Inhalation Dosimetry/Exposure Index of Fiber Aerosol

描述(由申请人提供)：接触空气中的石棉和 人造玻璃体纤维(MMVF)会增加肺癌的发病率， 石棉肺和间皮瘤。沉积在支气管和肺泡内的纤维 随后转移到实质的区域被认为是 对这些疾病的发展负有责任。物理-化学特性 纤维的长度、直径和在肺中的耐久性是主要的 这些肺部疾病的病因学因素。因为吸气是主要的 接触途径，呼吸道中的沉积模式作为 纤维尺寸的功能是理解关键的新信息 呼吸剂量学与健康防护暴露指数的确定 目的。对志愿者体内纤维沉积的对照研究不是 出于道德方面的考虑而可用。然而，总的和区域的证词 已经从身体测量中估计了吸入纤维的数量，数学上 建模和动物毒性研究。越来越多地，数学沉积 模型已被用于评估吸入MMVFS的剂量学。然而， 目前人类呼吸道纤维的肺剂量学模型是 基于理论公式，而这些公式尚未得到实验验证 数据。这项建议有三个目标：(1)开展试验性 关于纤维状气溶胶沉积随纤维变化的信息 真实人类呼吸道复制品的直径和长度，(2)到 验证和改进纤维剂量估计在人肺中的预测 经验数据和计算流体动力学技术，以及(3) 为了定义基于光纤穿透数据的尺寸选择性曝光指数。 由于吸入纤维引起的肺部疾病发生在支气管， 肺泡区和副肺泡区，胸部部分被定义为部分 必须确定穿透喉部并到达肺部的颗粒 并将根据本研究中获得的实验数据进行定义。这 研究将产生有关吸入纤维剂量学的基本信息 在人类肺中，用于改进的肺沉积数学模型的数据，以及 用于暴露评估的胸部纤维部分的定义。 基于此尺寸选择定义的采样设备可在 改善工人暴露评估的未来。

DESCRIPTION (provided by applicant): Exposures to airborne asbestos and man-made vitreous fibers (MMVFS) increase the incidence of lung cancer, asbestosis, and mesothelioma. Fibers that deposit in the bronchial and alveolar regions, subsequently translocating to the parenchyma, are thought to be responsible for the development of these diseases. Physico-chernical properties of fibers, including length, diameter, and durability in the lung, are major factors in the etiology of these lung diseases. Because inhalation is the main route of exposure, the deposition pattern in the respiratory tract as a function of fiber dimensions is new information critical to understanding respiratory dosimetry and defining the index of exposure for health protection purposes. Controlled studies of fiber deposition in human volunteers are not available because of ethical concerns. However, total and regional depositions of inhaled fibers have been estimated from postmortem measurement, mathematical modeling, and animal toxicity studies. Increasingly, mathematical deposition models have been used to assess the dosimetry of inhaled MMVFS. However, current lung dosimetric models for fibers in the human respiratory tract are based on theoretical equations, which have not been verified with experimental data. This proposal has three objectives: (1) to develop experimental information on the deposition of fibrous aerosols as a function of fiber diameter and length in realistic human respiratory tract replicas, (2) to verify and improve the prediction of fiber dose estimate in human lungs using both empirical data as well as a computational fluid dynamic technique, and (3) to define,.a size-selective exposure index based on fiber penetration data. Because lung diseases caused by inhaled fibers occur in the bronchial, alveolar, and parachymal regions, a thoracic fraction defined as the fraction of particles penetrating the larynx and reaching the lung must be established and will be defined from experimental data obtained in this study. This research will generate essential information on the dosimetry of inhaled fibers in the human lung, data for an improved mathematical lung deposition model, and a definition of the thoracic fraction of fibers for exposure assessment. Sampling devices based on this size-selection definition can be developed in the future for improved assessment of worker exposure.