The distribution of lead in human hemopoietic tissue and spongy bone after lead poisoning and Ca-EDTA chelation therapy

Abstract

Two iliac crest needle biopsies were taken from a 43-year-old lead-poisoned woman during and after completion of a Ca-EDTA treatment. By atomic absorption spectroscopy the first and second biopsy were found to contain 56, respectively 41.6 micrograms lead/g wet tissue. In both biopsies 36% of the lead was extractable in 0.1 N HCl. Electron microbeam X-ray analysis proved to have too low sensitivity for quantitation of the lead in these biopsies. Laser microbeam mass analysis (LAMMA), performed only on the second biopsy, revealed a high and fairly constant residual lead concentration in all bone marrow cell nuclei (approximately 55 micrograms/g) and a low lead concentration in the cytoplasm of the same cells (4-12 micrograms/g). The extracellular bone matrix lead was greatly concentrated in the superficial 3-6 microns osteoid zone of the bony trabeculae and totally absent from deeper parts of the mineralized matrix. The LAMMA results are in good agreement with those of subcellular fractionation experiments and atomic absorption spectroscopy, provided that the relative volume fraction of nucleus and cytoplasm is accounted for. The high residual osteoid lead after completed chelation therapy indicates that lead has a stronger affinity for the organic than the mineral components of bone matrix.

Pb distribution in bones from the Franklin expedition: synchrotron X-ray fluorescence and laser ablation/mass spectroscopy

“…The second statement is consistent with the existing literature on the mechanism and kinetics of bone Pb/bone blood exchange [16][17][18][19][20][21][22][23]. The long half-life of Pb in bone is especially relevant to an understanding of the Pb content of the Beechey Island burials, which occurred early in the expedition.…”

“…Individual metals are displayed using a color scale based on the maximum concentration of the metal; the scale is not normalized in such a way as to allow direct comparison of the concentrations of different metals. While it has been suggested that a detailed study of the Haversion canals in bone may provide a chronology of Pb accumulation [36], the existing literature [16][17][18][19][20][21][22][23] on the kinetics of Pb/bone exchange make it clear that the Pb distribution patterns within bone will provide a realistic chronology of uptake. The significance of the distribution of other metals must be uncertain, though the Beechey Island materials (Fig.…”

“…Elements such as Sr and Pb are incorporated in bone during remodeling [19] and are taken to be indicative of diet and Zn might be included as dietary indicator [20]. Modern Pb values vary widely but concentrations in the order of 3 to 30 ppm might be expected [21].…”

An age-specific kinetic model of lead metabolism in humans.

“…Actually, the processes giving rise to intermediate-term loss from bone have not been dearly established, either for lead or for the alkaline earth elements. For lead, much of the loss from bone occurring from a few days to a year or more after exposure might result in part from the bone diffusion process generally hypothesized and in part from other processes, such as turnover of lead-binding components of the organic matrix of bone (93) or gradual release of lead from cellular components of bone.…”

Evaluation of the potential role of chelation therapy in treatment of low to moderate lead exposures.

“…Also, the data help to explain the rebound in PbB immediately after treatment, which presumably is due to internal redistribution of lead. Even after multiple courses of CaNa2EDTA, body lead stores are likely to remain elevated (13 (14). The Chinese first reported the use of DMSA as an antidote for poisoning due bCalculations: A,= (A/ -e -k' where A, = prechelation lead pool, A, = total lead excreted in 5 days, and k = rate constant.…”