CHILDHOOD BLOOD LEAD--PRE AND POSTNATAL SOURCES

安全水平新标准的确认和实施 儿童血铅低于10微克/分升主要是基于 母体血铅水平较高时，胎儿转移的风险增加。 这项研究的前两年有22名18-36个月大的儿童， 重复饲料、手擦、血液、血浆和尿液的独特定量 并确定室内灰尘为外源性铅的主要来源， 食品中的主要污染物铅。 它建立了（206/207）铅比 仔细收集的袋装尿液与同位素比例一致 血液和血浆中铅含量的变化 同位素比值分析 的选定的科目定义动员内源性铅为主导 循环血铅含量。 很明显，我们开始了 学习至少要晚18到36个月。 四年竞争力 因此，更新可以追溯到过去， 内源性母体和母体获得性铅及其对 儿童的血铅 这是一项纵向研究，采用热电离/质谱 在超净环境中进行TI/MS同位素稀释分析 实验室，内源性和外源性血铅的来源， 怀孕、哺乳和哺乳后以及从出生到两岁。 这项研究将在24名妇女的头三个月进行， 第一次或第二次怀孕以及婴儿从出生到 24个月 受试者将是居住在1950年以前住房中的妇女，她们将 完全母乳喂养或奶瓶喂养婴儿至少4 月龄，预期在整个怀孕期间居住在同一地点， 孩子的头两年，不要指望孩子离开家 超过20小时/周。 所有实验对象都将住在奥马哈市区的一个冶炼厂 土壤铅残留量相对较高的城市，但空气和水导致 可以忽略不计。 产前和产后相对贡献的测定 获得的内源性铅和当前的外源性铅是至关重要的 预防产前和产后死亡率上升的不良后果 血铅

The recognition and implementation of the new criteria for a safe level of childhood blood lead as below 10 micrograms/dl is primarily based on risk of increased fetal transfer at higher levels of maternal blood lead. The first two years of this study of 22 children 18-36 months old provide unique quantitation of duplicate diet, handwipe, blood, plasma and urine lead and identify housedust as the primary source of exogenous lead and a major contaminant of food lead. It establishes the (206/207) lead ratio of carefully collected, bagged urine as identical with the isotopic ratio of the simultaneous blood and plasma lead. The isotopic ratio analyses of selected subjects defines mobilized endogenous lead as the dominant fraction of circulating blood lead. It is obvious that we began the study at least 18 to 36 months too late. The four year competitive renewal thus goes back in time to quantitate the mobilization of endogenous maternal and neonatally acquired lead and its contribution to the blood lead of children. This is a longitudinal study, employing thermal ionization/mass spectrometry (TI/MS) isotopic dilution analysis in an ultraclean laboratory, of endogenous and exogenous sources of blood lead during pregnancy, lactation and post lactation and from birth to two years. This study will be conducted on 24 women from the first trimester of their first or second pregnancy and on their infants from birth through 24 months. The subjects will be women in pre-1950 housing who will exclusively breast feed or bottle feed their infants through at least 4 months of age, anticipate the same residence throughout pregnancy and the child's first two years and do not expect the child to be out of the home for more than 20 h/wk. All subjects will live in urban Omaha, a smelter city with relatively high residual soil lead but where air and water lead are negligible. Determination of the relative contribution of prenatally and postnatally acquired endogenous lead and of current exogenous lead is critical to the prevention of adverse sequelae to prenatal and postnatal increases in the blood lead.