饮水和燃煤砷污染生态系统中砷从环境到人体转化的比较研究

Quantitative assessment of arsenic exposure is the key to resolve the dose-effect relationship between arsenic exposure and adverse health effects or health risks. A parallel study on the total arsenic exposure of population living in arsenic contaminated areas by drinking water and indoor air will be done in this project. It will be conducted in Inner Mongolia (Bayinmaodao rural district and district without changing water source around Hohhot) and Shaanxi Province (Zhenping County, Pingli County and Ziyang County). All people exposed to high level of arsenic in environment of the study areas will be taken as target population, and all arsenic exposure pathways from environment will be taken into the research object. The prevalence of arsenic induced skin lesions will be obtained by epidemiological survey. Detailed physical examinations will be conducted by trained medical doctors according to the Standards of Diagnosis for Endemic Arsenism (WS/T 211-2001). Environmental samples, including water, air, food, soil, grain, vegetables and coal, as well as samples from human body, including urine, nail and hair, will be collected in different seasons of a year. Concentrations of the total arsenic in all samples and different arsenic species in water and urine samples will be analyzed by inductively coupled plasma mass spectroscopy (ICP-MS) or high- performance liquid chromatography (HPLC) combined with ICP-MS. Fates of arsenic in drinking water, food and coal/air will be simulated by lab test. The differences of clinical skin lesions between the two types of arsenic poisoning found by epidemical studies are going to be taken as the starting point of this project.The focus study topics are as follows: (1) The prevalence of skin lesions and related influence factors will be sudied by clinical diagnosis and epidemical survey. (2).The dynamic processes of arsenic transmission from environment to human body and arsenic metabolism in human body are going to be studied, with the aim to elucidating the relationship between arsenic metabolism and the development of skin lesions. (3)The total arsenic exposure from all the potential routes (ingestion, inhalation, and dermal absorption) and pathways (water, food and air), will be estimated, and the bioavailability of arsenic species in environmental media will be discussed. Aims of the studies is to evaluate the dose-response relationship between environmental arsenic exposure and arsenic in human body, to clarify the reason of the clinical differences between the two types of arsenic exposure. The research work will be helpful to reduce the uncertainties of arsenic exposure assessment, and be helpful to define the tolerance guidlines of arsenic in water, air and food by the governments in the future. The anticipated achievement of this project will contribute to the development of arsenic exposure risk assessment and management.

暴露是人体接触环境有毒物质的过程。无论是砷健康效应研究，还是砷健康风险评价研究，都离不开对砷暴露过程的解析和砷从环境到人体转化的定量评估。本项目以我国典型饮水和燃煤砷污染区域暴露人群及环境为对象，从两类慢性砷中毒区不同人群皮肤损伤的差异分析着手，通过对暴露人群的砷暴露和人体砷代谢过程的动态监测，揭示人体砷负荷和砷代谢的动态变化及其与砷中毒人群临床皮肤病变发生发展的关系；继而通过对整个人类生态系统中不同暴露途径（呼吸、饮水、食物）砷的形态和全暴露分析，建立外环境砷的累积暴露与人体砷负荷及代谢的关系，探讨不同形态、不同途径砷从环境到人体转化的有效性及影响因素，阐明饮水型和燃煤型砷暴露及其健康后果差异性的原因，其结果不仅对降低砷中毒的风险评估的不确定性、确定环境载体砷含量阈值和暴露标志物的筛选有重要理论意义，而且能为砷污染健康风险的分类、分区管理和环境标准的制订提供决策依据。

地方性砷中毒受环境砷含量、砷暴露量、人体对砷的代谢效率和甲基化能力等因素的影响。本项目开展了饮水砷和燃煤砷污染区环境中砷的含量以及人群对砷的环境总暴露量、暴露人群的砷负荷及其与环境砷暴露的关系、砷暴露人群皮肤损伤的流行规律及其影响机制等研究。项目研究结果阐明了饮用地下水总砷和形态砷的含量及其时间变化和季节变化规律，以及燃煤引起的室内空气砷的污染特征；评估饮水型和燃煤型砷中毒区人群对环境砷的不同暴露途径的总暴露量，识别主要暴露途径；揭示暴露人群对砷的代谢效率和甲基化能力特征及其影响因素；阐明饮水型和燃煤型砷中毒区暴露人群的皮肤损伤流行规律，以及皮肤损伤受环境砷的暴露量、人体对砷的代谢效率和对砷的甲基化能力的影响机制，并揭示两种砷中毒区人群的皮肤损伤流行特征及其影响机制的差异特征；阐明饮水砷暴露人群的血压与砷暴露量的关系，以及高血压与人体对砷的代谢效率和对砷的甲基化能力的关系；评估饮水砷的暴露量和指甲砷的含量与皮肤损伤之间的剂量-反应关系，并评估燃煤砷暴露人群皮肤损伤的最低砷累积暴露量；调查了改水后，原砷暴露人群皮肤损伤患者的患病率和患病程度的变化趋势。另外，本项目获取了研究区环境砷含量、砷暴露量、人体对砷的代谢和甲基化能力、皮肤损伤流行、暴露人群人口学、暴露人群健康状况等数据，并建成数据库。本项目的研究结果解决了饮水型和燃煤型砷中毒皮肤损伤流行的差异特征及其影响因素、砷暴露量与皮肤损伤的剂量－效应关系、以及砷的代谢效率和甲基化能力对皮肤损伤的影响机制等科学问题，这些研究结果和获取的数据也为未来进一步研究环境砷暴露的健康效应提供科学基础和原始数据。同时，研究结果也为政府部门制定地方性砷中毒防治措施和决策提供科学依据和数据支撑。