Blood lead levels maternal

A later analysis (Emhart et al. 1987) related PbB levels obtained at delivery (maternal and cord blood) and at 6 months, 2 years, and 3 years of age to developmental tests (MDI, PDI, Kent Infant Development Scale [KID], and Stanford-Binet IQ) administered at 6 months, 1 year, 2 years, and 3 years of age, as appropriate. After controlling for covariates and confounding risk factors, the only significant associations of blood lead with concurrent or later development were an inverse association between maternal (but not cord) blood lead and MDI, PDI, and KID at 6 months, and a positive association between 6-month PbB and 6-month KID. The investigators concluded that, taken as a whole, the results of the 21 analyses of correlation between blood lead and developmental test scores were "reasonably consistent with what might be expected on the basis of sampling variability," that any association of blood lead level with measures of development was likely to be due to the dependence of both PbB and... 

The effects of low levels of lead on birth weight and gestational age are controversial. The earlier evidence for such effects was not reproduced in more studies by Factor-Litvak et al. (1991) and Greene and Emhart (1991). A significant inverse association between prenatal maternal blood lead levels and birth weight was reported in the Cincinnati study (Bomschein et al. 1989 Dietrich et al. 1986, 1987a). 

Needleman et al. 1984). The limitations of these studies include possible bias introduced by use of hospital records and a restricted range of maternal and cord blood lead levels. The sizes of the groups studied were not sufficient for the detection of differences in low frequencies of anomalies. 

A1 Khayat A, Habibullah J, Koutouby A, et al. 1997b. Correlation between maternal and cord blood lead levels. International Journal of Environmental Health Research 7(4) 323-328. 

Rothenberg SJ, Manalo M, Jiang J, et al. 1999a. Maternal blood lead level and blood pressure during pregnancy in South Central Los Angeles. Archives of Environmental Health, in press. 

What are these subclinical effects Very simply, they are effects that occur at blood lead levels below those that produce clinically measurable effects - they occur in the absence of any sign of overt lead poisoning. These effects can be detected only by studying various forms of behavior, such as degree of hyperactivity and classroom attention span, and performance on various tests of intelligence and mental development. Deficits in neurobehavioral development, as measured by two widely used tests - the Bayley and McCarthy Scales - have been reported in children exposed prenatally (via maternal blood) to blood... 

A correlation has been reported between lead levels in maternal blood and in the placenta (Schramel et al. 1988). Placental levels were higher in occupationally lead-exposed women than in non-exposed ones. There is a transplacental passage of lead to the fetus, both in animal experiments and in humans (Mayer-Popken et al. 1986). In animal experiments, the growing organism accumulated more lead in the CNS than did the adult animal (Momcilovic and Kos-tial 1974). Blood-lead levels in the child at birth are associated with those in the mother. Concentrations in the child appear to be somewhat lower than in the mother, in whole blood as well as in red blood cells and plasma (Cavalleri etal. 1978). There is usually a decrease in B-Pb at the start of pregnancy, but this is probably mainly due to an expansion of the plasma volume. 

In the study of the toxic element status of healthy Austrian women (n = 51) and their new-born babies a significant correlation between maternal and neonatal blood lead level (P < 0.001) was found. The mean concentration of lead was 3.7 (SD 1.27) xg/dl in whole blood of the mothers, 2.63 (SD 1.16) fJig/dl in whole blood of the new-borns, and 35.8 (SD 15.0) jLg/l in breast milk (Plockinger et al., 1993). 

Studies have shown an association between umbilical blood lead concentration under 10 gg/dL and reduced head circumference (Al-Saleh et al. 2008b), effects on infant attention (Plusquellec et al. 2007), abnormal reflexes and abnormal results on neurologic soft signs scales (Emhart et al. 1986), reduced body-weight gain (Sanin et al. 2001), and decreased body-mass index (NTP 2012). Deficits in visual function in children were also seen at umbihcal blood lead levels as low as 10.5 gg/dL (Rothenberg et al. 2002). Increased maternal... 

Most of these studies have shown that blood lead values are invariably increased by exposure, but little or no health hazard has been adduced. This may be due to the fact that minor effects (e.g. behavioural ones), have not usually been investigated. Lansdowne et al. (1974) linked proximity to a lead smelter in London with increase in blood lead levels. There was however no link between lead and any measure of mental capability that was investigated, and any observed differences that were found could be related to social factors. Hebei et al, (1976) compared distance from a Birmingham battery factory with 11-plus examination scores and found that children who lived near the factory since birth scored more than those with a low lead-load or living in unpolluted areas. They also reported that this difference remained when adjustments were made for social class, birth rank and maternal age. 

Blood lead levels associated with encephalopathy in the rat range from 570 tg Pb/lOOml (LeFauconnier et al., 1980) and 610 g Pb/lOOml (Press, 1977a) to 1297 tg Pb/l(X)ml (Alfano and Petit, 1981). Exceptionally, using 4% lead acetate in the maternal diet from parturition, McConnell and Berry (1979) found lesions of encephalopathic type in rats with blood lead levels reported at 258/ g Pb/lOOml. 

II. Maternal Blood Lead Levels During Pregnancy... 

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... 

Given these conclusions, the obvious question is, "What are the implications for the public health " First, what portion of the population is at risk Based on data from the National Center for Health Statistics (1982), approximately 3.6 million live births occurred in the United States in 1980. Data from the US National Health and Nutrition Examination Survey for about the same period (February 1979 to February 1980) indicate that about 27% of the women of child-bearing age had PbB concentrations of 10 /ig/dl or more cf. Schwartz et al, 1985). Thus, nearly 1 million infants may have been bom in the United States around 1980 to mothers with maternal PbB levels high enough to put the infants at risk for developmental impairments. Blood lead levels in the United States have probably declined somewhat since then due to reduced ambient levels (Schwartz et al, 1985), but the scope of potential concern is still significant, particularly in parts of the world where ambient levels may be greater. 

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