PREDICTION OF RESPONSE OF BLOOD LEAD TO AIRBORNE AND DIETARY LEAD FROM VOLUNTEER EXPERIMENTS WITH LEAD ISOTOPES
PREDICTION OF RESPONSE OF BLOOD LEAD TO AIRBORNE AND DIETARY LEAD FROM VOLUNTEER EXPERIMENTS WITH LEAD ISOTOPES
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DOI：
10.1098/rspb.1985.0027
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发表时间：
1985-01-01
期刊：
影响因子：
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通讯作者：
CHAMBERLAIN, AC
中科院分区：
文献类型：
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作者：
CHAMBERLAIN, AC
要预测血液中铅对空气中铅和饮食中铅的反应，需要了解铅从肺和肠道进入人体的吸收率、随后在各隔室之间的分配、在这些隔室中停留的时间以及再分配或排泄。对志愿者进行的示踪剂研究表明，无论是吸入、摄入还是注射，无机铅在组织间的全身分布没有差异。铅从血浆迅速转移到红细胞，然后再以较慢的速度转移到肝脏和其他软组织、骨骼和排泄物。在哈维尔和其他地方对203pb的研究表明，最初的快速分布使超过一半的被同化的铅附着在红细胞上。结果非常一致，也适用于狗和狒狒。已测量了203pb人体受试者的肾清除率（Vu） （futocb的比率，或以具有相同铅含量的血量表示的日尿量）和内源性粪便清除率（Vf）。结果与vu一致，用稳定铅测量，许多结果给vu约0.1 kg d-1。然而，有证据表明，当血压高于正常水平时，血压会升高。这也许可以解释在暴露于环境铅的人类中观察到的铅摄取与相应的cb之间的非线性关系。vfi大约是vu的一半，类似的结果也适用于钙。测量了203pb从血液到骨骼的清除率，并回顾了文献中的各种人类和动物数据来支持这一结果。结合骨周转率（来自90sr的数据），对骨骼的假设输入给出了与死后结果一致的骨骼负荷估计。结果结合在一个隔室模型中。然后，通过使用放射性示踪剂（203Pb）、稳定同位素示踪剂（204Pb）和总铅测量，考虑铅气溶胶在肺部的滞留和从肠道的摄取。这里有各种各样的结果。颗粒大小影响肺的部分保留和保留的位置，这反过来又影响到血液的部分摄取。当铅被摄入时，胃中食物的存在或缺失极大地影响了肠道的部分摄取。最后，一个有限的选择的结果，自愿暴露于稳定的铅空气或饮食进行了审查。结果表明，在某些情况下，如果对输入参数做出合理的假设，则可以用所提出的代谢模型的结果解释数周或数年测量摄入量的incb升高。
To predict the response of blood lead to airborne and dietary lead requires knowledge of the rate of uptake of lead into the body from lung and gut, its subsequent partitioning between compartments, the stay time in those compartments, and its redistribution or excretion. Tracer studies with volunteers have shown no differences in systemic distribution of inorganic lead between tissues whether it is taken by inhalation, ingestion or injection. Lead is rapidly transferred from plasma to red cells, and there is slower movement thence into liver and other soft tissues, to bone, and to excreta. Work at Harwell and elsewhere with203Pb has shown that the initial rapid distribution leaves rather over half the assimilated lead attached to red cells. The result is remarkably consistent, and applies also to dogs and baboons. The renal clearance (Vu) (ratio ofUtoCB, or daily urinary output expressed as mass of blood having the same lead content), and also the endogenous faecal clearance excretion rate (Vf), have been measured on human subjects with203Pb. The results are consistent withVu, as measured with stable lead, with many results givingVuabout 0.1 kg d-1. However, there is evidence thatVuincreases whenCBis elevated above the normal. This may explain the nonlinear relation between uptake of lead and the correspondingCB, which has been observed in humans exposed to environmental lead.Vfis about halfVu, and a similar result applies to calcium. The clearance rateVaof203Pb from blood to bone has been measured, and a variety of human and animal data in the literature has been reviewed to support this result. Combined with bone turnover rates (from data on90Sr), the postulated inputs to bone give estimates of skeletal burdens which agree with post-mortem results. The results are combined in a compartment model. The retention of lead aerosol in the lung, and uptake from the gut are then considered, with use made of radioactive tracer (203Pb), stable isotopic tracer (204Pb) and total lead measurements. Here there is great diversity of results. Particle size affects the fractional lung retention and the site of retention, which in turn affects the fractional uptake to blood. Presence or absence of food in the stomach when lead is ingested greatly affects the fractional gut uptake. Finally, a limited selection of results of volunteer exposures to stable lead in air or diet are reviewed. It is shown that the elevation inCBfrom the measured intakes, over weeks or years in some cases, can be explained by the results of the proposed metabolic model, provided reasonable assumptions are made about the input parameters.