Lead in Vertebral Bone Biopsies from Active and Retired Lead Workers

Abstract

Samples of vertebral bone were obtained by skeletal biopsy and lead concentrations were determined by atomic absorption spectroscopy. The median level of lead in bone in 27 active lead workers was 29 micrograms/g wet weight (range 2-155), corresponding to 370 micrograms/g calcium (range 30-1,120). In 9 retired workers, the corresponding levels were 19 micrograms/g (5-76) and 250 micrograms/g calcium (60-700); in 14 reference subjects without occupational exposure, 1.3 micrograms/g (1-4) and 13 micrograms/g calcium (8-40). The bone lead content rose with time of exposure. Comparison of levels in vertebra with those in fingerbone, as measured by in vivo x-ray fluorescence in the same subjects, strongly suggested the presence of lead pools with different kinetics. The accumulation pattern, as well as the relation between levels in vertebra and fingerbone, suggests a much shorter half-time of lead in the mainly trabecular vertebral bone as compared to the mainly cortical fingerbone. Further, there was an association between vertebral and blood lead levels in the retired workers, which shows a considerable endogenous lead exposure from the skeletal pool.

Chelated lead and bone lead.

“…Most of the body burden is in the skeleton . There are, however, differences in calcium metabolic activity between different bone types leg, trabecular and cortical (24,25)], which was assumed would be reflected in lead turnover rates. Hence, in deciding on the choice of bone sites for a study of lead uptake, of which this work forms a part, the calcaneus was chosen as a large trabecular bone to complement measurements in the largely cortical tibia and phalanx.…”

Sequential Measurements of Bone Lead Content by L X-Ray Fluorescence in CaNa 2 EDTA-Treated Lead-Toxic Children

“…By using net corrected LXRF counts and PbB values to predict CaNa2EDTA outcomes, the specificity and sensitivity of these two predictors were 86 and 93%, respectively (Table 5) (13). In 20 and 24% of CaNa2EDTA-negative and CaNa2-EDTA-positive children, respectively, cortical bone lead values were similar to lead concentrations measured in bone biopsies from normal adults (16,17). Remarkably, an additional 40% of CaNa2EDTA-positive children had bone lead concentrations observed in industrially exposed adults (16,17).…”

“…In 20 and 24% of CaNa2EDTA-negative and CaNa2-EDTA-positive children, respectively, cortical bone lead values were similar to lead concentrations measured in bone biopsies from normal adults (16,17). Remarkably, an additional 40% of CaNa2EDTA-positive children had bone lead concentrations observed in industrially exposed adults (16,17). In this longitudinal study, lead-toxic children who did not qualify for treatment and other children who underwent one or two courses of CaNa2EDTA treatment were re-evaluated 6 weeks and 24 weeks postenrollment.…”

Lead intoxication caused by skeletal disease

“…A total content of approximately a few milligrams has been observed in bones from prehistoric individuals (3). Measurements in contemporary Scandinavians have yielded levels in finger bone and tibia of a few micrograms per gram of bone (4,5,Borjesson et al,unpublished report) corresponding to 10-30 mg, and higher values, about 100 mg, have been reported for occupationally unexposed subjects in, for example, the United Kingdom (2,6) and the United States (3,7). Lead workers may have very high skeletal lead levels, up to 130 p g .…”

“…Lead workers may have very high skeletal lead levels, up to 130 p g . g-' in finger bone (4,8,9), col~esponding to a total content of about 1 g.…”