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

Sex dependent intergenerational effects of lead in mouse model

Lead (Pb) exposure negatively impacts fertility in both males and females, pregnancy outcomes, and child brain development. We investigated the reproductive and neurological effects of Pb exposure on male and female mice via Pb-contaminated soil for 4 weeks. Breeding was conducted after completion of exposure, in four groups; group 1 consisted of exposed dams and unexposed sires, group 2 consisted of exposed sires and unexposed dams, group 3 consisted of exposed sires and exposed dams and group 4 was the control. Generally, Pb exposure reduced observed conception rates, with a cumulative decrement observed when both males and females are exposed. Gene expression of the testes revealed oxidative stress as the cause of reduced conception rates. Neurological tests: Morris water maze and rotarod were conducted on F1 generation offspring. Maternally and paternally exposed F1 mice performed poorly in the Morris water maze when compared to the control. The severity of the neurological effects was also parent-dependent and sex-dependent. Paternal Pb exposure effects were more pronounced in female offspring. A comparison of gene expression changes of the hippocampus and prefrontal cortex showed paternal Pb-exposure resulted in more prefrontal cortex changes than in the hippocampus, a trend also recorded in the exposed sires. The pronounced effects in female offspring of paternal Pb exposure may suggest that Pb neurological effects may be X-chromosome-linked.

Prenatal Lead Exposure, Genetic Factors, and Cognitive Developmental Delay

Importance

Although the effects of lead (Pb) exposure on neurocognition in children have been confirmed, the individual associations of prenatal Pb exposure and its interaction with genetic factors on cognitive developmental delay (CDD) in children remain unclear.

Objective

To investigate the association of prenatal Pb exposure and its interaction with genetic factors with CDD risk.

Design, Setting, and Participants

Women in Wuhan, China, who had an expected delivery date between March 2014 and December 2017, were recruited for this prospective cohort study. Children were assessed for cognitive development at approximately 2 years of age (March 2016 to December 2019). Maternal venous blood, cord blood, and venous blood from children were collected in a longitudinal follow-up. Data analysis was performed from March 2022 to February 2023.

Exposure

Prenatal Pb exposure, and genetic risk for cognitive ability evaluated by polygenic risk score constructed with 58 genetic variations.

Main Outcomes and Measures

Cognitive developmental delay of children aged approximately 2 years was assessed using the Chinese revision of the Bayley Scale of Infant Development. A series of multivariable logistic regressions was estimated to determine associations between prenatal Pb exposure and CDD among children with various genetic backgrounds, adjusting for confounding variables.

Results

This analysis included 2361 eligible mother-child pairs (1240 boys [52.5%] and 1121 girls [47.5%]; mean [SD] ages of mothers and children, 28.9 [3.6] years and 24.8 [1.0] months, respectively), with 292 children (12.4%) having CDD. Higher maternal Pb levels were significantly associated with increased risk of CDD (highest vs lowest tertile: odds ratio, 1.55; 95% CI, 1.13-2.13), adjusting for demographic confounders. The association of CDD with maternal Pb levels was more evident among children with higher genetic risk (highest vs lowest tertile: odds ratio, 2.59; 95% CI, 1.48-4.55), adjusting for demographic confounders.

Conclusions and Relevance

In this cohort study, prenatal Pb exposure was associated with an increased risk of CDD in children, especially in those with a high genetic risk. These findings suggest that prenatal Pb exposure and genetic background may jointly contribute to an increased risk of CDD for children and indicate the possibility for an integrated strategy to assess CDD risk and improve children's cognitive ability.

Uncovering the Molecular Link Between Lead Toxicity and Parkinson's Disease

Significance: Parkinson's disease (PD) is a progressive neurodegenerative disorder that affects millions around the world. The etiology of PD remains unknown, but environmental and occupational exposures to heavy metals are likely at play, and may impact the severity of the disease. Lead is a toxin known to affect many organs in the body throughout life, particularly the central nervous system. Recent Advances: In this study, we summarize and examine the evidence for such environmental and/or occupational exposures, with a focus on the molecular mechanisms associated with lead exposure and its potential contribution to the onset of parkinsonism in PD. In particular, populational studies suggest higher bone and blood lead levels are associated with increased risk of PD. Interestingly, low levels of lead exposure in the very early stages of life cause increase the production of alpha-synuclein protein in animal models. Critical Issues: Although the specific mechanisms underlying this association have not been fully assessed, oxidative stress and mitochondrial dysfunction are likely implicated and may explain the toxic effects that connect lead exposure to parkinsonism. Future Directions: Additional pre-clinical and clinical studies should be performed in order to further document the molecular link between lead toxicity and PD, as this may open novel perspectives in terms of disease prevention. Antioxid. Redox Signal. 39, 321-335.

Associations Between the Lead Level in Maternal Blood and Umbilical Cord Blood and Congenital Heart Diseases in Offspring

The incidence of congenital heart diseases (CHDs) shows an increasing trend and results in large health burdens in China. However, there have been inconsistent results of the relationship between lead (Pb) level and risk of CHDs. We performed a pair-matched case-control study and included 97 cases and 194 controls to investigate the association between pregnancy Pb exposure and the risk of CHDs in a birth cohort study conducted in Lanzhou, China. The results showed that compared to the lowest Pb tertile, both highest tertile levels of maternal blood and umbilical cord blood Pb were associated with an increased risk of CHDs. The similar significant results were found in cases with isolated CHDs. Compared to both lowest tertiles of Pb level in maternal blood and umbilical cord blood, the highest tertile was associated with an increased risk of CHDs, especially for isolated CHDs. Overall, our study suggests a significant association between pregnancy Pb exposure and risk of CHDs, especially for isolated CHDs. Future studies are needed to elucidate the underlying mechanism.

Trends in elemental Pb concentrations within atmospheric PM2.5 and associated risk to human health in major cities of China

High concentrations of elemental lead (Pb) in the atmosphere pose a serious threat to human health. This study presents and summarizes data obtained from relevant literature on Pb concentrations within fine particulate matter (PM_2.5) recorded in major cities in China from 2008 to 2019. An environmental health risk assessment model was then used to evaluate the health hazards of inhaling Pb among adults and children in China. Owing to the promulgation and implementation of a series of air pollution control measures, the Pb concentrations within PM_2.5 measured in major cities in China showed a downward trend after peaking in 2013. The concentrations were higher in winter than in summer, and higher in northern cities than in southern cities. Although the Pb concentrations in most cities did not exceed the limit (500 ng/m³) set by China, they remained much higher than concentrations recorded in developed countries. The results of the environmental health risk analysis showed that the non-carcinogenic risk from atmospheric Pb exposure was higher in children than in adults (adult females > adult males), while the carcinogenic risk was higher in adults than in children. This study shows that even if the health risk of Pb in PM_2.5 does not exceed the acceptable limit, stricter Pb pollution control measures are required to safeguard population health due to the dangers of Pb.

Maternal omega-3 fatty acid supplementation against prenatal lead exposure induced cognitive impairment in offspring mice

Maternal lead exposure is associated with poor outcomes in fetal brain development such as cognitive dysfunction. Here, we aimed to reveal the effect and mechanism of omega-3 fatty acids in ameliorating maternal lead exposure-induced cognitive impairment in mouse offspring. The activity levels of locomotor and anxiety, memory and learning capacity, spatial working memory, and cognitive behavioral function were determined using the open field test, Morris water maze, Y-maze, and nest-building test, respectively. The protein levels of brain-derived neurotrophic factor (BDNF), nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) were measured using enzyme-linked immunosorbent assay or Western blot. The mRNA levels of BDNF, tyrosine kinase B (TrkB) and cyclic AMP response element binding protein (CREB) were measured by real-time qPCR. Malondialdehyde (MDA) and anti-oxidants, including SOD, GSH and CAT, were measured using bioassay kits. We found that supplementing omega-3 significantly improved cognitive behavioral function in offspring after prenatal lead exposure. The protein and mRNA levels of BDNF, TrkB and CREB in the prenatal lead exposure group were significantly upregulated by omega-3 supplementation. The MDA level in the prenatal lead exposure group was markedly elevated compared with the control group, which was significantly reduced by omega-3. Omega-3 restored anti-oxidants SOD, GSH and CAT to control levels after prenatal lead exposure. Omega-3 significantly upregulated Nrf2 nuclear expression and HO-1 expression after prenatal lead exposure. Overall, omega-3 supplementation significantly elevated the BDNF/TrkB/CREB pathway and restores anti-oxidants by upregulating the Nrf2/HO-1, thereby improving cognitive function in offspring after prenatal lead exposure.

Association of newborn blood lead concentration with neurodevelopment outcome in early infancy

BACKGROUND

In utero exposure to toxic metal substances can cause severe neurodevelopmental deficits in developing fetus and infant.

METHODS

We evaluated the association of newborn umbilical cord blood lead concentration with early neurodevelopmental performance (cognitive, receptive language, expressive language, fine motor, gross motor and social-emotional development). The Bayley Scale of Infants Developments-III (BSID-III) was used to perform neurodevelopment outcomes at an average age of 6.5 months. In this prospective study, total of 167 mother-child pairs were enrolled from Western Rajasthan, India. Association between risk factors of lead contamination and newborn umbilical cord blood lead levels was observed. Multivariate regression was performed to see the association of cord blood lead level with infant neurodevelopment outcome.

RESULTS

The obtained newborn umbilical cord blood lead concentration 5.0-10.5 μg/dL was negatively associated with the sub-scale score of gross motor development (β-coefficient with 95 % CI; -0.29 (-5.0-0.11), p = 0.04). However, no associations were found with the score of cognitive, language, gross motor, and social-emotional development. The umbilical cord blood lead concentration <5.0 μg/dL was also not associated with the BSID-III scores. The mother's regular intake of calcium supplements during the antenatal period was significantly associated with a lower umbilical cord blood lead level (p-value 0.031).

CONCLUSION

The data suggest that newborn umbilical cord blood lead concentration 0.5-10.5 μg/dL has a negative association with early gross motor development during infancy.

Lead (Pb) and neurodevelopment: A review on exposure and biomarkers of effect (BDNF, HDL) and susceptibility

Lead (Pb) is a ubiquitous environmental pollutant and a potent toxic compound. Humans are exposed to Pb through inhalation, ingestion, and skin contact via food, water, tobacco smoke, air, dust, and soil. Pb accumulates in bones, brain, liver and kidney. Fetal exposure occurs via transplacental transmission. The most critical health effects are developmental neurotoxicity in infants and cardiovascular effects and nephrotoxicity in adults. Pb exposure has been steadily decreasing over the past decades, but there are few recent exposure data from the general European population; moreover, no safe Pb limit has been set. Sensitive biomarkers of exposure, effect and susceptibility, that reliably and timely indicate Pb-associated toxicity are required to assess human exposure-health relationships in a situation of low to moderate exposure. Therefore, a systematic literature review based on PubMed entries published before July 2019 that addressed Pb exposure and biomarkers of effect and susceptibility, neurodevelopmental toxicity, epigenetic modifications, and transcriptomics was conducted. Finally included were 58 original papers on Pb exposure and 17 studies on biomarkers. The biomarkers that are linked to Pb exposure and neurodevelopment were grouped into effect biomarkers (serum brain-derived neurotrophic factor (BDNF) and serum/saliva cortisol), susceptibility markers (epigenetic markers and gene sequence variants) and other biomarkers (serum high-density lipoprotein (HDL), maternal iron (Fe) and calcium (Ca) status). Serum BDNF and plasma HDL are potential candidates to be further validated as effect markers for routine use in HBM studies of Pb, complemented by markers of Fe and Ca status to also address nutritional interactions related to neurodevelopmental disorders. For several markers, a causal relationship with Pb-induced neurodevelopmental toxicity is likely. Results on BDNF are discussed in relation to Adverse Outcome Pathway (AOP) 13 ("Chronic binding of antagonist to N-methyl-D-aspartate receptors (NMDARs) during brain development induces impairment of learning and memory abilities") of the AOP-Wiki. Further studies are needed to validate sensitive, reliable, and timely effect biomarkers, especially for low to moderate Pb exposure scenarios.

Insight into biosorption of heavy metals by extracellular polymer substances and the improvement of the efficacy: a review

Heavy metals are continuously released into aquatic environments in which they accumulate. This phenomenon endangers public health because heavy metals accumulate along the food chain. However, conventional remediation methods are inefficient, expensive and yield toxic intermediate products, which adversely affect the environment. The discovery of green bio-adsorbents such as microbial extracellular polymer substance (EPS) has quickly attracted considerable worldwide attention because of their low cost, high removal efficiency of heavy metals and industrial availability. Hence, this review considers the sources, hazards and treatment methods of heavy metals pollution, particularly the biosorption mechanism of EPS to heavy metals and the influencing factors of the bio-adsorption process, which are significant in the efficient removal of heavy metals-containing wastewater treatment. This review also focuses on strengthening the process of EPS adsorption of heavy metals, which can further contribute to heavy metals removal. Finally, it has been proposed that improving the yield, stability, selectivity and recoverability of EPS is the key direction of further research.

Breast milk to blood lead ratios among women from the West Bank of Palestine: a cross-sectional study of associated factors

Background

Infants fed contaminated breast milk are at an increased risk of exposure to lead. Breast milk to blood (M/B) ratios have not been investigated among women in Palestine. The aim of this study was to assess blood, breast milk, and M/B lead ratios in samples collected from Palestinian breastfeeding women. Associations between sociodemographic characteristics with breast milk lead levels and M/B lead ratios were also investigated.

Methods

This study was conducted in a cross-sectional design in the period between October 2017 and April 2018. Breastfeeding women visiting maternity care centers in different regions of the West Bank of Palestine were recruited to the study by the nurses in the maternity care centers. Sociodemographic characteristics, venous blood, and breast milk samples were collected from each participant. Lead concentrations were analyzed using a validated inductively coupled plasma-mass spectrometric method. Mann–Whitney U test, Pearson’s Chi-square, Fisher’s exact, and Spearman’s correlations were used to analyze the data. Odds ratios (OR) were computed using a multivariate logistic regression model.

Results

Matching blood and milk samples were collected from 80 women. Lead concentrations in 11 (13.8%) of the breast milk samples were above the World Health Organization’s recommended levels. Breast milk lead levels were more likely to be ≥5 μg/L in breastfeeding women who lived in urban areas (aOR 4.96; 95% CI 1.10, 22.38) compared to those who lived in rural areas. Breast milk to blood lead ratios were more likely to be ≥25% in breastfeeding women who lived in urban areas (aOR 7.06; 95% CI 1.68, 29.77), used eye kohl (aOR 14.29; 95% CI 1.32, 155.06), and used hair dye (aOR 5.33; 95% CI 1.58, 18.00) compared to those who lived in rural areas, did not use eye kohl, and did not use hair dye, respectively.

Conclusions

Higher M/B lead ratios were predicted by living in urban areas, using eye kohl, and using hair dye. Decision makers in health authorities should address sources of exposure to lead in urban areas. Cosmetics containing lead should be assessed and regulated for lead content.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13006-021-00410-3.

DNA methylation at birth potentially mediates the association between prenatal lead (Pb) exposure and infant neurodevelopmental outcomes

Early-life lead (Pb) exposure has been linked to adverse neurodevelopmental outcomes. Recent evidence has indicated a critical role of DNA methylation (DNAm) in cognition, and Pb exposure has also been shown to alter DNAm. However, it is unknown whether DNAm is part of the mechanism of Pb neurotoxicity. This longitudinal study investigated the associations between trimester-specific (T1, T2, and T3) maternal blood Pb concentrations, gene-specific DNAm in umbilical cord blood, and infant neurodevelopmental outcomes at 12 and 24 months of age (mental development index, psychomotor development index, and behavioral rating scale of orientation/engagement and emotional regulation) among 85 mother-infant pairs from the Early Life Exposure in Mexico to Environmental Toxicants (ELEMENT) study. In the mediation analysis for this pilot study, P < 0.1 was considered significant. DNAm at a locus in CCSER1 (probe ID cg02901723) mediated the association between T2 Pb on 24-month orientation/engagement [indirect effect estimate 4.44, 95% confidence interval (-0.09, 10.68), P = 0.06] and emotional regulation [3.62 (-0.05, 8.69), P = 0.05]. Cg18515027 (GCNT1) DNAm mediated the association of T1 Pb [-4.94 (-10.6, -0.77), P = 0.01] and T2 Pb [-3.52 (-8.09, -0.36), P = 0.02] with 24-month EMOCI, but there was a positive indirect effect estimate between T2 Pb and 24-month psychomotor development index [1.25 (-0.11, 3.32), P = 0.09]. The indirect effect was significant for cg19703494 (TRAPPC6A) DNAm in the association between T2 Pb and 24-month mental development index [1.54 (0, 3.87), P = 0.05]. There was also an indirect effect of cg23280166 (VPS11) DNAm on T3 Pb and 24-month EMOCI [2.43 (-0.16, 6.38), P = 0.08]. These associations provide preliminary evidence for gene-specific DNAm as mediators between prenatal Pb and adverse cognitive outcomes in offspring.

Neurodevelopment and exposure to neurotoxic metal(loid)s in environments polluted by mining, metal scrapping and smelters, and e-waste recycling in low and middle-income countries

This review covers a wide body of literature to gain an understanding of the impacts of informal activities related to metal extraction (primary mining and recycling) on early life exposure to neurotoxicants and on neurodevelopment. In primary mining, gold extraction with Hg amalgamation is the main environmental cause of Hg pollution in most artisanal small-scale gold mining (ASGM) activities around the world. Nevertheless, in Sub-Saharan Africa (SSA), Pb disrupted from gold-related ores, mining, and artisanal cookware production are an important neurotoxicant that seriously contaminates the affected population, with devastating effects on children. In e-waste recycling settings, the range of neurotoxic substances that contaminate mothers and children is wider than in primary mining environments. Thus, Hg and Pb are major pre- and postnatal neurotoxicants affecting children in the informal metal extraction activities and SSA countries show the highest record of human contamination and of neurotoxic effects on children. There are additional sources of neurotoxic contamination from mining and metal processing activities (cyanide tailing in South America and SSA) and/or co-exposure to Hg-containing products such as cosmetics (soaps and Hg-based skin lightning creams in Africa) and pediatric Thimerosal-containing vaccines (TCVs, that breaks down to ethyl-mercury) in current use in middle and low income countries. However, the action of these neurotoxicants (per se or in combination) on children needs more attention and research. Studies show a negative association between biomarkers of all environmental metal(loid)s (As, Cd, Hg, Mn, and Pb) studied and neurodevelopment in young children. Sadly, in many unregulated activities, child labor is widely employed, thus presenting an additional occupational exposure. Children living in polluted environments related to metal processing are disproportionately exposed to a wide range of co-occurring neurotoxic substances. The review showed compelling evidence from highly representative parts of the world (Africa, Asia, and Latin America) that the studied neurotoxic substances negatively affected areas of the brain associated with language, memory and executive function, as well as psychosocial behavior. Protecting the environment and children from unregulated and highly polluting metal extraction and processing are inextricably intertwined and deserve urgent attention.

Effect of combined pharmacological, behavioral, and physical interventions for procedural pain on salivary cortisol and neurobehavioral development in preterm infants: a randomized controlled trial

Repeated procedural pain may lead to increased secretion of cortisol and future neurobehavioral development disorders in preterm infants. Changes in the cortisol level may mediate the effect of neonatal repetitive procedural pain on altered childhood neurobehavioral development in preterm infants. However, few studies have investigated the effect of combined pharmacological, behavioral, and physical interventions over repeated painful procedures on pain response, cortisol level, and neurobehavioral development. This study examined (1) the efficacy and safety of sucrose combined with massage, music, non-nutritive sucking, and gentle human touch to treat preterm infants with repeated procedural pain; (2) the cortisol level at discharge from the neonatal intensive care unit (NICU); (3) neurobehavioral development at 40 weeks' corrected gestational age; and (4) the potential mediating effect of the cortisol level in the combined interventions on neurobehavioral development. Stable preterm infants (n = 76) were randomized to receive routine care or combined interventions across repeated painful procedures throughout their NICU stay. The Premature Infant Pain Profile scores in the early, middle, and late periods of the NICU stay were measured, as were the basal salivary cortisol level at admission and discharge, the Neonatal Behavioral Neurological Assessment score at 40 weeks' corrected gestational age, and the incidence of adverse effects during the study period. Our findings indicated that the combined interventions remained efficacious and safe for reducing repeated procedural pain, decreased the cortisol level at discharge, and promoted early neurobehavioral development in preterm infants. This effect may have been mediated through decreased cortisol levels and reduced repeated procedural pain.

Brain Development in Infants of Mothers With Gestational Diabetes Mellitus: A Diffusion Tensor Imaging Study

OBJECTIVE

The objective of this study was to investigate clinical neurocognitive performance and microstructural white matter (WM) alterations in infants of mothers with gestational diabetes mellitus (GDM) using diffusion tensor imaging.

MATERIALS AND METHODS

Infants (corrected gestational age, 33.42-36.00 weeks) of mothers with GDM (n = 31) and gestational age- and sex-matched unexposed controls (n = 31) accomplished 3-T diffusion tensor imaging scans and neurocognitive tests. Diffusion tensor imaging measures, mainly referring to fractional anisotropy (FA) values, were compared between 2 groups, and within-group analysis of correlation between FA values and neurocognitive testing outcomes in GDM-exposed infants was conducted subsequently.

RESULTS

Fractional anisotropy was significantly decreased in the splenium of corpus callosum, posterior limb of internal capsule, thalamus in infants of mothers with GDM when compared with controls (P < 0.05), reflecting microstructural WM abnormalities in the GDM group. Decreased FA was associated with worse neurocognitive performance in the exposed group (P < 0.05).

CONCLUSIONS

Individuals of mothers with GDM showed microstructural WM abnormalities in different brain regions, which were significantly related to worse neurocognitive performance. This might reveal that GDM directly insults the brain development of the offspring.

Maternal Δ-aminolevulinic acid dehydratase 1-2 genotype enhances fetal lead exposure and increases the susceptibility to the development of cerebral palsy

Limited epidemiologic studies questioned the association between pre- and postnatal lead exposure and the development of cerebral palsy (CP). Moreover, the genotypes of δ-aminolevulinic acid dehydratase (δ-ALAD) in CP patients and their mothers and their association to the blood lead levels (BLLs) were not previously studied. This study aimed to evaluate the association between δ-ALAD gene polymorphism and BLL in cases of CP and their mothers. A case control study was carried out on 23 CP cases and equal number of healthy matched controls. The mothers of the included children were asked to answer a questionnaire involving the baseline clinical and demographic characteristics. Also, questionnaires were done to detect the sources of environmental lead exposure and screen lead exposure during the pregnancy period. BLL, δ-ALAD enzyme activity, and genetic analysis for ALAD G177C were done for each child and his mother. There was significant (p < 0.001) elevation of BLL in CP cases and their mothers that was positively correlated (r = 0.436, p < 0.05). There were progressive decreases in δ-ALAD activity with increasing BLL in both children and mothers (p < 0.05). There were non-significant (p > 0.05) differences between CP and the control group regarding frequency of ALAD G177C genotypes, while there was a significant (p = 0.04) increase in the frequency of ALAD 1-2 (GC) genotype in the mothers of the CP group associated with high BLL and significant decrease in δ-ALAD activity (p < 0.001). The study can indicate the significance of δ-ALAD gene polymorphism in the prenatal exposure to lead and the affection of the developing brain, pointing to the importance of controlling lead in pregnant women especially those with ALAD 1-2 genotype.

Deep Eutectic Solvent-Based Microextraction of Lead(II) Traces from Water and Aqueous Extracts before FAAS Measurements

Microextraction procedures for the separation of Pb(II) from water and food samples extracts were developed. A deep eutectic solvent composed of α-benzoin oxime and iron(III) chloride dissolved in phenol was applied as a phase separator support. In addition, this deep eutectic mixture worked as an efficient extractor of Pb(II). The developed microextraction process showed a high ability to tolerate the common coexisting ions in the real samples. The optimum conditions for quantitative recoveries of Pb(II) from aqueous extracts were at pH 2.0, conducted by adding 150 µL from the deep eutectic solvent. The quantitative recoveries were obtained with various initial sample volumes up to 30 mL. Limits of detection and limits of quantification of 0.008 and 0.025 µg L^-1 were achieved with a relative standard deviation (RSD%) of 2.9, which indicates the accuracy and sensitivity of the developed procedure. Recoveries from the reference materials, including TMDA 64.2, TMDA 53.3, and NCSDC-73349, were 100%, 97%, and 102%, respectively. Real samples, such as tap, lake, and river water, as well as food samples, including salted peanuts, chickpeas, roasted yellow corn, pistachios, and almonds, were successfully applied for Pb(II) analysis by atomic absorption spectroscopy (AAS) after applying the developed deep eutectic solvent-based microextraction procedures.

Perspectives from the Society for Pediatric Research: contaminants of water and children's health: Can we do better?

Children are uniquely susceptible to the health consequences of water contamination. In this review, we summarize the existing, robust literature supporting the importance of examining specific water contaminants (i.e., lead, pesticides, nitrates, arsenic, perchlorate) and the routes of contamination in the United States and globally. We also discuss the health effects of exposure to contaminated water and significant disparities related to access to clean water. Lastly, we offer strategies for prevention and intervention-including those focused on the individual patient level-and review the current US policy framework pertaining to regulation of these toxicants. IMPACT: A key message in this article is that exposure to water contaminants have serious and long-lasting consequences on children's health. This review summarizes current existing literature and adds policy recommendations supporting clean water for children. Information from this review has two potential impacts: Guide health professionals in screening and/or treating children's health problems resulting from water contaminant exposure. Guide policy makers in using evidence-based approaches to improve water quality and clean water access.

Trimester-Specific Associations of Prenatal Lead Exposure With Infant Cord Blood DNA Methylation at Birth

Gestational exposure to lead (Pb) adversely impacts offspring health through multiple mechanisms, one of which is the alteration of the epigenome including DNA methylation. This study aims to identify differentially methylated CpG sites associated with trimester-specific maternal Pb exposure in umbilical cord blood (UCB) leukocytes. Eighty-nine mother-child dyads from the Early Life Exposure in Mexico to Environmental Toxicants (ELEMENT) longitudinal birth cohorts with available UCB samples were selected for DNA methylation analysis via the Infinium Methylation EPIC BeadChip, which quantifies methylation at >850 000 CpG sites. Maternal blood lead levels (BLLs) during each trimester (T1: 6.56 ± 5.35 µg/dL; T2: 5.93 ± 5.00 µg/dL; T3: 6.09 ± 4.51 µg/dL), bone Pb (patella: 11.8 ± 9.25 µg/g; tibia: 11.8 ± 6.73 µg/g), a measure of cumulative Pb exposure, and UCB Pb (4.86 ± 3.74 µg/dL) were measured. After quality control screening, data from 786 024 CpG sites were used to identify differentially methylated positions (DMPs) and differentially methylated regions (DMRs) by Pb biomarkers using separate linear regression models, controlling for sex and estimated UCB cell-type proportions. We identified 3 DMPs associated with maternal T1 BLL, 2 with T3 BLL, and 2 with tibia bone Pb. We identified one DMR within PDGFRL associated with T1 BLL, one located at chr6:30095136-30095295 with T3 BLL, and one within TRHR with tibia bone Pb (adjusted P-value < .05). Pathway analysis identified 15 overrepresented gene pathways for differential methylation that overlapped among all 3 trimesters with the largest overlap between T1 and T2 (adjusted P-value < .05). Pathways of interest include nodal signaling pathway and neurological system processes. These data provide evidence for differential methylation by prenatal Pb exposure that may be trimester-specific.

Systematic Review and Meta-Analysis of the Effect of Nutrients on Blood Lead Levels in Pregnancy

OBJECTIVE

To synthesize experimental and nonexperimental research on the relationship between nutrients and blood lead levels in pregnant women. We also performed a meta-analysis on a subgroup of studies on calcium and blood lead levels.

DATA SOURCES

PubMed, Embase, and CINAHL databases were searched in July 2019.

STUDY SELECTION

We included articles published in English in any year that reported the results of experimental or observational studies on the effect of nutrients on blood lead levels in pregnancy.

DATA EXTRACTION

Three nurse reviewers extracted data and appraised the studies using tools from the Joanna Briggs Institute.

DATA SYNTHESIS AND META-ANALYSIS

We included 28 studies from 16 countries. Study authors examined 14 distinct nutrients, with calcium being the most frequent. The metaregression included nine analyses of the effect of calcium on blood lead levels and showed a small but significant inverse relationship. The quality of evidence for the effect of calcium on lead levels was high. Eleven analyses were related to the effect of iron on blood lead levels. The quality of evidence was high, and we found mostly negative associations between iron intake and blood lead levels. The quality of evidence for the remaining nutrients was moderate, with few significant findings.

CONCLUSION

Targeted nutritional interventions may be beneficial for pregnant women with current lead exposure or a history of elevated lead levels, particularly those with calcium- or iron-deficient diets. More rigorously designed studies are needed in this area.

Probabilistic estimates of prenatal lead exposure at 195 toxic hotspots in low- and middle-income countries

BACKGROUND

Prior estimates of pediatric lead-related disease burden in low- and middle-income countries (LMICs) used population estimates of maternal blood lead levels (BLLs). This approach may underestimate fetal BLLs by not considering potentially high prenatal lead exposure from toxic hotspots. OBJECTIVES: We developed a probabilistic approach to using the Adult Lead Methodology (ALM) to estimate fetal BLLs from prenatal exposure to lead-contaminated soil at hotspots in the Toxic Site Identification Program (TSIP).

METHODS

We created distributions for each ALM parameter using published literature and extracted soil lead measurements from the TSIP database. Each iteration of the probabilistic ALM randomly selected values from the input distributions to generate a site-specific fetal BLL estimate. For each site, we ran 5000 model iterations, producing a site-specific fetal BLL distribution.

RESULTS

195 TSIP sites, in 33 LMICs, met our study inclusion criteria; an estimated 820,000 women of childbearing age are at risk for lead exposure at these sites. The predicted geometric means (GM) for site-specific fetal BLLs ranged from 3.3 μg/dL to 534 μg/dL, and 98% of sites had estimated GM fetal BLLs >5 μg/dL, the current reference level of the United States Centers for Disease Control and Prevention (CDC), while 11 sites had estimated GM fetal BLLs above the CDC chelation threshold of 45 μg/dL.

DISCUSSION

The TSIP soil lead data and this probabilistic approach to the ALM show that pregnant women living near TSIP sites may have BLLs that put their fetus at risk for neurologic damage and other sequelae, underscoring the need for interventions to reduce lead exposure at toxic hotspots.

Persistent Effects on Cardiorespiratory and Nervous Systems Induced by Long-Term Lead Exposure: Results from a Longitudinal Study

Long-term lead (Pb) exposure alters the normal development of the nervous system and physiology. It affects multiple organ systems, causing hypertension, cardiorespiratory dysfunction, being a well-known neurotoxin, inducing changes in neurogenesis, neurodegeneration, and glial cells. However, studies of the developmental effects of lead and its outcomes throughout life are lacking. Determine morphofunctional, behavioral, and cognitive developmental effects of long-term lead exposure at three different ages. Wistar rats were exposed to a Pb-acetate solution from fetal period until adulthood and compared to a non-exposed control group. General behavior and cognitive skills were evaluated by behavioral tests and physiological data and cardiorespiratory reflexes measured. Neurodegeneration, neuroinflammation, and synaptic activity were assessed by immunohistochemistry. Lead exposure caused long-lasting anxiety-like behavior and strong long-term memory impairment without changes in locomotor and exploratory activity. Hypertension was observed at all time points, concomitant with baroreflex impairment and increased chemoreflex sensitivity. Persistent neuroinflammation, transient synaptic overexcitation without neurodegeneration was observed. Long-term Pb exposure, since fetal period, causes long-lasting anxiety-like behavior, concomitant with hypertension, without general motor skills impairment. Synaptic overexcitation, reactive astrogliosis, and microgliosis could underlie behavioral and long-term memory changes, which might have been caused during developmental phases and consolidated during adulthood. Also, alterations observed in the cardiorespiratory reflexes can explain persistent hypertension. This longitudinal study identifies and characterizes lead toxicity nature and magnitude, important to devise and test potential interventions to attenuate the long-term harmful effects of lead on the nervous and cardiovascular systems.

Children's environmental health based on birth cohort studies of Asia (2) - air pollution, pesticides, and heavy metals

The life style and child raising environment in Asia are quite different compared with Western countries. Besides, the children's environmental threats and difficulties in conducting studies could be different. To address children's environmental health in Asia area, the Birth Cohort Consortium of Asia (BiCCA) was co-established in 2011. We reviewed the mercury, polychlorinated biphenyls, perfluoroalkyl substances, phthalates, and environmental tobacco smoke in pervious based on birth cohort studies in Asia. The aim of this study was to summarize the traditional environmental pollution and the target subjects were also based on the birth cohort in Asia area. Environmental pollutants included air pollutants, pesticides focusing on organochlorine pesticides, diakylphosphates, and pyrethroid, and heavy metals including lead, arsenic, cadmium, manganese, vanadium, and thallium. Fetal growth and pregnancy outcomes, childhood growth and obesity, neurodevelopment and behavioral problems, and allergic disease and immune function were classified to elucidate the children's health effects. In total, 106 studies were selected in this study. The evidences showed air pollution or pesticides may affect growth during infancy or childhood, and associated with neurodevelopmental or behavioral problems. Prenatal exposure to lead or manganese was associated with neurodevelopmental or behavioral problems, while exposure to arsenic or cadmium may influence fetal growth. In addition to the harmonization and international collaboration of birth cohorts in Asia; however, understand the whole picture of exposure scenario and consider more discipline in the research are necessary.

Selenium status in lactating mothers-infants and its potential protective role against the neurotoxicity of methylmercury, lead, manganese, and DDT

A total of 206 lactating mothers and their infants (3-12 months) were included in this study to evaluate postnatal exposure to neurotoxic pollutants such as methylmercury (MeHg), lead (Pb), manganese (Mn), dichlorodiphenyltrichloroethane (DDT) and its metabolites [dichlorodiphenyldichloroethane (DDD), and dichlorodiphenyldichloroethylene (DDE)] and their association with delayed neurological development and to explore the protective role of selenium (Se) against chemical neurotoxicity. Neurodevelopmental performance was evaluated using Denver Developmental Screening Test II and Parents' Evaluation of Developmental Status (PEDS). Multivariate log-binomial regression modeling was applied for both single and multiple exposures to chemicals using a principal component analysis that generated six principal components. Both mothers and their infants had been exposed to metals and DDT metabolites, with some exceeding the accepted permissible limits. The geometric means of MeHg, Pb, Mn, DDD, DDE and DDT levels in breast milk were 1.333, 45.327, 15.576, 0.069, 0.542 and 1.08 μg/l, respectively. A single-exposure model identified a high risk of reduced PEDS performance significantly associated with DDD in breast milk [relative risk (RR) = 1.484; 95% confidence interval (95%CI) = 1.091-2.019] and marginally significantly associated with Pb in the mothers' blood (RR = 2.164; 95%CI = 0.87-5.382). We did not find a protective role of Se in neurodevelopment due to its high levels in the mothers. Models of multi-chemical exposure indicated that Mn in blood and breast milk, Se in blood and Pb in the mothers' urine were marginally significantly associated with a high risk of reduced PEDS performance (RR = 0.424; 95%CI = 0.176-1.022). The use of multi-chemical exposure approach in early life risk assessments is important because it indicates real-world exposure. Our results were not conclusive because the sample size was small, so future studies examining the implications to health of the impact of prenatal/postnatal exposure to a mixture of chemicals in the Saudi population are merited.

Assessment of the LeadCare® Plus for Use on Scandinavian Brown Bears (Ursus arctos)

Lead (Pb) exposure is associated with adverse health effects in both humans and wildlife. Blood lead levels (BLL) of sentinel wildlife species can be used to monitor environmental lead exposure and ecosystem health. BLL analyzers, such as the LeadCare®, are validated for use in humans, assessed for use in some avian species and cattle, and are increasingly being used on wildlife to monitor lead exposure. The LeadCare® analyzers use a technique called anodic stripping voltammetry (ASV). Species-specific conversion equations have been proposed to approximate the levels found with gold standard measuring methods such as inductively coupled plasma mass spectrometry (ICP-MS) because the ASV method has been shown to underestimate BLL in some species. In this study we assessed the LeadCare® Plus (LCP) for use on Scandinavian brown bears (Ursus arctos). LCP measurements were correlated with ICP-MS with a Bland-Altman analyzed bias of 16.3-22.5%, showing a consistent overestimation of BLL analyzed with LCP. Based on this analysis we provide conversion equations for calculating ICP-MS BLL based on the LCP results in Scandinavian brown bears. Our study shows that the LeadCare® Plus can be used for monitoring of lead exposure by approximating gold standard levels using conversion equations. This enables comparison with other gold standard measured BLL within the observed range of this study (38.20-174.00 μg/L). Our study also found that Scandinavian brown bears are highly exposed to environmental lead.

Memantine Is Protective against Cytotoxicity Caused by Lead and Quinolinic Acid in Cultured Rat Embryonic Hippocampal Cells

Quinolinic acid (QA) is an excitotoxic metabolite of the kynurenine pathway of tryptophan metabolism produced in response to inflammation and oxidative stress. Lead (Pb) causes oxidative stress and thus may produce neurotoxicity by increasing QA production. We investigated the in vitro cytotoxic effects of Pb and QA and the protective effects of the NMDA receptor antagonist memantine. Primary cultures of embryonic hippocampal cells from Wistar rats were treated with different concentrations of Pb, QA, and Pb + QA with and without memantine. Cell viability was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Apoptosis was analyzed by flow cytometry after Annexin-V/propidium iodide staining. The numbers of immunostained neurons (with β3-Tubulin; Tuj1) and astrocytes (with glial fibrillary acidic protein) were counted. Pb at 20 μg/dL (0.97 μM) and QA at 500 nM concentrations showed significant cytotoxic effects, as evidenced by decreased cell viability, increased apoptosis, and a decrease in the number of both astrocytes and neurons. The combination of Pb and QA showed significant synergistic apoptotic effects at lower doses. Memantine (500 nM) was largely protective against the cytotoxic effects of both Pb and QA, suggesting that Pb's and QA's cytotoxicity involves NMDA receptor activation. Whereas the neuroprotection by memantine from QA-induced toxicity has been previously reported, this is the first study reporting the protection by memantine against Pb-induced cytotoxicity in cultured hippocampal cells. Protection by memantine against these neurotoxicants in vivo needs to be investigated.

Metal concentrations in pregnant women and neonates from informal electronic waste recycling

Electronic waste (e-waste) is the fastest growing solid waste stream worldwide and mostly ends up in developing countries where residents use primitive methods for recycling. The most infamous e-waste recycling town, Guiyu in Southeast China, has been recycling since the mid-1990s. E-waste contains several harmful chemicals, including lead (Pb), cadmium (Cd), chromium (Cr), and manganese (Mn). In 2011-12, the e-waste Recycling Exposures and Community Health (e-REACH) Study enrolled 634 pregnant women living in Guiyu and Haojiang, a control site, both in Shantou, China. The women completed a questionnaire and gave maternal blood, cord blood, and maternal urine, which were analyzed for Pb, Cd, Cr, and Mn. Maternal blood Pb, Cd, and Cr concentrations were significantly higher in Guiyu compared to Haojiang. In Guiyu, the geometric mean of Pb concentration in maternal blood was 6.66 µg/dL (range: 1.87-27.09 µg/dL) and was 1.74-fold greater than in Haojiang (95% CI: 1.60, 1.89). In cord blood, Pb concentration was 1.53-fold higher in Guiyu (95% CI: 1.38, 1.68). In maternal urine, Cd (ratio: 2.15, 95% CI: 1.72, 2.69) and Mn (ratio: 2.60, 95% CI: 2.04, 3.31) concentrations were significantly higher in Guiyu in comparison to Haojiang. In conclusion, pregnant women in Guiyu were at risk for increased exposure to heavy metals.

Heavy Metals in Indigenous Preparations Used for Sex Selection During Pregnancy in India

Indigenous preparations (IPs) have evoked a considerable interest in alleviating infections and chronic diseases and improving wellbeing. While such formulations have been a part of traditional practice in several countries and many have been reviewed scientifically for their claims, several of them until date remain to be investigated. A class of IPs for sex selection by Indian pregnant women exists with an aim of begetting a male offspring. In view of the leads obtained from our previous studies on detrimental effects of the newborn, for instance stillbirths and congenital malformations, we attempted to investigate the samples for heavy metal toxicity. Three samples were chosen following phytochemical analysis and reproductive toxicity of such preparations under in vivo conditions. The selected samples were examined for heavy metals-lead, cadmium, arsenic, and mercury using Microwave-assisted atomic absorption spectroscopy. The upper limit level of lead, mercury, and cadmium was found to be 18.56, 0.11, and 0.84 mg/kg respectively whereas arsenic was not detected. The levels of lead and mercury were found to be manifolds high in the IP samples that were primarily contributed by its constituents. The results of our study indicate the potential risk conferred upon, to both the mother and fetus on account of high levels of lead, mercury, and cadmium.

First-trimester blood concentrations of drinking water trihalomethanes and neonatal neurobehavioral development in a Chinese birth cohort

Toxicological evidence indicates that exposure to drinking water trihalomethanes (THMs) can impair neural development. However, no epidemiologic study to date has evaluated the relation of trihalomethanes exposure with neonatal neurobehavioral development. Here we aimed to evaluate if prenatal exposure to THMs during early pregnancy is associated with neonatal neurobehavioral development in 451 Chinese mother-child pairs. First trimester blood THMs [chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM)] were determined by solid phase micro-extraction gas chramatography. Neonatal neurobehavioral development was assessed using neonatal behavioral neurological assessment (NBNA) on the third day after birth. Multivariable linear regression models and restricted cubic spline models were constructed to evaluate the associations between blood THMs and neonatal neurological development scores. Blood concentrations of BDCM, whether modeled as continuous or categorical variables, were inversely associated with total NBNA score of newborns based on the multivariable linear regression. The association was further confirmed in the cubic spline model, and a linear dose-response relationship was observed. Stratified analysis showed that the inverse association between blood BDCM and total NBNA score was more evident in male infants than females. Our findings suggest that exposure to THMs during early pregnancy may be associated with impaired neonatal neurobehavioral development.

Toxics (Pb, Cd) and trace elements (Zn, Cu, Mn) in women during pregnancy and at delivery, South Benin, 2014-2015

During pregnancy, fetal development can be hindered by maternal exposure to toxic elements and abnormal concentrations of trace elements. Few data are available in African countries. Our goal was to assess the body burden of lead (Pb), cadmium (Cd), manganese (Mn), zinc (Zn) and copper (Cu) in pregnant women in Benin. The study was carried out in Sô-Ava district, from November 2015 to April 2016. Sixty women were recruited from the RECIPAL pre-conceptional cohort study. In all women, blood samples were collected during the first trimester of pregnancy. Thirty-two women had additional maternal and cord blood samples collected at delivery. Blood samples were analyzed by inductively coupled plasma mass spectrometry. At delivery, Cd median (IQR) concentration in maternal blood was 0.34 µg/L (0.24-0.46) in this non-smoking population. Pb median (IQR) concentration in maternal blood at delivery was 37.4 µg/L (30.5-52.0), with 31.3% of blood Pb levels above the 50 μg/L threshold. These pregnant women lived in semi-rural lakeside villages. Potential sources of Pb exposure identified during pregnancy were having water supply by drill pump and activities such as smoking fish by the woman and fishing by the household head. At delivery, Zn, Cu, and Mn median (IQR) concentrations in maternal blood were, respectively, 5415 μg/L (4894-5822), 1609 μg/L (1295-1771) and 16.0 μg/L (12.5-20.8). Pb, Cd, Mn and Cu blood concentrations were significantly higher at delivery than during the first trimester of pregnancy. Pb, Cd, Zn and Cu concentrations were significantly lower in cord blood than in maternal blood, contrary to Mn concentration, which was significantly higher in cord blood than in maternal blood at delivery. This exploratory study is the first one performed in Benin, and warns us about exposition of women from Sô-Ava district to Pb and Cd during pregnancy.

Intraventricular infusion of quinolinic acid impairs spatial learning and memory in young rats: a novel mechanism of lead-induced neurotoxicity

Background

Lead (Pb), a heavy metal, and quinolinic acid (QA), a metabolite of the kynurenine pathway of tryptophan metabolism, are known neurotoxicants. Both Pb and QA impair spatial learning and memory. Pb activates astrocytes and microglia, which in turn induce the synthesis of QA. We hypothesized increased QA production in response to Pb exposure as a novel mechanism of Pb-neurotoxicity.

Methods

Two experimental paradigms were used. In experiment one, Wistar rat pups were exposed to Pb via their dams’ drinking water from postnatal day 1 to 21. Control group was given regular water. In the second protocol, QA (9 mM) or normal saline (as Vehicle Control) was infused into right lateral ventricle of 21-day old rats for 7 days using osmotic pumps. Learning and memory were assessed by Morris water maze test on postnatal day 30 or 45 in both Pb- and QA-exposed rats. QA levels in the Pb exposed rats were measured in blood by ELISA and in the brain by immunohistochemistry on postnatal days 45 and 60. Expression of various molecules involved in learning and memory was analyzed by Western blot. Means of control and experimental groups were compared with two-way repeated measure ANOVA (learning) and t test (all other variables).

Results

Pb exposure increased QA level in the blood (by ~ 58%) and increased (p < 0.05) the number of QA-immunoreactive cells in the cortex, and CA1, CA3 and dentate gyrus regions of the hippocampus, compared to control rats. In separate experiments, QA infusion impaired learning and short-term memory similar to Pb. PSD-95, PP1, and PP2A were decreased (p < 0.05) in the QA-infused rats, whereas tau phosphorylation was increased, compared to vehicle infused rats.

Conclusion

Putting together the results of the two experimental paradigms, we propose that increased QA production in response to Pb exposure is a novel mechanism of Pb-induced neurotoxicity.

Intermittent low-level lead exposure provokes anxiety, hypertension, autonomic dysfunction and neuroinflammation

BACKGROUND

Exposures to lead (Pb) during developmental phases can alter the normal course of development, with lifelong health consequences. Permanent Pb exposure leads to behavioral changes, cognitive impairment, sympathoexcitation, tachycardia, hypertension and autonomic dysfunction. However, the effects of an intermittent lead exposure are not yet studied. This pattern of exposure has been recently increasing due to migrations, implementation of school exchange programs and/or residential changes.

OBJECTIVE

To determine and compare lead effects on mammal's behavior and physiology, using a rat model of intermittent and permanent Pb exposures.

METHODS

Fetuses were intermittently (PbI) or permanently (PbP) exposed to water containing lead acetate (0.2% w/v) throughout life until adulthood (28 weeks of age). A control group (CTL) without any exposure to lead was also used. Anxiety was assessed by elevated plus maze (EPM) and locomotor activity and exploration by open field test (OFT). Blood pressure (BP), electrocardiogram (ECG), heart rate (HR), respiratory frequency (RF), sympathetic and parasympathetic activity and baro- and chemoreceptor reflex profiles were evaluated. Immunohistochemistry protocol for the assessment of neuroinflammation, neuronal loss (NeuN), gliosis and synaptic alterations (Iba-1, GFAP, Syn), were performed at the hippocampus. One-way ANOVA with Tukey's multiple comparison between means were used (significance p < 0.05) for statistical analysis.

RESULTS

The intermittent lead exposure produced a significant increase in diastolic and mean BP values, concomitant with a tendency to sympathetic overactivity (estimated by increased low-frequency power) and without significant changes in systolic BP, HR and RF. A chemoreceptor hypersensitivity and a baroreflex impairment were also observed, however, less pronounced when compared to the permanent exposure. Regarding behavioral changes, both lead exposure profiles showed an anxiety-like behavior without changes in locomotor and exploratory activity. Increase in GFAP and Iba-1 positive cells, without changes in NeuN positive cells were found in both exposed groups. Syn staining suffered a significant decrease in PbI group and a significant increase in PbP group.

CONCLUSION

This study is the first to show that developmental Pb exposure since fetal period can cause lasting impairments in physiological parameters. The intermittent lead exposure causes adverse health effects, i.e, hypertension, increased respiratory frequency and chemoreflex sensitivity, baroreflex impairment, anxiety, decreased synaptic activity, neuroinflammation and reactive gliosis, in some ways similar to a permanent exposure, however some are lower-grade, due to the shorter duration of exposure. This study brings new insights on the environmental factors that influence autonomic and cardiovascular systems during development, which can help in creating public policy strategies to prevent and control the adverse effects of Pb toxicity.

Water Quality and Brain Function

In the United States, regulations are in place to ensure the quality of drinking water. Such precautions are intended to safeguard the health of the population. However, regulatory guidelines may at times fail to achieve their purpose. This may be due to lack of sufficient data regarding the health hazards of chronic low dose exposure to contaminants or the introduction of new substances that pose a health hazard risk that has yet to be identified. In this review, examples of different sources of contaminants in drinking water will be discussed, followed by an evaluation of some select individual toxicants with known adverse neurological impact. The ability of mixtures to potentially cause additive, synergistic, or antagonistic neurotoxic responses will be briefly addressed. The last section of the review will provide examples of select mechanisms by which different classes of contaminants may lead to neurological impairments. The main objective of this review is to bring to light the importance of considering trace amounts of chemicals in the drinking water and potential brain abnormalities. There is continued need for toxicology studies to better understand negative consequences of trace amounts of toxins and although it is beyond the scope of this brief overview it is hoped that the review will underscore the paucity of studies focused on determining how long-term exposure to minute levels of contaminants in drinking water may pose a significant health hazard.

Blood lead levels in a group of children: the potential risk factors and health problems

OBJECTIVE

To investigate blood lead levels in schoolchildren in two areas of Egypt to understand the current lead pollution exposure and its risk factors, aiming to improve prevention politicies.

SUBJECTS AND METHOD

This was a cross-sectional study in children (n=400) aged 6-12 years recruited from two areas in Egypt (industrial and urban). Blood lead levels were measured using an atomic absorption method. Detailed questionnaires on sources of lead exposure and history of school performance and any behavioral changes were obtained.

RESULTS

The mean blood lead level in the urban area of Egypt (Dokki) was 5.45±3.90μg/dL, while that in the industrial area (Helwan) was 10.37±7.94μg/dL, with a statistically significant difference between both areas (p<0.05). In Dokki, 20% of the studied group had blood lead levels≥10μg/dL, versus 42% of those in Helwan. A significant association was found between children with abnormal behavior and those with pallor with blood lead level≥10μg/dL, when compared with those with blood lead level<10μg/dL (p<0.05). Those living in Helwan area, those with bad health habits, and those living in housing with increased exposure were at a statistically significantly higher risk of having blood lead level≥10μg/dL.

CONCLUSION

Lead remains a public health problem in Egypt. High blood lead levels were significantly associated with bad health habits and housing with increased exposure, as well as abnormal behavior and pallor.

Maternal serum lead level during pregnancy is positively correlated with risk of preterm birth in a Chinese population

Lead (Pb) is a well-known developmental toxicant. The aim of the present study was to analyze the association between maternal serum Pb level and risk of preterm birth in a population-based birth cohort study. The present study analyzed a sub-study of the China-Anhui Birth Cohort that recruited 3125 eligible mother-and-singleton-offspring pairs. Maternal serum Pb level was measured by graphite furnace atomic absorption spectrometry. All subjects were classified into three groups by tertile division according to serum Pb level: Low-Pb (L-Pb, <1.18 μg/dl), Medium-Pb (M-Pb, 1.18-1.70 μg/dl), and High-Pb (H-Pb, ≥1.71 μg/dl). The rate of preterm birth was 2.8% among subjects with L-Pb, 6.1% among subjects with M-Pb, and 8.1% among subjects with H-Pb, respectively. After controlling confounding factors, the adjusted OR for preterm birth was 2.33 (95%CI: 1.49, 3.65) among subjects with M-Pb and 3.09 (95%CI: 2.01, 4.76) among subjects with H-Pb. Of interest, maternal Pb exposure in early gestational stage than in middle gestational stage was more susceptible to preterm birth. Moreover, maternal serum Pb level was only associated with increased risk of late preterm birth. The present study provides evidence that maternal serum Pb level during pregnancy is positively associated with risk of preterm birth in a Chinese population.

Effects of low-level prenatal lead exposure on child IQ at 4 and 8 years in a UK birth cohort study

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The association between prenatal exposure to lead and deficits in offspring cognitive function is not well established.

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Our aim was to evaluate the association between prenatal lead exposure and child IQ at age 4 and 8 years in an observational birth cohort study.

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There was no association of prenatal lead exposure with child IQ at either 4 or 8 years old.

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There was a suggestion, however, that boys are more susceptible than girls to prenatal exposure to lead.

Background

The association between childhood exposure to lead (Pb) and deficits in cognitive function is well established. The association with prenatal exposure, however, is not well understood, even though the potential adverse effects are equally important.

Objectives

To evaluate the association between low prenatal exposure to lead and IQ in children, to determine whether there were sex differences in the associations, and to evaluate the moderation effect of prenatal Pb exposure on child IQ.

Methods

Whole blood samples from pregnant women enrolled in ALSPAC (n = 4285) and from offspring at age 30 months (n = 235) were analysed for Pb. Associations between prenatal blood lead concentrations (B-Pb) and child IQ at age 4 and 8 years (WPPSI and WISC-III, respectively) were examined in adjusted regression models.

Results

There was no association of prenatal lead exposure with child IQ at 4 or 8 years old in adjusted regression models, and no moderation of the association between child B-Pb and IQ. However, there was a positive association for IQ at age 8 years in girls with a predicted increase in IQ (points) per 1 μg/dl of: verbal 0.71, performance 0.57, total 0.73. In boys, the coefficients tended to be negative (−0.15, −0.42 and −0.29 points, respectively).

Conclusion

Prenatal lead exposure was not associated with adverse effects on child IQ at age 4 or 8 years in this study. There was, however, some evidence to suggest that boys are more susceptible than girls to prenatal exposure to lead. Further investigation in other cohorts is required.

Sex differences in the effects of prenatal lead exposure on birth outcomes

Studies on the associations between prenatal lead exposure and birth outcomes have been inconsistent, and few data are available on the sex differences in these associations. We measured the cord blood lead levels of newborns in Shanghai and determined their associations with birth outcomes, which included birth weight, birth length, head circumference, and the ponderal index, in the total sample and within sex subgroups. A total of 1009 mother-infant pairs were enrolled from 10 hospitals in Shanghai between September 2008 and October 2009. The geometric mean of the cord blood lead concentrations was 4.07 μg/dl (95% CI: 3.98-4.17 μg/dl). A significant inverse association was found between cord blood lead levels and head circumference only in the male subgroup, and increasing cord blood lead levels were related to significant decreases in the ponderal index only in females. The birth weights of the male infants were positively associated with cord blood lead levels; after adjusting for the maternal intake frequency of preserved eggs, the estimated mean differences in birth weights decreased by 11.7% for each 1-unit increase in the log10-transformed cord blood lead concentration. Our findings suggest that prenatal lead exposure may have sex-specific effects on birth outcomes and that maternal dietary intake may be a potential confounder in these relationships. Further studies on this topic are highly warranted.

Early-life metal exposure and schizophrenia: A proof-of-concept study using novel tooth-matrix biomarkers

BACKGROUND

Despite evidence for the effects of metals on neurodevelopment, the long-term effects on mental health remain unclear due to methodological limitations. Our objective was to determine the feasibility of studying metal exposure during critical neurodevelopmental periods and to explore the association between early-life metal exposure and adult schizophrenia.

METHODS

We analyzed childhood-shed teeth from nine individuals with schizophrenia and five healthy controls. We investigated the association between exposure to lead (Pb(2+)), manganese (Mn(2+)), cadmium (Cd(2+)), copper (Cu(2+)), magnesium (Mg(2+)), and zinc (Zn(2+)), and schizophrenia, psychotic experiences, and intelligence quotient (IQ). We reconstructed the dose and timing of early-life metal exposures using laser ablation inductively coupled plasma mass spectrometry.

RESULTS

We found higher early-life Pb(2+) exposure among patients with schizophrenia than controls. The differences in log Mn(2+) and log Cu(2+) changed relatively linearly over time to postnatal negative values. There was a positive correlation between early-life Pb(2+) levels and psychotic experiences in adulthood. Moreover, we found a negative correlation between Pb(2+) levels and adult IQ.

CONCLUSIONS

In our proof-of-concept study, using tooth-matrix biomarker that provides direct measurement of exposure in the fetus and newborn, we provide support for the role of metal exposure during critical neurodevelopmental periods in psychosis.

Low-level prenatal lead exposure and infant sensory function

BACKGROUND

Lead is a pervasive neurotoxicant that has been associated with poorer cognitive, behavioral, and motor outcomes in children. The effects of lead on sensory function have not been well characterized. The aim of this study was to assess the effects of prenatal lead exposure on infant sensory function, as measured by auditory brainstem response (ABR) and grating visual acuity (VA).

METHODS

Lead was measured in maternal blood in mid- and late-pregnancy (mean gestational age = 15.5 and 39.0 weeks, respectively) and umbilical cord blood in a cohort of full-term infants in rural northeastern China. ABR latencies (peaks I, III, V) were measured in newborns during unsedated sleep (n = 315). The ABR central-to-peripheral (C-P) ratio was calculated as the ratio between the III-V and I-III interpeak intervals. VA was measured in 6-week-olds using Teller Acuity Cards (n = 1019) and assigned as the narrowest grid the infant fixated on. Multivariate linear regression was used to evaluate relationships between tertiles of mid-pregnancy, late-pregnancy, or cord lead and newborn ABR or 6-week VA.

RESULTS

Higher late-pregnancy lead levels were associated with higher ABR C-P ratios and lower VA. In covariate-adjusted analyses, mean C-P ratios were 4.6 and 3.2 % higher in infants whose mothers had lead > 3.8 μg/dL and lead = 2-3.8 μg/dL, respectively, than for infants whose mothers had lead < 2 μg/dL (p-trend =0.002). In adjusted analyses for VA, mean scores were 8.5 and 7.2 % lower for maternal lead > 3.8 μg/dL and lead = 2-3.8 μg/dL, respectively, compared to lead < 2 μg/dL (p-trend =0.009).

CONCLUSION

Auditory and visual systems maturation appears delayed in infants with higher prenatal lead exposure during late-pregnancy, even at relatively low levels. Both systems start myelinating in late gestation and mature rapidly in infancy. Higher ABR C-P ratio and lower grating VA scores suggest effects of low-level lead exposure on sensory system myelination.

Preconception Care: A New Standard of Care within Maternal Health Services

Emerging research suggests that much pediatric affliction has origins in the vulnerable phase of fetal development. Prenatal factors including deficiency of various nutrients and exposure to assorted toxicants are major etiological determinants of myriad obstetrical complications, pediatric chronic diseases, and perhaps some genetic mutations. With recent recognition that modifiable environmental determinants, rather than genetic predestination, are the etiological source of most chronic illness, modification of environmental factors prior to conception offers the possibility of precluding various mental and physical health conditions. Environmental and lifestyle modification through informed patient choice is possible but evidence confirms that, with little to no training in clinical nutrition, toxicology, or environmental exposures, most clinicians are ill-equipped to counsel patients about this important area. With the totality of available scientific evidence that now exists on the potential to modify disease-causing gestational determinants, failure to take necessary precautionary action may render members of the medical community collectively and individually culpable for preventable illness in children. We advocate for environmental health education of maternity health professionals and the widespread adoption and implementation of preconception care. This will necessitate the translation of emerging knowledge from recent research literature, to health professionals, to reproductive-aged women, and to society at large.

Autophagy in Neurodegenerative Diseases and Metal Neurotoxicity

Autophagy generally refers to cell catabolic and recycling process in which cytoplasmic components are delivered to lysosomes for degradation. During the last two decades, autophagy research has experienced a recent boom because of a newfound connection between this process and many human diseases. Autophagy plays a significant role in maintaining cellular homeostasis and protects cells from varying insults, including misfolded and aggregated proteins and damaged organelles, which is particularly crucial in neuronal survival. Mounting evidence has implicated autophagic dysfunction in the pathogenesis of several major neurodegenerative disorders, such as Parkinson's disease, Alzheimer's disease and Huntington's disease, where deficient elimination of abnormal and toxic protein aggregates promotes cellular stress, failure and death. In addition, autophagy has also been found to affect neurotoxicity induced by exposure to essential metals, such as manganese, copper, and iron, and other heavy metals, such as cadmium, lead, and methylmercury. This review examines current literature on the role of autophagy in the mechanisms of disease pathogenesis amongst common neurodegenerative disorders and of metal-induced neurotoxicity.

Select Prenatal Environmental Exposures and Subsequent Alterations of Gene-Specific and Repetitive Element DNA Methylation in Fetal Tissues

Strong evidence implicates maternal environmental exposures in contributing to adverse outcomes during pregnancy and later in life through the developmental origins of health and disease hypothesis. Recent research suggests these effects are mediated through the improper regulation of DNA methylation in offspring tissues, specifically placental tissue, which plays a critical role in fetal development. This article reviews the relevant literature relating DNA methylation in multiple tissues at or near delivery to several prenatal environmental toxicants and stressors, including cigarette smoke, endocrine disruptors, heavy metals, as well as maternal diet. These human studies expand upon previously reported outcomes in animal model interventions and include effects on both imprinted and non-imprinted genes. We have also noted some of the strengths and limitations in the approaches used, and consider the appropriate interpretation of these findings in terms of their effect size and their relationship to differential gene expression and potential health outcomes. The studies suggest an important role of DNA methylation in mediating the effects of the intrauterine environment on children's health and a need for additional research to better clarify the role of this epigenetic mechanism as well as others.

A cross-study analysis of prenatal exposures to environmental contaminants and the epigenome: support for stress-responsive transcription factor occupancy as a mediator of gene-specific CpG methylation patterning

A biological mechanism by which exposure to environmental contaminants results in gene-specific CpG methylation patterning is currently unknown. We hypothesize that gene-specific CpG methylation is related to environmentally perturbed transcription factor occupancy. To test this hypothesis, a database of 396 genes with altered CpG methylation either in cord blood leukocytes or placental tissue was compiled from 14 studies representing assessments of six environmental contaminants. Subsequently, an in silico approach was used to identify transcription factor binding sites enriched among the genes with altered CpG methylation in relationship to the suite of environmental contaminants. For each study, the sequences of the promoter regions (representing -1000 to +500 bp from the transcription start site) of all genes with altered CpG methylation were analyzed for enrichment of transcription factor binding sites. Binding sites for a total of 56 unique transcription factors were identified to be enriched within the promoter regions of the genes. Binding sites for the Kidney-Enriched Krupple-like Factor 15, a known responder to endogenous stress, were enriched (P < 0.001-0.041) among the genes with altered CpG methylation associated for five of the six environmental contaminants. These data support the transcription factor occupancy theory as a potential mechanism underlying environmentally-induced gene-specific CpG methylation.

Current sources of lead exposure and their relative contributions to the blood lead levels in the general adult population of Northern France: The IMEPOGE Study, 2008-2010

There is justification for limiting lead (Pb) exposure as much as possible, given its impact on health at low concentrations. Consequently, the aim of this study was to measure blood lead levels (BLL) and examine exposure factors related to BLL variations in the general adult population of northern France, a current and past industrial area. Two thousand inhabitants of northern France, aged between 20 and 59 years, were recruited using the quota method with caution. Blood lead levels were quantified by inductively coupled plasma-mass spectroscopy (ICP-MS), and variation factors were studied separately in men and women using multivariate stepwise linear and logistic regression models. The geometric mean of the BLL was 18.8 μg/L (95% confidence interval [CI]: 18.3-19.3). Occupational factors affected BLL only in men and represented 14% of total explained variance of BLL. External occupational factors significantly increasing mean levels of BLL were tobacco, consumption of some beverages (wine, coffee, tea, and/or tap water), raw vegetables, housing characteristics (built prior to 1948, Pb piping in the home) and do-it-yourself or leisure activities (paint stripping or rifle shooting). Consumption habits accounted together for 25% and 18% of the total explained variance, respectively, in men and women. Industrial environment did not significantly contribute to BLL variations. Blood lead levels observed in the general population of this industrial part of France did not appear to be excessively elevated compared to values found internationally. Nonetheless, these BLL remain a public health issue in regard to nonthreshold toxicity attributed to Pb.

Lead Exposure in Different Organs of Mammals and Prevention by Curcumin-Nanocurcumin: a Review

Chronic lead exposure is related to many health diseases in mammals. Exposure to lead forms reactive oxygen species reducing body antioxidant enzymes inflicting injury to numerous macromolecules or cell necrosis. Recent studies have revealed oxidative stress as the vital mechanism for lead toxicity. Lead is found to be toxic to several organ systems such as hematopoietic, skeletal, renal, cardiac, hepatic, and reproductive systems and extremely toxic to the central nervous system (CNS). Curcumin, an active ingredient of the dietary spice, and nanocurcumin, a nanoform of curcumin, are found to decrease toxicity due to lead in various organ systems in mouse models. Higher bioavailability, chelating property, and retention time of nanocurcumin over bulk curcumin may pave the way to expand the utility of nanocurcumin to remove lead toxicity from various organ systems within humans.

Lead in school children from Morelos, Mexico: levels, sources and feasible interventions

Background: Lead is a pervasive pollutant, associated at low levels to many adverse health effects. Objective: To investigate lead levels, exposure pathways and intervention possibilities in school children from Alpuyeca, in Morelos, Mexico. Methods: Blood lead concentrations (BPb) were measured in 226 children in 2011. Exposure pathways were assessed through a questionnaire, lead measurements in different environmental matrices and spatial aggregation analysis of lead concentrations. Results: BPb ranged from 1.5 to 36.5 µg/dL, with a mean (SD) of 7.23 (4.9) µg/dL. Sixty-four and 18% of the children had BPb > 5 µg/dL and > 10 µg/dL, respectively. The use of lead glazed ceramics was reported in almost half of the households; it was the main BPb determinant and it was associated with an increased risk of having BPb > 5 g/dL by 2.7 times (p = 0.001). Environmental samples were within US EPA’s lead recommended limits, and blood lead levels were randomly distributed in the community. Conclusions: Lead remains a public health problem in Alpuyeca, Mexico. Unlike other local pollutants, lead exposure prevention can be achieved inexpensively and in a short term. Interventions should make mothers aware of lead’s health effects and empower them to safeguard their children’s health by avoiding the culturally ingrained use of lead glazed pottery.