高污染环境肺部沉降特性研究

 2022-04-02 10:04

论文总字数:44253字

摘 要

职业性呼吸系统疾病主要是由于劳动者在职业活动中长期接触粉尘引起的,包括尘肺、慢阻肺等。据国际卫生组织(WHO)报告,从2000年开始,全球每年约有300万人死于慢阻肺,而12%的慢阻肺病例可归因于职业风险。尽管政府以法律形式规定了工作场所的职业卫生要求,近十年职业性呼吸系统疾病的发病率在中国仍居高不下。

为研究高污染职业环境中颗粒物在肺部的沉降特性,本研究搭建了一个体外测量系统,其核心为包含人面部、G5支气管以上的上呼吸道和肺部边界的真实人体呼吸道模型,利用采样泵在呼吸道模型下游产生恒定流量,还原工人在正常工作时的吸气过程。利用该体外测量系统,在正常持续性生产的机械加工厂房内进行测量,获取真实职业环境中人体的吸入暴露浓度,并计算得到上呼吸道的沉降比和下呼吸道的有效剂量浓度,分别描述颗粒物在上、下呼吸道的沉降特性,将上呼吸道的总沉降比与ICRP模型的计算结果进行对比,观察分析本研究所使用的基于单肺建立的呼吸道模型与被广泛应用的平均人模型之间的异同之处。另外,对比个体在暴露前后血常规和尿常规的检验结果,初步表征短期暴露可能带来的健康效应。

本研究为首次使用呼吸道模型在真实厂房环境中进行体外测量。测量结果证明,所用体外测量系统和测量方案可简单地测得人体下呼吸道的有效剂量浓度,且测量结果具有可重复性,与平均人模型的预测结果也具有一致性。这有利于未来进一步建立应用于高污染职业环境的人体暴露-剂量-健康效应评估体系,并可推广至一般大气环境和其他室内环境。

关键字:职业性呼吸系统疾病,呼吸道模型,有效剂量

ABSTRACT

Occupational respiratory diseases, including pneumoconiosis, chronic obstructive pulmonary disease (COPD), etc., are triggered mainly because of labours’ long-term exposure to dusts and particulates at work. According to World Health Organization(WHO), about 3 million people died of COPD per year since year 2000,and 12 percent of people who suffer from COPD should put the blame on occupational risks. Although the government has enacted laws to mandate workplaces meet occupational health requirements, the morbidity of occupational respiratory diseases remained high in China in the past decade.

In order to characterize particles’ deposition pattern in human lungs in heavily polluted occupational environment, we established an in-vitro measurement system, of which the key component is an airway replica based on real human respiratory tracts, which includes the face, upper airways down to G5 and the lungs. Sampling pumps were used to generate steady flow downstream of the replica, in order to simulate workers’ inhalation process during work. With the employment of this system, the measurements were conducted in a machining workshop running normally. Thus, workers’ exposure concentration was measured, and the deposition fraction of upper airways as well as the applied dose concentration of lower airways was obtained and utilized as for characterizing particles’ deposition pattern in upper and lower airways, respectively. We compared the total deposition fraction of upper airways gained in our measurements with the results calculated using ICRP model to see how the single lung model we used is different from or similar to the widely-used model. Furthermore, both of the volunteers’ blood and urine were examined before and after exposure, and the results were compared to roughly find out the health effects related to the short-term exposure in factory.

It is the first time that the airway replica was employed in in-vitro measurements conducted in a normally running factory. The in-vitro measurement system proves to have the capacity of measuring the applied dose concentration of lower airways easily. The results we gained are repeatable, and match with the results of the widely-used ICRP model. In a word, our study contributes to the establishment of human exposure-dose-health effect evaluation system in heavily polluted occupational environment. The in-vitro measurement system may be promoted to other kinds of indoor environment and natural environment as well.

KEY WORDS: occupational respiratory disease, airway replica, applied dose

目 录

摘 要 I

ABSTRACT II

第一章 引言 1

第二章 实验方法 4

2.1 气道几何数据提取 4

2.2 快速原型技术分析 6

2.3 测量方案 7

2.3.1吸入暴露量测量 7

2.3.2下呼吸道有效剂量测量 9

2.3.3测量流程 19

第三章 实验结果 20

3.1 吸入暴露浓度 20

3.2 上呼吸道总沉降比和下呼吸道有效剂量浓度 24

3.2.1初始阶段 24

3.2.2稳定阶段 30

3.3 健康效应 39

第四章 结论 40

参考文献(References) 42

致 谢 45

第一章 引言

职业病,是指企业、事业单位和个体经济组织等用人单位的劳动者在职业活动中,因接触粉尘、放射性物质和其他有毒、有害因素而引起的疾病。国际劳工组织(International Labour Organization, ILO)指出,每天全球都有7500人因不安全或不健康的工作环境而死亡,其中6500例由职业病引起,而全球每年约有1亿6千万新增的职业病例。为改善劳动者的健康状况,国际卫生组织(World Health Organization, WHO)联合国际劳工组织等国际组织和研究机构,自2008年起,实行了长达十年的工人健康全球行动计划(Global Plan of Action on Workers’ Health(2008-2017)),推动职业性健康效应监测体系的建立和职业健康保护标准的制定[1]。在我国,职业病高发的现象也早已引起国家高度关注[2],于2001年颁布的《中华人民共和国职业病防治法》[3]以法律形式对产生职业病危害的工作场所提出了职业卫生要求,并详细规定应使工作场所中“职业病危害因素的强度或者浓度符合国家职业卫生标准”。根据我国国家卫生健康委员会近十年发布的全国职业病报告,自2010年以来,全国每年报告新发职业病25000-30000例左右,其中呼吸系统疾病占比在85-90%之间波动,每年新发25000例左右,约为2009年(14495例)时的两倍。根据我国《职业病分类和目录》[4],职业性呼吸系统疾病主要包括13种尘肺病和过敏性肺炎、哮喘、慢阻肺等6种其他呼吸系统疾病。目前,我国仅职业性尘肺病累计患者数就已接近百万,每年的直接经济损失达上百亿元。职业性呼吸系统疾病的发生往往和职业环境中的颗粒物浓度和种类有关,我国也以国标形式,在国家职业卫生标准《工作场所有害因素职业接触限值第1部分:化学有害因素(GBZ2.1-2007)》中给出了47种工作场所中粉尘的职业接触限值。但是颗粒物通常只有在吸入并沉降后才会产生生物效应甚至致病。从《职业病分类和目录》中给出的疾病种类不难看出,大部分职业性呼吸系统疾病都与颗粒物在人体下呼吸道的沉降有关。因此,高污染职业环境中的人体吸入暴露和下呼吸道有效剂量研究有利于未来建立应用于高污染职业环境的个体暴露-剂量-健康效应评估体系,也为日后给职业暴露个体提供精确防护奠定基础。

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