Bernstein D M, Drew R T, Kuschner M
Environ Health Perspect. 1980 Feb;34:47-57. doi: 10.1289/ehp.803447.
A number of studies have shown that glass fibers induce both malignant mesothelioma and fibrosis in rats and that these reactions may be primarily a function of the physical properties of the fiber. However, these studies were carried out with fibers having broad size distributions and used methods of administration which bear little resemblance to the way man is exposed. To better characterize the health effects of glass fibers, techniques have been developed to expose rats to glass fibers of defined sizes by intratracheal instillation of aqueous suspensions and by "nose only" inhalation exposure, and to determine the deposition, translocation, and ultimate fate of these fibers in the rat. The fibers have known size distributions with geometric mean diameters of 1.5 micrometers (sigma g = 1.1) and lengths of either 5 micrometers (sigma g = 1.49) or 60 micrometers (sigma g = 3.76). The fibers have been activated with neutron irradiation. Of the several resulting radionuclides, 65Zn appeared to be the most suitable for long-term clearance studies by use of in vivo whole body radioassay techniques. A fluidized bed aerosol generator has been developed to expose rats by "nose only" inhalation to approximately 500 fibers/cm3. The generator and exposure system permits reuse of fibers which pass through the exposure chamber and produces no significant alteration of the fiber size distribution. Rats were exposed by intratracheal instillations to 20 mg of the longer fibers and to equal numbers (2 mg) and equal mass (20 mg) of the shorter fibers. Through approximately 19 weeks little difference was observed in the whole rat clearance rate of long versus short fibers in the initial exposure group. Histopathology, however, showed differences at this time with the short fibers apparently successfully phagocytized by alveolar macrophages and cleared to the lymph nodes, while the long fibers were not.
多项研究表明，玻璃纤维可在大鼠体内诱发恶性间皮瘤和纤维化，且这些反应可能主要取决于纤维的物理特性。然而，这些研究使用的纤维尺寸分布较宽，给药方式与人类的接触方式几乎没有相似之处。为了更好地描述玻璃纤维对健康的影响，已开发出相关技术，通过气管内滴注水性悬浮液和“仅经鼻”吸入暴露的方式，使大鼠接触特定尺寸的玻璃纤维，并确定这些纤维在大鼠体内的沉积、转运及最终归宿。这些纤维具有已知的尺寸分布，几何平均直径为1.5微米（几何标准差σg = 1.1），长度分别为5微米（σg = 1.49）或60微米（σg = 3.76）。这些纤维已用中子辐照进行了活化处理。在产生的几种放射性核素中，65Zn似乎最适合通过体内全身放射性测定技术进行长期清除研究。已开发出一种流化床气溶胶发生器，通过“仅经鼻”吸入的方式使大鼠接触约500根/立方厘米的纤维。该发生器和暴露系统可重复使用通过暴露室的纤维，且不会使纤维尺寸分布发生显著改变。通过气管内滴注，使大鼠接触20毫克较长的纤维以及数量相等（2毫克）、质量相等（20毫克）的较短纤维。在最初的暴露组中，经过约19周的时间，未观察到长纤维和短纤维在大鼠体内的整体清除率有明显差异。然而，组织病理学显示，此时存在差异，短纤维显然已被肺泡巨噬细胞成功吞噬并清除至淋巴结，而长纤维则未被清除。
