Lead in bone: storage site, exposure source, and target organ.

The primary site of lead storage is in bone but relatively little attention has focused on this physiological compartment. Recent advances in measurement technology now permit the direct in vivo quantitative measurement of lead in bone, and this measure has great use in clinical and epidemiologic studies. Lead in bone is not a physiological sink, but can be mobilized back into the circulation in response to normal or pathological changes in mineral metabolism. Bone lead may be a significant source of target organ exposure under certain conditions, such as pregnancy, kidney disease, and menopause. Finally, the accumulation of lead in bone cells may have toxic consequences for bone status, and some of the mechanisms by which lead could affect bone mineral metabolism may also play a role in other target organ effects of lead.