Laboratory of Inorganic and Nuclear Chemistry, Wadsworth Center, New York State Department of Health, PO Box 509 Albany, NY 12201, USA; Department of Environmental Health Sciences, University at Albany, Albany, NY 12222, USA.
Cornell High Energy Synchrotron Source, Ithaca, NY 14850, USA.
J Trace Elem Med Biol. 2019 Sep;55:143-153. doi: 10.1016/j.jtemb.2019.05.013. Epub 2019 Jun 20.
The principal goal of this study was to investigate the uptake and distribution of lead (Pb) in the horns of Pb-dosed goats, and to explore possible links to their historical Pb dosing records. Horn is a keratinized material that grows in discrete increments with the potential to preserve the historical record of past environmental exposures. While previous studies have leveraged this potential to examine environmental and biological phenomena in horns, Pb uptake has never been explored.
Horns were collected post-mortem from three goats that had been previously used to produce blood lead reference materials for the New York State proficiency testing program. The animals were periodically dosed with lead acetate, administered orally in a capsule, over a 5 to 8-year period. Horn cross sections were taken from each animal and analyzed using synchrotron radiation-induced micro X-ray fluorescence spectrometry (SR-μXRF) at the Cornell High Energy Synchrotron Source (CHESS).
Elemental distribution maps were obtained by SR-μXRF for Pb, Ca, S, Se, and three other elements (Br, Zn and Cu), with values reported quantitatively as a mass fraction (μg/g for trace elements and mg/g for Ca and S). Accumulations of Pb were clearly visible as a series of narrow "rings" in each of the horn samples analyzed. The elements Ca, S, Br, Zn, and Cu were also detected as discrete rings within each cross-section, with Br strongly correlated with S in the samples examined. A marginal increase in Se may coincide with Pb accumulation in horn cross-sections. Annual mineralization estimates based on the relative distribution of Ca and S were used to establish a tentative timeline for horn growth, with each timeline linked to the pattern of Pb accumulation in the corresponding horn cross-section sample.
Following ingestion, absorbed Pb is eventually deposited into caprine horns, resulting in discrete accumulations or "rings." Elemental mapping by SR-μXRF clearly show Ca-rich layers that vary with annual periodicity, consistent with previous reports of horn mineralization. Localized enrichment of Cu, Zn, Br and S appear to coincide with the keratinized regions related to the annual growth ring pattern in horns. Spatial analysis of horns for Pb accumulation may be useful as a qualitative marker of time-resolved exposures that may reflect specific periods of acute Pb absorption.
本研究的主要目的是研究铅（Pb）在经 Pb 处理的山羊角中的摄取和分布，并探讨其与历史 Pb 给药记录之间可能存在的联系。角是一种角质化物质，以离散的增量生长，具有保留过去环境暴露历史记录的潜力。虽然以前的研究利用了这种潜力来研究角中的环境和生物学现象，但从未探索过 Pb 的摄取。
从三只先前用于生产纽约州能力验证计划血液铅参考材料的山羊死后收集角。这些动物在 5 到 8 年的时间里定期口服给予醋酸铅胶囊。使用康奈尔同步加速器光源（CHESS）上的同步辐射诱导微 X 射线荧光光谱法（SR-μXRF）对来自每只动物的角横截面进行分析。
通过 SR-μXRF 获得了 Pb、Ca、S、Se 和另外三个元素（Br、Zn 和 Cu）的元素分布图谱，以质量分数（痕量元素为μg/g，Ca 和 S 为 mg/g）报告定量值。在分析的每个角样本中，Pb 的积累明显可见为一系列狭窄的“环”。Ca、S、Br、Zn 和 Cu 等元素也在每个横截面内检测为离散环，在检查的样品中 Br 与 S 强烈相关。角横截面上 Se 的微量增加可能与 Pb 的积累同时发生。基于 Ca 和 S 的相对分布估计的年度矿化量用于建立角生长的暂定时间表，每个时间表都与相应角横截面样本中 Pb 积累的模式相关联。
摄入后，吸收的 Pb 最终沉积到山羊角中，导致离散的积累或“环”。SR-μXRF 的元素映射清楚地显示了富含 Ca 的层，这些层随年度周期性而变化，与以前对角矿化的报道一致。Cu、Zn、Br 和 S 的局部富集似乎与角中与年度生长环模式相关的角蛋白化区域同时发生。角中 Pb 积累的空间分析可能是一种定性标记，用于反映特定时期急性 Pb 吸收的时间分辨暴露。
