Effect of repeated occupational exposure to lead, cessation of exposure, and chelation on levels of lead in bone.
A sensitive K-X-ray fluorescence (K-XRF) instrument was used to measure lead levels in the tibia and patella on a series of twelve subjects who had relatively well-documented histories of lead exposure and blood lead levels. For some subjects, K-XRF measurements were taken at multiple points in time, and before and after chelation with EDTA (ethylenediamine tetraacetic acid). Results confirm that K-XRF measured bone lead levels correspond to cumulative blood lead indices and not to current blood lead levels. Moreover, the data suggest that bone lead levels; (1) correspond to urinary lead following the EDTA mobilization test unless previous chelation has occurred; (2) rise initially after lead exposure ceases and blood lead levels decrease, probably from redistribution from soft tissue, and then fall; and (3) do not decrease with a 3- to 5-day course of therapeutic EDTA chelation. K-XRF levels in the patella were noted to decrease more rapidly than levels in the tibia after cessation of lead exposure, a finding that probably reflects the greater turnover of lead in trabecular bone than in cortical bone.
Hu
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H
Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115.
Pepper
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L
Goldman
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R
D000328:Adult; D001842:Bone and Bones / Q000378:metabolism*; D004492:Edetic Acid / Q000627:therapeutic use*; D005453:Fluorescence; D006801:Humans; D007262:Infusions, Intravenous; D007854:Lead / Q000009:adverse effects* / Q000378:metabolism; D007855:Lead Poisoning / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000378:metabolism*; D016273:Occupational Exposure / Q000009:adverse effects*
D007854:Lead; D004492:Edetic Acid