Prenatal Pb Exposure Research Articles

Growth in Inuit children exposed to polychlorinated biphenyls and lead during fetal development and childhood

BackgroundBecause of their geographical location and traditional lifestyle, Canadian Inuit children are highly exposed to polychlorinated biphenyls (PCBs) and lead (Pb), environmental contaminants that are thought to affect fetal and child growth. We examined the associations of these exposures with the fetal and postnatal growth of Inuit children. MethodsWe conducted a prospective cohort study among Inuit from Nunavik (Arctic Québec). Mothers were recruited at their first prenatal visit; children (n=290) were evaluated at birth and at 8–14 years of age. Concentrations of PCB 153 and Pb were determined in umbilical cord and child blood. Weight, height and head circumference were measured at birth and during childhood. ResultsCord blood PCB 153 concentrations were not associated with anthropometric measurements at birth or school age, but child blood PCB 153 concentrations were associated with reduced weight, height and head circumference during childhood. There was no association between cord Pb levels and anthropometric outcomes at birth, but cord blood Pb was related to smaller height and shows a tendency of a smaller head circumference during childhood. InterpretationOur results suggest that chronic exposure to PCBs during childhood is negatively associated with skeletal growth and weight, while prenatal Pb exposure is related to reduced growth during childhood. This study is the first to link prenatal Pb exposure to poorer growth in school-age children.

Lead exposure at each stage of pregnancy and neurobehavioral development of neonates

PurposeOur pilot studies showed that there was a significant relationship between blood lead levels of women at the first trimester and scores of neonatal behavioral neurological assessment (NBNA). This study went further (1) to determine particular neurotoxicity during a specific trimester, (2) to analyze “safe” levels of Pb in neonates, and (3) to identify influencing factors for prenatal Pb exposure. MethodA total of 415 mothers with newborn located Shenzhen, Guangdong, China participated in the study: 219 in the high lead group [blood lead levels (BLLs) at first trimester≥4.89μg/dl] and 196 in the low lead group [BLLs≤1.96μg/dl]. The maternal BLLs at each stage of pregnancy and delivery were measured by atomic absorption spectrophotometry, equipped with a graphite furnace. The developmental functioning of newborns was assessed with NBNA in 3 days. The children's birth outcome and the rest of information was obtained from their medical records or a comprehensive questionnaire from their parents, which contained demographic characteristics, lifestyle, IQ, occupation and influencing factors for lead exposure during and before first trimester, etc. ResultsOf 415 newborns, 332 (80.00%) had complete data collection for all variables at four-stage follow-up. The maternal mean BLL at first trimester for 332 newborns was 3.98±1.15μg/dl (0.38–15.86μg/dl) and the geometric mean (GM) was 3.63±0.35μg/dl (95%CI: 2.98–4.32μg/dl). In total, about 4.82% of newborns had maternal BLLs>10μg/dl. Significant inverse associations have been found between the maternal BLLs at the first trimester and the NBNA scores (P<0.05). Drinking milk and supplements of Ca, Fe, or Zn are protective factors of high BLLs (OR=0.363, P<0.05). ConclusionOur study demonstrate that fetal lead exposure as low as 5μg/dl has an adverse effect on neurodevelopment, most expressed during the first trimester and best arrested by measuring maternal BLLs. The collective evidence indicates that screening and intervention after the first trimester may be too late to prevent the fetal neurotoxic effects.

ENVIRONMENTAL LEAD EXPOSURE AND ODDS OF EARLIER PUBERTAL ONSET

Background and Aims: Evidence for associations between lead (Pb) and late onset of puberty have come primarily from cross-sectional studies. Early life exposure to lead may be important for puberty onset because of the long-term effects of lead on the endocrine system. We examined the association of maternal bone Pb, a marker of cumulative prenatal Pb exposure, with odds of earlier pubertal onset. Methods: Maternal bone Pb was assessed at 1-month postpartum using in vivo K-X-ray fluorescence (K-XRF). Multivariable logistic regression was used to investigate the association of prenatal Pb levels with onset of puberty as assessed by self-reported Tanner stage greater or equal than 2 for genitalia (G2 among boys), breast (B2 among girls) and pubic hair development (P2 for each sex), adjusting for child’s age and maternal education. Results: There were 69 girls and 59 boys aged 6 to 15 years with Tanner staging and prenatal Pb measures. Among girls, mean age at study visit was 8.9 years (SD= 2.1); 39% were at stage B2 or above and 16% at stage P2 or above. Mean age at menarche was 10.6 years (SD= 1.7). Among boys, mean age was 9.1 years (SD= 2.2); 66% were at stage G2 or above, and 17% at stage P2 or above. Associations were primarily null between maternal bone Pb and odds for earlier or later onset of puberty, though slightly higher odds for later puberty onset with increased Pb levels was detected (for example for boy’s pubic hair OR=1.09, 95% CI= 0.94 to 1.27). Conclusion: These results suggest that prenatal Pb levels are not associated with odds of earlier or later pubertal onset in a longitudinal cohort study in Mexico, but interpretation is limited by small sample size. Investigation of this association in a larger study sample is warranted.

Perinatal lead and mercury exposure in Austria

Objective The heavy metals lead (Pb) and mercury (Hg) are ubiquitous environmental pollutants with high neurotoxic potential. We aimed to compare perinatal Pb and Hg concentrations and to explore the potential association between Pb and Hg exposure and newborn anthropometry. Study design Pregnant women were recruited in 2005 at the General Hospital Vienna for participation in this longitudinal study. Pb and Hg concentrations were measured in maternal blood and hair, placenta, cord blood, meconium, and breast milk of 53 mother-child pairs by CV-AAS, GF-AAS, and HPLC-CV-ICPMS. We conducted bivariate analyses and categorical regression analysis (CATREG) to evaluate the determinants of Pb and Hg exposure, and of infant anthropometry. Results Median Pb and total Hg contents were low, i.e., 25 μg/L (maternal blood-Pb), 13 μg/L (cord blood-Pb), 0.7 μg/L (maternal blood-Hg), and 1.1 μg/L (cord blood-Hg). Hg levels in maternal and fetal tissues were frequently correlated ( r > 0.3, P < 0.05, respectively). Regarding Pb, only maternal blood and cord blood concentrations correlated ( P = 0.043). Cord blood levels indicated higher Hg exposure but lower Pb exposure relative to maternal blood contents. Adjusted CATREG models indicated the significant predictors of birth length (placenta-Pb, gestational length, meconium-Pb), birth weight (placenta-Pb, gestational length, maternal blood-Pb), and head circumference (maternal education, maternal height). Besides one significant correlation between maternal hair Hg and birth length, the mercury levels were not associated with newborn anthropometry. Conclusions Our data implicate that different modes of action may exist for placentar transfer of Pb and Hg as well as that low Pb exposure levels can result in lower birth weight. The findings related to newborn anthropometry need to be confirmed by the examination of larger study groups. Further research is needed to clarify the mechanisms of Pb and Hg transfer via the placenta, and to explore how prenatal Pb exposure is related to intrauterine growth.

The relation of lead neurotoxicity to the event-related potential P3b component in Inuit children from arctic Québec

The event-related potential (ERP) P3b, a cognitive electrophysiological measure that has been linked to working memory processing in many experimental paradigms, was measured in Inuit children from Nunavik (Arctic Québec, Canada) to assess lead (Pb) neurotoxicity. Visual and auditory oddball paradigms were administered at 5 ( N = 27) and 11 ( N = 110) years of age, respectively, to elicit this ERP component. Pearson correlations and multiple regression analyses were performed to examine the associations between Pb levels and P3b parameters (peak latency and amplitude). Greater prenatal Pb exposure was related to a decrease in P3b amplitude at 5 years of age, and early childhood Pb exposure was associated with delayed P3b latency at 5 years. No significant association was observed at 11 years. These results, in line with those from previous neurobehavioral studies, suggest that Pb exposure affects cognitive processing in children even though the Pb levels measured in a large majority of our sample were below the threshold value for public health intervention used by federal agencies. This study strengthens the arguments for reducing sources of Pb exposure in Nunavik and for lowering the blood Pb concentrations considered “acceptable” in governmental policies.

Prenatal Exposure to Lead, δ-Aminolevulinic Acid, and Schizophrenia: Further Evidence

BackgroundA previously conducted study of prenatal lead exposure and schizophrenia using δ-aminolevulinic acid, a biologic marker of Pb exposure, in archived maternal serum samples collected from subjects enrolled in the Childhood Health and Development Study (1959–1966) based in Oakland, California, suggested a possible association between prenatal Pb exposure and the development of schizophrenia in later life.ObjectivesIn the present study we extend these findings using samples collected from the New England cohort of the National Collaborative Perinatal Project (1959–1966). Using similar methods, in this study we found results that suggest a comparable association in this cohort.MethodsWe pooled matched sets of cases and controls from both the California and New England sites using a multilevel random-intercept logistic regression model, accounting for matching and site structure as well as adjusting for maternal age at delivery and maternal education.ResultsThe estimated odds ratio for schizophrenia associated with exposure corresponding to 15 μg/dL of blood Pb was 1.92 (95% confidence interval, 1.05–3.87; p = 0.03).ConclusionAlthough several limitations constrain generalizability, these results are consistent with previous findings and provide further evidence for the role of early environmental exposures in the development of adult-onset psychiatric disorders.

The relation of low-level prenatal lead exposure to behavioral indicators of attention in Inuit infants in Arctic Quebec

The aim of this study was to investigate the association between prenatal exposure to lead (Pb) and several aspects of behavioral function during infancy through examiner ratings and behavioral coding of video recordings. The sample consisted of 169 11-month-old Inuit infants from Arctic Quebec. Umbilical cord and maternal blood samples were used to document prenatal exposure to Pb. Average blood Pb levels were 4.6 μg/dL and 5.9 μg/dL in cord and maternal samples respectively. The Behavior Rating Scales (BRS) from the Bayley Scales of Infant Development (BSID-II) were used to assess behavior. Attention was assessed through the BRS and behavioral coding of video recordings taken during the administration of the BSID-II. Whereas the examiner ratings of behaviors detected very few associations with prenatal Pb exposure, cord blood Pb concentrations were significantly related to the direct observational measures of infant attention, after adjustment for confounding variables. These data provide evidence that increasing the specificity and the precision of the behavioral assessment has considerable potential for improving our ability to detect low-to-moderate associations between neurotoxicants, such Pb and infant behavior.

Effect of magnitude and timing of maternal pregnancy blood lead (Pb) levels on birth outcomes

Associations between magnitude and timing of maternal pregnancy blood lead (Pb) levels (BLLs), birth weight, and total days of gestation were examined, as well as associations with related clinical diagnoses of low birth weight (LBW), preterm, and small-for-gestational-age (SGA) birth. Among a sample of 262 mother-infant pairs studied retrospectively, one-way analysis of variance and regression statistics were used to measure the relationship between level of maternal pregnancy BLLs and birth outcomes while controlling for key maternal and newborn factors. Women with maximum pregnancy BLLs (max-PBLLs) > or =10 microg/dl tended to give birth earlier and their babies were at substantially increased risk for preterm and SGA birth. By holding other explanatory factors constant, each unit increase in max-PBLL above 10 mug/dl was found to be associated with a decrease of -0.3 in total days of gestation. Compared to women with lower levels, women with max-PBLLs > or =10 microg/dl were at a threefold increased risk for preterm birth (adjusted OR=3.2, 95% CI 1.2-7.4) and more than a fourfold increased risk for having an SGA infant (adjusted OR=4.2, 1.3-13.9). Second trimester maximum BLLs > or =10 microg/dl were associated with a steep decrease in total days of gestation (a decrease of -1.0 days per each unit increase above 10 microg/dl). These data provide evidence of the adverse effects of maternal pregnancy BLLs, particularly when levels are > or =10 microg/dl. Prenatal Pb exposure at these levels was associated with significant decreases in total days of gestation and an increased risk of preterm and SGA birth.

Genderbasic: Promoting attention to sex and gender differences in life sciences research in Europe

The heavy metals lead (Pb) and mercury (Hg) are ubiquitous environmental pollutants with high neurotoxic potential. We aimed to compare perinatal Pb and Hg concentrations and to explore the potential association between Pb and Hg exposure and newborn anthropometry.Pregnant women were recruited in 2005 at the General Hospital Vienna for participation in this longitudinal study. Pb and Hg concentrations were measured in maternal blood and hair, placenta, cord blood, meconium, and breast milk of 53 mother-child pairs by CV-AAS, GF-AAS, and HPLC-CV-ICPMS. We conducted bivariate analyses and categorical regression analysis (CATREG) to evaluate the determinants of Pb and Hg exposure, and of infant anthropometry.Median Pb and total Hg contents were low, i.e., 25 μg/L (maternal blood-Pb), 13 μg/L (cord blood-Pb), 0.7 μg/L (maternal blood-Hg), and 1.1 μg/L (cord blood-Hg). Hg levels in maternal and fetal tissues were frequently correlated (r > 0.3, P < 0.05, respectively). Regarding Pb, only maternal blood and cord blood concentrations correlated (P = 0.043). Cord blood levels indicated higher Hg exposure but lower Pb exposure relative to maternal blood contents. Adjusted CATREG models indicated the significant predictors of birth length (placenta-Pb, gestational length, meconium-Pb), birth weight (placenta-Pb, gestational length, maternal blood-Pb), and head circumference (maternal education, maternal height). Besides one significant correlation between maternal hair Hg and birth length, the mercury levels were not associated with newborn anthropometry.Our data implicate that different modes of action may exist for placentar transfer of Pb and Hg as well as that low Pb exposure levels can result in lower birth weight. The findings related to newborn anthropometry need to be confirmed by the examination of larger study groups. Further research is needed to clarify the mechanisms of Pb and Hg transfer via the placenta, and to explore how prenatal Pb exposure is related to intrauterine growth.