RESUMEN
Concentrations and isotope ratios of lead in blood, urine, 24-h duplicate diets, and hand wipes were measured for 12 women from the second trimester of pregnancy until at least 8 months after delivery. Six bottle fed and six breast fed their infants. One bottle feeder fell pregnant for a second time, as did a breast feeder, and each was followed semicontinuously for totals of 44 and 54 months, respectively. Bone resorption rather than dietary absorption controls changes in blood lead, but in pregnancy the resorption of trabecular and cortical bone are decoupled. In early pregnancy, only trabecular bone (presumably of low lead content) is resorbed, causing blood leads to fall more than expected from hemodilution alone. In late pregnancy, the sites of resorption move to cortical bone of higher lead content and blood leads rise. In bottle feeders, the cortical bone contribution ceases immediately after delivery, but any tendency for blood leads to fall may be compensated by the effect of hemoconcentration produced by the postpartum loss of plasma volume. In lactation, the whole skeleton undergoes resorption and the blood leads of nursing mothers continue to rise, reaching a maximum 6-8 months after delivery. Blood leads fall from pregnancy to pregnancy, implying that the greatest risk of lead toxicity lies with first pregnancies.
Asunto(s)
Huesos/metabolismo , Plomo/metabolismo , Embarazo/metabolismo , Adulto , Remodelación Ósea/fisiología , Alimentación con Biberón , Lactancia Materna , Femenino , Humanos , Lactancia , Plomo/sangre , Radioisótopos de Plomo , Estudios Longitudinales , Periodo Posparto/sangre , Periodo Posparto/metabolismo , Embarazo/sangreRESUMEN
The concentrations and isotope ratios of lead in blood and urine, on the hands, and in duplicate diet samples were measured for children living in Omaha, Nebraska. One group consisted of 22 children followed from birth to between 1 and 2 years of age and another group was 20 2- to 4-year-old children followed for 1 year, although some in each group were followed for periods between 3 and 4 years. At no time in life was a component of dietary lead identified in blood by isotope ratios, and blood lead appears dominated by lead derived from the hands, which in turn appears derived from the floors. For some homes floor lead appeared to be a mixture of lead from window sills and from the exterior. Only 2 of the children appear to have ingested lead directly from window sills. Several who lived in homes being remodeled were exposed to lead before the age of 2 years. For those who had been briefly exposed during professional remodeling the blood lead fell with a half-life of 10 months but for those who had suffered prolonged exposure during remodeling by parents the apparent half-life was longer, between 20 and 38 months.
Asunto(s)
Plomo/farmacocinética , Adulto , Preescolar , Dieta , Polvo/análisis , Exposición a Riesgos Ambientales , Femenino , Pisos y Cubiertas de Piso , Contaminación de Alimentos/análisis , Mano , Vivienda , Humanos , Lactante , Recién Nacido , Isótopos , Plomo/sangre , Plomo/orina , Masculino , Espectrometría de Masas , Leche Humana/química , Nebraska , Embarazo , GemelosRESUMEN
The objective was to determine, from analysis of the naturally occurring stable isotopes of lead, the relative contribution of food, handdust, housedust, soil and air lead to the absorbed (urinary) lead and the blood lead of children living in a former smelter city. A longitudinal 12 month study was conducted of 21 children, 2 - 3 years of age, living in central Omaha, balanced for race, gender and socioeconomic status. Field clean samples were collected monthly of 24 hour duplicate diet, handwipe and urine, with quarterly blood lead, annual environmental lead, weekly air for total lead and 206Pb, 207Pb and 208Pb by thermal ionization/mass spectrometry with a 205Pb spike in a Class II laboratory. Despite residence in a smelter city each child had a unique isotopic ratio of handwipe, blood and urine lead, the latter being identical. There was no correlation of handwipe isotopic ratio with proximity to a lead emission source or to the decade of the housing stock. The isotopic ratio of the annual mean handwipe lead predicted 43% of the variance of the annual mean blood and urine lead ratio (r2 = .43; p = .001). Handwipe lead ratios correlated (p < or = .05) with those of the windowsills and air ducts. The mean isotopic ratios of blood and urine lead were lower than those of handwipe and food, consistent with a contribution by endogenous bone lead. Clean catch urine provides a noninvasive index of blood lead isotopic ratio in children, as in adults.
Asunto(s)
Isótopos , Plomo/análisis , Preescolar , Monitoreo del Ambiente , Contaminación Ambiental , Femenino , Contaminación de Alimentos , Humanos , Estudios Longitudinales , Masculino , NebraskaRESUMEN
As funds become increasingly scarce, an effective nutrition education method which reaches large numbers of elderly individuals is appropriate. A nutrition workshop was provided for 30 managers of government-sponsored nutrition centers for the elderly in a 5-county area. The workshop curriculum, determined after interests of both center managers and participants at the nutrition centers were assessed, was presented in a packet of materials to each workshop attendee and supplemented with explanations and demonstrations. A pre- and post-test evaluation instrument, which included videotaped simulations of typical nutritional situations encountered with elderly persons at the centers, was used to measure attitudes and knowledge before and after the workshop. As a result of the workshop, knowledge increased significantly as measured by the test instrument and 75% of the managers reported use of materials and ideas during the 5 months following the workshop.