Acute And Chronic Health Effects From Lead In Drinking Water Of Schools And Day Care Facilities: Detection, Bio-Availability, And Predicted Impacts On Blood Lead

0933246爱德华美国目前有一项自愿计划，以确定、检测和缓解学校和日托中心饮用水中的铅问题。尽管传统观点认为，学校水中的铅对健康的危害很小，但认识上的实质性差距可能导致这个问题的严重性被低估。“最坏情况”的管道配置和水流模式，以及非常年幼的儿童易受影响的人群，使得对这一问题的详细评估是可取的。研究分为三个阶段，旨在解决最重要的问题。第一项研究使用密集抽样事件来检查学校饮用水中铅的存在的关键方面，这些抽样事件旨在统计水中铅的自然变异性。一个类似的分析将对选定的“问题”水龙头进行，这些水龙头已知至少会以一定的频率释放危险废物水平的铅。热水中的铅含量也将首次进行系统测试。采样方案的设计是为了确保水中的铅不会“遗漏”，这是在使用水中常规的铅分析程序和指南时经常发生的情况。然后，使用一系列分析技术，将水中高铅的出现与特定的管道来源进行法证联系。第二阶段的工作是系统地评估铅的生物利用度。有人推测，水中的微粒铅是不可生物利用的，对健康的危害很小，但另一方面，最近发生的几起儿童铅中毒事件明确表明，水中存在微小的铅焊料颗粒。学校水中的微粒铅样本将暴露在一系列具有代表性的模拟胃酸、搅拌条件和胃滞留时间中。将跟踪样品中铅的溶解情况，作为颗粒大小和存在的铅颗粒类型的函数。此外，亦会进行测试，以研究烹调过程中水中微粒铅在意大利面中的分配情况，以及胃酸中微量还原剂在使微粒铅或多或少可生物利用方面所扮演的角色。这项基础性研究以前从未对来自真实饮用水的铅颗粒进行过。最后，将利用生物动力学模型，纳入前两个研究阶段的结果，以评估儿童在学校期间可能暴露在水中铅的一系列现实暴露情景。先前的建模工作严重偏向于低估接触受铅污染的饮用水可能导致的血铅升高。这项建模工作将首先考虑急性和慢性健康风险，2)评估使用热水生产速溶婴儿配方奶粉、汤和茶所产生的潜在危险(怀疑热水中的铅含量通常比冷水高得多)，以及3)确定在受污染的水中烹调的食物中铅的可能贡献。这项研究工作是弗吉尼亚理工大学、S儿童国家医学中心、健康家庭联盟、无毒替代品家长以及关心此事的家长和高中学生/教师网络共同努力的结果。结果将用于考虑现有方法的保护性，这些方法用于控制和减轻学校和家庭饮用水中的铅危害。我们没有资金的初步努力已经产生了重大效果，华盛顿州和加拿大的更严格的标准证明了这一点，并重新评估了2001-2007年期间水中高铅对华盛顿特区儿童血铅的影响。这些初步的成功、跨学科的方法和明确的公共卫生影响支持了这项研究的必要性。

0933246 EdwardsThe United States currently has a voluntary program to identify, detect and mitigate problems with lead in drinking water of schools and day care centers. Although the conventional wisdom is that lead in school water poses little health risk, substantive gaps in understanding may have caused the magnitude of this problem to be underestimated. The combination of "worst case" plumbing configurations and water flow patterns, and susceptible populations of very young children, makes a detailed evaluation of this issue desirable. Three phases of research are directed at resolving the most important issues. The first examines key aspects of lead occurrence in potable water of schools using intensive sampling events designed to statistically characterize the natural variability of lead in water. A similar analysis will be conducted for selected "problem" taps that are known to dispense hazardous waste levels of lead with at least some frequency. The level of lead in hot water will also be systematically tested for the first time. Sampling protocols are designed to ensure that none of the lead in water is "missed", as often occurs when using conventional lead in water analytical procedures and guidance. The occurrence of high lead in water will then be forensically linked to specific plumbing sources using an array of analytical techniques. The second phase of work systematically evaluates the bioavailability of the lead. It has been speculated that the particulate lead in water is not bioavailable and poses little health risk, but on the other hand several recent cases of lead poisoning for children were unambiguously tied to the presence of small particles of lead solder in the water. Samples of particulate lead from water of schools will be exposed to a range of representative simulated gastric acids, churn conditions, and stomach retention times. Lead dissolution will be tracked in samples as a function of particle size and type of lead particle present. Tests will also be conducted to examine partitioning of particulate lead in water to pasta during cooking, and the role of trace reducing agents in gastric acid in rendering particulate lead more or less bioavailable. This fundamental research has not been previously conducted for lead particulates derived from real drinking waters. Finally, bio-kinetic models will be utilized that incorporate results of the first two phases of research, in order to evaluate a range of realistic exposure scenarios by which children might be exposed to lead in water while in schools. Prior modeling efforts were significantly biased towards underestimating the elevation in blood lead that might result from exposure to lead contaminated drinking water. This modeling work will be the first to: 1) consider acute as well as chronic health risks, 2) evaluate the potential hazard that arises from use of hot water for instant infant formula, soups, and tea (it is suspected that there is often much more lead in hot water than cold water), and 3) determine the possible contribution of lead in foods cooked in contaminated water. This research work is a collaborative effort between Virginia Tech, the Children?s National Medical Center (CNMC), the Alliance for Healthy Homes, Parents for Non-toxic Alternatives, and a network of concerned parents and high school students/teachers. Results will be used in considering the protectiveness of existing approaches that are used to control and mitigate lead hazards in potable water of schools and homes. Our unfunded preliminary efforts have already had a significant effect, as evidenced by tougher standards in the State of Washington and in Canada, and through a re-evaluation of effects of high lead in water on blood lead of children in Washington D.C. from 2001-2007. These initial successes, interdisciplinary approach, and clear public health implications support the need for the research.