The USEPA issued the “Framework for Metal Risk Assessment” in 2007, recognizing that human and environmental exposure to metals and metalloids (MMEs) poses challenges risk assessment. Inhalation of aerosols containing MMEs is a primary pathway for exposure in the occupational setting, for consumer exposure, and to general population exposure associated with point-source emissions or ambient sources. The impacts of inhalation can be at the point of deposition (local exposure) or may manifest after uptake into the body (systemic exposure). Both local and systemic exposure can vary with factors that determine the regional deposition of MME-containing aerosols. Aerosol characteristics such as particle size combine with species-specific characteristics of airway morphology and lung function to modulate the deposition and clearance of MME particulates. In contrast to oral exposure, often monitored by measuring MME levels in blood or urine, inhalation exposure can produce local pulmonary impacts in the absence of significant systemic distribution. Exposure assessment for nutritionally essential MMEs can be further complicated by homeostatic controls that regulate systemic MME levels. Predictions of local exposure can be facilitated by computer models that estimate regional patterns of aerosol deposition, permitting calculation of exposure intensity in different regions of the respiratory tract. The utility of deposition modeling has been demonstrated in assessments of nutritionally essential MMEs regulated by homeostatic controls and in the comparison of results from inhalation studies in experimental animals. This facilitates extrapolation from animal data to humans and comparisons of exposures possessing mechanistic linkages to pulmonary toxicity and carcinogenesis. Pulmonary deposition models have significantly advanced and have been applied by USEPA in evaluations of particulate matter. However, regional deposition modeling has yet to be incorporated into the general guidance offered by the agency for evaluating inhalation exposure. Integr Environ Assess Manag 2023;00:1–13. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

中文翻译：

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吸入暴露后局部和全身接触金属和类金属的建模：建议更新 USEPA 金属框架

USEPA 于 2007 年发布了“金属风险评估框架”，认识到人类和环境接触金属和准金属 (MME) 给风险评估带来了挑战。吸入含有 MME 的气溶胶是职业环境、消费者接触以及与点源排放或环境源相关的一般人群接触的主要途径。吸入的影响可能发生在沉积点（局部暴露），也可能在摄入体内后显现（全身暴露）。局部和全身暴露可能因决定含 MME 气溶胶区域沉积的因素而异。颗粒大小等气溶胶特征与气道形态和肺功能的物种特异性特征相结合，可调节 MME 颗粒的沉积和清除。与通常通过测量血液或尿液中的 MME 水平来监测的口服暴露相比，吸入暴露在没有显着的全身分布的情况下会产生局部肺部影响。调节全身 MME 水平的稳态控制可能会使营养必需 MME 的暴露评估变得更加复杂。计算机模型可以估计气溶胶沉积的区域模式，从而有助于计算呼吸道不同区域的暴露强度，从而有助于预测局部暴露。沉积模型的实用性已在评估由稳态控制调节的营养必需 MME 以及比较实验动物吸入研究的结果中得到证明。这有助于从动物数据推断到人类，并比较与肺毒性和致癌作用具有机械联系的暴露。肺沉积模型已取得显着进展，并已被美国环保署应用于颗粒物评估。然而，区域沉积模型尚未纳入该机构提供的评估吸入暴露的一般指南中。整体环境评估管理2023；00:1–13。© 2023 作者。综合环境评估和管理由 Wiley periodicals LLC 代表环境毒理学与化学学会 (SETAC) 出版。