The role of the placenta in fetal exposure to heavy metals

Maternal APOE ε2 as a possible risk factor for elevated prenatal Pb levels

Lead (Pb) is a global contaminant associated with multiple adverse health effects. Humans are especially vulnerable during critical developmental stages. During pregnancy, exposure to Pb can occur through diet and release from maternal bones. Apolipoprotein E gene (APOE) variants (ɛ2, ɛ3, ɛ4 alleles) may influence sex steroid hormones, bone metabolism, and Pb kinetics. We examined the interplay among maternal APOE (mAPOE) genotypes, fetal sex, parity, and Pb in maternal and cord blood (mB-Pb, CB-Pb) using linear regression models. Our study involved 817 pregnant women and 772 newborns with measured adequate levels of zinc and selenium. We compared carriers of the ε2 and ε4 alleles to those with the ε3/ε3 genotype. The geometric means (range) of mB-Pb and CB-Pb were 11.1 (3.58-87.6) and 9.31 (1.82-47.0) ng/g, respectively. In cases with female fetuses, the maternal mAPOE ε2 allele was associated with higher, while the mAPOE ε4 allele was associated with lower mB-Pb and CB-Pb levels. Nulliparity increased the strength of the observed associations. These findings highlight the significance of mAPOE genetics, fetal sex, and parity in prenatal Pb kinetics. Notably, the maternal ε2 allele may increase the risk of Pb exposure.

Association between gestational arsenic exposure and infant physical development: a prospective cohort study

BACKGROUND

Arsenic pollution is widespread worldwide. The association between gestational arsenic exposure and adverse birth outcomes has been demonstrated in previous studies; however, few investigations have examined whether gestational arsenic exposure has adverse effects on infant growth and development after birth.

OBJECTIVE

Our study was designed to evaluate particular associations between gestational arsenic exposure during pregnancy and newborn birth size and to investigate whether these associations continue to affect infants after birth.

METHODS

An ongoing prospective cohort study of 1100 pregnant women was conducted at the Wuxi Maternity and Child Health Care Hospital. The total urinary arsenic concentrations in the 2nd and 3rd trimester were determined using atomic fluorescence spectrometry. The relationships between urinary arsenic concentration and foetal growth parameters (birth weight, head circumference, length, and ponderal index), SGA (Small for gestational age), and physical growth of infants within one year after birth were analysed.

RESULTS

Urinary arsenic concentration in the 3rd trimester was associated with an increased incidence of SGA [adjusted model: OR = 2.860 (95% CI: 1.168, 7.020), P = 0.021)]. Arsenic exposure in late pregnancy had an adverse effect on the physical development of infants before the age of 1 year, and there was an interaction effect with the sex of infants. The weight and length of boys at 6 and 12 months negatively correlated with maternal urinary arsenic levels during late pregnancy.

CONCLUSIONS

In addition to affecting foetal growth, exposure to arsenic in the 3rd trimester also negatively affected the growth of offspring within the first year of life.

The Relationship Between Heavy Metals and Missed Abortion: Using Mediation of Serum Hormones

Accumulating evidence suggests that heavy metal exposure may have adverse effects on the fetal development. Furthermore, disruption of serum hormone homeostasis can result in the adverse pregnancy outcomes. Therefore, this study aimed to investigate the potential association between heavy metals and missed abortion, with a focus on whether serum hormones mediate this relationship. The concentrations of heavy metals and hormones in serum were measured in this case-control study. Statistical models including, logistic regression model, principal component analysis (PCA), and weighted quantile sum (WQS) regression model were employed to examine the relationship between heavy metals, serum hormones, and missed abortion. Furthermore, the mediation analysis was performed to assess the role of serum hormones as potential mediators in this relationship. This study revealed significant associations between heavy metal exposure and missed abortion. Notable, the WQS index weight, which was mainly influenced by copper (Cu) and zine (Zn), is associated with missed abortion. Moreover, heavy metals including manganese (Mn), nickel (Ni), Zn, arsenic (As), Cu, cadmium (Cd), and lead (Pb) were found to be associated with serum levels of β-human chorionic gonadotropin (β-hCG), progesterone (P), estradiol (E2), and lactogen (HPL). In addition, the mediation analysis indicated that β-hCG explained a portion of the association (ranging from 18.77 to 43.51%) of between Mn, Ni, Zn, and As exposure and missed abortion. Serum P levels explained 17.93 to 51.70% of the association between Ni, Cu, and As exposure and missed abortion. Serum E2 levels played a significant mediating role, explaining a portion of the association (ranging from 22.14 to 73.60%) between Mn, Ni, Cu, As, Cd, and Pb exposure and missed abortion. Our results suggested that β-hCG, P, and E2 are one of the potential mediators in the complex relationship between heavy metals exposure and missed abortion. These results highlight the importance of considering both heavy metal exposure and serum hormone levels in understanding the etiology of missed abortion.

Gestational exposure to organochlorine compounds and metals and infant birth weight: effect modification by maternal hardships

BACKGROUND

Gestational exposure to toxic environmental chemicals and maternal social hardships are individually associated with impaired fetal growth, but it is unclear whether the effects of environmental chemical exposure on infant birth weight are modified by maternal hardships.

METHODS

We used data from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, a pan-Canadian cohort of 1982 pregnant females enrolled between 2008 and 2011. We quantified eleven environmental chemical concentrations from two chemical classes - six organochlorine compounds (OCs) and five metals - that were detected in ≥ 70% of blood samples collected during the first trimester. We examined fetal growth using birth weight adjusted for gestational age and assessed nine maternal hardships by questionnaire. Each maternal hardship variable was dichotomized to indicate whether the females experienced the hardship. In our analysis, we used elastic net to select the environmental chemicals, maternal hardships, and 2-way interactions between maternal hardships and environmental chemicals that were most predictive of birth weight. Next, we obtained effect estimates using multiple linear regression, and plotted the relationships by hardship status for visual interpretation.

RESULTS

Elastic net selected trans-nonachlor, lead, low educational status, racially minoritized background, and low supplemental folic acid intake. All were inversely associated with birth weight. Elastic net also selected interaction terms. Among those with increasing environmental chemical exposures and reported hardships, we observed stronger negative associations and a few positive associations. For example, every two-fold increase in lead concentrations was more strongly associated with reduced infant birth weight among participants with low educational status (β = -100 g (g); 95% confidence interval (CI): -215, 16), than those with higher educational status (β = -34 g; 95% CI: -63, -3). In contrast, every two-fold increase in mercury concentrations was associated with slightly higher birth weight among participants with low educational status (β = 23 g; 95% CI: -25, 71) compared to those with higher educational status (β = -9 g; 95% CI: -24, 6).

CONCLUSIONS

Our findings suggest that maternal hardships can modify the associations of gestational exposure to some OCs and metals with infant birth weight.

Multimetal exposure: Challenges in diagnostics, prevention, and treatment

Extensive use of heavy metals has posed a serious concern for ecosystem and human too. Heavy metals are toxic in nature and their accumulation in human body causes serious disorders such as neurological disease, cardiac disease, gastrointestinal problems, skin disorders, reproductive disease, lungs diseases, and so on. Furthermore, heavy metals not only affect the human health but also have a negative impact on the economy. In the current review, we have elaborated the impact of heavy metal exposure on human health and socioeconomics. We have discussed the molecular mechanism involved in the heavy metal-induced human disorders such as oxidative stress, neuroinflammation, and protein misfolding. Finally, we discussed the preventive measure and treatment strategy that could counter the negative effects of heavy metal intoxications. In conclusion, there is a substantial correlation between heavy metals and the onset and advancement of several health issues. Chelation treatment could be a useful tactic to lessen the toxic metal load and the difficulties that come with it.

Integrating Data Across Multiple Sites in the Northeastern United States to Examine Associations Between a Prenatal Metal Mixture and Child Cognition

We applied a novel hierarchical Bayesian weighted quantile sum (HBWQS) regression to combine data across 3 study sites to examine associations between prenatal exposure to metals and cognitive functioning in childhood. Data from 326 mother-child dyads enrolled in an ongoing cohort study, the Programming of Intergenerational Stress Mechanisms (PRISM) Study, based in New York, New York (recruitment in 2013-2020) and Boston, Massachusetts (recruitment 2011-2013), and the First Thousand Days of Life (FTDL) cohort study (recruitment 2012-2019), based in northern Virginia, were used. Arsenic, cadmium, manganese, lead, and antimony were measured in urine collected during pregnancy. Cognitive functioning was assessed in children aged 3-11 years using the National Institutes of Health Toolbox Cognition Battery. The HBWQS regression showed a negative association between the urinary metal mixture and the Cognition Early Childhood Composite Score in the PRISM New York City (β = -3.67, 95% credible interval (CrI): -7.61, -0.01) and FTDL (β = -3.76, 95% CrI: -7.66, -0.24) samples, with a similar trend in the PRISM Boston sample (β = -3.24, 95% CrI: -6.77, 0.144). We did not detect these associations in traditionally pooled models. HBWQS regression allowed us to account for site heterogeneity and detect associations between prenatal metal-mixture exposure and cognitive outcomes in childhood. Given the ubiquity of metals exposure, interventions aimed at reducing prenatal exposure may improve cognitive outcomes in children. This article is part of a Special Collection on Environmental Epidemiology.

Prenatal exposure to metal mixtures and childhood temporal processing in the PROGRESS Birth Cohort Study: Modification by childhood obesity

Children are frequently exposed to various biological trace metals, some essential for their development, while others can be potent neurotoxicants. Furthermore, the inflammatory and metabolic conditions associated with obesity may interact with and amplify the impact of metal exposure on neurodevelopment. However, few studies have assessed the potential modification effect of body mass index (BMI). As a result, we investigated the role of child BMI phenotype on the relationship between prenatal exposure to metal mixtures and temporal processing. Leveraging the PROGRESS birth cohort in Mexico City, children (N = 563) aged 6-9 years completed a Temporal Response Differentiation (TRD) task where they had to hold a lever down for 10-14 s. Blood and urinary metal (As, Pb, Cd, and Mn) measurements were collected from mothers in the 2nd and 3rd trimesters. Child BMI z-scores were dichotomized to normal (between -2 and +0.99) and high (≥1.00). Covariate-adjusted weighted quantile sum (WQS) regression models were used to estimate and examine the combined effect of metal biomarkers (i.e., blood and urine) on TRD measures. Effect modification by the child's BMI was evaluated using 2-way interaction terms. Children with a high BMI and greater exposure to the metal mixture during prenatal development exhibited significant temporal processing deficits compared to children with a normal BMI. Notably, children with increased exposure to the metal mixture and higher BMI had a decrease in the percent of tasks completed (β = -10.13; 95 % CI: -19.84, -0.42), number of average holds (β = -2.15; 95 % CI: -3.88, -0.41), longer latency (β = 0.78; 95 % CI: 0.13, 1.44), and greater variability in the standard deviation of the total hold time (β = 2.08; 95 % CI: 0.34, 3.82) compared to normal BMI children. These findings implicate that high BMI may amplify the effect of metals on children's temporal processing. Understanding the relationship between metal exposures, temporal processing, and childhood obesity can provide valuable insights for developing targeted environmental interventions.

Role of SIRT1 in Potentially Toxic Trace Elements (Lead, Fluoride, Aluminum and Cadmium) Associated Neurodevelopmental Toxicity

The formation of the central nervous system is a meticulously planned and intricate process. Any modification to this process has the potential to disrupt the structure and operation of the brain, which could result in deficiencies in neurological growth. When neurotoxic substances are present during the early stages of development, they can be exceptionally dangerous. Prenatally, the immature brain is extremely vulnerable and is therefore at high risk in pregnant women associated with occupational exposures. Lead, fluoride, aluminum, and cadmium are examples of possibly toxic trace elements that have been identified as an environmental concern in the aetiology of a number of neurological and neurodegenerative illnesses. SIRT1, a member of the sirtuin family has received most attention for its potential neuroprotective properties. SIRT1 is an intriguing therapeutic target since it demonstrates important functions to increase neurogenesis and cellular lifespan by modulating multiple pathways. It promotes axonal extension, neurite growth, and dendritic branching during the development of neurons. Additionally, it contributes to neurogenesis, synaptic plasticity, memory development, and neuroprotection. This review summarizes the possible role of SIRT1 signalling pathway in potentially toxic trace elements -induced neurodevelopmental toxicity, highlighting some molecular pathways such as mitochondrial biogenesis, CREB/BDNF and PGC-1α/NRF1/TFAM.

Prenatal exposure to environmental heavy metals and newborn telomere length: A systematic review and meta-analysis

Exposure to environmental heavy metals is associated with telomere length (TL) alteration. Available information regarding the effect of prenatal exposure to environmental pollutants on newborn TL is controversial. The aim of this study is to systematically review and conduct a meta-analysis of the existing epidemiological studies on the associations between prenatal metal exposure and newborn TL. A comprehensive literature search was performed using the online databases of PubMed, Web of Science, and ScienceDirect from their inception to December 1, 2023. Thirteen eligible studies were included from the overall initial identification of 3559 records. The effect size was expressed as standardized beta coefficients with 95% confidence intervals (CIs) by the restricted maximum-likelihood approach with a weighted random-effects model. Prenatal exposure to environmental heavy metals was associated with a shorter newborn TL (standardized beta = -0.04; 95% CI: -0.08, 0.00; p = 0.05). Subgroup analysis showed that prenatal exposure to cadmium was significantly, negatively associated with TL in newborns (standardized beta = -0.05; 95% CI: -0.10, -0.01; p = 0.021). Heavy metal exposure during the third trimester was significantly associated with a shorter TL in newborns (standardized beta = -0.05; 95% CI: -0.11, -0.01; p = 0.045). No significant association was found between the newborn's sex and exposure sample type. This study provides evidence for the negative effect of prenatal exposure to heavy metals on newborn TL. In particular, cadmium exposure and exposure during the third trimester of pregnancy are critical factors associated with heavy metal-induced TL shortening.

Effects of heavy metal exposure during pregnancy on birth outcomes

Exposure to heavy metals such as lead, cadmium, and mercury poses serious health risks to pregnant women because of their high toxicity. In this study, we investigated the associations of heavy metal exposure with birth outcomes of Korean infants. Data of 5,215 women between 2015 and 2019 were analyzed. This study was part of the Korean Children's Environmental Health (Ko-CHENS) study. Linear regression and logistic regression analyses were used to examine effects of concentrations of lead, cadmium, and mercury on birth weight, small for gestational age, and large for gestational age after adjusting for maternal age groups, parity, infant sex, education, income, smoking, drinking, body mass index, stillbirth, premature birth, diabetes, hypertension, and gestational diabetes. Besides adjusting for these covariates, each metal was mutually adjusted to estimate birth weight and large for gestational age status. Maternal cadmium concentrations during early pregnancy (β =  - 39.96; 95% confidence interval (CI): - 63.76, - 16.17) and late pregnancy (β =  - 37.24; 95% CI - 61.63, - 12.84) were significantly associated with birth weight. Cadmium levels during early pregnancy (adjusted OR = 0.637; 95% CI 0.444, 0.912) were also associated with large for gestational age status. Our findings suggest that prenatal cadmium exposure, even at a low level of exposure, is significantly associated with low birth weight.

Associations between area-level arsenic exposure and adverse birth outcomes: An Echo-wide cohort analysis

BACKGROUND

Drinking water is a common source of exposure to inorganic arsenic. In the US, the Safe Drinking Water Act (SDWA) was enacted to protect consumers from exposure to contaminants, including arsenic, in public water systems (PWS). The reproductive effects of preconception and prenatal arsenic exposure in regions with low to moderate arsenic concentrations are not well understood.

OBJECTIVES

This study examined associations between preconception and prenatal exposure to arsenic violations in water, measured via residence in a county with an arsenic violation in a regulated PWS during pregnancy, and five birth outcomes: birth weight, gestational age at birth, preterm birth, small for gestational age (SGA), and large for gestational age (LGA).

METHODS

Data for arsenic violations in PWS, defined as concentrations exceeding 10 parts per billion, were obtained from the Safe Drinking Water Information System. Participants of the Environmental influences on Child Health Outcomes Cohort Study were matched to arsenic violations by time and location based on residential history data. Multivariable, mixed effects regression models were used to assess the relationship between preconception and prenatal exposure to arsenic violations in drinking water and birth outcomes.

RESULTS

Compared to unexposed infants, continuous exposure to arsenic from three months prior to conception through birth was associated with 88.8 g higher mean birth weight (95% CI: 8.2, 169.5), after adjusting for individual-level confounders. No statistically significant associations were observed between any preconception or prenatal violations exposure and gestational age at birth, preterm birth, SGA, or LGA.

CONCLUSIONS

Our study did not identify associations between preconception and prenatal arsenic exposure, defined by drinking water exceedances, and adverse birth outcomes. Exposure to arsenic violations in drinking water was associated with higher birth weight. Future studies would benefit from more precise geodata of water system service areas, direct household drinking water measurements, and exposure biomarkers.

Development of a physiologically based toxicokinetic model for lead in pregnant women: The role of bone tissue in the maternal and fetal internal exposure

Epidemiological studies have shown associations between prenatal exposure to lead (Pb) and neurodevelopmental effects in young children. Prenatal exposure is generally characterized by measuring the concentration in the umbilical cord at delivery or in the maternal blood during pregnancy. To assess internal Pb exposure during prenatal life, we developed a pregnancy physiologically based pharmacokinetic (p-PBPK) model that to simulates Pb levels in blood and target tissues in the fetus, especially during critical periods for brain development. An existing Pb PBPK model was adapted to pregnant women and fetuses. Using data from literature, both the additional maternal bone remodeling, that causes Pb release into the blood, and the Pb placental transfers were estimated by Bayesian inference. Additional maternal bone remodeling was estimated to start at 21.6 weeks. Placental transfers were estimated between 4.6 and 283 L.day-1 at delivery with high interindividual variability. Once calibrated, the p-PBPK model was used to simulate fetal exposure to Pb. Internal fetal exposure greatly varies over the pregnancy with two peaks of Pb levels in blood and brain at the end of the 1st and 3rd trimesters. Sensitivity analysis shows that the fetal blood lead levels are affected by the maternal burden of bone Pb via maternal bone remodeling and by fetal bone formation at different pregnancy stages. Coupling the p-PBPK model with an effect model such as an adverse outcome pathway could help to predict the effects on children's neurodevelopment.

Exposure of Reproductive-Aged Women to Multiple Metals and Its Associations with Unexplained Recurrent Miscarriage

Exposure to heavy metals exerts toxic effects on female reproduction and embryo development. This study examined the exposure of patients with unexplained recurrent miscarriage (uRM) to multiple metals and the correlations among exposures to different metals. A total of 275 participants were enrolled, including 43 healthy women without previous miscarriage (the control group) and 232 uRM women (the case group); among these uRM women, 159 had two miscarriages (2M), 42 had three miscarriages (3M) and 31 had four or more miscarriages (≥4M). A total of 22 elements were measured in serum samples via inductively coupled plasma-mass spectrometry. The levels of calcium (104.37 mg/L vs. 92.65/93.02/92.61/92.47 mg/L) and selenium (131.85 µg/L vs. 117.80/118.04/115.88/124.35 µg/L) were higher in the controls than in the total uRM group and the 2M, 3M and ≥4M subgroups. The level of vanadium was significantly lower in the controls than in the total uRM group (0.15 µg/L vs. 0.23 µg/L), and the level of lead was lower in the controls than that in the total uRM group and the 2M, 3M and ≥4M subgroups (0.01 µg/L vs. 0.28/0.18/0.63/0.34 µg/L). After adjusting for age, body mass index and education level, calcium and selenium exposure were consistently negatively associated with miscarriage, while lead exposure was positively associated with miscarriage. In addition, the correlations among exposures to different metals slightly differed between the control and uRM groups. Therefore, changes in some metal elements in the blood might be related to the risk of uRM.

Blocked erythroid differentiation and delayed enucleation of erythroblasts may contribute to murine embryonic toxicity upon exposure to low dose of cadmium

Epidemiological and experimental studies have demonstrated the association of spontaneous abortion or embryonic atrophy with heavy metals, including some well-known anemia inducers, such as cadmium (Cd). However, the direct adverse effect of Cd on embryos without inducing maternal anemia remains unclear. In this study, we treated mice with a low dose of Cd before and after mating to minimize Cd-induced maternal anemia. Although most embryos developed normally, embryonic atrophy was still observed in a small percentage of embryos from Cd-exposed pregnant mice. Compared to the embryos from the control pregnant mice, a complete blockage of erythroid differentiation was observed in the atrophic embryos but no obvious alteration of erythroid differentiation in the non-atrophic embryos, respectively. Moreover, our results suggested delayed enucleation of erythroblasts in these non-atrophic embryos. Mechanically, the inhibited iron transport from the placenta to the fetus together with the increased iron export in the fetal livers might contribute to embryonic atrophy and delayed enucleation of erythroblasts upon Cd exposure. Our data may provide new insights into the embryonic toxicity of low-dose Cd.

In Utero Exposure to Metals and Birth Outcomes in an Artisanal and Small-Scale Gold Mining Birth Cohort in Madre de Dios, Peru

BACKGROUND

Few birth cohorts in South America evaluate the joint effect of minerals and toxic metals on neonatal health. In Madre de Dios, Peru, mercury exposure is prevalent owing to artisanal gold mining, yet its effect on neonatal health is unknown.

OBJECTIVES

We aimed to determine whether toxic metals are associated with lower birth weight and shorter gestational age independently of antenatal care and other maternal well-being factors.

METHODS

Data are from the COhorte de NAcimiento de MAdre de Dios (CONAMAD) birth cohort, which enrolled pregnant women in Madre de Dios prior to their third trimester and obtained maternal and cord blood samples at birth. We use structural equation models (SEMs) to construct latent variables for the maternal metals environment (ME) and the fetal environment (FE) using concentrations of calcium, iron, selenium, zinc, magnesium, mercury, lead, and arsenic measured in maternal and cord blood, respectively. We then assessed the relationship between the latent variables ME and FE, toxic metals, prenatal visits, hypertension, and their effect on gestational age and birth weight.

RESULTS

Among 198 mothers successfully enrolled and followed at birth, 29% had blood mercury levels that exceeded the U.S. Centers for Disease Control and Prevention threshold of 5.8 μ g / L and 2 mothers surpassed the former 5 - μ g / dL threshold for blood lead. The current threshold value is 3.5 μ g / dL . Minerals and toxic metals loaded onto ME and FE latent variables. ME was associated with FE (β = 0.24; 95% CI: 0.05, 0.45). FE was associated with longer gestational age (β = 2.31; 95% CI: - 0.3 , 4.51) and heavier birth weight. Mercury exposure was not directly associated with health outcomes. A 1% increase in maternal blood lead shortened gestational age by 0.05 d (β = - 0.75 ; 95% CI: - 1.51 , - 0.13 ), which at the 5 - μ g / dL threshold resulted in a loss of 3.6 gestational days and 76.5 g in birth weight for newborns. Prenatal care visits were associated with improved birth outcomes, with a doubling of visits from 6 to 12 associated with 5.5 more gestational days (95% CI: 1.6, 9.4) and 319 g of birth weight (95% CI: 287.6, 350.7).

DISCUSSION

Maternal lead, even at low exposures, was associated with shorter gestation and lower birth weight. Studies that focus only on harmful exposures or nutrition may mischaracterize the dynamic maternal ME and FE. SEMs provide a framework to evaluate these complex relationships during pregnancy and reduce overcontrolling that can occur with linear regression. https://doi.org/10.1289/EHP10557.

Epigallocatechin-3-Gallate Reduces Cd-Induced Developmental Toxicity of Bodysize in Caenorhabditis elegans via the PEK-1/eIF-2α/ATF-4 Pathway

Cadmium (Cd), a harmful heavy metal that has no biological purpose, can harm healthy fetal and child development. Epigallocatechin-3-gallate (EGCG), the most abundant polyphenol in tea, has been shown to increase cell viability under Cd exposure and ameliorate Cd-induced kidney injury in adult male rats. Using the Caenorhabditis elegans (C. elegans) model, we demonstrated that EGCG mitigated Cd-induced body size developmental toxicity through a mechanism that did not involve chelation with EGCG and was not associated with Cd accumulation and efflux. Our research indicated that the beneficial effects of EGCG on Cd-induced body size developmental toxicity were associated with the mitigation of endoplasmic reticulum stress. Furthermore, our observations indicate that EGCG reduced Cd-induced developmental toxicity in C. elegans via the PEK-1/eIF-2α/ATF-4 pathway. Our results provide important evidence for the potential benefits of consuming tea as a detoxification agent.

Associations of ambient manganese exposure with brain gray matter thickness and white matter hyperintensities

Manganese (Mn) exposure is associated with increased risks of dementia and cerebrovascular disease. However, evidence regarding the impact of ambient Mn exposure on brain imaging markers is scarce. We aimed to investigate the association between ambient Mn exposure and brain imaging markers representing neurodegeneration and cerebrovascular lesions. We recruited a total of 936 adults (442 men and 494 women) without dementia, movement disorders, or stroke from the Republic of Korea. Ambient Mn concentrations were predicted at each participant's residential address using spatial modeling. Neurodegeneration-related brain imaging markers, such as the regional cortical thickness, were estimated using 3 T brain magnetic resonance images. White matter hyperintensity volume (an indicator of cerebrovascular lesions) was also obtained from a certain number of participants (n = 397). Linear regression analyses were conducted after adjusting for potential confounders. A log-transformed ambient Mn concentration was associated with thinner parietal (β = -0.02 mm; 95% confidence interval [CI], -0.05 to -0.01) and occipital cortices (β = -0.03 mm; 95% CI, -0.04 to -0.01) after correcting for multiple comparisons. These associations remained statistically significant in men. An increase in the ambient Mn concentration was also associated with a greater volume of deep white matter hyperintensity in men (β = 772.4 mm3, 95% CI: 36.9 to 1508.0). None of the associations were significant in women. Our findings suggest that ambient Mn exposure may induce cortical atrophy in the general adult population.

Prenatal Exposure to Toxic Metals and Neural Tube Defects: A Systematic Review of the Epidemiologic Evidence

BACKGROUND

Neural tube defects (NTDs) affect > 300,000 pregnancies worldwide annually. Few nongenetic factors, other than folate deficiency, have been identified that may provide intervenable solutions to reduce the burden of NTDs. Prenatal exposure to toxic metals [arsenic (As), cadmium (Cd), mercury (Hg), manganese (Mn) and lead (Pb)] may increase the risk of NTDs. Although a growing epidemiologic literature has examined associations, to our knowledge no systematic review has been conducted to date.

OBJECTIVE

Through adaptation of the Navigation Guide systematic review methodology, we aimed to answer the question "does exposure to As, Cd, Hg, Mn, or Pb during gestation increase the risk of NTDs?" and to assess challenges to evaluating this question given the current evidence.

METHODS

We selected available evidence on prenatal As, Cd, Hg, Mn, or Pb exposure and risk of specific NTDs (e.g., spina bifida, anencephaly) or all NTDs via a comprehensive search across MEDLINE, Embase, Web of Science, and TOXLINE databases and applied inclusion/exclusion criteria. We rated the quality and strength of the evidence for each metal. We applied a customized risk of bias protocol and evaluated the sufficiency of evidence of an effect of each metal on NTDs.

RESULTS

We identified 30 studies that met our criteria. Risk of bias for confounding and selection was high in most studies, but low for missing data. We determined that, although the evidence was limited, the literature supported an association between prenatal exposure to Hg or Mn and increased risk of NTDs. For the remaining metals, the evidence was inadequate to establish or rule out an effect.

CONCLUSION

The role of gestational As, Cd, or Pb exposure in the etiology of NTDs remains unclear and warrants further investigation in high-quality studies, with a particular focus on controlling confounding, mitigating selection bias, and improving exposure assessment. https://doi.org/10.1289/EHP11872.

Metals and per- and polyfluoroalkyl substances mixtures and birth outcomes in the New Hampshire Birth Cohort Study: Beyond single-class mixture approaches

We aimed to investigate the joint, class-specific, and individual impacts of (i) PFAS, (ii) toxic metals and metalloids (referred to collectively as "metals"), and (iii) essential elements on birth outcomes in a prospective pregnancy cohort using both established and recent mixture modeling approaches. Participants included 537 mother-child pairs from the New Hampshire Birth Cohort Study. Concentrations of 6 metals and 5 PFAS were measured in maternal toenail clippings and plasma, respectively. Birth weight, birth length, and head circumference at birth were abstracted from medical records. Joint, index-wise, and individual associations of the metals and PFAS concentrations with birth outcomes were evaluated using Bayesian Kernel Machine Regression (BKMR) and Bayesian Multiple Index Models (BMIM). After controlling for potential confounders, the metals-PFAS mixture was associated with a larger head circumference at birth, which was driven by manganese. When using BKMR, the difference in the head circumference z-score when changing manganese from its 25th to 75th percentiles while holding all other mixture components at their medians was 0.22 standard deviations (95% posterior credible interval [CI]: -0.02, 0.46). When using BMIM, the posterior mean of index weight estimates assigned to manganese for head circumference z-score was 0.72 (95% CI: 0, 0.99). Prenatal exposure to the metals-PFAS mixture was not associated with birth weight or birth length by either BKMR or BMIM. Using both traditional and new mixture modeling approaches, prenatal exposure to manganese was associated with a larger head circumference at birth after accounting for exposure to PFAS and multiple toxic and essential metals.

Prenatal blood lead levels and Birth Weight: a Meta-analysis study

Purpose

Lead, a known toxic metal, causes several adverse reproductive effects, including low birth weight. Fortunately, the exposure level has sharply decreased during the recent decades, but a definitive safe level did not introduce for pregnant women yet. The current meta-analysis study aimed to conduct a quantitative estimation of maternal and umbilical cord blood lead effects on birth weight.

Methods

Two researchers have independently searched the scientific literature for retrieving related studies using the PRISMA criteria for data extraction. Twenty-one full-text articles were selected from primary 5006 titles, limited by the English language and published between 1991 and 2020 on humans.

Results

The pooled mean of maternal and umbilical cord blood lead levels were 6.85 µg/dL (95% CI: 3.36-10.34) and 5.41 µg/dL (95%CI: 3.43-7.40), respectively. The correlation coefficient analysis showed a significant inverse association between the mean maternal blood lead level and birth weight, which was confirmed by Fisher Z-Transformation analysis (-0.374, 95% CI: -0.382, -0.365, p < 0.01). In addition, a significantly lower birth weight (∆: 229 gr, p < 0.05) was found in the relatively high level of maternal blood lead than in low-level exposure (> 5 µg/dL vs. ≤ 5 µg/dL, respectively).

Conclusion

In short, the present study findings suggest an increasing maternal blood lead levels could be a potential risk factor for reducing birth weight. Thus, pregnant women should avoid lead exposure, as much as possible.

Supplementary information

The online version contains supplementary material available at 10.1007/s40201-022-00843-w.

BDNF and KISS-1 Levels in Maternal Serum, Umbilical Cord, and Placenta: The Potential Role of Maternal Levels as Effect Biomarker

Brain-derived neurotrophic factor (BDNF) and kisspeptin-1 (KISS-1) regulate placental development and fetal growth. The predictive value of maternal serum BDNF and KISS-1 concentrations for placental and umbilical cord levels has not yet been explored. The influence of prenatal lead (Pb) and cadmium (Cd) exposure and maternal iron status on BDNF and KISS-1 levels is also unclarified and of concern. In a pilot cross-sectional study with 65 mother-newborn pairs, we analyzed maternal and cord serum levels of pro-BDNF, mature BDNF, and KISS-1, BDNF, and KISS-1 gene expression in placenta, Pb and Cd in maternal and umbilical cord blood (erythrocytes), and placenta. We conducted a series of in vitro experiments using human primary trophoblast cells (hTCs) and BeWo cells to verify main findings of the epidemiological analysis. Strong and consistent correlations were observed between maternal serum levels of pro-BDNF, mature BDNF, and KISS-1 and corresponding levels in umbilical serum and placental tissue. Maternal red blood cell Pb levels were inversely correlated with serum and placental KISS-1 levels. Lower expression and release of KISS-1 was also observed in Pb-exposed BeWo cells. In vitro Pb exposure also reduced cellular BDNF levels. Cd-treated BeWo cells showed increased pro-BDNF levels. Low maternal iron status was positively associated with low BDNF levels. Iron-deficient hTCs and BeWo cells showed a consistent decrease in the release of mature BDNF. The correlations between maternal BDNF and KISS-1 levels, placental gene expression, and umbilical cord serum levels, respectively, indicate the strong potential of maternal serum as predictive matrix for BDNF and KISS-1 levels in placentas and fetal sera. Pb exposure and iron status modulate BDNF and KISS-1 levels, but a clear direction of modulations was not evident. The associations need to be confirmed in a larger sample and validated in terms of placental and neurodevelopmental function.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12403-023-00565-w.

The Effect of Maternal Exposure to Air Pollutants and Heavy Metals during Pregnancy on the Risk of Neurological Disorders Using the National Health Insurance Claims Data of South Korea

The objective of this study was to evaluate the effects of high levels of maternal exposure to ambient air pollution and heavy metals on risks of autism spectrum disorder (ASD) and epilepsy using the National Health Insurance claims data of South Korea. The data of mothers and their newborns from 2016 to 2018 provided by the National Health Insurance Service were used (n = 843,134). Data on exposure to ambient air pollutants (PM2.5, CO, SO₂, NO₂, and O₃) and heavy metals (Pb, Cd, Cr, Cu, Mn, Fe, Ni, and As) during pregnancy were matched based on the mother's National Health Insurance registration area. SO₂ (OR: 2.723, 95% CI: 1.971-3.761) and Pb (OR: 1.063, 95% CI: 1.019-1.11) were more closely associated with the incidence of ASD when infants were exposed to them in the third trimester of pregnancy. Pb (OR: 1.109, 95% CI: 1.043-1.179) in the first trimester of pregnancy and Cd (OR: 2.193, 95% CI: 1.074-4.477) in the third trimester of pregnancy were associated with the incidence of epilepsy. Thus, exposure to SO₂, NO₂, and Pb during pregnancy could affect the development of a neurologic disorder based on the timing of exposure, suggesting a relationship with fetal development. However, further research is needed.

Nutrition paves the way to environmental toxicants and influences fetal development during pregnancy

Nutrition plays a major role in the healthy pregnancy and development of the fetus. In addition, nutrition can expose humans to a wide range of potentially hazardous environmental constituents, such as organic pollutants and heavy metals from marine or agricultural food products while processing, producing, and packaging. Humans constantly face these constituents through air, water, soil, food, and domestic products. During pregnancy, the rate of cellular division and differentiation is higher; exposure to any of these environmental toxicants can lead to developmental defects as they cross the placental barrier and, in some cases, can harm the successive generation too, as some contaminants can act on the reproductive cells of the fetus (Diethylstilbestrol). Pregnant women are considered a vulnerable population to food contaminant exposure and require a proper dietary chart and conscious food choices. Food is a source of both essential nutrients and environmental toxicants. Here, we have researched the possible toxicants of the food industry and their influence on the fetus's in-utero development, along with the importance of dietary interventions and the need to balance a healthy diet to overcome the harms. The cumulative exposure to environmental toxicants can influence the mother's prenatal environment and affect the fetus's development.

Attenuating effects of selenium and zinc against hexavalent chromium-induced oxidative stress, hormonal instability, and placenta damage in preimplanted rats

As a toxic metal, hexavalent chromium (CrVI) has effects on both the reproductive and endocrine systems. This study aimed to evaluate the protective effects of selenium (Se) and zinc (Zn) against the toxicity of chromium on the placenta in pregnant Wistar albino rats. Thirty pregnant Wistar rats were divided into control and four treated groups, receiving subcutaneously (s.c) on the 3rd day of pregnancy, K₂Cr₂O₇ (10 mg/kg body weight (bw)) alone, or in association with Se (0.3 mg/kg bw), ZnCl₂ (20 mg/kg bw), or both of them simultaneously. Plasma steroid hormones, placenta histoarchitecture, oxidative stress profile, and developmental parameters were investigated. These results showed that K₂Cr₂O₇ exposure induced a significant increase in the levels of both plasma estradiol (E₂) and placenta malondialdehyde (MDA), the number of fetal resorptions, and percent of post-implantation loss. On the other hand, K₂Cr₂O₇ significantly reduced developmental parameters, maternal body and placenta weight, and plasma progesterone (P) and chorionic gonadotropin hormone (β HCG) levels. However, K₂Cr₂O₇ significantly decreased the placenta activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), reduced glutathione (GSH), and nonprotein sulfhydryl (NPSH). These changes have been reinforced by histopathological evaluation of the placenta. Se and/or ZnCl₂ supplementation provoked a significant improvement in most indices. These results suggest that the co-treatment with Se or ZnCl₂ strongly opposes the placenta cytotoxicity induced by K₂Cr₂O₇ through its antioxidant action.

Effects of Non-Essential "Toxic" Trace Elements on Pregnancy Outcomes: A Narrative Overview of Recent Literature Syntheses

Adverse pregnancy outcomes and their complications cause increased maternal and neonatal morbidity and mortality and contribute considerably to the global burden of disease. In the last two decades, numerous narrative and systematic reviews have emerged assessing non-essential, potentially harmful, trace element exposure as a potential risk factor. This narrative review summarizes the recent literature covering associations between exposure to cadmium, lead, arsenic, and mercury and pregnancy outcomes and highlights common limitations of existing evidence that may hinder decision-making within public health. Several initial scoping searches informed our review, and we searched PubMed (latest date July 2022) for the literature published within the last five years reporting on cadmium, lead, arsenic, or mercury and pre-eclampsia, preterm birth, or prenatal growth. Pre-eclampsia may be associated with cadmium and strongly associated with lead exposure, and exposure to these metals may increase risk of preterm birth. Many reviews have observed cadmium to be negatively associated with birth weight. Additionally, lead and arsenic exposure may be negatively associated with birth weight, with arsenic exposure also adversely affecting birth length and head circumference. These findings should be interpreted with caution due to the limitations of the reviews summarized in this paper, including high heterogeneity due to different exposure assessment methods, study designs, and timing of sampling. Other common limitations were the low quality of the included studies, differences in confounding variables, the low number of studies, and small sample sizes.

Heavy metals content in fresh tuna and swordfish caught from Hindian and Pacific Oceans: Health risk assessment of dietary exposure

Background and Aim

Yellowfin tuna and swordfish are seafood commodities commonly caught from deep oceans worldwide. Therefore, this study aimed to assess the levels of three heavy metals, namely, cadmium (Cd), lead (Pb), and mercury (Hg) in yellowfin tuna and swordfish. The results are expected to provide consumers with information on the safety of consuming or exporting these fishes caught in the Hindian and Pacific Oceans.

Materials and Methods

Fresh yellowfin and swordfish were obtained from fishermen's catches in FAO Fishing Zone 57 (Indian Ocean) and 71 (Pacific Ocean) and then collected at Benoa Harbor, Bali Province. The comparative method was to evaluate the levels of heavy metals in each fish. Furthermore, heavy metal concentrations, including Pb, Cd, and Hg, were determined using atomic absorption spectroscopy analysis. These results were then used to assess the safety of these fishes by calculating the estimated daily intake (EDI) and target hazard quotients-total target hazard quotients (THQs-TTHQs).

Results

The analysis showed that none of the samples exceeded the threshold levels for the three heavy metals, which was specified by the Indonesian National Standard (SNI) and European Commission Regulation (CR) No. 1881/2006. The EDI and provisional tolerable weekly index (PTWI) obtained in this study were still in the safe range. However, the PTWI values for Pb in yellowfin tuna product from the Indian Ocean were higher (0.0038 mg/kg) compared to the recommended standard for the adult population. The THQ-TTHQ values of fish caught from these oceans were also within the acceptable range specified by the two agencies, indicating that they are safe for consumption by people with various age groups and for export purposes.

Conclusion

The average levels of three heavy metals (Cd, Pb, and Hg) in muscle samples of yellowfin tuna and swordfish caught from the Pacific and Hindian Oceans were within the acceptable range as specified by the SNI and CR No. 1881/2006. Furthermore, the EDI and THQs values indicated that fishes caught from the Pacific and Hindian Oceans were safe for consumption. This research is still limited to assessing two capture fisheries commodities. Further research is needed on the assessment of heavy metal levels in other capture fisheries commodities in this capture zone.

Select Early-Life Environmental Exposures and DNA Methylation in the Placenta

PURPOSE OF REVIEW

To summarize recent literature relating early-life environmental exposures on DNA methylation in the placenta, to identify how variation in placental methylation is regulated in an exposure-specific manner, and to encourage additional work in this area.

RECENT FINDINGS

Multiple studies have evaluated associations between prenatal environmental exposures and placental methylation in both gene-specific and epigenome-wide frameworks. Specific exposures lead to unique variability in methylation, and cross-exposure assessments have uncovered certain genes that demonstrate consistency in differential placental methylation. Exposure studies that assess methylation effects in a trimester-specific approach tend to find larger effects during the 1st trimester exposure. Earlier studies have more targeted gene-specific approaches to methylation, while later studies have shifted towards epigenome-wide, array-based approaches. Studies focusing on exposures such as air pollution, maternal smoking, environmental contaminants, and trace metals appear to be more abundant, while studies of socioeconomic adversity and circadian disruption are scarce but demonstrate remarkable effects. Understanding the impacts of early-life environmental exposures on placental methylation is critical to establishing the link between the maternal environment, epigenetic variation, and long-term health. Future studies into this field should incorporate repeated measures of exposure throughout pregnancy, in order to determine the critical windows in which placental methylation is most heavily affected. Additionally, the use of methylation-based scores and sequencing technology could provide important insights into epigenetic gestational age and uncovering more genomic regions where methylation is affected. Studies examining the impact of other exposures on methylation, including pesticides, alcohol, and other chemicals are also warranted.

A unique investigation of thallium, tellurium, osmium, and other heavy metals in recurrent pregnancy loss: A novel approach

OBJECTIVE

To study the impact of heavy metals especially tellurium, thallium, and osmium, in recurrent pregnancy loss (RPL) and to study their association with antioxidant status and DNA damage.

METHODS

This case-control study included women with RPL (n = 30) and healthy pregnant women as control (n = 30). Following blood collection, serum levels of thallium, tellurium, osmium, lead, mercury, and cadmium were estimated by inductively coupled plasma mass spectrophotometer.

RESULTS

Women with RPL exhibited significantly higher levels of heavy metals (P < 0.001) when compared with control women. Intriguingly, increased levels of serum thallium, tellurium, osmium, and lead were negatively correlated with total antioxidant status (P < 0.05). Further, the RPL group demonstrated strong positive correlation between heavy metals (thallium, tellurium, osmium, lead) and DNA damage (P < 0.05). No significant correlation between other heavy metals and markers of cellular damage was noted.

CONCLUSION

Enhanced levels of heavy metals in women with RPL and correlation of thallium, tellurium, osmium, and lead with markers of cellular damage reflect the role of heavy metal poisoning, especially thallium, tellurium, and osmium, as potential risk factor in the etiology underlying recurrent miscarriage.

Experimental human placental models for studying uptake, transport and toxicity of micro- and nanoplastics

Micro- and nanoplastics (MNPs) are ubiquitous in the environment and have recently been found in human lungs, blood and placenta. However, data on the possible effects of MNPs on human health is extremely scarce. The potential toxicity of MNPs during pregnancy, a period of increased susceptibility to environmental insults, is of particular concern. The placenta provides a unique interface between maternal and fetal circulation which is essential for in utero survival and healthy pregnancy. Placental toxicokinetics and toxicity of MNPs are still largely unexplored and the limited studies performed up to now focus mainly on polystyrene particles. Practical and ethical considerations limit research options in humans, and extrapolation from animal studies is challenging due to marked differences between species. Nevertheless, diverse in vitro and ex vivo human placental models exist e.g., plasma membrane vesicles, mono-culture and co-culture of placental cells, placenta-on-a-chip, villous tissue explants, and placental perfusion that can be used to advance this research area. The objective of this concise review is to recapitulate different human placental models, summarize the current understanding of placental uptake, transport and toxicity of MNPs and define knowledge gaps. Moreover, we provide perspectives for future research urgently needed to assess the potential hazards and risks of MNP exposure to maternal and fetal health.

Associations between prenatal multiple plasma metal exposure and newborn telomere length: Effect modification by maternal age and infant sex

Exposure to metals during pregnancy may affect maternal and infant health. However, studies on the combined effects of metals on the telomere length (TL) of newborns are limited. A prospective cohort study was conducted among 1313 mother-newborn pairs in the Guangxi Zhuang Birth Cohort. The concentrations of metals in maternal plasma during the first trimester were measured using inductively coupled plasma-mass spectrometry. We explored the associations between nine plasma metals and newborn TL using generalized linear models (GLMs), principal component analysis (PCA), quantile g-computation (qgcomp), and Bayesian kernel machine regression (BKMR). The GLMs revealed the inverse association between plasma arsenic (percent change, -5.56%; 95% CI: -7.69%, -3.38%) and barium concentrations (-9.84%; 95% CI: -13.81%, -5.68%) and newborn TL. Lead levels were related to significant decreases in newborn TL only in females. The PCA revealed a negative association between the PC3 and newborn TL (-4.52%; 95% CI: -6.34%, -2.68%). In the BKMR, the joint effect of metals was negatively associated with newborn TL. Qgcomp indicated that each one-tertile increase in metal mixture levels was associated with shorter newborn TL (-9.39%; 95% CI: -14.32%, -4.18%). The single and joint effects of multiple metals were more pronounced among pregnant women carrying female fetuses and among pregnant women <28 years of age. The finding suggests that prenatal exposure to arsenic, barium, antimony, and lead and mixed metals may shorten newborn TLs. The relationship between metal exposures and newborn TL may exhibit heterogeneities according to infant sex and maternal age.

Prenatal Metal Exposures and Associations with Kidney Injury Biomarkers in Children

Prenatal exposure to arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) may be nephrotoxic, yet limited studies have examined subclinical kidney injury biomarkers in children. We assessed whether metal exposure in the second trimester (2T), a crucial time of kidney development, is associated with altered urine kidney injury and function biomarkers in preadolescent children. Analyses included 494 children participating in a birth cohort study in Mexico City. Concentrations of As, Cd, and Pb were measured from pregnant women in 2T blood and urine, and Hg in urine only. Kidney biomarkers were measured from children in urine at age 8-12 years. We assessed the associations between individual metals and (1) kidney biomarkers using linear regression and (2) a multi-protein kidney mixture using weighted quantile sum (WQS) regression. Associations of separate urine and blood metal mixtures with individual kidney biomarkers were assessed via WQS. Within the multi-protein mixture, the association with increased urinary As was predominated by urine alpha-1-microglobulin (A1M), interferon gamma-induced protein 10 (IP10), and fatty acid binding protein 1; the association with increased urinary Cd was predominated by A1M, clusterin, and albumin. The urine metal mixture was associated with increased albumin (0.23 ng/mL; 95% confidence interval (CI): 0.10, 0.37), IP10 (0.15 ng/mL; 95% CI: 0.02, 0.28), and cystatin C (0.17 ng/mL; 95% CI: 0.04, 0.31); these associations were mainly driven by urinary As and Cd. We observed null associations between prenatal blood or urine metal mixtures and estimated glomerular filtration rate. Higher prenatal urinary metals, individually and as a mixture were associated with altered kidney injury biomarkers in children. Further research and longer participant follow-up are required to ascertain the risk of kidney disease later in life.

Detection of Relevant Heavy Metal Concentrations in Human Placental Tissue: Relationship between the Concentrations of Hg, As, Pb and Cd and the Diet of the Pregnant Woman

Heavy metals can cross the placental barrier and reach the fetal compartment, threatening fetal development. Pregnant women can acquire these through food, drinking water, toxic habits or simply by breathing polluted air. The placenta has been described as a biomarker of maternal and fetal exposure to different toxic elements.

OBJECTIVES

The main objective of this study was to test the possible existence of heavy metal deposits (Pb, As, Cd and Hg) in the placentas of women who gave birth at term in our setting, analyzing the influence of daily life and dietary habits.

METHODS

We studied 103 placentas, obtained by consecutive sampling, of women that delivered in the Regional Maternity Hospital of Malaga between March and June, 2021. As, Cd and Pb concentrations were analyzed using mass spectrometry techniques. Hg concentration was studied according to US EPA method 7473. Women also answered a questionnaire with epidemiological variables.

RESULTS

Detectable concentrations were found in 14.56% [As], 44.6% [Cd], 81.5% [Pb] and 100% [Hg]. [Pb] and [As] correlated significantly (Spearman's Rho of 0.91 and <0.001), as did [Hg] and [Cd] (Spearman's Rho 0.256, p < 0.004). The [Pb] and [AS] concentrations were significantly higher in cases of tap water consumption. [Hg] concentrations predicted the birth weight of female newborns.

Prenatal Co-Exposure to Manganese, Mercury, and Lead, and Neurodevelopment in Children during the First Year of Life

Lead (Pb), mercury (Hg), and manganese (Mn) are neurotoxic, but little is known about the neurodevelopmental effects associated with simultaneous prenatal exposure to these metals. We aimed to study the associations of Pb, Hg, and Mn prenatal levels (jointly and separately) with neurodevelopment in the first year of life. Methods: Pb, Hg, and Mn blood lead levels were measured in 253 pregnant women. Their offspring's neurodevelopment was assessed through the Bayley Scale of Infant Development III^® at one, three, six, and twelve months. The metals' mean blood levels (µg/L) were Pb = 11.2, Hg = 2.1, and Mn = 10.2. Mean language, cognitive, and motor development scores of the infants at each age were between low-average and average. Multilevel models' results showed that language development coefficients of the offspring decreased by 1.5 points per 1 µg/dL increase in maternal blood lead levels (p = 0.002); the magnitude of the aforementioned association increased in children with maternal blood Mn < 9.6 µg/L (ß = -1.9, p = 0.003) or Hg > 1.9 µg/L (ß = -1.6, p = 0.013). Cognitive and motor development had negative associations with maternal blood Pb levels; the latter was statistically significant when the interaction term between Pb, Mn, and Hg was included (ß = -0.037, p = 0.03). Prenatal exposure to low Pb levels may impair infants' neurodevelopment in the first year of life, even more so if they are exposed to Hg or deficient in Mn.

No association between prenatal lead exposure and neurodevelopment during early childhood in the Japan Environment and Children's Study

Compared with the relatively well-investigated effects of childhood exposure to lead on neurocognitive deficits, those of prenatal exposure remain relatively inconclusive. We aimed to investigate the association between prenatal blood lead levels and neurodevelopmental delay during the first three years of life. From a prospective cohort of the Japan Environment and Children’s Study, we analyzed a total of 80,759 children. The exposure factors were prenatal lead concentrations measured from maternal whole blood in the second/third trimesters and umbilical cord blood at birth. Neurodevelopment was assessed at 6, 12, 18, 24, 30, and 36 months old using a screening tool, the Ages and Stages Questionnaires, third edition (ASQ). The outcome measures were any suspected neurodevelopmental delay (sNDD) identified via the ASQ during the first (sNDD-1Y), second (sNDD-2Y), and third (sNDD-3Y) years of life. sNDD-1Y, 2Y, and 3Y were identified in 18.0%, 16.2%, and 17.2% of children, respectively. The geometric means of blood lead concentration in this study were much lower (0.62 μg/dL in maternal blood and 0.50 μg/dL in cord blood) than previously investigated levels. Multivariable regression models revealed that there were no associations between maternal blood lead and sNDD-1Y and 2Y and between cord blood lead and sNDD-1Y, 2Y, and 3Y. Although a higher maternal blood lead was associated with a reduced risk of sNDD-3Y (adjusted relative risk: 0.84, 95% confidence interval 0.75–0.94, per 1 increase in common logarithm of lead concentration), there were no dose–response relationships in the analysis using quintiles of lead concentrations. Using a large-scale data set, the present study demonstrated no convincing evidence for an inverse association between levels of prenatal blood lead and neurodevelopment in early childhood. Longitudinal measurements of prenatal and postnatal lead levels are needed to understand the relationship between lead exposure and neurocognitive development.

Reprint of: Elemental dysregulation in psychotic spectrum disorders: A review and research synthesis

Accumulating evidence from observational studies, genetic research, and animal models suggests a relationship between toxic and nutritive elements and psychotic spectrum disorders (PSD). This review systematically evaluates the current research evidence for two hypotheses: 1) that exposures to abnormal levels of toxic and nutritive elements early in life contributes to the subsequent development of PSD, and 2) that an imbalance of element levels is linked to psychotic illness and clinical severity. We focused on the extant literature on five elements, lead (Pb), copper (Cu), magnesium (Mg), manganese (Mn), and zinc (Zn), because of their previously documented associations with psychiatric problems and the availability of pertinent literature. The review identified 38 studies of which 11 measured Pb, 27 measured Cu, 16 measured Mg, 15 measured Mn, and 25 measured Zn concentrations in PSD patients and controls. A majority of research has been conducted on nutritive element imbalance, and findings are largely mixed. While it is biologically plausible that element dysregulation is an important modifiable risk factor for PSD, more research into exposure in early life is needed to better characterize this relationship.

The Intersection of Immigrant and Environmental Health: A Scoping Review of Observational Population Exposure and Epidemiologic Studies

BACKGROUND

Transnational immigration has increased since the 1950s. In countries such as the United States, immigrants now account for > 15 % of the population. Although differences in health between immigrants and nonimmigrants are well documented, it is unclear how environmental exposures contribute to these disparities.

OBJECTIVES

We summarized current knowledge comparing immigrants' and nonimmigrants' exposure to and health effects of environmental exposures.

METHODS

We conducted a title and abstract review on articles identified through PubMed and selected those that assessed environmental exposures or health effects separately for immigrants and nonimmigrants. After a full text review, we extracted the main findings from eligible studies and categorized each article as exposure-focused, health-focused, or both. We also noted each study's exposure of interest, study location, exposure and statistical methods, immigrant and comparison groups, and the intersecting socioeconomic characteristics controlled for.

RESULTS

We conducted a title and abstract review on 3,705 articles, a full text review on 84, and extracted findings from 50 studies. There were 43 studies that investigated exposure (e.g., metals, organic compounds, fine particulate matter, hazardous air pollutants) disparities, but only 12 studies that assessed health disparities (e.g., mortality, select morbidities). Multiple studies reported higher exposures in immigrants compared with nonimmigrants. Among immigrants, studies sometimes observed exposure disparities by country of origin and time since immigration. Of the 50 studies, 43 were conducted in North America.

DISCUSSION

The environmental health of immigrants remains an understudied area, especially outside of North America. Although most identified studies explored potential exposure disparities, few investigated subsequent differences in health effects. Future research should investigate environmental health disparities of immigrants, especially outside North America. Additional research gaps include the role of immigrants' country of origin and time since immigration, as well as the combined effects of immigrant status with intersecting socioeconomic characteristics, such as race/ethnicity, income, and education attainment. https://doi.org/10.1289/EHP9855.

Essential and non-essential trace element concentrations in muscle and liver of a pregnant Munk's pygmy devil ray (Mobula munkiana) and its embryo

During gestation, essential and non-essential trace elements are transferred from the pregnant females to embryos. This study aimed to determine and compare the concentrations of seven essential trace elements (Fe, Zn, Se, Cu, Mn, Cr, Co) and six non-essential trace elements (As, Cd, V, U, Tl, Ag) in the muscle and the liver of a Munk's pygmy devil ray pregnant female, Mobula munkiana, and its embryo. Transfer evidence of essential and non-essential trace elements was detected in M. munkiana tissues. Arsenic was found in elevated concentrations in the pregnant female and the embryo tissues. Elevated levels of Cd, V, U, and Ag were found in the pregnant female liver, but were minimal in the embryo tissue. This is the first study to investigate maternal transfer of essential and non-essential trace elements in these species and their reproductive strategy.

Prenatal exposure to Cannabis smoke induces early and lasting damage to the brain

Cannabis is the most widely used illegal drug during pregnancy, however, the effects of gestational exposure to Cannabis smoke (CS) on the central nervous system development remain uncharacterised. This study investigates the effects of maternal CS inhalation on brain function in the offspring. Pregnant mice were exposed daily to 5 min of CS during gestational days (GD) 5.5-17.5. On GD 18.5 half of the dams were euthanized for foetus removal. The offspring from the remaining dams were euthanized on postnatal days (PND) 20 and 60 for evaluation. Brain volume, cortex cell number, SOX2, histone-H3, parvalbumin, NeuN, and BDNF immunoreactivity were assessed in all groups. In addition, levels of NeuN, CB1 receptor, and BDNF expression were assessed and cortical primary neurons from rats were treated with Cannabis smoke extract (CSE) for assessment of cell viability. We found that male foetuses from the CS exposed group had decreased brain volume, whereas mice at PND 60 from the exposed group presented with increased brain volume. Olfactory bulb and diencephalon volume were found lower in foetuses exposed to CS. Mice at PND 60 from the exposed group had a smaller volume in the thalamus and hypothalamus while the cerebellum presented with a greater volume. Also, there was an increase in cortical BDNF immunoreactivity in CS exposed mice at PND 60. Protein expression analysis showed an increase in pro-BDNF in foetus brains exposed to CS. Mice at PND 60 presented an increase in mature BDNF in the prefrontal cortex (PFC) in the exposed group and a higher CB1 receptor expression in the PFC. Moreover, hippocampal NeuN expression was higher in adult animals from the exposed group. Lastly, treatment of cortical primary neurons with doses of CSE resulted in decreased cell viability. These findings highlight the potential negative neurodevelopmental outcomes induced by gestational CS exposure.

Examination of Trace Metals and Their Potential Transplacental Transfer in Pregnancy

With the ever-growing concern for human health and wellbeing, the prenatal period of development requires special attention since fetuses can be exposed to various metals through the mother. Therefore, this study explored the status of selected toxic (Pb, Cd, Ni, As, Pt, Ce, Rb, Sr, U) and essential trace metals (Mn, Co, Cu, Zn, Se) in the umbilical cord (UC) sera, maternal sera, and placental tissue samples of 92 healthy women with normal pregnancies. A further aim focuses on the potential transplacental transfer of these trace metals. Based on the obtained levels of investigated elements in clinical samples, it was observed that all of the trace metals cross the placental barrier and reach the fetus. Furthermore, statistical analysis revealed significant differences in levels of toxic Ni, As, Cd, U, Sr, Rb, and essential Mn, Cu, and Zn between all three types of analyzed clinical samples. Correlation analysis highlighted As to be an element with levels that differed significantly between all tested samples. Principal component analysis (PCA) was used to enhance these findings. PCA demonstrated that Cd, Mn, Zn, Rb, Ce, U, and Sr were the most influential trace metals in distinguishing placenta from maternal and UC serum samples. As, Co, and Cu were responsible for the clustering of maternal serum samples, and PCA demonstrated that the Pt level in UC sera was responsible for the clustering of these samples. Overall, the findings of this study could contribute to a better understanding of transplacental transfer of these trace metals, and shed a light on overall levels of metal exposure in the population of healthy pregnant women and their fetuses.

Maternal urban particulate matter exposure and signaling pathways in fetal brains and neurobehavioral development in offspring

It is well understood that exposure to particulate matter (PM) can have adverse effects on the nervous system. When pregnant women are exposed to PM, their fetuses are also affected through the placenta. However, the mechanisms by which fetal brain development is regulated between mother and fetus remain unclear. C57BL/6J pregnant mice were exposed to PM at embryonic day (E) 2.5, 5.5, 8.5, 11.5, 14.5, and 17.5 via nasal drip at three doses (3, 6, 12 mg/kg of body weight) or PBS control. Neurobehavioral changes in the offspring were examined at 5-6-week-old by open field test (OFT) and elevated plus maze (EPM). The maternal and fetal brain and placenta were collected at E18.5, and molecular signal changes were explored using transcriptome analysis. We found that both male and female low-dose pups and male middle-dose pups traveled a significantly longer distance than controls in EPM tests. Both male and female low-dose pups showed a higher frequency of entering the center area and female low-dose pups exhibited a higher percentage of distance moved in the center area than controls in OFT tests. Gene expression in the maternal brain, fetal brain, and placenta at E18.5 was altered. Differentially expressed genes were enriched in the neuroactive ligand-receptor interaction pathway in all three tissue types. Pathway analysis revealed that the PI3K-Akt and PKC signaling was dysregulated in the fetal brain in the high-dose group compared with the control group. The pathways play a role in neuronal survival and apoptosis. Furthermore, there is a dose-dependent increase in Caspase-6, neuronal apoptosis and neurodegeneration biomarker, levels in E18.5 fetal brain (P = 0.06). In conclusion, our study demonstrated that prenatal PM exposure enhanced exploration and locomotor activity in adolescent offspring and altered molecular events in maternal brain, fetal brain, and placenta. The connections of these changes warrant further investigations.

A Role for Gene-Environment Interactions in Autism Spectrum Disorder Is Supported by Variants in Genes Regulating the Effects of Exposure to Xenobiotics

Heritability estimates support the contribution of genetics and the environment to the etiology of Autism Spectrum Disorder (ASD), but a role for gene-environment interactions is insufficiently explored. Genes involved in detoxification pathways and physiological permeability barriers (e.g., blood-brain barrier, placenta and respiratory airways), which regulate the effects of exposure to xenobiotics during early stages of neurodevelopment when the immature brain is extremely vulnerable, may be particularly relevant in this context. Our objective was to identify genes involved in the regulation of xenobiotic detoxification or the function of physiological barriers (the XenoReg genes) presenting predicted damaging variants in subjects with ASD, and to understand their interaction patterns with ubiquitous xenobiotics previously implicated in this disorder. We defined a panel of 519 XenoReg genes through literature review and database queries. Large ASD datasets were inspected for in silico predicted damaging Single Nucleotide Variants (SNVs) (N = 2,674 subjects) or Copy Number Variants (CNVs) (N = 3,570 subjects) in XenoReg genes. We queried the Comparative Toxicogenomics Database (CTD) to identify interaction pairs between XenoReg genes and xenobiotics. The interrogation of ASD datasets for variants in the XenoReg gene panel identified 77 genes with high evidence for a role in ASD, according to pre-specified prioritization criteria. These include 47 genes encoding detoxification enzymes and 30 genes encoding proteins involved in physiological barrier function, among which 15 are previous reported candidates for ASD. The CTD query revealed 397 gene-environment interaction pairs between these XenoReg genes and 80% (48/60) of the analyzed xenobiotics. The top interacting genes and xenobiotics were, respectively, CYP1A2, ABCB1, ABCG2, GSTM1, and CYP2D6 and benzo-(a)-pyrene, valproic acid, bisphenol A, particulate matter, methylmercury, and perfluorinated compounds. Individuals carrying predicted damaging variants in high evidence XenoReg genes are likely to have less efficient detoxification systems or impaired physiological barriers. They can therefore be particularly susceptible to early life exposure to ubiquitous xenobiotics, which elicit neuropathological mechanisms in the immature brain, such as epigenetic changes, oxidative stress, neuroinflammation, hypoxic damage, and endocrine disruption. As exposure to environmental factors may be mitigated for individuals with risk variants, this work provides new perspectives to personalized prevention and health management policies for ASD.

Heavy metal and metalloid - induced reproductive toxicity

Heavy metals and metalloid exposure are among the most common factors responsible for reproductive toxicity in human beings. Several studies have indicated that numerous metals and metalloids can display severe adverse properties on the human reproductive system. Metals like lead, silver, cadmium, uranium, vanadium, and mercury and metalloids like arsenic have been known to induce reproductive toxicity. Moderate to minute quantities of lead may affect several reproductive parameters and even affect semen quality. The ecological and industrial exposures to the various heavy metals and metalloids have disastrous effects on the reproductive system ensuing in infertility. This work emphasizes the mechanism and pathophysiology of the aforementioned heavy metals and metalloids in reproductive toxicity. Additionally, this work aims to cover the classical protective mechanisms of zinc, melatonin, chelation therapy, and other trending methods to prevent heavy metal-induced reproductive toxicity.

Maternal Metals/Metalloid Blood Levels Are Associated With Lipidomic Profiles Among Pregnant Women in Puerto Rico

Background/Aim: The association between heavy metal exposure and adverse birth outcomes is well-established. However, there is a paucity of research identifying biomarker profiles that may improve the early detection of heavy metal-induced adverse birth outcomes. Because lipids are abundant in our body and associated with important signaling pathways, we assessed associations between maternal metals/metalloid blood levels with lipidomic profiles among 83 pregnant women in the Puerto Rico PROTECT birth cohort.

Methods: We measured 10 metals/metalloid blood levels during 24–28 weeks of pregnancy. Prenatal plasma lipidomic profiles were identified by liquid chromatography–mass spectrometry-based shotgun lipidomics. We derived sums for each lipid class and sums for each lipid sub-class (saturated, monounsaturated, polyunsaturated), which were then regressed on metals/metalloid. False discovery rate (FDR) adjusted p-values (q-values) were used to account for multiple comparisons.

Results: A total of 587 unique lipids from 19 lipid classes were profiled. When controlling for multiple comparisons, we observed that maternal exposure to manganese and zinc were negatively associated with plasmenyl-phosphatidylethanolamine (PLPE), particularly those containing polyunsaturated fatty acid (PUFA) chains. In contrast to manganese and zinc, arsenic and mercury were positively associated with PLPE and plasmenyl-phosphatidylcholine (PLPC).

Conclusion: Certain metals were significantly associated with lipids that are responsible for the biophysical properties of the cell membrane and antioxidant defense in lipid peroxidation. This study highlighted lipid-metal associations and we anticipate that this study will open up new avenues for developing diagnostic tools.

Associations of maternal blood mercury with preeclampsia and birth outcomes

BACKGROUND

Mercury (Hg) is a highly toxic substance, and its harmful effects on maternal and infant health have been reported. Yet, the associations of Hg exposure with preeclampsia (PE) and adverse birth outcomes are not well understood.

OBJECTIVE

The aim of this study was to investigate the potential effects of maternal Hg exposure on PE and birth outcomes.

METHODS

We conducted a case-control study with 84 participants in China. Logistic models were used to estimate odds ratios for PE risk and birth outcomes according to maternal blood Hg levels, adjusting for potential confounding factors.

RESULTS

Elevated blood Hg levels were associated with increased risks of mild PE (aOR, 7.03; 95% CI, 1.61, 30.62; P < 0.01) and severe PE (aOR, 47.55; 95% CI, 5.27, 429.05; P < 0.05). We also found that increased blood Hg levels were associated with low birth weight (aOR, 1.12; 95% CI, 1.00, 1.25; P < 0.05) and preterm birth (PTB) (aOR, 1.22; 95% CI, 1.08, 1.38; P < 0.05).

CONCLUSIONS

Our study provided evidence that elevated blood Hg levels were significantly associated with an increased risk of PE. In addition, our findings support that increased blood Hg levels might be associated with low birth weight and PTB.

Advanced human developmental toxicity and teratogenicity assessment using human organoid models

Tremendous progress has been made in the field of toxicology leading to the advance of developmental toxicity assessment. Conventional animal models and in vitro two-dimensional models cannot accurately describe toxic effects and predict actual in vivo responses due to obvious inter-species differences between humans and animals, as well as the lack of a physiologically relevant tissue microenvironment. Human embryonic stem cell (hESC)- and induced pluripotent stem cell (iPSC)-derived three-dimensional organoids are ideal complex and multicellular organotypic models, which are indispensable in recapitulating morphogenesis, cellular interactions, and molecular processes of early human organ development. Recently, human organoids have been used for drug discovery, chemical toxicity and safety in vitro assessment. This review discusses the recent advances in the use of human organoid models, (i.e., brain, retinal, cardiac, liver, kidney, lung, and intestinal organoid models) for developmental toxicity and teratogenicity assessment of distinct tissues/organs following exposure to pharmaceutical compounds, heavy metals, persistent organic pollutants, nanomaterials, and ambient air pollutants. Combining next-generation organoid models with innovative engineering technologies generates novel and powerful tools for developmental toxicity and teratogenicity assessment, and the rapid progress in this field is expected to continue.

Association of both prenatal and early childhood multiple metals exposure with neurodevelopment in infant: A prospective cohort study

BACKGROUND

Impaired neurodevelopment of children has become a growing public concern; however, the associations between metals exposure and neurocognitive function have remained largely unknown.

OBJECTIVES

We systematically evaluated the associations of multiple metals exposure during pregnancy and childhood on the neurodevelopment of children aged 2-3 years.

METHODS

We measured 22 metals in the serum and urine among703 mother-child pairs from the Guangxi Birth Cohort Study. The neurocognitive development of children was assessed by the Gesell Development Diagnosis Scale (GDDS; Chinese version). Multiple linear regression models were used to evaluate the relationship between the metals (selected by elastic net regression) and the outcomes. The Bayesian kernel machine regression (BKMR) was used to evaluate the possible joint effect between the multiple metal mixture and the outcomes.

RESULTS

Prenatal aluminum (Al) exposure was negatively associated with the fine motor developmental quotient (DQ) (β = -1.545, 95%CI: 2.231, -0.859), adaption DQ (β = -1.182, 95%CI: 1.632, -0.732), language DQ (β = -1.284, 95% CI: 1.758, -0.809), and social DQ (β = -1.729, 95% CI: 2.406, -1.052) in the multi-metal model. Prenatal cadmium (Cd) exposure was negatively associated with gross motor DQ (β = -2.524, 95% CI: 4.060, -0.988), while postpartum Cd exposure was negatively associated with language DQ (β = -1.678, 95% CI: 3.227, -0.129). In stratified analyses, infants of different sexes had different sensitivities to metal exposure, and neurobehavioral development was more significantly affected by metal exposure in the first and second trimester. BKMR analysis revealed a negative joint effect of the Al, Cd, and selenium (Se) on the language DQ score; postpartum Cd exposure played a major role in this relationship.

CONCLUSION

Prenatal exposure to Al, Ba, Cd, molybdenum (Mo), lead (Pb), antimony (Sb), and strontium (Sr), and postpartum exposure to cobalt (Co), Cd, stannum (Sn), iron (Fe), nickel (Ni), and Se are associated with neurological development of infants. The first and second trimester might be the most sensitive period when metal exposure affects neurodevelopment.

Association between placental toxic metal exposure and NICU Network Neurobehavioral Scales (NNNS) profiles in the Rhode Island Child Health Study (RICHS)

BACKGROUND

Prenatal exposure to heavy metals has been linked to a variety of adverse outcomes in newborn health and later life. Toxic metals such as cadmium (Cd), manganese (Mn) and lead (Pb) have been implicated to negatively affect newborn neurobehavior. Placental levels of these metals may provide additional understandings on the link between prenatal toxic metal exposures and neurobehavioral performances in newborns.

OBJECTIVE

To evaluate associations between placental concentrations of toxic metals and newborn neurobehavioral performance indicated through the NICU Network Neurobehavioral Scales (NNNS) latent profiles.

METHOD

In the Rhode Island Child Health Study cohort (n = 625), newborn neurobehavioral performance was assessed with NNNS, and a latent profile analysis was used to define five discrete neurobehavioral profiles based on summary scales. Using multinomial logistic regression, we determined whether increased levels of placental toxic metals Cd, Mn and Pb associated with newborns assigned to the profile demonstrating atypical neurobehavioral performances.

RESULTS

Every doubling in placenta Cd concentration was associated with increased odds of newborns belonging to the atypical neurobehavior profile (OR: 2.72, 95% CI [1.09, 6.79]). Detectable placental Pb also demonstrated an increased odds of newborns assignment to the atypical profile (OR: 3.71, 95% CI [0.97, 13.96]) compared to being in the typical neurobehavioral profile.

CONCLUSIONS

Toxic metals Cd and Pb measured in placental tissue may adversely impact newborn neurobehavior. Utilizing the placenta as a prenatal toxic metal exposure biomarker is useful in elucidating the associated impacts of toxic metals on newborn health.

Prenatal metal(loid) mixtures and birth weight for gestational age: A pooled analysis of three cohorts participating in the ECHO program

BACKGROUND

A growing number of studies have identified both toxic and essential metals which influence fetal growth. However, most studies have conducted single-cohort analyses, which are often limited by narrow exposure ranges, and evaluated metals individually. The objective of the current study was to conduct an environmental mixture analysis of metal impacts on fetal growth, pooling data from three geographically and demographically diverse cohorts in the United States participating in the Environmental Influences on Child Health Outcomes program.

METHODS

The pooled sample (N = 1,002) included participants from the MADRES, NHBCS, and PROTECT cohorts. Associations between seven metals (antimony, cadmium, cobalt, mercury, molybdenum, nickel, tin) measured in maternal urine samples collected during pregnancy (median: 16.0 weeks gestation) and birth weight for gestational age z-scores (BW for GA) were investigated using Bayesian Kernel Machine Regression (BKMR). Models were also stratified by cohort and infant sex to investigate possible heterogeneity. Chromium and uranium concentrations fell below the limits of detection for most participants and were evaluated separately as binary variables using pooled linear regression models.

RESULTS

In the pooled BKMR analysis, antimony, mercury, and tin were inversely and linearly associated with BW for GA, while a positive linear association was identified for nickel. The inverse association between antimony and BW for GA was observed in both males and females and for all three cohorts but was strongest for MADRES, a predominantly low-income Hispanic cohort in Los Angeles. A reverse j-shaped association was identified between cobalt and BW for GA, which was driven by female infants. Pooled associations were null for cadmium, chromium, molybdenum, and uranium, and BKMR did not identify potential interactions between metal pairs.

CONCLUSIONS

Findings suggest that antimony, an understudied metalloid, may adversely impact fetal growth. Cohort- and/or sex-dependent associations were identified for many of the metals, which merit additional investigation.

What to Expect When Expecting in Lab: A Review of Unique Risks and Resources for Pregnant Researchers in the Chemical Laboratory

Pregnancy presents a unique risk to chemical researchers due to their occupational exposures to chemical, equipment, and physical hazards in chemical research laboratories across science, engineering, and technology disciplines. Understanding “risk” as a function of hazard, exposure, and vulnerability, this review aims to critically examine the state of the science for the risks and associated recommendations (or lack thereof) for pregnant researchers in chemical laboratories (labs). Commonly encountered hazards for pregnant lab workers include chemical hazards (organic solvents, heavy metals, engineered nanomaterials, and endocrine disruptors), radiation hazards (ionizing radiation producing equipment and materials and nonionizing radiation producing equipment), and other hazards related to the lab environment (excessive noise, excessive heat, psychosocial stress, strenuous physical work, and/or abnormal working hours). Lab relevant doses and routes of exposure in the chemical lab environment along with literature and governmental recommendations or resources for exposure mitigation are critically assessed. The specific windows of vulnerability based on stage of pregnancy are described for each hazard, if available. Finally, policy gaps for further scientific research are detailed to enhance future guidance to protect pregnant lab workers.

Prenatal exposure to metal mixtures and newborn neurobehavior in the Rhode Island Child Health Study

BACKGROUND

Prenatal exposure to metals can affect the developing fetus and negatively impact neurobehavior. The associations between individual metals and neurodevelopment have been examined, but little work has explored the potentially detrimental neurodevelopmental outcomes associated with the combined impact of coexisting metals. The objective of this study is to evaluate prenatal metal exposure mixtures in the placenta to elucidate the link between their combined effects on newborn neurobehavior.

METHOD

This study included 192 infants with available placental metal and NICU Network Neurobehavioral Scale data at 24 hours-72 hours age. Eight essential and nonessential metals (cadmium, cobalt, copper, iron, manganese, molybdenum, selenium, zinc) detected in more than 80% of samples were tested for associations with atypical neurobehavior indicated by NICU Network Neurobehavioral Scale using logistic regression and in a quantile g-computation analysis to evaluate the joint association between placental metal mixture and neurobehavioral profiles.

RESULTS

Individually, a doubling of placental cadmium concentrations was associated with an increased likelihood of being in the atypical neurobehavioral profile (OR = 2.39; 95% CI = 1.05 to 5.71). In the mixture analysis, joint effects of a quartile increase in exposure to all metals was associated with 3-fold increased odds of newborns being assigned to the atypical profile (OR = 3.23; 95% CI = 0.92 to 11.36), with cadmium having the largest weight in the mixture effect.

CONCLUSIONS

Prenatal exposure to relatively low levels of a mixture of placental metals was associated with adverse newborn neurobehavior. Examining prenatal metal exposures as a mixture is important for understanding the harmful effects of concomitant exposures in the vulnerable populations.