CHILDHOOD BLOOD LEAD--PRE AND POSTNATAL SOURCES

对安全水平新标准的认识和实施 儿童血铅低于10微克/分升的主要依据是 母亲血铅水平较高时，胎儿移植增加的风险。 这项研究的前两年对22名18-36个月大的儿童提供 独特的定量重复饮食，手擦，血液，血浆和尿液 铅，并确定家庭粉尘是外源性铅的主要来源 食物铅的主要污染物。它确定了(206/207)铅的比率 仔细收集的袋装尿液与同位素比率一致 同时检测血液和血浆中的铅。同位素比值分析 的受试者将活动性内源性铅定义为主导 循环血铅的分数。很明显，我们开始了 学习至少晚了18到36个月。四年的竞争 因此，更新可以追溯到过去，以量化动员 内源性母体和新生儿获得的铅及其对 儿童的血铅。 这是一项纵向研究，采用热电离/质量。 光谱分析(TI/MS)超净样品中的同位素稀释分析 实验室，内源性和外源性血铅在 怀孕、哺乳和哺乳后以及从出生到两岁。 这项研究将对24名怀孕前三个月的妇女进行 他们的第一次或第二次怀孕以及他们的婴儿从出生到 24个月。这些主题将是1950年前住房中的女性，她们将 纯母乳喂养或奶瓶喂养婴儿至少4个月 几个月大，预计在怀孕期间和怀孕期间住在同一个地方 孩子的头两年，不要指望孩子会离开家 超过20小时/周。所有受试者都将住在奥马哈市区的冶炼厂 土壤残留铅相对较高但空气和水铅含量较高的城市 可以忽略不计。 产前和产后相对贡献率的测定 获得性内源性铅和当前外源性铅对 预防出生前和出生后体重增加的不良后遗症 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.