Inhalation Dosimetry/Exposure Index of Fiber Aerosol

描述（由申请人提供）：暴露于空气中的石棉和 人造玻璃纤维（MMVFS）增加肺癌的发病率， 石棉沉着病和间皮瘤。存款在支气管和肺泡的纤维 区域，随后转移到薄壁组织，被认为是 导致这些疾病的发展。物理化学性质 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因素。因为吸入是主要的 暴露途径，呼吸道中的沉积模式作为 纤维尺寸的函数是理解纤维尺寸的新信息， 呼吸剂量学和确定健康防护照射指数 目的在人类志愿者中进行的纤维沉积的对照研究并不 因为道德问题。然而，总的和区域的证词 已经从死后测量中估计了吸入纤维的数量， 建模和动物毒性研究。越来越多的数学沉积 模型已被用于评估吸入MMVFS的剂量测定。然而，在这方面， 目前用于人体呼吸道中纤维的肺剂量测定模型是 基于理论方程，这些方程尚未得到实验验证 数据本建议有三个目标：（1）开发实验 关于纤维气溶胶作为纤维的函数的沉积的信息 直径和长度在现实的人类呼吸道复制品，（2）， 验证和改进人体肺部纤维剂量估计的预测， 经验数据以及计算流体动力学技术，以及（3） 基于纤维渗透数据定义尺寸选择性暴露指数。 因为吸入纤维引起的肺部疾病发生在支气管， 肺泡和近缘区，胸部部分定义为 必须确定微粒穿透喉部到达肺部 并将由本研究中获得的实验数据定义。这 研究将产生关于吸入纤维剂量测定的基本信息 在人肺中，用于改进的数学肺沉积模型的数据，以及 用于暴露评估的胸部纤维分数的定义。 基于这种尺寸选择定义的采样装置可以在 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.