Interdepartmental Center G Scansetti for Studies on Asbestos and Other Toxic Particulates and Department of Chemistry IFM and Interdipartmental Centre for Nanostructured Interfaces and Surfaces, Universita degli Studi di Torino, Via Pietro Giuria 7, 10125 Torino, Italy.
Chem Res Toxicol. 2010 Mar 15;23(3):620-9. doi: 10.1021/tx900369x.
"Vitreous silica" is a particular form of amorphous silica, much neglected in experimental studies on silica toxicity. In spite of the incorrect term "quartz glass", often employed, this material is fully amorphous. When reduced in powdered form by grinding, the particulate appears most close to workplace quartz dust but, opposite to quartz, is not crystalline. As silicosis and lung cancer are also found among workers exposed to "quartz glass", the question arises of whether crystallinity is the prerequisite feature that makes a silica dust toxic. We compare here the behavior of comminuted quartz, vitreous silica, and monodispersed silica spheres, as it concerns surface reactivity and cellular responses involved in the accepted mechanisms of silica toxicity. Care was taken to choose samples of extreme purity, to avoid any effect due to trace contaminants. Quartz and vitreous silica, opposite to silica spheres, show irregular particles with sharp edges, stable surface radicals, and sustained release of HO(*) radicals via a Fenton-like mechanism. The evolution of the heat of adsorption of water as a function of coverage shows with quartz and vitreous silica a similar pattern of strong hydrophilic sites, nearly absent on the other silica specimen. When tested on a macrophage cell line (MH-S), vitreous silica and pure quartz, but not the monodispersed silica spheres, showed a remarkable potency in cytotoxicity, nitric oxide synthase activation and release of nitrite, and tumor necrosis factor-alpha production, suggesting a common behavior in inducing an oxidative stress. All of the above features appear to indicate that crystallinity might not be a necessary prerequisite to make a silica particle toxic.
“玻璃体二氧化硅”是一种特殊的无定形二氧化硅，在二氧化硅毒性的实验研究中被严重忽视。尽管常使用“石英玻璃”这一不正确的术语，但这种材料是完全无定形的。当以粉末形式通过研磨还原时，颗粒状物质最接近工作场所的石英粉尘，但与石英相反，它不是结晶的。由于接触“石英玻璃”的工人也会出现矽肺和肺癌，因此就出现了这样一个问题：结晶度是否是使二氧化硅粉尘具有毒性的必要特征。我们在这里比较了粉碎的石英、玻璃体二氧化硅和单分散二氧化硅球的行为，因为它涉及到表面反应性和细胞反应，这些反应涉及到公认的二氧化硅毒性机制。我们特别注意选择极端纯净的样品，以避免任何由于痕量污染物引起的影响。与二氧化硅球相反，石英和玻璃体二氧化硅显示出具有锐利边缘的不规则颗粒，稳定的表面自由基，并通过类 Fenton 机制持续释放 HO(*)自由基。作为覆盖度的函数的水的吸附热的演化表明，在石英和玻璃体二氧化硅上具有类似的强亲水性位的模式，而在其他二氧化硅样品上几乎不存在。在巨噬细胞系（MH-S）上进行测试时，玻璃体二氧化硅和纯石英，但不是单分散二氧化硅球，显示出显著的细胞毒性、一氧化氮合酶激活和亚硝酸盐释放以及肿瘤坏死因子-α产生的能力，表明在诱导氧化应激方面具有共同的行为。所有上述特征似乎表明，结晶度可能不是使二氧化硅颗粒具有毒性的必要前提。
