Prenatal lead exposure

The studies by Emhart et al. (1988) and Emhart and Greene (1990) found no associations between prenatal lead exposure and intelligence or language development, whereas those by Dietrich et al. 

A few studies have reported associations between prenatal lead exposure and changes in heme metabolism. In a study of 294 mother-infant pairs, Haas et al. (1972) reported mean PbB levels of 16.98 pg/dL for mothers and 14.98 pg/dL for newborns. Infant PbB levels and ALA-U were positively correlated. The authors, however, did not report the levels of ALA-secretion in infants and mothers with no lead exposure. In pregnant urban women (Kuhnert et al. 1977), cord erythrocyte lead levels ranged... 

Developmental Toxicity. Three human studies that described congenital malformations as an end point allow no definitive conclusion to be drawn regarding an association between prenatal lead exposure and the occurrence of congenital anomalies (Emhart et al. 1985, 1986 McMichael et al. 1986 ... 

University of Rochester, The influence of prenatal lead exposure National Institute of Dental Rochester, NY on susceptibility to dental caries and on Research... 

Bomschein RL, Grote J, Mitchell T, et al. 1989. Effects of prenatal lead exposure on infant size at birth. In Smith M, Grant LD, Sors A, eds. Lead exposure and child development An international assessment. Lancaster, UK Kluwer Academic Publishers. 

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. 

Andrews KW, Savitz DA, Hertz-Picciotta I Prenatal lead exposure in relation to gestational age and birth weight a review of epidemiologic studies. AmJ Ind Med 26 13-32, 1994... 

Several heavy metals have been identified as teratogens and possible abortifacients in humans and animals, and the adverse effects of prenatal lead exposure on the developing nervous systems of both human and laboratory animal species have been well documented (Evans et al, 2003 Rice, 1998 Rogers and Kavlock, 2008). Prenatal exposure to organotins has been associated with pregnancy loss and... 

Subsequent investigations adopted an even more forceful strategy they undertook prospective studies in which children with documented prenatal lead exposures were followed from birth. These studies demonstrated that even lead levels so low that they would have been considered insignificant just a few years earlier could reduce scores on IQ and analogous developmental tests. 

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,... 

Opler, M. G., Brown, A. S., Graziano, J., Desai, M., Zheng, W., Schaefer, C., Factor-Litvak, P., Susser, E. S. (2004). Prenatal lead exposure, delta-aminolevulinic acid, and schizophrenia. Environ. Health Perspect. 112 548—552. 

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. 

Plusquellec, P., G. Muckle, E. Dewailly, P. Ayotte, S.W. Jacobson, and J.L. Jacobson. 2007. The relation of low-level prenatal lead exposure to behavioral indicators of attention in Inuit infants in Arctic Quebec. Neurotoxicol. Teratol. 29(5) 527-537. 

Rothenberg, S.J., L. Schnaas, M. Salgado-Valladares, E. Casanueva, A.M. Geller, H.K. Hudnell, and D.A. Fox. 2002. Increased ERG a- and b-wave amplitudes in 7- to 10-year-old children resulting from prenatal lead exposure. Invest. Ophthalmol. 

Baumeister, A. A. (1982). An investigation of the effects of chronic low-level prenatal lead exposure on behavioral development, general activity and learning in neonatal and adult rats. Dissertation Abstr. Int., 42, 4592 (abstract)... 

Schnaas, L., Rothenberg, S.J., Flores, M.-F., Martinez, S., Hernandez, C., Osorio, E., et al., 2006. Reduced intellectual development in children with prenatal lead exposure. Environ. Health Perspect. 114, 791—797. 

Levine, F., Muenke, M., 1991. VACTERL association with high prenatal lead exposure similarities to animal models of lead teratogenicity. Pediatrics 87, 390—392. 

Ernhart, Claire B. 1992. A Critical Review of Low-Level Prenatal Lead Exposure in the Human 1. Effects on the Fetus and Newborn. Reproductive Toxicology Reviews 6 9-19. 

Reyes, Jessica Wolpaw. 2005. The Impact of Prenatal Lead Exposure on Health. Unpublished manuscript, Department of Economics, Amherst College. Rice, D. C. 1992. Behavioral Impairment Produced by Developmental Lead Exposure Evidence from Primate Research. In Human Lead Exposure, ed. Hebert L. Needleman, 137-154. Boca Raton, Fla. CRC Publisher. 

Xie X, Ding G, Cui C, Chen L, Gao Y, Zhou Y, et al. The effects of low-level prenatal lead exposure on birth outcomes. Environ Pollut 2013 175 30. ... 

Table 2 summarizes some of the main features of the study populations for each of the four prospective studies to be examined here. Note that the study populations are generally adequate in size, with ns numbering in the hundreds. However, the actual number of subjects used in specific analyses may be somewhat less than the enrolled population. For the most part, prenatal lead exposure was indicated by the maternal PbB level prior to or at delivery, or cord PbB level at delivery. Note that these average PbB levels were all below 15 jUg/dl and are probably representative of past and/or still prevalent levels in various parts of the world. 

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