Blood lead levels umbilical cord

Shucard JL, Shucard DW, Patterson R, et al. 1988. Prenatal lead exposure and its potential significance for developmental disabilities A preliminary study of umbilical cord blood lead levels. Neurotoxicology 9 317-326. 

Maternal blood lead levels and umbilical cord blood lead levels are the most direct measure of fetal exposure to lead, reflecting recent lead exposure and lead mobilized from tissue stores (Mushak 1989). Recent studies of mobilized... 

Rabinowitz, M., Needleman, H. L., Petrol Sales and Umbilical Cord Blood Lead Levels in Boston, Massachusetts, Lancet 19831 63. 

Umbilical cord blood and capillary blood samples, collected using standardized techniques (Australian Standards Association, 1983) at age 6 months, 15 months, 2 years, and annually thereafter, were assayed for blood lead (PbB). Blood lead assays were made using electrothermal atomic absorption spectrophotometry, after standard complexing and extraction of lead (Australian Standards Association, 1984). The laboratory undertaking the analyses participates in several national and international quality control programmes. Crude blood lead levels were standardized to a packed cell volume (PCV) of 35% before being included in subsequent data analysis (except in cord blood where standardization was to a PCV of 50%). A capillary-venous correlation coefficient of + 0.97 has been achieved in a sample of children of this age using these techniques (ACH, unpublished data). 

To assess the association between prenatal/early postnatal lead exposure and development, we followed a group of urban US infants from birth to 2 years of age. Estimates of the association between lead and Bayley Mental Development Index (MDI) scores at ages 6, 12, 18, and 24 months were obtained using several regression options. In all multivariate models examined, MDI scores were associated with umbilical cord blood lead levels, but not with postnatal blood lead levels. Infants with high cord blood lead levels (10-25 jUg/dl) consistently scored 4 to 8 points lower than infants with low cord blood lead levels (< 3 jUg/dl). Infants vulnerability to lead s developmental toxicity appears to be greatest during the fetal period. 

The inverse association in this sample between MDI scores and umbilical cord blood lead levels in the 0 to 25 jUg/dl range appears to be robust. Estimates of its magnitude and precision are relatively independent of analytic approach. Furthermore, the association does not appear to be attributable to the inordinate influence of outliers. Most infants with high lead levels contribute to the overall poorer performance of this group relative to infants with lower levels of prenatal exposure. 

Of the several ways we used the blood lead data, only one achieved statistical significance umbilical cord blood lead levels. That measure was highly statistically significant. For these children the subsequent measurements, including protoporphyrin, provided little predictive power. 

Transplacental transfer of lead in humans has been demonstrated in a number of studies, and lead has been identified in umbilical cord blood. In the work of Bellinger et al. (1987a), the mean lead concentration in umbilical cord blood from a sample size of 11,000 women was 6.6 3.2 pg/dL. In a study of 236 pregnant women in Glasgow, Scotland, the geometric mean PbB levels were 14 pg/dL for... 

Lead concentrations in maternal and umbilical cord blood have been reported by Greek researchers for 50 parturient women at delivery. Twenty-five of the women lived in industrial areas with high air pollution, and twenty-five lived in agricultural areas with low air pollution. The mean lead concentrations (expressed as mean standard deviation) for the women living in areas with high air pollution were 37.2 4.7 pg/L in maternal blood and 20 3.4 pg/L in umbilical cord blood (correlation coefficient, r = 0.57). The mean lead concentrations for the women living in areas with low air pollution were 20.5 5.6 pg/L in maternal blood and 12.9 3.6 pg/L in umbilical cord blood (correlation coefficient, r = 0.70). The authors conclude that the placenta demonstrates a dynamic protective function that is amplified when maternal PbB levels are raised (Vasilios et al. 1997). 

In any case, it s estimated that the human fetus is ten to a hundred times more sensitive to ambient lead than children or adults, such that the so-called national averages are almost certainly dangerous for the fetus. In 2006, researchers reported a study of 146 pregnant women in Mexico City.13 It s one of the few studies to measure maternal lead values during each trimester of pregnancy. The researchers examined the impact of prenatal lead exposure on fetal neurodevelopment by measuring whole blood and plasma levels of lead in the pregnant mothers at each trimester and then in umbilical cord blood at delivery. When the infants were at 12 and 24 months of age, the researchers measured their BLL and also evaluated their neural development with a standard method (the Spanish version of the Bayley Scales of Infant Development). From the evidence,... 

Lead can pass through the placental barrier and lead levels in the mother s blood are comparable to concentrations of lead in the umbilical cord at birth. Transplacental passage becomes detectable at 12-14 weeks of gestation and increases until birth. 

Chuang, H.-Y., Schwartz, J., Gonzales-Cossio, T., Lugo, M.C., Palazuelos, E., et al., 2001. Interrelations of lead levels in bone, venous blood, and umbilical cord blood with exogenous lead exposure through maternal plasma lead in peripartum women. Environ. Health... 

Rabinowitz MB, Needleman HL (1982) Temporal trends in the lead concentrations of umbilical cord blood. Science 216 1429-1431 Rossouw J, Offermeier J, Van Rooyen JM (1987) Apparent central neurotransmitter receptor changes induced by low-level lead exposure during different developmental phases in the rat. Toxicol Appl Pharmacol 91 132-139 Samarawickrama GP, Webb M (1979) Acute effects of cadmium on the pregnant rat and embryo-fetal development. Environ Health Perspect 28 245-249 Scharpf LG Jr, Hill ID, Wright PL, Plank JB, Keplinger ML, Calandra JC (1972) Effect of sodium nitrilotriacetate on toxicity, and tissue distribution of cadmium. Nature 239 231-234... 

---