【作者】 李奕霖；

【导师】 倪师军； 张成江；

【作者基本信息】 成都理工大学 ， 环境地球化学， 2009， 博士

【摘要】 呼吸道疾病已连年列成都市居民死因首位。文献调查发现,成都市肺癌发病率年增长高达44%,此现象可能与大气污染有关。对呼吸道疾病与大气污染的相关性研究目前大都集中于大气中简单氧化物和大气颗粒物颗粒本身上,对大气颗粒物上元素的健康效应研究较少。本文依托中国地质大调查项目子课题《四川省成都经济区城市生态地球化学调查评价(200314200015)》和教育部博士点基金《成都市近地表大气尘中重金属元素的分配规律及机理研究(20060616020)》,专题研究居民呼吸道疾病与大气尘重金属元素之间的相关性。大气颗粒物中的元素通过呼吸进入人体,可能是导致呼吸道疾病的重要原因。为了论证这一观点,本文选择在成都经济区,将大气环境地球化学原理与方法应用于居民健康效应研究,寻找呼吸道疾病的元素起因。本文以近地表大气尘样品代表大气颗粒物,以肺癌和儿童哮喘代表居民呼吸道疾病,测试各个区域大气尘的元素含量(共测试20余种元素),同时统计各区域呼吸道疾病入院率,从宏观和微观两个层面,分析“大气颗粒物元素含量”和“居民呼吸道疾病发病”之间的相关性。宏观上,对整个成都经济区进行研究,比较各地区大气颗粒物元素状况和呼吸道疾病发病状况,发现重金属富集大的区域呼吸道疾病发病高;微观上,在成都市区按每平方公里设置网格,统计网格内的大气尘元素含量和呼吸道疾病入院率,通过多元回归计算各元素浓度与呼吸道疾病入院率的相关程度,结果显示,各网格中元素含量与肺癌入院率的回归结果较好,与儿童哮喘回归结果较差,Hg与两种呼吸道疾病的相关系数都最高。在以上结果的基础上,本文通过大气尘粒径分析和大气飘尘元素分析、人发元素分析、元素的致癌性检验等方法,进一步验证重金属元素与肺癌的关系:首先,证实可以用近地表大气尘元素含量代表大气颗粒物元素含量。由于近地表大气尘是粗微粒,大气颗粒物是细微粒,对近地表大气尘做了粒径分析,确认其中有细微粒的成分,证实近地表大气尘与大气颗粒物有物质上的联系。为了检验近地表大气尘和大气颗粒物的元素相关性,本文在成都市区采集了大气飘尘样品13件,测试元素Hg含量,与相同位置近地表大气尘中Hg元素含量对比,发现两者的元素分布是一致的,说明用近地表大气尘元素含量代表大气颗粒物元素含量的方法是可信的。其次,根据元素富集程度和居民健康情况的不同,在全经济区范围选取4个重点地区,采集居民人发样品,并采取肺癌确诊患者的人发,分析其中9种元素含量,揭示居民体内元素赋存状况。一方面,对比地区间大气尘重金属元素含量和居民人发元素含量;另一方面对比肺癌患者和普通人群人发元素含量。来验证大气的元素赋存是否影响居民体内元素赋存,肺癌发病与否是否伴随体内元素含量的差异。第三,对前文中发现的与肺癌有关的元素进行致癌性检验,分作两个子实验。一是选择元素Hg,以甲基汞为受试物进行单细胞凝胶电泳致突变实验,推断Hg的致癌性。二是由于烟草是已知导致肺癌的因素,采用一种新方法进行烟草燃烧过程11种元素迁移状况的研究,探究与肺癌有关的元素在吸烟过程中以多大比例转移进入气相,从而可能危害人体健康。同时有机物燃烧是向大气排放重金属的重要途径,选择烟草作为有机物样品进行燃烧过程的元素气固分配比实验,还可揭示哪些元素容易向大气富集。本文取得如下结论:(1)将大气元素地球化学的原理和方法用于居民呼吸道疾病的元素起因研究,发现近地表大气尘中有约17%的细粒子能随呼吸进入呼吸道深处,并在人体存留,发挥健康效应。定性分析和定量的多元回归计算均表明大气中的Hg、Cd、Pb、As等重金属元素与肺癌发病存在相关性,后续实验认定大气颗粒物中的Hg元素是导致肺癌的原因之一。(2)实地调查数据显示,在成都经济区范围内大气颗粒物中Hg、Cd、As、Pb等元素的富集程度高,分别达到上地壳克拉克值的58倍、35倍、20倍、17倍,这与该地区肺癌、儿童哮喘两种呼吸道疾病发病率平均年增长约20%的情况相对应。其中,德阳元素富集最大,呼吸道疾病发病率最高;而眉山元素富集最小,呼吸道疾病发病最低。说明大气颗粒物中的元素确实对健康造成影响。(3)居民人发中元素含量与环境中大气颗粒物元素含量存在对应关系,肺癌组与对照组人发中元素Hg含量存在差异,P<0.05。(4)致突变毒理实验表明甲基汞很可能是一种致癌物,香烟燃烧元素气固分配比实验也表明烟草燃烧过程中约90%的Hg元素迁移进入气相,Hg可能是吸烟致癌的又一原因。综合以上结论,本文认为,大气中以Hg为代表的Hg、Cd、Pb、As等元素可能是导致肺癌的起因之一,与居民呼吸道疾病发病有一定的联系,这些元素通常都被划入重金属范畴。降低这些元素在大气中的赋存可能是防治居民呼吸道疾病的途径之一。更多还原

【Abstract】 According to the references, respiratory diseases incidence has been rising these years, especially in Chengdu city, which rises 44% per year. Respiratory diseases have been the most mortality there. It had been concluded that the pollution acts as the main factor explaining the high incidence of respiratory diseases. Most research limited in the gas pollution such as oxide and particulate itself, paying less attention to the toxic elements. Thinking the meteorology characteristic of Chengdu area, windless and inversion, basing on the fact that toxic elements of particulate enter human body through breath and effect respiratory tract, this paper observed the relationship between respiratory diseases and the toxic elements in the air particulate. Hope to find the elements which cause respiratory diseases, this paper would give a reference to the environment study, to help to promote people’s health level.The Air Particulate Near the Surface(APNS) was collected in Chengdu area, and surveyed 22 elements contents, to be the sample which informs the elements distribution of air particulate. The medical cases of lung cancer and children asthma were collected to calculate the respiratory diseases incidence. This paper evaluated the relation between the distribution of air elements and the distribution of respiratory diseases both with the method of microcosmic and macrocosm. In macrocosm, this paper taking the whole Chengdu area as object, juxtaposed the elements and diseases levels among the six cities; In microcosmic, this paper focusing in a small area, the Chengdu downtown, cut it to be 93 squares(1km*1km), estimated the elements concentration and the respiratory diseases incidence in each square, and did Partial Least-Squares (PLS) regress between the elements and the diseases. The interrelation was found. To make sure the relation between them, three more experiments were done to examine the result, the particulate diameter analysis and the Particulate Matter in 10um(PM10), hair elements analysis, elements toxicological experiment.At first, because the APNS is coarse, and the air particulate is fine, so the diameter of APNS was survyed to make sure APNS includes fine particulate. Then, 13 PM10 samples were collected in APNS’s same area, to survey the elements distribution of PM 10, comparing with the elements of APNS, to make sure the elements in APNS is the proper sample to the elements in the air particulate.Second, 4 special area were picked up according to the elements content and respiratory diseases incidence. The citizen and lung cancer patients hair samples were collected to comparing that the different elements condition of air environment and different diseases condition, do or do not effect in human elements distribution.Third, two elements toxicological experiments were done. (1) According to the previous conclusion, Hg was proven to promote the probability of lung cancer, so a Single Cell Gel Electrophoresis(SCGE) test was be done to judge the mutagenic Hg, further to judge the carcinogenicity of Hg. (2) Since papers had reported that part harmful elements in the air come from the combustion of organism, and smoking is one of the reasons that cause lung cancer, tobacco was chosen to be the example of organism to burn to survey the elements rates of ash and gas phase. Using a new geochemical method, the Element Ratio Method(ERM), 11 elements were surveyed in the ash and the cigarette sample, to show how much elements transfer to the air. Those elements would be one of the reasons that smoking cause cancer, and wold move to the air in other burning process.The conclusion include:(1) 17% APNS is fine particulate which could enter the deep respiratory passage, and store in human body, cause respiratory diseases. Many analysis methods showed that Hg、C d、P b、As in the APNS are relative to respiratory diseases, Hg could be one of the reasons which cause lung cancer.(2) The incidence of lung cancer and children asthma in Chengdu area have been rising 20% per year, corresponding Hg、C d、A s、P b concentrated in APNS reaching 58, 35, 20, 17 times of Clarke Value. The most medical cases incidence hanppened in Deyang district and least happened in Meishan, corresponding the elements content were high and low in Deyang and Meishan.(3) Hair analysis showed that the element content in human hair is changed according to the differnent air environment in districts. There is significant differences between Hg content in lung cancer patients hair and normal people hair, P<0.05.(4) The SCGE experiment showed the HgCH3Cl is mutagenicity, which means that it probably is carcinogenicity. The cigarette elements distribution rates of ash and gas phase experiment showed that about 90% Hg elment moved into the air during smoke, Hg could be a new reason of“smoking cause cancer”.So, this paper believe that the elements leading by Hg, Cd, Pb, As are relative with the sufferance of respiratory diseases. Most of these elements are heavy metals. To hold down the content of these elements in the air must be one of the ways to prevent and cure respiratory diseases.更多还原