Rabinowitz M B
Research Unit, Children's Hospital, Boston Marine Biological Laboratory, Woods Hole, MA 02543.
Environ Health Perspect. 1991 Feb;91:33-7. doi: 10.1289/ehp.919133.
This article discusses bone as a source of lead to the rest of the body and as a record of past lead exposure. Bone lead levels generally increase with age at rates dependent on the skeletal site and lead exposure. After occupational exposure, the slow decline in blood lead, a 5- to 19-year half-life, reflects the long skeletal half-life. Repeated measurements of bone lead demonstrate the slow elimination of lead from bone. Stable isotope ratios have revealed many details of skeletal uptake and subsequent release. The bulk turnover rates for compact bone are about 2% per year and 8% for spine. Turnover activity varies with age and health. Even though lead approximates calcium, radium, strontium, barium, fluorine, and other bone seekers, the rates for each are different. A simple, two-pool (bone and blood) kinetic model is presented with proposed numerical values for the changes in blood lead levels that occur with changes in turnover rates. Two approaches are offered to further quantify lead turnover. One involves a study of subjects with known past exposure. Changes in the ratio of blood lead to bone lead with time would reflect the course of bone lead availability. Also, stable isotopes and subjects who move from one geographical area to another offer opportunities. Sequential isotope measurements would indicate how much of the lead in blood is from current exposure or bone stores, distinct from changes in absorption or excretion.
本文讨论了骨骼作为身体其他部位铅的来源以及过去铅暴露记录的情况。骨骼中的铅含量通常随年龄增长而增加，其速率取决于骨骼部位和铅暴露情况。职业性铅暴露后，血铅水平缓慢下降，半衰期为5至19年，这反映了铅在骨骼中的半衰期较长。对骨骼铅含量的重复测量表明铅从骨骼中缓慢排出。稳定同位素比率揭示了骨骼摄取和随后释放的许多细节。致密骨的总体更新率约为每年2%，脊柱为8%。更新活动随年龄和健康状况而变化。尽管铅与钙、镭、锶、钡、氟及其他趋向于在骨骼中蓄积的元素相似，但每种元素的更新速率不同。本文提出了一个简单的双池（骨骼和血液）动力学模型，并给出了随着更新率变化血铅水平变化的建议数值。还提供了两种进一步量化铅更新的方法。一种方法涉及对已知过去暴露情况的受试者进行研究。血铅与骨骼铅的比率随时间的变化将反映骨骼中铅的可利用过程。此外，稳定同位素以及从一个地理区域迁移到另一个地理区域的受试者也提供了研究机会。连续的同位素测量将表明血液中的铅有多少来自当前暴露或骨骼储存，这与吸收或排泄的变化不同。
