Source identification of lead exposure by lead isotopic measurement in human nails and hair

人体头发或指甲的铅同位素比值有望成为通过与环境样品的铅同位素比值进行比较来区分人体铅暴露源的有用手段。收集人体组织很困难。头皮头发和指甲容易收集，对人体危害最小。本研究探讨了LA/ICP-MS同位素测量方法，并对铅同位素比值鉴定人体铅来源的可能性进行了评价。激光系统由一个脉冲Nd: YAG激光器组成，该激光器与ICP-MS耦合。样品的铅同位素比率的测量值通过NIST标准参考物质981铅的认证值进行归一化。作为第一步标准参考物质，BCR 397人的头发被压成颗粒状并安装在双面胶带上作为测量样品（称为胶带样品）。颗粒样品的同位素测量精度高于纸带样品。用上述方法对头皮毛发进行预处理后的同位素测定。分析前有必要洗头。用不同的溶剂依次清洗头皮毛发：丙酮三次水-丙酮。洗后的样品用暖空气干燥，并在2000℃下灰化。对BCR标准人发样品和头皮发样品进行高压氧燃烧后样品溶液的ICP-MS测定。本研究收集的邻近地区妇女头皮头发铅同位素比值的差异不能被认为是显著的。但我们可以区分同位素比值与国外文献报道的同位素比值。

The lead isotopic ratio of human hair or nails is expected to be a useful means for discriminating the source of lead exposure to human body by comparison with that of environmental samples. It is difficult to collect human tissue. Scalp hair and nails are easy to collect with minimal hazard to human. In this study we investigated the isotopic measurement by LA/ICP-MS and evaluated the possibility for identifying the source of human lead by lead isotopic ratio. Laser system consists of a pulsed Nd : YAG laser, which is coupled to the ICP-MS. A measured value of the lead isotopic ratio of the sample was normalized by the certified value of that of the NIST standard reference material 981 lead. As a first step standard reference material BCR 397 Human Hair was used as a measurement sample by pressed into a form of pellet and mounted on the double sided tape(called tape sample). The isotopic measurements of pellet sample were capable greater precision than tape sample. The isotopic measurement of scalp hair was carried out above method after pre-treatment. It is necessary to wash the hair prior to analysis. Scalp hair was washed with different solvents in sequence : acetone three times of water - acetone. The washed samples were dried with warm air, and ashed at 2000C for lh. BCR standard human hair sample and scalp hair sample also were measured by ICP-MS for sample solution after high pressure oxygen combustion. The differences in lead isotopic ratios of scalp hair collected from some women lived in adjoining area measured of this study cannot be regarded as significant. But we can discriminate between isotopic ratio and that reported in reference literature collected foreign area.