饮水型砷中毒病区人群砷暴露量及尿砷的季节变化

地下水高砷暴露的健康危害是环境与健康领域面临的巨大挑战。水砷含量及暴露人群饮水量参数的季节性变化可能影响饮水砷暴露评估的准确性。本研究选择内蒙古饮水砷中毒病区为研究区,测定丰水期(2013年5月)和枯水期(2013年12月)居民饮用水和尿液各形态砷(三价无机砷iAs~(3+)、五价无机砷iAs~(5+)、一甲基砷MMA~(5+)和二甲基砷DMA~(5+)+)含量,研究砷暴露量和尿砷的季节变化。结果表明,丰水期水砷含量(134.4±25.8)μg·L~(-1)显著低于枯水期的(163.2±38.1)μg·L~(-1),且丰水期水中iAs~(3+)的含量(58.9±51.2)μg·L~(-1)也显著低于枯水期的(100.1±49.0)μg·L~(-1)。研究人群丰水期通过饮水的摄砷量为313.1μg·d~(-1),低于枯水期的378.6μg·d~(-1)。此外,丰水期居民尿液总砷含量(218.6μg·L~(-1))显著低于枯水期(283.1μg·L~(-1))。丰水期女性居民尿液iAs、MMA~(5+)和总砷含量随当季饮水iAs~(5+)含量的升高而显著降低,枯水期女性尿液MMA5+含量随当季饮水iAs~(3+)及iAs含量的升高而显著升高。可见,病区居民饮水砷暴露量与尿砷含量具有明显的季节差异性,饮水砷与尿砷的关系受饮水砷形态、季节变化及性别等因素影响。     

燃煤型砷中毒的最低有效累积暴露剂量初探

以陕南燃煤型砷中毒病区的5个自然村为调查采样点,通过现场流行病学调查和环境样品的分析测定,分析砷暴露人群的砷暴露途径,估算各暴露途径(呼吸、饮水和食物)的暴露剂量及对总暴露的贡献率,探讨引发燃煤型地方性砷中毒发病的最低有效暴露剂量。研究结果表明,除对照村外,采暖季各村的烤火间和卧室空气砷含量均有不同程度的超标,水和粮食未受燃煤砷污染。在采暖季,高砷煤燃烧污染的空气是人群砷暴露的主要来源;在非采暖季消化道砷暴露是各村的主要摄砷途径;表明消化道暴露对累积砷暴露的贡献不容忽视。结合问卷调查和流行病学调查结果,估算陕南病区引发燃煤型砷中毒的最低累积暴露剂量在1 712 mg左右。     

燃煤型砷中毒的最低有效累积暴露剂量初探

以陕南燃煤型砷中毒病区的5个自然村为调查采样点,通过现场流行病学调查和环境样品的分析测定,分析砷暴露人群的砷暴露途径,估算各暴露途径(呼吸、饮水和食物)的暴露剂量及对总暴露的贡献率,探讨引发燃煤型地方性砷中毒发病的最低有效暴露剂量。研究结果表明,除对照村外,采暖季各村的烤火间和卧室空气砷含量均有不同程度的超标,水和粮食未受燃煤砷污染。在采暖季,高砷煤燃烧污染的空气是人群砷暴露的主要来源;在非采暖季消化道砷暴露是各村的主要摄砷途径;提示消化道暴露对累积砷暴露的贡献不容忽视。结合问卷调查和流行病学调查结果,估算陕南病区引发燃煤型砷中毒的最低累积暴露剂量在1 712 mg左右。     

燃煤型砷中毒病区尿砷甲基化代谢和砷致皮肤损伤危险度的关系初探

砷中毒具有特异的皮肤损伤特征。为了研究燃煤型砷中毒病区高砷暴露、人体甲基化代谢能力与皮肤损伤患病风险之间的关系,在陕南典型燃煤型砷中毒村进行了皮肤损伤诊断和流行病学调查,采集尿样并分析总砷及形态砷含量,同时计算了用于表征人体砷甲基化代谢能力的指标包括尿中无机砷、一甲基砷和二甲基砷占总砷的百分含量(i As%、MMA%、DMA%),以及一甲基化率(PMI=MMA/i As)和二甲基化率(SMI=DMA/MMA)。Logistic回归分析结果表明:尿总砷含量(UTAs)是砷致皮肤损伤的危险因素(OR=1.038,95%CI:1.003~1.073),二甲基砷百分含量和SMI是皮肤损伤的保护因素(OR=0.883,95%CI:0.798~0.976;OR=0.724,95%CI:0.535~0.978);且砷致皮肤损伤的危险度随砷暴露水平的增高和甲基化能力的降低而增大。     

内蒙古自治区河套平原砷中毒高发区作物中砷的检测及健康风险评价

为了研究地方性砷中毒高发区作物中砷含量及其对人体健康的威胁,在内蒙古自治区河套平原4个自然村采集了72个谷物蔬菜水果、81份人体尿样和8个自来水样品。用高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)分析测定采集的样品中各形态砷及其含量;用ICP-MS分析测定消解后的作物样品中砷总量。结果表明,自来水中总砷含量均小于1.0μg·L-1。尿液样品中总砷含量为4.50～319μg·L-1(平均值为56.9μg·L-1),二甲基砷(DMA)是尿砷的主要形态(>70%)。作物中砷的主要形态有无机三价砷As(III)、无机五价砷As(V)和DMA。谷物和蔬菜水果中总砷含量的最大值分别为102和335μg·kg-1。成人和儿童最大日摄入砷量分别为232和205μg。通过分析采样地人体尿砷、作物砷和地方性砷中毒发病率的相关性得出,作物中砷的含量虽未明显超过国家标准,但对人体健康有明显的潜在威胁。政府改水后(饮用水由井水变为达标的自来水),人体的健康风险主要来自作物中的砷,而不是饮用水中的砷。     

地方性砷中毒地区环境砷暴露健康风险研究进展

自然因素引起的环境高砷暴露及其健康效应,尤其是饮水型地方性砷中毒是砷污染健康风险评估的基础。总结地方性砷中毒在环境砷暴露的风险识别、暴露途径和暴露与健康效应关系研究中的作用基础上,指出了地方性砷中毒研究中仅强调了饮水污染,关注的暴露途径比较单一,因此,人体多途径联合砷暴露的健康风险评估过程存在较大的不确定性。我国是唯一存在饮水和燃煤2种自然环境高砷暴露的国家,是研究2种类型砷暴露异同的天然场地,然而目前环境高砷的暴露及其健康效应的研究均为独立研究,对燃煤型地方性砷中毒在呼吸链砷暴露风险评估中的作用重视不够。因此,通过开展两种环境砷暴露及其健康效应的综合比较研究,建立呼吸链暴露评估和暴露-健康效应模型,可以为人体多途径联合砷暴露的健康风险研究提供新的依据。     

土著细菌对江汉平原浅层含水层沉积物中砷迁移的影响

对江汉平原水文地质调查发现,该地区地下水砷含量已远超国家饮用水标准。以沉积物培养的土著细菌混合液为生物材料,以江汉平原高砷含水层沉积物为研究对象,在实验室内模拟地下水系统,研究厌氧环境条件下,不同生物量土著细菌和pH值对沉积物中砷迁移转化的影响,以及土著细菌活动下砷在不同沉积物中的迁移转化。结果表明,不同生物量菌悬液都能促进沉积物中As的释放,增加总As和As(III)的浓度,但150mL处理组,在研究后期,总As和As(III)的浓度呈现减缓趋势;在初始生物量一定的条件下,沉积物中As含量越高,细菌活动下总As相对释出量就越低,而且As(III)占所释出总As的比值就越高,但两个高砷含量沉积物组的差异较小;在初始pH值为5、7和9的培养条件下,细菌都能加速砷的迁移,但pH值为5的处理组(简称pH5处理组)最弱,在前8天,pH9处理组较pH7处理组的低,随后超过pH7处理组。研究表明,土著细菌悬液能加速As从沉积物中释出,并且释出的As以As(III)为主;在耐受的弱碱性环境条件下,细菌对砷的迁移和转化随环境的pH值增加而增强。     

饮水砷中毒病区水砷形态变化特征

水源水经水管传输后,其砷形态的含量及其百分比变化特征研究较少.因此,本文选择内蒙古某饮水型砷中毒病区为研究区,分析饮用的水源水日际和日内总无机砷含量(iAs)、以及水源水传输到用户端的末梢水和储存水的无机砷形态含量(iAs~Ⅲ、iAs~Ⅴ).结果发现,水源水iAs~Ⅲ、iAs~Ⅴ和iAs的平均含量分别为32.19、64.58、96.77μg·L~(-1),末梢水iAs~Ⅲ、iAs~Ⅴ和iAs的平均含量分别为100.11、63.09、163.21μg·L~(-1),而储存水iAs~Ⅲ、iAs~Ⅴ和iAs的平均含量分别为14.72、126.41、141.12μg·L_(-1).水源水的iAs~Ⅴ和iAs含量日内具有明显的变化,iAs含量在日际间无明显的差异,而iAs~Ⅲ和iAs~Ⅴ含量在日际间存在较为明显的变化.此外,水源水、末梢水和储存水的iAs~Ⅲ占总无机砷的比例分别为33.26%、61.33%和10.43%,而iAs~Ⅴ占总无机砷的比例分别为66.74%、38.67%和89.57%.该结果表明,饮水砷形态的转化可能受到水与空气接触时间、气温、气压和水温等因素的影响,且水源水在水管传输过程中可能导致末梢水和储存水的iAs含量增加.因此,饮水砷的暴露评估应关注不同形态的砷暴露以及饮水类型的砷暴露.     

砷中毒易感性与基因多态性的关系研究进展

无机砷是一种确认的人类致癌物,但其致癌机制至今仍不很清楚.人类的大多数肿瘤是环境与遗传因素共同作用的结果.砷中毒在不同种属(族)和个体之间存在着明显的差异,除年龄、性别、砷暴露量、营养状况等因素外,近年来研究发现,个体间砷中毒易感性的不同可能与某些基因多态性密切相关,这些基因包括谷胱苷肽-S-转移酶基因、5,10-亚甲基四氢叶酸还原酶基因、着色性干皮病D基因、髓性过氧化物酶基因、过氧化氢酶基因以及p53基因等.只有充分考虑遗传因素的作用,才能深入阐明砷中毒的机制.     

奎屯河及玛纳斯河流域平原区地下水中氮素对砷迁移富集的影响

研究奎屯河及玛纳斯河流域氮素对地下水中As浓度的影响,可以深入了解研究区高砷地下水的迁移富集机理.通过对奎屯河和玛纳斯河流域的34个地下水样品的采集和测试,分析了研究区地下水的水化学成分以及地下水中硝酸盐、氨氮与砷浓度之间的关系,并探讨了地下水系统中氧化还原环境对砷迁移富集的影响.结果表明,奎屯河和玛纳斯河流域高砷地下水水化学类型分别主要为SO_4·HCO_3-Na和HCO_3·SO_4-Na型.研究区高砷地下水赋存于低Eh和NO_3~-,高NH_4~+/NT、Fe、Mn的还原性环境中,在水平上主要分布于流域的地下水排泄区、湖积平原处,奎屯河流域地下水样中砷浓度都超标且明显高于玛纳斯河流域;在垂直方向上,主要集中在80—200 m.地下水中砷浓度和NO_3~-浓度呈负相关关系,这是因为在由NO_3~-指示的处于氧化环境的地下水系统中,铁锰化合物未被还原,因此其吸附的砷的化合物也没有释放.地下水中砷浓度随着NH_4~+/NT增大而增大,NH_4~+/NT可以指示地下水系统的还原环境的强弱程度,NH_4~+/N_T越大,地下水系统还原环境越强,含砷化合物越容易产生还原性溶解,将其吸附的砷释放到地下水中,且五价砷被还原成三价砷.     

Characteristics of Environmental Geochemistry in the Arseniasis Area of the Inner Mongolia of China

In China, endemic arseniasis attributable to the geological-geochemistry environment is mainly found in the plain of the Great Bend of the Yellow River and the Hu-Bao plain in the Inner Mongolia Autonomous Region, in the Datong basin of Shanxi Province, the floodplain of the northern side of the Tian Mountain of Xinjiang Uygur Autonomous Region, and in the southwest coastal plain of Taiwan. These areas share many similar characteristics including widespread occurrences, a large population being affected, and the magnitude of risk involved. The population living in these areas is estimated to be around 5.5 × 10⁵, of which of 2.5 × 10⁵ are resident in Inner Mongolia. Based on our systematic research and comparison of various areas, we found the different types of arseniasis are often associated with different regions. The neural arseniasis is distributed in Xinjiang Uygur Autonomous Region and Shanxi Province, caused by inorganic arsenic in drinking water while the cycling-obstacle arseniasis is mainly found in Inner Mongolia and Taiwan, associated with organic arsenic in water. The distribution of arsenic affected villages in Inner Mongolia exhibits orientation and focus on low-lying land in the subsiding centre of the Great Bend basin, which was enriched with humus in the lake and limnetic deposits. Much CH₄ gas can be detected in the water of shallow and deep wells in these villages. Some of the wells with higher concentrations of CH₄ can even be ignited. This is a typical reductive geochemical environment. We tested the total amount of arsenic (As), As³⁺, and methyl arsenate in all types of water sources. It is found that the number of arseniasis cases is not clearly related to the total amount of arsenic (As) in the water. However, it is related to the ratio of As³⁺ plus methyl arsenic to the total amount of arsenic (As). The higher the ratio, the higher the number of people affected and the more serious the illness. The statistical results also indicate that good drinking water accounts for 60% of the drinking water source while the arsenic contaminated water makes up about 25% of the drinking water in the study area. This research reveals that the local geochemical environment is responsible for the spreading of the endemic arseniasis in the area and thus suggests a new direction of how to prevent such disease.     

Humic Acids from Endemic Arsenicosis Areas in Inner Mongolia and from the Blackfoot-Disease Areas in Taiwan: A Comparative Study

The physical and chemical properties of humic acids (HA) extracted from drinking waters from the endemic arsenicosis areas in Inner Mongolia and from the Blackfoot disease (BD) areas in Taiwan are studied by using AAS (atomic absorption spectrophotometry), ICP-MS (inductively coupled plasma emission-mass spectrometry), IR (Infrared spectroscopy), FR (fluorescence spectrometry) and TLS (total luminescence spectroscopy) in order to shed light on the pathogenesis of BD with the concern as to whether the disease may eventually occur in arsenicosis-affected areas in the Mainland of China. Ames test and lipid peroxidation experiments were also conducted on these HA samples. It is found that water samples from the two regions are high in arsenic (As) with strong fluorescence and apparent positive correlations between As content, fluorescence, pH and total dissolved solids (TDS). The water samples are similar in fluorescence spectra but differ somewhat in IR and TLS between the two regions. The difference may be a reflection of the difference in radicals and structure of the HA owing to different hydrogeological conditions, and may also be related to the difference in their biological effects, i.e., HA from Inner Mongolia have a stronger ability to cause lipid peroxidation while HA from Taiwan exhibits a more prominent effect of mutation with respect to TA98(±S9).     

Arsenism Clinical Stages and their Relation with Hair Arsenic Concentration of Residents of Bayinmaodao Rural District, Inner Mongolia, China

The clinical skin lesions of arsenism in men and women in Bayinmaodao rural district in Inner Mongolia, Peoples Republic of China, have been examined by doctors, and their hair and drinking water samples analysed for arsenic by hydride generation and ICP-AES. Altogether 311 arsenism patients with a 15.53% prevalence rate for the district were recorded. The disease prevalence rate was positively related to population, age, and their exposure to elevated arsenic concentrations in the drinking water from 1983 when new wells were dug and drinking of surface water was abandoned. Hyperkeratosis was the most serious skin lesion with the highest occurrence rate, then depigmentation and pigmentation in decreasing order. With increasing severity of the disease, ranging from skin lesion with single hyperkeratosis 1° to hyperkeratosis 3° with depigmentation 3° and pigmentation 3°, the results showed that arsenic concentrations in head hair had increased. Arsenic concentrations in hair were positively correlated with the arsenic concentrations in drinking water obtained from local wells.     

The Relationship Between Exposure to Arsenic Concentrations in Drinking Water and the Development of Skin Lesions in Farmers from Inner Mongolia, China

Associations between the concentration of arsenic naturally occurring in drinking water and the development of skin lesions in people have been documented for some years at various locations around the world. Data on the exposure-response relationship between concentrations of arsenic in drinking water and prevalence of skin lesions in farmers from five locations in Inner Mongolia, China have been collected from the original publications and re-analysed together as a meta-study. The calculated data show a positive linear exposure-response relationship without a threshold. The reasons for this linear correlation are discussed and compared with the data from Xinjiang, another arsenism area located in a different geographical area of China. Here a different relationship was recorded that involved a threshold concentration before skin lesions developed. The significance of these two different exposure-response scenarios is discussed.     

Arsenic species in the well water and sediments of the blackfoot disease area in Taiwan

The blackfoot disease (BFD) observed in southwestern Taiwan is due to drinking high arsenic concentrations in well water. This paper presents some results concerning the distributions of arsenic species in water and sediments collected in the BFD (well, river and coastal) area and the background (lake and ocean) area for comparison. The results show that the concentrations of arsenate (870 ± 26 ug/L) and arsenite (70.2 ± 2.6 ug/ L) in well waters, and the contents of arsenic (1640 ug/g) with high percentage of easily reducible (Fe and Mn oxides, 91.7%) and exchangeable and carbonate (4.6%) phases in well sediments were much higher than those in river, lake and coastal samples. Low arsenic (3.46–31.8 ug/g) with high percentages (73.8–97.3%) of detritus and minerals phase with low percentages (0.4–9.8%) of total carbonate and exchangeable phases were found in the river and coastal samples in the BFD area as well as the lake and ocean samples in background area. It might suggest that the higher concentrations of toxic As(III) in well water and arsenic with higher values of easily reducible, carbonate and exchangeable phases in the well sediments, combined with the higher values of dissolved organic carbon, humic and fulvic acids and aromatic carbon as well as the higher fluorescence indensity in the well water are the key factors to cause the BFD in Taiwan.     

Characterization of dissolved organic carbon and Humic substances in the well water of the Blackfoot disease area in Taiwan

Since the early 1960s, many investigators have reported that blackfoot disease, a peripheral vascular disease, observed in southwestern Taiwan is due to drinking the higher arsenic concentration in well water. However, recent studies indicated that the relationship with blackfoot disease is not only with arsenic but also humic substances. This paper presents some results concerning the characterization (such as fluorescence, elemental composition, molecular weight and carbon distribution) of humic substances isolated from the Fuhsing well water of the blackfoot disease area. For comparison, the dissolved organic carbon (DOC) and humic substances in the normal well water from Chiuying and the Nanwan coastal water were also analyzed. In general, in the well water of the blackfoot disease area, extremely high concentrations of DOC (18.5mg/L) and fulvic acid (7.54mg/L) with high fluorescence intensity (59.1, equivalent to 0.0282uM quinine sulfate solution) and high percentages (over 50%) of low molecular weights of less than 1,000 were obtained compared with those of normal waters. C‐13 Nuclear magnetic resonance spectroscopy showed a high content (37.2%) of aromatic carbon. These higher concentrations of DOC and fulvic acid with the higher content of aromatic carbon in well water might be one of the key factors causing the blackfoot disease in Taiwan.     

大同盆地富砷地下水的水化学与地球化学研究

为弄清大同盆地地下水中影响砷的迁移、富集的主要地球化学与生物地球化学过程,为区域供水安全提供指导作用,针对高砷地下水系统开展了水文地球化学与含水层沉积物全岩地球化学研究;并在此基础上探讨了研究区高砷地下水成因。结果表明,研究区高砷地下水为偏碱性、强还原环境,砷含量为0.31～452μg·L-1,主要以砷酸盐形式存在,地下水中砷与三价铁的浓度有显著的相关性。高砷含水层沉积物中有机质、铁与砷含量表现出显著相关性。以上结果说明,碱性还原环境有利于地下水中砷的富集;微生物参与下,沉积物相有机质的氧化和Fe氧化物/氢氧化物的还原过程是本区高砷地下水形成的主控因素。     

Chronic kidney disease in two coastal districts of Andhra Pradesh, India: role of drinking water

Chronic kidney disease (CKD) has been reported in a few coastal regions of Srikakulam district and Chimakurthy mandal (~30–40 km away from the coast) in the Prakasham district of Andhra Pradesh, India. Some medical experts and the local population have apprehensions that the drinking water is the sole reason for this disease in these areas. As the source of drinking water for these two regions is only groundwater, major ions and trace elements were measured on waters from different sources to identify the causative element(s), if any. Comparison of hydrochemical data of both the areas indicates that groundwater in Srikakulam coastal region is less mineralized than that of the Prakasham region, which may be due to geological, hydrological and climatic reasons. However, the concentrations of various inorganic chemicals are within the permissible limits of drinking water. Hence, for the inorganic chemicals to cause ill health, including CKD, is unlikely or is ruled out in the study areas.