接触铀气溶胶的核工业工人可能面临肾损伤和辐射诱发癌症的风险。这就需要进行完善的剂量和风险评估，通过在 ICRP 人类呼吸道模型中使用特定材料的吸收参数可以大大改善这种评估。本研究的重点是评估缓慢溶解速率（ss，d-1），这是一个很难通过体外溶解研究量化的参数，特别是对于更难溶的铀化合物。停止慢性吸入暴露后对尿液排泄进行长期随访可以更好地估计慢速溶解。在这项研究中，两名曾在核燃料制造厂工作超过 20 年的工人在长达 6 年的时间里定期提供尿液样本。一名人员曾在已知存在二氧化铀 (UO2) 和八氧化三铀 (U3O8) 的造粒车间工作。第二个人在转化车间工作，车间内存在多种化合物，包括六氟化铀 (UF6)、二氧化铀 (UO2)、碳酸铀酰铵和 AUC [UO2CO3·2(NH4)2CO3]。两名工人还可以获得工作期间尿液中铀浓度的数据。通过对尿液数据应用非线性最小二乘回归拟合来表征尿液中铀的每日排泄量。材料特定参数，例如活性中位空气动力学直径 (AMAD)、呼吸道吸收参数、快速分数 (fr,)、快速溶出速率 (sr, d-1) 和慢速溶出速率 (ss, d-1) ）和消化道转移因子（fA）从之前的工作中获得，以及默认的吸收类型，应用于尿液数据，并评估拟合优度。此后进行摄入量估计和剂量计算。对于前制粒工人来说，清除半衰期为 662 ± 100 d (ss = 0.0010 d-1) 的单室模型最能代表尿液数据。对于前转换工人，采用两室模型，其中主要[初始尿排泄量 (A0) 的 93%] 快速室，半清除时间为 1.3 ± 0.4 d (sr = 0.5 d-1)，并且半衰期为 394 ± 241 d (ss = 0.002 d-1) 的次要慢室（A0 的 7%）提供了最佳拟合。前皈依工人的尿液数据与生物动力学模型的数据拟合结果表明，体外导出的实验参数（AMAD = 20 μm，fr = 0.32，sr = 27 d-1，ss = 0.0008 d-1，我们之前的工作中的 f A = 0.005）最能代表尿液数据。这导致估计摄入率为 0.66 Bq d-1。前制粒工人的尿液数据与生物动力学模型的数据拟合结果表明，实验参数（AMAD = 10 μm 和 20 μm，fr = 0.008，sr = 12 d-1，fA = 0.00019）来自我们的之前的溶出度研究采用针对尿液数据逐步优化的慢速参数 (ss = 0.0008 d-1) 给出了最佳拟合。这导致估计摄入率为 5 Bq d-1。来自体外溶出研究的实验参数为从转换车间工作退休的受试者提供了最佳的拟合，其中可以假设吸入暴露于可溶性（例如，AUC、UF6）和相对不溶性气溶胶（例如，UO2）的混合物。对于从造粒车间退休的受试者来说，该受试者接触相对不溶的气溶胶（UO2 和 U3O8），其 ss 比溶出研究中获得的高得多，可以更好地代表尿液数据，并且与报告的 UO2 的 ss 值相当。和其他研究中的 U3O8。这意味着不溶性物质的体外溶出研究可能是不确定的。当评估尿液数据的回顾性拟合结果时，很明显，停止暴露后采集的尿液样本波动较小。停止暴露后长期跟踪铀排泄是确定吸收参数的一个很好的替代方法，并且可以被认为是确定更难溶材料的慢速的最可行的方法。版权所有 © 2024 作者。由 Wolters Kluwer Health, Inc. 代表健康物理学会出版。

Nuclear industry workers exposed to uranium aerosols may risk kidney damage and radiation-induced cancer. This warrants the need for well-established dose and risk assessments, which can be greatly improved by using material-specific absorption parameters in the ICRP Human Respiratory Tract Model. The present study focuses on the evaluation of the slow dissolution rate (ss, d-1), a parameter that is difficult to quantify with in vitro dissolution studies, especially for more insoluble uranium compounds. A long-term follow-up of urinary excretion after the cessation of chronic inhalation exposure can provide a better estimate of the slow-rate dissolution. In this study, two workers, previously working for >20 y at a nuclear fuel fabrication plant, provided urine samples regularly for up to 6 y. One individual had worked at the pelletizing workshop with the known presence of uranium dioxide (UO2) and triuranium octoxide (U3O8). The second individual worked at the conversion workshop where multiple compounds, including uranium hexafluoride (UF6), uranium dioxide (UO2), ammonium uranyl carbonate, and AUC [UO2CO3·2(NH4)2CO3], are present. Data on uranium concentration in urine during working years were also available for both workers. The daily excretion of uranium by urine was characterized by applying non-linear least square regression fitting to the urinary data. Material-specific parameters, such as the activity median aerodynamic diameter (AMAD), the respiratory tract absorption parameters, rapid fraction (fr,), rapid dissolution rate (sr, d-1), and slow dissolution rate (ss, d-1) and alimentary tract transfer factor (fA) acquired from previous work along with default absorption types, were applied to urine data, and the goodness of fit was evaluated. Thereafter intake estimates and dose calculations were performed. For the ex-pelletizing worker, a one-compartment model with a clearance half-time of 662 ± 100 d (ss = 0.0010 d-1) best represented the urinary data. For the ex-conversion worker, a two-compartment model with a major [93% of the initial urinary excretion (A0)] fast compartment with a clearance half-time of 1.3 ± 0.4 d (sr = 0.5 d-1) and a minor (7% of A0) slow compartment with a half-time of 394 ± 241 d (ss = 0.002 d-1) provided the best fit. The results from the data-fitting of urinary data to biokinetic models for the ex-conversion worker demonstrated that in vitro derived experimental parameters (AMAD = 20 μm, fr = 0.32, sr = 27 d-1, ss = 0.0008 d-1, f A = 0.005) from our previous work best represented the urinary data. This resulted in an estimated intake rate of 0.66 Bq d-1. The results from the data-fitting of urinary data to biokinetic models for the ex-pelletizing worker indicated that the experimental parameters (AMAD = 10 μm and 20 μm, fr = 0.008, sr = 12 d-1, fA = 0.00019) from our previous dissolution studies with the slow rate parameter step-wise optimized to urine-data (ss = 0.0008 d-1) gave the best fit. This resulted in an estimated intake rate of 5 Bq d-1. Experimental parameters derived from in vitro dissolution studies provided the best fit for the subject retired from work at the conversion workshop, where inhalation exposure to a mix of soluble (e.g., AUC, UF6) and relatively insoluble aerosol (e.g., UO2) can be assumed. For the subject retired from work at the pelletizing workshop, which involved exposure to relatively insoluble aerosols (UO2 and U3O8), a considerably higher ss than obtained in dissolution studies provided a better representation of the urinary data and was comparable to reported ss values for UO2 and U3O8 in other studies. This implies that in vitro dissolution studies of insoluble material can be uncertain. When evaluating the results from the retrospective fitting of urine data, it is evident that the urine samples acquired after cessation of exposure provide less fluctuation. Long-term follow-up of uranium excretion after cessation of exposure is a good alternative for determining absorption parameters and can be considered the most viable way for determining the slow rate for more insoluble material.Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the Health Physics Society.