Maternal BLL

Adverse developmental effects were found in infants and children at maternal BLLs imder 10 pg/dL, and reduced fetal growth and low birth weight... 

Hg/dL and over are associated with adverse effects on sperm or semen and that BLLs of 20 pg/dL and over are associated with delayed conception time. Decreases in sperm count, density, and concentration were seen in men who had mean BLLs of 15-68 pg/dL. The NTP also concluded that there was sufficient evidence that maternal BLLs under 5 pg/dL are associated with reduced fetal growth or lower birth weight. There is limited evidence that maternal BLLs under 10 pg/dL are associated with preterm birth and spontaneous abortion. Prospective studies reviewed by the NTP provided limited evidence that prenatal exposure to BLLs under 10 pg/dL is associated with reduced postnatal growth in children. The NTP recognized that its conclusions about prenatal lead exposure were confounded by possible continuing postnatal exposure to lead (associated with BLLs under 10 pg/dL) that is also associated with reduced postnatal growth in children. 

Lead induces reproductive and developmental effects in laboratory rats after gestational or lactational exposure. Many of the effects occur in a concentration-dependent manner and have been observed at maternal BLLs that do not result in overt maternal toxicity (under 40 pg/dL). Animal studies have further demonstrated that effects of lead exposure during early development include impairment of retinal development and alterations in the developing hematopoietic and hepatic systems. Toxicology studies in male animals have reported de-... 

Although the results are not entirely consistent among studies, the evidence on maternal or umbilical cord blood lead (under 10 gg/dL) and the large number of studies led the NTP to conclude that there was sufficient evidence of an association between maternal BLL under 10 gg/dL and reduced fetal growth and low birth weight. In contrast, the NTP concluded that there was only limited evidence that maternal BLL under 10 gg/dL is associated with spontaneous abortion and preterm birth. Although a number of prospective and cross-sectional studies have reported an association between prenatal BLL under 10 gg/dL and preterm birth, the conclusion of limited evidence was based primarily on inconsistency of the data and a large study of mother-infant pairs that failed to find the same relationship. EPA (2012) also concluded that there was little evidence to support an association between maternal or paternal lead exposure and the incidence of spontaneous abortion. 

The committee concludes that the evidence is snfficient to infer causal relationships between BLLs over 40 pg/dL and adverse effects on sperm and semen, inclnding decreased sperm count, reduced sperm motility, and increased morphologic abnormalities (see Table 4-4). The committee concludes that the evidence to infer causal relationships between BLLs under 40 pg/dL and adverse effects on sperm and semen is limited. The committee also found strong evidence of a causal relationship between prenatal maternal BLLs under 10 pg/dL and adverse developmental effects in infants and children and sufficient evidence of an association between maternal BLLs under 5 pg/dL and reduced fetal growth and low birth weight (see Table 4-5). The committee s conclusions are consistent with those of EPA and the NTP. 

Maternal BLL after miscarriage in cases, at study oiroUment in controls >53 pg/dL... 

Altered postnatal development and growth (maternal BLL under 10 pg/dL). 

There is a linearity of response to graded cortisol treatment in traumatized adrenalectomized animals (Bll). The adrenal cortical control of the appearance of slow a2-globulin is incomplete in the 2-day postpartum maternal rat, because the globulin can be demonstrated in most adrenalectomized animals in this condition. Adrenal cortical control over the appearance of the globulin is not simply in the postpartum maternal animal, because the percentage of adrenalectomized rats with demonstrable slow [Pg.17]

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,... 

EPA s review of recent epidemiologic studies of enviroiunental lead e q)0-sure and reproductive function concludes that there is strong evidence that increasing lead exposure is associated with reduced male fecundity or fertility, decreases in sperm count, and reduced sperm velocity and motility. EPA s draft report further concludes that deleterious associations with sperm count and quality are observed in occupationally exposed men who have mean BLLs as low as 20-45 pg/dL. EPA concluded that there was some association between maternal lead exposure and low birth weight toxicologic studies in animals have shown that lead exposme during early fetal development can result in abnormal retinal development and alterations in the developing hematopoietic and hepatic systems. 

BLLs of 5, 10 pg/dL associated with average decrease in birth weight of 61 g and 87 g, respectively model assumed linear relationship between untransformed BLL and gestational age in days data adjusted for timing of lead test, maternal age, race, smoking, alcohol consumption, economics, parity, infant sex. 

Fetotoxicity Exposure to lead early in life may be a risk factor for foetal growth. A study measured maternal and cord BLLs and examined their associations with birth outcomes. Mother-infant pairs (n = 252) were selected from a... 

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