"G. Scansetti" Interdepartmental Center for Studies on Asbestos and other Toxic Particulates, Università di Torino, Torino, Italy.
Chem Res Toxicol. 2012 Apr 16;25(4):884-94. doi: 10.1021/tx2005019. Epub 2012 Apr 5.
High aspect-ratio nanomaterials (HARNs) have recently attracted great attention from nanotoxicologists because of their similarity to asbestos. However, the actual risk associated with the exposure to nanosized asbestos, which escapes most regulations worldwide, is still unknown. Nanometric fibers of chrysotile asbestos have been prepared from two natural sources to investigate whether nanosize may modulate asbestos toxicity and gain insight on the hazard posed by naturally occurring asbestos, which may be defined as HARNs because of their dimensions. Power ultrasound was used to obtain nanofibers from two different chrysotile specimens, one from the dismissed asbestos mine in Balangero (Italian Western Alps) and the other from a serpentine outcrop in the Italian Central Alps. Electron microscopy, X-ray diffraction, and fluorescence spectroscopy revealed that the procedure does not affect mineralogical and chemical composition. Surface reactions related to oxidative stress, free radical generation, bioavailability of iron, and antioxidant depletion, revealed a consistent reduction in reactivity upon reduction in size. When tested on A549 human epithelial cells, the pristine but not the nanosized fibers proved cytotoxic (LDH release), induced NO production, and caused lipid peroxidation. However, nanofibers still induced some toxicity relevant oxidative stress activity (ROS production) in a dose-dependent fashion. The reduction in length and a lack of poorly coordinated bioavailable iron in nanochrysotile may explain this behavior. The present study provides a one-step procedure for the preparation of a homogeneous batch of natural asbestos nanofibers and shows how a well-known toxic material might not necessarily become more toxic than its micrometric counterpart when reduced to the nanoscale.
高长径比纳米材料（HARNs）因其与石棉相似而引起了纳米毒理学家的极大关注。然而，与纳米级石棉（这种石棉逃脱了全球大多数法规的限制）相关的实际风险仍然未知。为了研究纳米尺寸是否会调节石棉毒性，并深入了解可能被定义为 HARNs 的天然存在的石棉所带来的危害，我们从两个天然来源制备了蛇纹石石棉的纳米纤维。我们使用超声功率来从两个不同的蛇纹石样本中获得纳米纤维，一个来自已废弃的意大利西阿尔卑斯山巴朗热罗石棉矿，另一个来自意大利中阿尔卑斯山的蛇纹石露头。电子显微镜、X 射线衍射和荧光光谱表明，该程序不会影响矿物学和化学成分。与氧化应激、自由基生成、铁的生物利用度和抗氧化剂耗竭相关的表面反应表明，尺寸减小会导致反应性一致降低。当将原始纤维和纳米纤维分别用于 A549 人上皮细胞时，只有原始纤维而非纳米纤维具有细胞毒性（LDH 释放），可诱导一氧化氮（NO）生成并引起脂质过氧化。然而，纳米纤维仍以剂量依赖的方式诱导一些与氧化应激相关的毒性活性（ROS 产生）。纳米蛇纹石中长度的缩短和缺乏配位不良的生物可利用铁可能解释了这种行为。本研究提供了一种制备均质天然石棉纳米纤维批料的一步法，并表明当将已知的有毒物质减小到纳米尺寸时，它不一定会比其微米级对应物更具毒性。
