ABSTRACT

Hair and/or nail analyses are sometimes used in biomonitoring studies due to the convenience of sample collection, storage, and transport, as well as the potential to assess past exposures to toxic metals, such as lead (Pb). However, the validity of Pb measurements in these keratinized matrices as biomarkers of absorbed dose remains unclear. The aim of this study was to examine the uptake of Pb into horns harvested postmortem from 11 goats that received a cumulative oral dose of up to 151 g Pb acetate over a period of 1–11 years as part of a long-term blood Pb proficiency testing program. Uptake of Pb into keratinized horn was compared to the corresponding underlying bony horn core, which, as part of the bone compartment, provided a measure of absorbed Pb dose. Two complementary analytical techniques were used to assess Pb: X-Ray Fluorescence (XRF) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Detectable amounts of Pb were found in all keratinized horn samples (0.45–6.6 µg/g) and in all but one bony core sample (1.4–68 µg/g). In both bony core and keratinized horn samples, Pb accumulation increased with dose over a low-to-moderate cumulative-dose interval, consistent with previous observations, but plateaued at higher doses. Significant associations were observed between Pb in keratinized horn and bony core samples particularly with XRF measurements, which represent the surface bone compartment. These findings provide evidence that Pb is excreted in keratinized tissues but reflects only a small fraction of the absorbed Pb dose, likely transferred from underlying bone tissue.

摘要

头发和/或指甲分析有时用于生物监测研究，因为样本收集、储存和运输都很方便，并且有可能评估过去接触有毒金属（如铅 (Pb)）的情况。然而，这些角化基质中铅测量作为吸收剂量生物标志物的有效性仍不清楚。本研究的目的是检查死后收获的角中 Pb 的吸收情况。作为长期血液铅水平测试计划的一部分，11 只山羊在 1-11 年的时间内接受了高达 151 克的醋酸铅累积口服剂量。将 Pb 吸收到角化角与相应的底层骨角核进行比较，后者作为骨隔室的一部分，提供了吸收 Pb 剂量的量度。两种互补的分析技术用于评估 Pb：X 射线荧光 (XRF) 和电感耦合等离子体质谱 (ICP-MS)。在所有角化角样品 (0.45–6.6 µg/g) 和除一个骨芯样品 (1.4–68 µg/g) 之外的所有样品中都发现了可检测量的 Pb。在骨核和角化角样品中，Pb 积累在低至中等累积剂量间隔内随剂量增加，这与之前的观察结果一致，但在较高剂量下趋于稳定。观察到角化角和骨芯样品中的 Pb 之间存在显着关联，尤其是 XRF 测量值，代表表面骨隔室。这些发现提供了证据，表明 Pb 会在角化组织中排泄，但仅反映了吸收的 Pb 剂量的一小部分，很可能是从下面的骨组织转移。