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题名: 涉铅企业周边儿童铅暴露的同位素源解析方法研究
作者: 曹素珍
学位类别: 博士
答辩日期: 2014-11
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 魏复盛 ; 江桂斌 ; 段小丽
关键词: 儿童,同位素,血铅,暴露途径,源解析,尿铅,Children, isotopic ratios, blood lead, exposure pathway, source appointment, urine lead
其他题名: A study on source appointment of lead exposure in children living in the vicinity of lead-related manufactures based on lead isotopic ratios
学位专业: 环境科学
中文摘要:       铅是一类可能致癌的,有毒有害的污染物,在人体的安全水平为零。含铅污染物进入人体后,可对人体免疫系统、神经系统、内分泌系统等造成健康损害。儿童由于其特殊的手—口行为模式,以及高吸收率和低排泄率,是铅中毒的易感人群。特别是生活在涉铅企业周边的儿童,多源污染、多途径暴露、长期累积、综合作用下的铅暴露对儿童带来的健康风险更为严竣。快速、有效的解析涉铅企业周边儿童铅暴露的主要来源和途径,是降低儿童铅暴露风险,防范儿童铅中毒的关键。由于儿童血液样品较难大规模获取,基于对样本数量和对采样点分布要求比较高的多元统计和地理空间分析等方法在实际应用中受到限制,也无法对多源体系进行有效辨析,难以定量的识别铅的来源和贡献。
      针对多元统计和地理空间分析源解析技术缺陷而发展起来的同位素源解析技术已日渐成熟,近年来从环境源解析逐渐发展应用于人体暴露源解析。本论文围绕涉铅企业周边儿童铅暴露,基于血铅生物标志物,利用铅稳定同位素源解析技术对单一涉铅企业周边儿童铅暴露途径和来源解析方法进行研究;并在多源涉铅企业周边儿童铅暴露途径和来源解析中进行血铅同位素源解析方法的应用和验证;另外,考虑到血液样品在实际调查中较难获取,本论文对基于尿铅的人体铅暴露负荷及源解析的可行性进行研究分析。
      本研究基于实验室建立的普通四级杆ICP-QMS同位素分析技术能对同位素标准品的分析能达到很好的准确性和精密性。对实际复杂的环境样品和生物样品的分析,结果表明,实际样品中不同同位素比值的RSD值(204Pb/206Pb: 0-0.30%;207Pb/206Pb: 0-2.02%; 208Pb/206Pb: 0.36-1.41%)均为可接受水平,建立的同位素分析测试方法对样品的分析具有较好的精密性。
      选择山西省某焦化企业作为单一源案例区,通过对企业周边环境铅污染特征和儿童血铅暴露特征的研究,基于血铅同位素指纹特征(208Pb/206Pb, 207Pb/206Pb, 下同)对儿童铅暴露途径和来源进行研究,并根据现场调查获得的暴露参数利用美国环保局推荐的暴露评价模型对儿童铅暴露的途径进行分析验证,评价基于血铅同位素源解析结果的准确性。结果表明,单一燃煤型涉铅企业周边,土壤、空气等环境污染(土壤: 28.77-80mg/kg,空气颗粒物: 0.05–0.47μg/m3)虽不严重,但大气颗粒物中铅的同位素比值特征 (2.1015, 0.8609)与焦化厂所使用的煤(2.1167, 0.8641)及燃煤飞灰(2.1110, 0.8596)的同位素比值特征相似,说明焦化厂燃煤飞灰的排放是其环境铅污染的重要来源;儿童血铅水平(n=72, x=52.5μg/L)虽然与全国平均水平相当,但血铅同位素比值特征(2.1128±0.0096,0.8640±0.0050)与其日常暴露的饮用水(2.1017±0.0129, 0.8666±0.0054)、食物(2.1095±0.0073, 0.8615±0.0045)、呼吸空气(2.1068±0.0206,0.8622±0.0093)和焦化厂的煤及燃煤飞灰相近。结合同位素多元混合模型分析,说明焦化厂的燃煤飞灰是儿童个体外暴露及血铅暴露的主要来源(贡献达80%以上),食物和饮用水(94%)是儿童铅暴露的主要暴露途径。基于US EPA推荐的暴露评价模型对儿童铅暴露途径的分析结果与基于铅同位素的分析结果一致,即儿童主要通过食物和饮用水的经口途径暴露铅(95%),验证了单一的涉铅企业周边基于血铅同位素指纹技术进行儿童铅暴露源解析方法的准确性。
      选择湖南省某一蓄电池厂作为方法验证的多源案例区,基于环境铅污染特征及人体血铅暴露水平,利用血铅同位素指纹特征和暴露评价模型分别进行儿童铅暴露的源解析和暴露途径研究。结果表明,企业周边环境污染较重,儿童血铅暴露水平较高(实验组n=60, X=124.46μg/L;  对照组n=60,X=92.12μg/L);儿童血铅同位素比值特征(实验组: 2.1280±0.0263, 0.8653±0.0092; 对照组: 2.1176±0.0280,0.8768±0.0106)与湖南矿石(2.1212±0.0354, 0.8476±0.0114)、无铅汽油(2.0904±0.0216, 0.8533± 0.0072)和燃煤(2.1062±0.0713, 0.8493±0.0190)存在不同的相似之处,其中与矿石最为接近;与其饮食(实验组: 2.1051±0.0091,0.8595±0.0039; 对照组: 2.1025±0.0144, 0.8609± 0.0044)、饮用水(实验组: 2.1271±0.0084, 0.8573±0.0045; 对照组: 2.1025±0.0177, 0.8609±0.0057)和呼吸空气(实验组: 2.1030±0.0197,0.8591±0.0086;对照组:2.1209±0.0200,0.8619±0.0071)较为相近,说明矿石可能是儿童铅暴露的主要来源,食物、饮用水和呼吸空气是其主要暴露途径。同位素多元混合模型分析表明,燃煤、矿石和无铅汽油对实验组儿童血铅的贡献分别为15%、77%和8%;基于US EPA推荐的暴露评价模型对儿童铅暴露途径的分析结果与基于铅同位素的分析结果一致。基于此案例区的研究,验证了儿童血铅暴露同位素源解析的分析方法在其它或复杂源周边儿童铅暴露源解析的适用性。
      考虑到相比血液而言,尿液在实际人群调查中容易获取,本研究以人体尿铅为生物指示物,基于铅同位素指纹特征对山西单一源和湖南多源案例区人体铅暴露来源进行研究。结果表明,虽然尿铅含量不能指示人体血铅水平,以准确地反映机体的铅污染负荷,但基于尿铅和血铅同位素指纹特征进行儿童铅暴露源解析的结果一致(基于尿铅:燃煤、矿石和无铅汽油分别为9%、78%和13%),初步表明可以应用尿铅进行人体铅暴露来源和暴露途径的解析。
英文摘要:       Lead is a well-known neurotoxin in humans and lead poisoning can result in impairments like in immune system and disturbance endocrine system. Because of frequent hand to mouth activity, high absorption and low excretion rate, children are more susceptible to lead than the adults. Since the exposure of children to lead has the characteristics of multi-pollution sources, multi-exposure pathways, comprehensive action and long period accumulation, the children living around lead-related manufactures would suffer from severe health risks. It is an important issue to efficiently identify the major sources of lead contributing to children exposure and to find the exposure pathways. Considering the high acquirement to the number and distributed sites of the samples, the multivariate statistics and geographical spatial analysis methods for source appointment have some limits in practical application, and they could not determine the pollution sources in the multiple-sources case and appoint the contribution of each source quantitative.
      To fill the imperfection, isotopic ratio based technique for source appointment developed well, which has a widely use in environmental pollution and human exposure. Therefore, the study aims to establish an isotopic based analytical methodology to identify the major sources contributing to the level of children’s blood lead in a single pollution site, and evaluate the application in other multiple pollution sites. In addition, since it is difficult to obtain the blood samples in practical investigation on children’s health, the study also assess the feasibility of urine lead in defining the blood lead levels and source appointment.
      On the basis of comparing the analytical accuracy and precision of stable lead isotopic ratios between MC-ICP-MS and ICP-QMS, acceptable accuracy and precision were obtained based on the ICP-QMS. The Relative Standard Deviation (RSD) in the true samples was acceptable (204Pb/206Pb: 0-0.30%, 207Pb/206Pb: 0-2.02%;208Pb/206Pb: 0.36-1.41%), the analytical method of lead isotopic ratios (LIRs) relying on the ICP-QMS was established.
      In this study, a typical coking manufacture was selected as a case with “single pollution source”, based on the characteristics of environmental lead pollution and children’s lead exposure, isotopic ratio (208Pb/206Pb, 207Pb/206Pb, same as to the following) based identification of exposure sources and pathways to the children were studied. Human health risks and exposure dose were assessed based on the model from US EPA, to verify the reliability of source appointment based on lead isotopic ratios. Lead concentrations and LIRs (208Pb/206Pb and 207Pb/206Pb, same as to the below) of samples collected from soil, particulate matter, food, drinking water and fly ash of combustion were analyzed. The results showed that the lead concentrations of soil and PM were in a range of 28.77-80 mg/kg and 0.05-0.47μg/m3 respectively, while the LIRs of airborne PM (2.1015, 0.8609) were similar to those of coal (2.1167, 0.8461) and fly ash of coal combustion (2.1110, 0.8596) from the coking plant, suggesting that the lead in fly ash from the coking plant is the major source of environmental lead pollution. Moreover the data from samples of children’s blood indicated that the level of blood lead (n=72, X=52.5μg/L) was in accordance with the national level. The LIRs results of children’s blood lead (2.1128±0.0096, 0.8640±0.0050) were similar to those of drinking water (2.1017± 0.0129, 0.8666± 0.0054), food (2.1095± 0.0073, 0.8615± 0.0045) and ambient PM (2.1068±0.0206, 0.8622±0.0093). Furthermore it was also in consistent with that of coal and coal combustion fly ash from the coking plant. These results indicated that the fly ash of coal combustion was the major lead contributor to the environmental pollution and children’s blood lead (accounted to over 80%). While the ingestion pathway via food and drinking water (accounted to 94%) was the main exposure pathway in light of the multivariate mixed model analysis. On the basis of these data, the analytical method for identifying the external sources of children’s blood lead relying on LIRs was developed and further verified by comparing the results from exposure assessment model of US EPA, which confirmed that ingestion pathway via food and drinking water contributing 95% to children’s lead exposure which is in consistent with our results.
      A typical lead-acid battery manufacture was selected as a case with “multiple pollution source”. Based on the characteristics of environmental lead pollution and children’s lead exposure, isotopic ratio- and health risk exposure assessment model- based identification of exposure sources and pathways to the children were studied, to study the potential usefulness of the analytical LIRs method for identifying the sources of children’s blood lead. With the comparison of the lead concentrations and LIRs in environmental samples and children’s blood lead, the results showed that levels of children’s blood lead were quite high (experiment group (EG): n=60, X=124.46μg/L; control group (CG): n=60, X=92.12μg/L), while the LIRs of children’s blood lead (EG: 2.1280±0.0263, 0.8653±0.0092; CG: 2.1176±0.0280, 0.8768±0.0106) were somewhat similar to those of Hunan ore (2.1212±0.0354, 0.8476±0.0114), lead-free gasoline (2.0904±0.0216, 0.8533± 0.0072) and coal(2.1062±0.0713, 0.8493±0.0190). Furthermore, the LIRs properties of Hunan ore were quite similar to those of food (EG: 2.1051±0.0091, 0.8595±0.0039; CG: 2.1025±0.0144, 0.8609± 0.0044), drinking water (EG: 2.1271±0.0084, 0.8573±0.0045; CG: 2.1025±0.0177, 0.8609±0.0057) and PM (EG: 2.1030±0.0197, 0.8591±0.0086; CG: 2.1209±0.0200,0.8619±0.0071). These results suggest that the lead from ore would be the major contributor to children’s blood lead and the ingestion via food and drinking water and inhalation via PM could be the main exposure pathways. Based on the multivariate mixed model, the analysis indicated that the contributions of coal combustion, ore and lead-free gasoline to children’s blood lead would be 15%, 77% and 8%, respectively, suggesting that analytical LIRs may be useful for identifying the contributors among the environmental lead sources to assess risk of lead poisoning to children.
      Finally, since it is much easily to collect urine samples from humans than collection of blood samples, particularly for a large scale survey, I examined whether the LIRs of urine samples could be useful for identifying the lead sources to contribute to the level of children’s blood lead. In doing so, the urine samples were collected from the children lived in the vicinities of the coking plant and lead-acid battery plant and the concentrations of lead and LIRs were analyzed following the established method. The results illustrated that LIRs of urine could be used as an alternative of blood LIRs to identify sources of children’s blood lead in according to that the calculated lead contributors of children’s blood lead were identical in light of the analysis of LIRs of urine and blood, even though the children’s urinary lead concentration can’t be a proxy of their blood lead levels to accurately reflect the body lead burden.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/34489
Appears in Collections:环境化学与生态毒理学国家重点实验室_学位论文

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曹素珍. 涉铅企业周边儿童铅暴露的同位素源解析方法研究[D]. 北京. 中国科学院研究生院. 2014.
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