efficient Fe absorption that competed with Pb. In addition, EDTA was unique from other organic ligands, ingestion of which caused 12.0-fold higher Pb urinary excretion, decreasing Pb concentrations in mouse liver, kidney, and blood by 68-88 %. The two processes (Fe-Pb absorption competition and Pb urinary excretion with EDTA) interacted synergistically, leading to the lowest Pb absorption with EDTA-FeNa. The results provide evidence of a better inhibition of Pb absorption by EDTA-FeNa, highlighting that EDTA-FeNa may be the most appropriate supplement for intervention on human Pb exposure. Future researches are needed to assess the effectiveness of EDTA-FeNa for intervention on human Pb exposure.

Lead accumulation in tidemark of articular cartilage

OBJECTIVE

Determination of the spatial distribution of the toxic element lead (Pb) and other trace elements in normal articular cartilage and subchondral bone from adult humans with no history of work-related exposure to Pb.

METHODS

Four macroscopically normal femoral heads and three patellas were harvested from randomly selected forensic autopsies. All subjects died of acute illnesses, had no history of work-related exposure to Pb and had no metabolic bone disease. The elemental distribution of lead (Pb) together with zinc (Zn), strontium (Sr) and calcium (Ca) in the chondral and subchondral region was detected using high resolution synchrotron radiation induced micro X-ray fluorescence (SR mu-XRF) analysis. SR mu-XRF line scans in conventional and SR mu-XRF area scans in confocal geometry were correlated to backscattered electron (BE) images visualizing the mineralized tissue.

RESULTS

In all samples, we found a highly specific accumulation of Pb in the tidemark, the transition zone between calcified and non-calcified articular cartilage. Pb fluorescence intensities in the tidemark, which is thought to be a metabolically active mineralization front, were 13-fold higher when compared to subchondral bone. Pb intensities in the subchondral region were strongly correlated with Zn, but were distinctly different from Ca and Sr.

CONCLUSIONS

The finding of the highly specific accumulation of lead in the tidemark of human articular cartilage is novel. However at this point, the exact mechanisms of the local Pb accumulation as well as its clinical implications are unknown.

Trace element analysis in body fluids by glow discharge mass spectrometry: a study of lead mobilization by the drug cis-platin

A method is described, using glow discharge mass spectrometry, to measure lead and platinum levels at the p.p.b. level in the urine of patients receiving cancer chemotherapy with the drug cis-platin. Using bismuth added as an internal standard, the method is found to compare very favourably with other quantitative techniques, and requires relatively little sample preparation. The data obtained support the idea that normally stored body lead is displaced by the platinum complexed in the drug, but only to a small extent.