Langer A M, Nolan R P
Ann Occup Hyg. 1994 Aug;38(4):427-51, 407. doi: 10.1093/annhyg/38.4.427.
Chrysotile formation arises through serpentinization of ultramafics and silicified dolomitic limestones. Rock types tend to control the trace metal content and both the nature and amounts of admixed minerals in the ore, such as fibrous brucite (nemalite) and tremolite. Some associated minerals and trace metals are thought to play a role in biological potential. Tremolite, one of the important associated minerals, may occur with different morphological forms, called habits. These habits range from asbestiform (tremolite asbestos) to common blocky or non-fibrous form (tremolite cleavage fragments). The latter is most common in nature. Tremolite in chrysotile ore varies in habit and concentration, both factors determining the degree of risk following inhalation. Tremolite fibre is thought to be important in relation to the occurrence of mesothelioma. Chrysotile fibrils may vary in diameter. Dust clouds generated following manipulation vary in fibre number and surface area. Chrysotile fibres exhibit a range of physical characteristics. The fibre may be non-flexible ('stiff') and low in tensile strength ('brittle'), and may lack an ability to curl. This fibre, referred to as 'harsh', sheds water more quickly than its curly, flexible 'soft' variety. The behaviour of the harsh fibres is more amphibole-like and their splintery nature suggests an enhanced inhalation potential. Slip fibre ore from Canada tends to contain more fibrous brucite (nemalite) than cross-fibre ore in the same mine. Industrial manipulation, which includes chemical treatment, heating and milling, may impart new surface properties to chrysotile dusts. Biological potential may be enhanced (opening of fibre bundles) or reduced (disruption of surface bonds and lessened ability to interact with organic moieties). Leaching of magnesium from chrysotile occurs at a pH less than about 10. Chrysotile has been demonstrated to lose magnesium in vivo and undergo clearance from the lung. The biological potential of magnesium-depleted chrysotile is much reduced, or even eliminated. Reduction of mesothelioma-inducing and cytotoxic potential has been observed and quantified experimentally. Use of chrysotile products in high-temperature environments may heat the mineral to the point where it undergoes alteration of properties, especially by dehydroxylation. Chrysotile ore may vary in properties and associated minerals: it may form aerosols with different size distributions, especially fibre/fibril diameters and surface areas; it may be associated with varying quantities of tremolite (with differing habits); it may be manipulated both industrially and environmentally to yield surfaces with different properties and, hence, differing biological potentials. Chrysotile's properties may vary from place to place and among different user industries.
温石棉的形成源于超镁铁岩和硅化白云质灰岩的蛇纹石化作用。岩石类型往往控制着痕量金属含量以及矿石中混合矿物的性质和数量，如纤维状水镁石（纤水镁石）和透闪石。一些伴生矿物和痕量金属被认为在生物活性方面发挥作用。透闪石是重要的伴生矿物之一，可能以不同的形态出现，即习性。这些习性范围从石棉状（透闪石石棉）到常见的块状或非纤维状形态（透闪石解理碎片）。后者在自然界中最为常见。温石棉矿石中的透闪石在习性和浓度上存在差异，这两个因素决定了吸入后的风险程度。透闪石纤维被认为与间皮瘤的发生有关。温石棉纤维的直径可能不同。操作过程中产生的粉尘云在纤维数量和表面积方面存在差异。温石棉纤维具有一系列物理特性。这种纤维可能不灵活（“硬”）且抗拉强度低（“脆”），可能缺乏卷曲能力。这种被称为“粗糙”的纤维比卷曲、灵活的“柔软”纤维品种排水更快。粗糙纤维的行为更类似于闪石，其片状性质表明其吸入潜力增强。来自加拿大的滑石棉矿石往往比同一矿山的横纤维矿石含有更多的纤维状水镁石（纤水镁石）。包括化学处理、加热和研磨在内的工业操作可能会赋予温石棉粉尘新的表面特性。生物活性可能增强（纤维束打开）或降低（表面键断裂以及与有机部分相互作用的能力减弱）。在pH值小于约10时，温石棉会发生镁的浸出。已证明温石棉在体内会失去镁并从肺部清除。镁缺失的温石棉的生物活性会大大降低，甚至消除。实验观察并量化了间皮瘤诱导和细胞毒性潜力的降低。在高温环境中使用温石棉产品可能会使矿物加热到其性质发生改变的程度，尤其是通过脱羟基作用。温石棉矿石在性质和伴生矿物方面可能存在差异：它可能形成具有不同尺寸分布的气溶胶，尤其是纤维/纤维束直径和表面积；它可能与不同数量的透闪石（具有不同习性）相关联；它可能在工业和环境中进行处理，以产生具有不同性质、从而具有不同生物活性的表面。温石棉的性质可能因产地和不同用户行业而异。
