Environmental Notes

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 μg/g wet weight (range 2–155), corresponding to 370 μg/g calcium (range 30–1, 120). In 9 retired workers, the corresponding levels were 19 μg/g (5–76) and 250 μg/g calcium (60–700); in 14 reference subjects without occupational exposure, 1.3 μg/g (1–4) and 13 μg/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.