Exposure to mercury among 9-year-old children and neurobehavioural function

Emerging roles of histone modifications in environmental toxicants-induced neurotoxicity

Epigenetics describes itself as heritable modifications in gene function that eventually alter gene and protein expression levels without any alterations in the genome sequence. Epigenetic alterations are closely association with several neurological diseases and neurodevelopmental disorders. In recent years, growing shreds of evidences suggested the crucial role of epigenetic modifications especially histone modifications in environmental toxicants-induced neurotoxicity. This review will give an overview of the state of knowledge on histone alterations and the ways in which environmental pollutants bisphenol-A, heavy metals, pesticides, and phthalates affects post-translational modifications to alter gene transcription and cause neurological abnormalities. We provide a brief summary of the results of recent research on the effects of environmental toxins on each of the prior identified processes of histone modifications, including the neurological consequences and changes in histones. There is also discussion of the limitations of current research findings. Furthermore, this review aims to provide viewers a comprehensive knowledge regarding the role of histone modifications in various environmental toxicants-induced neurological diseases and offers insights for future research.

Association between heavy metals exposure and risk of attention deficit hyperactivity disorder (ADHD) in children: a systematic review and meta-analysis

Heavy metals can negatively affect children's neurodevelopment, yet the relationship between heavy metals exposure and attention deficit hyperactivity disorder (ADHD) in children remains unclear. We aimed to examine associations between exposure to five common heavy metals (lead, arsenic, mercury, cadmium, and manganese) with neurodevelopmental toxicity and the risk of ADHD in children. Online databases of PubMed, Web of Science, and Embase were searched before February 29, 2024. A total of 31 studies involving 25,258 children were included in the final analysis. Our findings revealed that lead exposure was positively associated with ADHD risk in children (OR = 1.95, 95% CI: 1.57-2.41) overall, while the associations varied among different WHO regions, with the strongest in the Americas. Sensitivity analyses revealed significant associations between arsenic (OR = 1.53, 95% CI: 1.01-2.32) and manganese (OR = 1.79, 95% CI: 1.28-2.49) exposure and ADHD risk after omitting one study. Arsenic exposure was positively associated with ADHD risk in studies conducted in the Americas and adjusted for environmental smoke exposure. Positive associations between manganese exposure and ADHD risk were also found in several subgroup analyses. No significant associations were found for mercury and cadmium exposure. Dose-response meta-analysis suggested that children with higher blood lead levels exhibited a higher probability of ADHD diagnosis. Lead exposure consistently increases the risk of ADHD in children, while arsenic and manganese exposure may be associated with ADHD under different occasions. More research is required to understand heavy metals' impact on ADHD across varying exposure levels, particularly in less contaminated regions.

Decoding trace element speciation in mushrooms: Analytical techniques, comprehensive data review, and health implications

This review focuses on trace element speciation in edible mushrooms, providing information on analytical methods, available literature data, and health risk assessment. All steps of analytical procedures were presented, including extraction, separation and quantification. It compiles fragmented literature data on trace element speciation, focusing on arsenic, chromium, selenium, mercury, and antimony. Key findings include non-bioaccumulative chromium, the prevalence of Sb(V), mercury accumulation in contaminated sites, diverse arsenic and selenium speciation. Safe intake limits by agencies like USEPA indicate low risk for Cr(VI) and Sb but significant hazards from mercury and methylmercury, especially in contaminated areas: about 10 % of samples exceed safe limits for inorganic arsenic, and selenium enrichment often surpasses safety thresholds. The review underscores the need for standardized methods, speciation analyses of all toxicologically relevant species, and research on cooking impacts to improve health risk evaluations: establishing safe conditions for mushroom consumption remains a far-fetched goal.

Seafood Toxicant Exposure During Pregnancy, Lactation, and Childhood and Child Outcomes: A Scoping Review

Determining dietary recommendations for seafood consumed during pregnancy, lactation, and childhood requires consideration of the known nutritional benefits and potential harm due to toxicant exposure as they relate to child outcomes. This study aimed to describe the scope of the evidence associated with seafood-related toxicant exposure and child outcomes and to identify toxicant-outcome pairs that may have sufficient evidence to conduct a systematic review. We included studies examining seafood toxicant exposure during pregnancy, lactation, and childhood, and child outcomes. In total, 81 studies were included: 69 studies on exposure during pregnancy and lactation and 14 on exposure during childhood. The number of studies varied by toxicant and exposure population (maternal; child): mercury (n = 49; 7), methylmercury (n = 13; 3), polychlorinated biphenyls (PCBs; n = 11; 1), selenium (n = 11; 1), lead (n = 9; 3), perfluoroalkyl and polyfluoroalkyl substances (n = 8; 2), dichlorodiphenyltrichloroethane (n = 5; 1), arsenic (n = 4; 4), cadmium (n = 4; 4), zinc (n = 3; 2), polybrominated diphenyl ethers (n = 3; 1), dioxin-like compounds (n = 3; 0), iron (n = 2; 1), and magnesium (n = 1; 1). No studies examined polybrominated biphenyls, polycyclic aromatic hydrocarbons, iodine, aldrin, dieldrin, chlordane, chlorpyrifos, or microplastic exposures. Outcomes also varied by exposure population (maternal;child): neurodevelopment (n = 35; 9), child exposure biomarkers (n = 22; 4), growth (n = 17; 1), other adverse events (n = 4; 0), cardiometabolic (n = 3; 2), chronic disease indicators (n = 2; 0), and immune-related (n = 1; 2). Twelve maternal toxicant-outcome pairs had ≥3 studies, including mercury, methylmercury, lead, PCBs, perfluoroalkyl and polyfluoroalkyl substances, and arsenic as exposures and neurodevelopment, child exposure biomarkers, growth, and cardiometabolic as outcomes. For child exposure, only mercury and neurodevelopment had ≥3 studies. In conclusion, this scoping review shows relevant evidence for 14 of the 22 toxicants. Only 12 maternal and 1 child toxicant-outcome pairs, the majority of which examined maternal (methyl)mercury exposure, had ≥3 studies, our cutoff for consideration for systematic review. This scoping review indicates a paucity of research examining seafood toxicants beyond mercury and exposure during childhood. Systematic reviews are required to evaluate the associations for each toxicant-outcome pairs. The protocol was registered at Open Science Framework (https://doi.org/10.17605/OSF.IO/FQZTA).

Advocating for planetary health is an essential part of advocating for children's health

Burning of fossil fuels along with deforestation and ecological disruption have led to the warming of the Earth and climate change. Children are especially vulnerable to adverse health effects of climate change associated changes in the air, soil, and water as their organs are still developing, have a faster breathing rate, higher per pound ingested and inhaled exposures, and greater relative body surface area. To protect this vulnerable population, health care professionals need to play a leading role. In 2015, the American Academy of Pediatrics (AAP) updated their original 2007 Global Climate Change and Children's Health policy statement (again updated in 2024) stating that, "failure to take prompt, substantive action would be an act of injustice to all children." Health care professionals need to educate themselves and their patients of the health risks posed by climate change and incorporate climate change counseling into their practice. They also need to go beyond the framework of the healthcare system and work collaboratively with communities, corporations, and governments to advocate for policies and solutions to mitigate and adapt to climate change. The health and wellbeing of future generations rests upon the actions we take today. IMPACT: Summarizes the adverse effects of increased anthropogenic activity and burning of fossil fuels on planetary and human health Details the increased vulnerability of children to environmental assaults and their long-term effects Provides guidance and resources to health care professionals to empower them to act as advocates for systemic and structural changes that protect children's health.

Maternal dietary patterns and offspring behavioral problems

BACKGROUND

Mental health problems often begin in early childhood and could predict psychiatric and behavioral outcomes. Prenatal factors such as maternal nutrition have an impact on neurodevelopment. This study aims to investigate the association between maternal dietary patterns and emotional and behavioral problems in 4-year-old children.

METHODS

Within a cohort of 205 mother-child pairs, three maternal dietary patterns were identified: 'Sweet and Superfluous', 'Fish and Vegetables' and 'Meat and Cereals'. Child behavior was evaluated by means of the Child Behavior Checklist 1.5-5 (CBCL 1.5-5), the Teacher's Report Form 1.5-5 (TRF 1.5-5), and the Behavior Rating Inventory of Executive Function - Preschool Version (BRIEF-P). Multivariable analysis determined associations between maternal dietary patterns and their children's behavior.

RESULTS

Maternal adherence to the 'Sweet and Superfluous' pattern was positively associated with externalizing and depressive problems in children. The 'Meat and Cereals' pattern was linked to a higher risk for attention, hyperactivity and depressive problems as somatic complaints. Conversely, the 'Fish and Vegetables' pattern was associated with a reduced risk of hyperactivity problems. All these associations were more pronounced in girls than in boys.

CONCLUSIONS

Maternal diet during pregnancy is associated with the emotional and behavioral development of children at 4 years of age.

IMPACT

Previous research on prenatal dietary patterns and children's behavior is inconclusive. In our study, children of mothers who had higher intakes of sugar and processed foods during pregnancy were more likely to have emotional and behavioral problems at age 4, especially girls. A high-quality diet characterized by fish and vegetable consumption during pregnancy was associated with reduced anxiety and hyperactivity problems in girls. Our findings highlight the importance of prenatal nutrition for child neurodevelopment.

Associations between Urinary Phthalate Metabolites with BDNF and Behavioral Function among European Children from Five HBM4EU Aligned Studies

Based on toxicological evidence, children's exposure to phthalates may contribute to altered neurodevelopment and abnormal regulation of brain-derived neurotrophic factor (BDNF). We analyzed data from five aligned studies of the Human Biomonitoring for Europe (HBM4EU) project. Ten phthalate metabolites and protein BDNF levels were measured in the urine samples of 1148 children aged 6-12 years from Italy (NACII-IT cohort), Slovakia (PCB-SK cohort), Hungary (InAirQ-HU cohort) and Norway (NEBII-NO). Serum BDNF was also available in 124 Slovenian children (CRP-SLO cohort). Children's total, externalizing and internalizing behavioral problems were assessed using the Child Behavior Checklist at 7 years of age (only available in the NACII-IT cohort). Adjusted linear and negative binomial regression models were fitted, together with weighted quantile sum (WQS) regression models to assess phthalate mixture associations. Results showed that, in boys but not girls of the NACII-IT cohort, each natural-log-unit increase in mono-n-butyl phthalate (MnBP) and Mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) was cross-sectionally associated with higher externalizing problems [incidence rate ratio (IRR): 1.20; 95% CI: 1.02, 1.42 and 1.26; 95% CI: 1.03, 1.55, respectively]. A suggestive mixture association with externalizing problems was also observed per each tertile mixture increase in the whole population (WQS-IRR = 1.15; 95% CI: 0.97, 1.36) and boys (IRR = 1.20; 95% CI: 0.96, 1.49). In NACII-IT, PCB-SK, InAirQ-HU and NEBII-NO cohorts together, urinary phthalate metabolites were strongly associated with higher urinary BDNF levels, with WQS regression confirming a mixture association in the whole population (percent change (PC) = 25.9%; 95% CI: 17.6, 34.7), in girls (PC = 18.6%; 95% CI: 7.92, 30.5) and mainly among boys (PC = 36.0%; 95% CI: 24.3, 48.9). Among CRP-SLO boys, each natural-log-unit increase in ∑DINCH concentration was associated with lower serum BDNF levels (PC: -8.8%; 95% CI: -16.7, -0.3). In the NACII-IT cohort, each natural-log-unit increase in urinary BDNF levels predicted worse internalizing scores among all children (IRR: 1.15; 95% CI: 1.00, 1.32). Results suggest that (1) children's exposure to di-n-butyl phthalate (DnBP) and di(2-ethylhexyl) phthalate (DEHP) metabolites is associated with more externalizing problems in boys, (2) higher exposure to DINCH may associate with lower systemic BDNF levels in boys, (3) higher phthalate exposure is associated with higher urinary BDNF concentrations (although caution is needed since the possibility of a "urine concentration bias" that could also explain these associations in noncausal terms was identified) and (4) higher urinary BDNF concentrations may predict internalizing problems. Given this is the first study to examine the relationship between phthalate metabolite exposure and BDNF biomarkers, future studies are needed to validate the observed associations.

Exploring the link between toxic metal exposure and ADHD: a systematic review of pb and hg

INTRODUCTION

Attention-Deficit/Hyperactivity Disorder (ADHD) is a recognized neurodevelopmental disorder with a complex, multifactorial origin. Lead (Pb) and mercury (Hg) are highly toxic substances that can potentially impair brain development and have been implicated in the development of ADHD. This systematic review aims to analyze the epidemiological literature regarding the association between Pb and Hg exposure and the diagnosis of ADHD.

METHODS

From November 1983 to June 2, 2023, a comprehensive search was conducted in multiple databases and search engines, including PubMed, Web of Science, Scopus, and Google Scholar. Observational studies (case-control, cohort, and cross-sectional) measuring Pb and Hg levels in various biological samples (blood, hair, urine, nail, saliva, teeth, and bone) of children with ADHD or their parents and their association with ADHD symptoms were included.

RESULTS

Out of 2059 studies, 87 met the inclusion criteria and were included in this systematic review. Approximately two-thirds of the 74 studies investigating Pb levels in different biological samples reported associations with at least one subtype of ADHD. However, most studies examining Hg levels in various biological samples found no significant association with any ADHD subtype, although there were variations in exposure periods and diagnostic criteria.

CONCLUSION

The evidence gathered from the included studies supports an association between Pb exposure and the diagnosis of ADHD, while no significant association was found with Hg exposure. Importantly, even low levels of Pb were found to elevate the risk of ADHD. Further research is needed to explore the comprehensive range of risk factors for ADHD in children, considering its significance as a neurodevelopmental disorder.

Abnormal Porphyrin Metabolism in Autism Spectrum Disorder and Therapeutic Implications

Autism spectrum disorder (ASD) is a mosaic of neurodevelopmental conditions composed of early-onset social interaction and communication deficits, along with repetitive and/or restricted patterns of activities, behavior, and interests. ASD affects around 1% of children worldwide, with a male predominance. Energy, porphyrin, and neurotransmitter homeostasis are the key metabolic pathways affected by heavy metal exposure, potentially implicated in the pathogenesis of ASD. Exposure to heavy metals can lead to an altered porphyrin metabolism due to enzyme inhibition by heavy metals. Heavy metal exposure, inborn genetic susceptibility, and abnormal thiol and selenol metabolism may play a significant role in the urinary porphyrin profile anomalies observed in ASD. Altered porphyrin metabolism in ASD may also be associated with, vitamin B6 deficiency, hyperoxalemia, hyperhomocysteinemia, and hypomagnesemia. The present review considers the abnormal porphyrin metabolism in ASD in relation to the potential pathogenic mechanism and discusses the possible metabolic therapies such as vitamins, minerals, cofactors, and antioxidants that need to be explored in future research. Such targeted therapeutic therapies would bring about favorable outcomes such as improvements in core and co-occurring symptoms.

The GSTP1 rs1695 Polymorphism Is Associated with Mercury Levels and Neurodevelopmental Delay in Indigenous Munduruku Children from the Brazilian Amazon

Genetic polymorphisms may influence mercury (Hg) toxicity. The aims of this study were to evaluate individual factors, such as the presence of the GSTP1 rs1695 polymorphism, associated with internal Hg dose and child neurodevelopment in indigenous people from the Brazilian Amazon chronically exposed to Hg. Eighty-two indigenous children were clinically evaluated, hair Hg was measured, and the GSTP1 rs1695 polymorphism was genotyped. The mean age was 4.8 years, the median Hg was 5.5 µg/g, and 93.8% of children exceeded the safe limit (2.0 µg/g). Fish consumption was associated with Hg levels (p = 0.03). The GSTP1 rs1695 A>G polymorphism was in the Hardy-Weinberg equilibrium and the highest prevalence of the GSTP1 AA genotype (80%) was found in Sawré Aboy, which had the highest Hg levels (10 µg/g) among the studied villages. The Hg levels tended to increase over the years in males and in carriers of the GSTP1 AA genotype (0.69 µg/g and 0.86 µg/g, respectively). Nine children failed the neurodevelopmental test, all of whom had Hg > 2.0 µg/g, and 88.9% carried the GSTP1 AA or AG genotypes, previously associated with the highest internal Hg doses and neurocognitive disorders. The genetic counseling of this population is important to identify the individuals at greater risk for neurodevelopmental disorders resulting from chronic Hg exposure.

Brain-derived neurotrophic factor (BDNF): an effect biomarker of neurodevelopment in human biomonitoring programs

The present narrative review summarizes recent findings focusing on the role of brain-derived neurotrophic factor (BDNF) as a biomarker of effect for neurodevelopmental alterations during adolescence, based on health effects of exposure to environmental chemical pollutants. To this end, information was gathered from the PubMed database and the results obtained in the European project Human Biomonitoring for Europe (HBM4EU), in which BDNF was measured at two levels of biological organization: total BDNF protein (serum) and BDNF gene DNA methylation (whole blood) levels. The obtained information is organized as follows. First, human biomonitoring, biomarkers of effect and the current state of the art on neurodevelopmental alterations in the population are presented. Second, BDNF secretion and mechanisms of action are briefly explained. Third, previous studies using BDNF as an effect biomarker were consulted in PubMed database and summarized. Finally, the impact of bisphenol A (BPA), metals, and non-persistent pesticide metabolites on BDNF secretion patterns and its mediation role with behavioral outcomes are addressed and discussed. These findings were obtained from three pilot studies conducted in HBM4EU project. Published findings suggested that exposure to some chemical pollutants such as fine particle matter (PM), PFAS, heavy metals, bisphenols, and non-persistent pesticides may alter circulating BDNF levels in healthy population. Therefore, BDNF could be used as a valuable effect biomarker to investigate developmental neurotoxicity of some chemical pollutants.

Postnatal methylmercury exposure and neurodevelopmental outcomes at 7 years of age in the Seychelles Child Development Study Nutrition Cohort 2

BACKGROUND

Consumption of fish yields many nutritional benefits, but also results in exposure to methylmercury (MeHg). The developing brain is known to be particularly susceptible to MeHg toxicity in high doses. However, the potential impact of low-level environmental exposure from fish consumption on children's neurodevelopment remains unclear.

METHODS

We investigated postnatal MeHg exposure at 7 years and its association with a battery of 17 neurodevelopmental outcomes in a subset of children (n = 376) from 1535 enrolled mother-child pairs in Nutrition Cohort 2 of the Seychelles Child Development Study (SCDS NC2). Each outcome was modeled in relation to postnatal MeHg exposure using linear regression, adjusting for prenatal MeHg exposure, levels of maternal polyunsaturated fatty acids (PUFA), and several other covariates known to be associated with neurodevelopmental outcomes.

RESULTS

Median postnatal MeHg exposure at 7 years was 2.5 ppm, while the median prenatal MeHg exposure was 3.5 ppm. We found no statistically significant associations between postnatal MeHg exposure and any of the 17 neurodevelopmental outcomes after adjusting for prenatal MeHg exposure and other covariates.

CONCLUSIONS

These findings are consistent with previous cross-sectional analyses of the SCDS Main Cohort. Continued follow-up of the entire NC2 cohort at later ages with repeated exposure measures is needed to further confirm these findings.

Revisiting Genetic Influence on Mercury Exposure and Intoxication in Humans: A Scoping Review

Human intoxication to mercury is a worldwide health problem. In addition to the type and length of exposure, the genetic background plays an important role in mercury poisoning. However, reviews on the genetic influence in mercury toxicity are scarce and not systematic. Therefore, this review aimed to systematically overview the most recent evidence on the genetic influence (using single nucleotide polymorphisms, SNPs) on human mercury poisoning. Three different databases (PubMed/Medline, Web of Science and Scopus) were searched, and 380 studies were found that were published from 2015 to 2022. After applying inclusion/exclusion criteria, 29 studies were selected and data on characteristics (year, country, profile of participants) and results (mercury biomarkers and quantitation, SNPs, main findings) were extracted and analyzed. The largest number of studies was performed in Brazil, mainly involving traditional populations of the Tapajós River basin. Most studies evaluated the influence of the SNPs related to genes of the glutathione system (GST, GPx, etc.), the ATP-binding cassette transporters and the metallothionein proteins. The recent findings regarding other SNPs, such as those of apolipoprotein E and brain-derived neurotrophic factor genes, are also highlighted. The importance of the exposure level is discussed considering the possible biphasic behavior of the genetic modulation phenomena that could explain some SNP associations. Overall, recommendations are provided for future studies based on the analysis obtained in this scoping review.

Genetic Susceptibility to Neurotoxicity Related to Prenatal Inorganic Arsenic Exposure in Young Spanish Children

We explored the influence of child and maternal single nucleotide polymorphisms (SNPs) in genes related to neurological function and arsenic metabolism (i.e., ABCA1, ABCB1, PON1, CYP3A, BDNF, GSTP1, MT2A, and APOE as well as AS3MT) on the association between prenatal arsenic (As) exposure and methylation efficiency and neuropsychological development in 4-5-year-old children. Participants were 549 mother-child pairs from the INMA (Environment and Childhood) Spanish Project. We measured inorganic arsenic (iAs) and the metabolites monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) in urine samples collected during pregnancy. Neuropsychological development was assessed at the age of 4-5 years using the McCarthy Scales of Children's Abilities (MSCA). Several SNPs were determined in maternal and child DNA; AS3MT and APOE haplotypes were inferred. The median ∑As (sum of iAs, DMA, and MMA) was 7.08 μg/g creatinine. Statistically significant interactions for children's APOE haplotype were observed. Specifically, ε4-carrier children had consistently lower MSCA scores in several scales with increasing ∑As and MMA concentrations. These results provide evidence regarding the neurotoxic effects of early life exposure to As, observing that the APOE ε4 allele could make children more vulnerable to this exposure.

Association of maternal prenatal urinary fluoride levels with ADHD symptoms in childhood

BACKGROUND

Health concerns about the potential impact of exposure to fluoride via drinking water (DW) on neuropsychological development include behavioral outcomes such as ADHD.

OBJECTIVE

We aimed to examine the association between prenatal maternal urinary fluoride and symptoms associated with attention-deficit/hyperactivity disorder (ADHD) at the age of 8 and 11 years.

METHOD

Data from 255 to 236 mother-child pairs from the "Infancia y Medio Ambiente" (INMA) birth cohort (Gipuzkoa; Spain) with maternal urinary F adjusted for creatinine (MUFcr) during pregnancy (first and third trimester) and child assessments of ADHD-like symptoms reported by Conners' Rating Scales-Revised at age of 8 and 11 years was available. Clinical approach was also used: cut off criteria (T > 66). Multiple linear regression models were fitted when outcomes were analyzed as continuous, and logistic regression models when the outcomes were analyzed with a categorical clinical approach. Covariates related to maternal characteristics, birth outcomes, childhood, quality of family context and biomarkers of neuro-toxicants were used.

RESULTS

No association was found between MUFcr levels during pregnancy and cognitive problems-inattention, hyperactivity or ADHD index score of symptoms at 8 or 11 years. When results were analyzed from the perspective of a clinical approach, at the age of 11 years, there were significant inverse association between MUFcr and being categorized as a cognitive problems-inattention case. ORs were also indicative of a lower risk, although not significant, for ADHD index at age 11. Sensitivity analyses, taking into consideration quality of family context or the levels of other toxicants during pregnancy showed similar results.

CONCLUSIONS

Higher levels of MUFcr in pregnant women were associated with a lower risk of cognitive problems-inattention at 11 years. These findings are inconsistent with those from previous studies and indicate the need for other population-based studies to confirm or overturn these results.

Polymorphism of Estrogen Receptor Genes and Its Interactions With Neurodevelopmental Genes in Attention Deficit Hyperactivity Disorder Among Chinese Han Descent

OBJECTIVE

Attention deficit hyperactivity disorder (ADHD) is a polygenic neurodevelopmental disorder with significant gender differences. The sexual dimorphism of ADHD may be associated with estrogen acting through estrogen receptors (ESR). This study investigates the impact of ESR gene polymorphism and its interactions with neurodevelopmental genes on ADHD susceptibility.

METHODS

The study compared genotyping data of single nucleotide polymorphisms in ESR1 and ESR2 in 1,035 ADHD cases and 962 controls. The gene-gene interactions between ESR genes and three neurodevelopmental genes (brain-derived neurotrophic factor [BDNF], synaptosomal-associated protein of 25 kDa gene [SNAP25], and cadherin-13 [CDH13]) in ADHD were investigated using generalized multifactor dimensionality reduction and verified by logistic regression analysis.

RESULTS

The G allele of rs960070/ESR2 (empirical p=0.0076) and the A allele of rs8017441/ESR2 (empirical p=0.0426) were found significantly higher in ADHD cases than in the controls but not in male or female subgroups. Though no difference was found in all subjects or females, the A allele of rs9340817/ESR1 (empirical p=0.0344) was found significantly higher in ADHD cases than controls in males. We also found genetic interaction models between ESR2 gene, neurodevelopmental genes and ADHD susceptibility in males (ESR2 rs960070/BDNF rs6265/BDNF rs2049046/SNAP25 rs362987/CDH13 rs6565113) and females (ESR2 rs960070/BDNF rs6265/BDNF rs2049046) separately, though it was negative in overall subjects.

CONCLUSION

The ESR gene polymorphism associates with ADHD among Chinese Han children, with interactions between ESR genes and neurodevelopmental genes potentially influencing the susceptibility of ADHD.

Determinants affecting the blood mercury levels of preschool children in Shanghai, China: A cross-sectional study

Infants and children are vulnerable to mercury (Hg)-induced toxicity, which has detrimental effects on their neurological development. This study measured blood Hg levels (BMLs) and identified potential factors influencing BMLs, including demographic and socioeconomic factors, lifestyle, and daily dietary habits, among 0 to 7-year-old children in Shanghai. Our study recruited 1474 participants, comprising 784 boys and 690 girls. Basic demographic and lifestyle information were obtained and blood Hg were analyzed using the Direct Mercury Analyzer 80. The blood Hg concentrations of children in Shanghai ranged from 0.01 to 17.20 μg/L, with a median concentration of 1.34 μg/L. Older age, higher familial socioeconomic status, higher residential floors, and a higher frequency of consuming aquatic products, rice, vegetables, and formula milk were identified as risk factors. Other potential influencing factors including the mother's reproductive history (gravidity and parity), smoking (passive smoking), supplementation of fish oil and calcium need to be further investigated. These findings can be useful in establishing appropriate interventions to prevent children's high blood Hg concentrations in Shanghai and other similar metropolitan cities.

Assessing the Correlation between Blood Trace Element Concentrations, Picky Eating Habits, and Intelligence Quotient in School-Aged Children

INTRODUCTION

Inadequate levels of iron, zinc, and copper have been linked to growth impairment and cognitive and motor development deficits. The objective of this study is to examine the deficiencies of trace elements and their correlation with selective eating patterns and the intelligence quotient (IQ) of children.

METHODS AND PATIENTS

The cross-sectional analysis involved 430 children aged between 7 and 10 years. Blood samples were analyzed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to measure the trace elements levels. Children's IQs were assessed using Raven's Standard Progressive Matrices.

RESULTS

Among the sample group, 20.3% exhibited iron deficiency, 42.5% had zinc deficiency, and 14% had insufficient copper levels. Single trace element deficiency was observed in 56.9% of the children, while 66.7% showed coexisting deficiencies of iron and zinc. Children with lower development levels exhibited significantly lower serum zinc levels compared to those with higher development levels (76.78 ± 10.67 vs. 81.14 ± 10.19 μg/dL). The analysis reveals that picky eaters had lower serum iron levels (76.59 ± 10.42 μg/dL) and higher serum copper levels (123.74 ± 13.45 μg/dL).

CONCLUSION

A strong association was observed between zinc deficiency, picky eating habits, and lower developmental stages. The findings underscore the importance of monitoring nutritional status in children, given the significant implications for their cognitive development.

Association of heavy metal complex exposure and neurobehavioral function of children

Background

Exposure to heavy metals is a public health concern worldwide. Previous studies on the association between heavy metal exposure and neurobehavioral functions in children have focused on single exposures and clinical manifestations. However, the present study evaluated the effects of heavy metal complex exposure on subclinical neurobehavioral function using a Korean Computerized Neurobehavior Test (KCNT).

Methods

Urinary mercury, lead, cadmium analyses as well as symbol digit substitution (SDS) and choice reaction time (CRT) tests of the KCNT were conducted in children aged between 10 and 12 years. Reaction time and urinary heavy metal levels were analyzed using partial correlation, linear regression, Bayesian kernel machine regression (BKMR), the weighted quantile sum (WQS) regression and quantile G-computation analysis.

Results

Participants of 203 SDS tests and 198 CRT tests were analyzed, excluding poor cooperation and inappropriate urine sample. Partial correlation analysis revealed no association between neurobehavioral function and exposure to individual heavy metals. The result of multiple linear regression shows significant positive association between urinary lead, mercury, and CRT. BMKR, WQS regression and quantile G-computation analysis showed a statistically significant positive association between complex urinary heavy metal concentrations, especially lead and mercury, and reaction time.

Conclusions

Assuming complex exposures, urinary heavy metal concentrations showed a statistically significant positive association with CRT. These results suggest that heavy metal complex exposure during childhood should be evaluated and managed strictly.

Neurotransmitter disturbances caused by methylmercury exposure: Microbiota-gut-brain interaction

The fetal and early postnatal stages are periods of rapid brain development, during which, methylmercury (MeHg) exposure can cause lasting cognitive impairments. MeHg exposure disrupts neurotransmitter metabolites, which increased susceptibility to neurological responses. However, the neurotoxic mechanism underlying the MeHg-induced disruption of neurotransmitter metabolism requires further exploration. To this end, female Sprague-Dawley (SD) rats were administered NaCl (control group) or MeHg (0.6 mg/kg, 1.2 mg/kg and 2.4 mg/ kg body weight (bw), where the body weight refers to the dams) during the perinatal period, and then changes in neurotransmitter profiles and the gut microbiota of offspring were detected. The results showed that tryptophan (Trp) and tyrosine (Tyr) pathway neurotransmitter metabolites, including serotonin (5-HT), 5-hydroxy indole acetic acid (5-HIAA), N-acetyl-5-hydroxytryptamin (NAS), Tyr, dopamine (DA) and epinephrine (E), were significantly changed, and the Kynurenine/Tryptophan (Kyn/Trp) ratio was increased in the MeHg-treated groups. Meanwhile, acetylcholine (ACh) and neurotransmitters involved in the amino acid pathway were significantly reduced. Notably, MeHg treatment induced a significant reduction in tight junctions in the colon and hippocampal tissue. Furthermore, fecal microbiota analysis indicated that the diversity and composition characteristics were significantly altered by MeHg exposure. Mediation analysis showed that the gut microbiota mediated the effect of MeHg treatment on the neurotransmitter expression profiles. The present findings shed light on the regulatory role of the gut microbiota in MeHg-disrupted neurotransmitter metabolic pathways and the potential impact of perinatal MeHg treatment on the "cross-talk" between the gut and brain.

Chronic Mercury Exposure and GSTP1 Polymorphism in Munduruku Indigenous from Brazilian Amazon

Genetic polymorphisms may be involved with mercury levels and signs and symptoms of intoxication from this exposure. Therefore, the aims were to describe the frequency of the GSTP1 polymorphism and to evaluate its effects on mercury levels and neurological signs in three Munduruku indigenous villages in the Brazilian Amazon. One-hundred-and-seven indigenous (over 12 years old) were included and genotyped (rs1695) using a TaqMan validated assay. Then, associations were evaluated by binary logistic regression, using odds ratios (OR) and 95% confidence intervals (CI). Mean age was 27.4 ± 13.9 years old, 52.3% were male, mean hair mercury concentration was 8.5 ± 4.3, exceeding the reference limit (≥6.0 µg/g), and were different among the three villages: 13.5 ± 4.6 µg/g in Sawré Aboy, 7.4 ± 2.3 µg/g in Poxo Muybu and 6.9 ± 3.5 µg/g in Sawré Muybu. The minor allele frequency of GSTP1 G was significantly different among the villages: 57% Sawré Muybu, 21% Poxo Muybu and 15% Sawré Aboy. Finally, after adjustment, GSTP1 GG and GA genotypes were associated with lower levels of Hg (OR = 0.13; CI95% = 0.03-0.49) and abnormal somatosensory signs (OR = 3.7; 95%IC = 1.5-9.3), respectively. In conclusion, monitoring this population is imperative to identify individuals at higher risk of developing signs of chronic mercury exposure based on the genetic profile.

The combined effect between BDNF genetic polymorphisms and exposure to metals on the risk of Chinese dyslexia

BDNF gene has been implicated in the development of cognition and language. Meanwhile, exposure to metals might interact with BDNF gene to increase the risk of neurodevelopmental disorders. The present study aimed to explore the association between BDNF genetic polymorphisms and dyslexic risk and examine whether BDNF polymorphisms would interact with metal exposures, jointly contributing to dyslexia. Among a case-control study composed of 238 children with dyslexia and 228 healthy controls, the BDNF genetic polymorphisms were genotyped by the Sequenom MassARRAY system, and the exposure to eight metals, such as lead (Pb), mercury (Hg) and copper (Cu), were measured using an inductively coupled plasma-mass spectrometer (ICP-MS). Multivariable logistic regression models were used to assess the adjusted odds ratios (ORs) and 95% confidence interval (CI) of dyslexia. After multivariate adjustment, significant associations of dyslexic risk with rs6265 polymorphisms of the BDNF gene were observed (OR = 1.99; 95% CI: 1.15-3.44). Furthermore, exposure to Cu could interact with rs6265 to increase the risk of dyslexia (P interaction = 0.045). High-Cu children with the rs6265 TT genotype were more likely to have dyslexia compared with low-Cu children carrying CC + CT genotypes (OR = 3.19; 95% CI: 1.38-7.39). The findings of this study suggested that the polymorphism of rs6265 in BDNF gene could interact with Cu exposure to increase the occurrence of dyslexia.

Prenatal Exposure to Mercury, Manganese, and Lead and Adverse Birth Outcomes in Suriname: A Population-Based Birth Cohort Study

Globally, adverse birth outcomes are increasingly linked to prenatal exposure to environmental contaminants, such as mercury, manganese, and lead. This study aims to assess an association between prenatal exposure to mercury, manganese, and lead and the occurrence of adverse birth outcomes in 380 pregnant women in Suriname. The numbers of stillbirths, preterm births, low birth weights, and low Apgar scores were determined, as well as blood levels of mercury, manganese, lead, and relevant covariates. Descriptive statistics were calculated using frequency distributions. The associations between mercury, manganese, and lead blood levels, on the one hand, and adverse birth outcomes, on the other hand, were explored using contingency tables, tested with the χ2-test (Fisher's exact test), and expressed with a p value. Multivariate logistic regression models were computed to explore independent associations and expressed as (adjusted) odds ratios (aOR) with 95% confidence intervals (CI). The findings of this study indicate no statistically significant relationship between blood mercury, manganese, or lead levels and stillbirth, preterm birth, low birth weight, and low Apgar score. However, the covariate diabetes mellitus (aOR 5.58, 95% CI (1.38-22.53)) was independently associated with preterm birth and the covariate hypertension (aOR 2.72, 95% CI (1.081-6.86)) with low birth weight. Nevertheless, the observed high proportions of pregnant women with blood levels of mercury, manganese, and lead above the reference levels values of public health concern warrants environmental health research on risk factors for adverse birth outcomes to develop public health policy interventions to protect pregnant Surinamese women and their newborns from potential long-term effects.

Associations between time-weighted postnatal methylmercury exposure from fish consumption and neurodevelopmental outcomes through 24 years of age in the Seychelles Child Development Study Main Cohort

PURPOSE

Methylmercury (MeHg) is a known neurodevelopmental toxicant in sufficient dosage and is universally found in fish. Current fish advisories for children are based on epidemiology studies examining prenatal exposure with a premise that MeHg exposure resulting from children eating fish could also be neurotoxic and have long-term consequences. However, the evidence that this assumption is true is limited. We investigated postnatal MeHg exposure from regular fish consumption using time weighted Hg measurements to determine if there are neurotoxic consequences.

METHODS

We examined 85 neurodevelopmental outcomes measured from ages 9-24 years in the Seychelles Child Development Study Main Cohort (n = 312-550) and examined their association with time-weighted measures of postnatal MeHg exposure in childhood and early adulthood. Postnatal MeHg exposure measured in the first cm of participants' hair samples collected at seven evaluations were used to create two time-weighted (TW) average MeHg exposure metrics, one for childhood (TW-C) and the other for early adulthood (TW-A). TW-C was based on Hg measures at three ages between 6 months and 5.5 years, and TW-A was based on Hg measured at up to four ages between 17 and 24 years. We examined the association between each of these exposure metrics and the neurodevelopmental outcomes using linear regression with adjustment for covariates known to influence neurodevelopmental outcomes.

RESULTS

There were 14 statistically significant associations between a postnatal metric and an endpoint. Six were associated with the TW-C and eight with the TW-A. Thirteen were adverse. Only the TW-C association at 9 years with the Bender Gestalt error score showed improvement. TW-C was adversely associated at 9 years with the Continuous Performance Task risk score, at 22 years with the Boston Naming Test (BNT) total and no cues scores, and at 24 years with the Test of Variables of Attention (TOVA) auditory response time variability and visual response time mean on the logarithmic scale. TW-A was adversely associated at 17 years with the Wisconsin Card Sorting Test % total errors, the Woodcock-Johnson passage comprehension, and the CANTAB rapid visual information processing false alarms, and at 22 years with the BNT total and no cue scores, the CANTAB rapid visual information processing false alarms and the intra-extra dimensional shift total errors and trials.

CONCLUSION

These findings suggest that postnatal MeHg exposure may be adversely associated with neurodevelopmental outcomes in early adulthood. However, the associations are statistical and of unknown, if any, clinical significance. The results need confirmation in other cohorts.

Transcutaneous electrical acupoint stimulation for children with attention-deficit/hyperactivity disorder: a randomized clinical trial

Little is known about the effects of transcutaneous electrical acupoint stimulation (TEAS) for children with attention-deficit/hyperactivity disorder (ADHD). Here, we carried out a 4 week randomized clinical trial in which patients aged 6-12 years old with an ADHD diagnosis received TEAS or sham TEAS. The primary outcome measure was the investigator-rated Clinical Global Impression-Improvement (CGI-I) score at week 4. Secondary outcomes included changes from baseline to week 4 in the investigator-rated Clinical Global Impression-Severity of Illness (CGI-S) score, the Conners' Parent/Teacher Rating Scales-Revised: Short Form (CPRS-R: S/CTRS-R: S) score, go/no-go task performance, and functional near-infrared spectroscopy (fNIRS)-based oxygenated hemoglobin level within the prefrontal cortex. At week 4, the CGI-I score indicated improvement in 33.3% of the TEAS group compared with 7.7% of the sham group (P = 0.005). The TEAS group had a greater decrease in the mean CGI-S score (-0.87) than the sham TEAS group (-0.28) (P = 0.003). A greater enhancement in the mean cerebral oxygenated hemoglobin within the prefrontal cortex was found in the TEAS group (0.099 mM mm) compared with the sham TEAS group (0.005 mM mm) (P < 0.001). CPRS-R: S score, CTRS-R: S score, and go/no-go performance exhibited no significant improvement after TEAS treatment. The manipulation-associated adverse events were uncommon in both groups, and events were very mild. Our results show that noninvasive TEAS significantly improved general symptoms and increased prefrontal cortex blood flow within 4 weeks for children with ADHD. Further clinical trials are required to understand the long-term efficacy in a larger clinical sample. This trial was registered on ClinicalTrials.gov (NCT03917953).

Residence in an Area with Environmental Exposure to Heavy Metals and Neurobehavioral Performance in Children 9-11 Years Old: An Explorative Study

We explored the association between residence in an area polluted with metals and neurobehavioral performance in children aged 9 to 11. A cross-sectional study was conducted with thirty boys and thirty girls aged 9 to 11 from public schools in a heavily industrialized area, matched by age (±4 months) and gender with 15 boys and 15 girls from public schools in cities without relevant industrial activity. Neurobehavioral performance was assessed with the Behavioral Assessment and Research System. Linear regression models were used, adjusting for age, sex, social class and multimedia activities to predict each of the neurobehavioral outcome variables. No differences in neurobehavioral performance were found when all children with residence in areas with environmental exposure to metals were classified as exposed and the children from the other provinces as unexposed. However, when we compared children living <1 km from an industrial area with respect to those living more than 1 km away, significant differences were found. Children living <1 km away had lower scores on Finger Tapping (p = 0.03), Symbol-Digit (p = 0.07) and Continuous Performance (p = 0.02) than those living farther away. Our results support the hypothesis that residing close to an area with industrial activity (<1 km) is associated with deficits in neurobehavioral performance among children aged 9 to 11.

A novel coumarin-benzopyrylium based near-infrared fluorescent probe for Hg2+ and its practical applications

A novel colorimetric and ratiometric NIR fluorescent probe for Hg²⁺ was designed and synthesized based on a coumarin-benzopyrylium platform. The ring-open form of the probe exhibits NIR absorption (670 nm) and emission (720 nm). The probe shows high sensitivity, high selectivity and rapid response (30 s) to Hg²⁺. The detection limit was as low as 6.94 nM. The probe shows high stability in a wide pH range from 2 to 10. Moreover, the probe can be employed for detecting Hg²⁺ in food and biological samples.

Role of endocrine disrupting chemicals in children's neurodevelopment

Environmental stressors, like endocrine disrupting chemicals (EDC), are considered important contributors to the increased rates of neurodevelopmental dysfunctions. Considering the cumulative research on adverse neurodevelopmental effects associated with prenatal exposure to EDC, the purpose of this study was to review the available limited literature about the effects of postnatal exposure to EDC on child neurodevelopment and behaviour. Despite widespread children's exposure to EDC, there are a limited number of epidemiological studies on the association of this exposure with neurodevelopmental disorders, in particular in the postnatal period. The available research suggests that postnatal EDC exposure is related to adverse neurobehavioral outcomes in children; however the underlying mechanisms of action remain unclear. Timing of exposure is a key factor determining potential neurodevelopmental consequences, hence studying the impact of multiple EDC co-exposure in different vulnerable life periods could guide the identification of sensitive subpopulations. Most of the reviewed studies did not take into account sex differences in the EDC effects on children neurodevelopment. We believe that the inclusion of sex in the study design should be considered as the role of EDC on children neurodevelopment are likely sex-specific and should be taken into consideration when determining susceptibility and potential mechanisms of action.

Proximity to coal-fired power plants and neurobehavioral symptoms in children

BACKGROUND

Coal-fired power plants are a major source of air pollution that can impact children's health. Limited research has explored if proximity to coal-fired power plants contributes to children's neurobehavioral disorders.

OBJECTIVE

This community-based study collected primary data to investigate the relationships of residential proximity to power plants and neurobehavioral problems in children.

METHODS

235 participants aged 6-14 years who lived within 10 miles of two power plants were recruited. Exposure to particulate matter ≤10 μm (PM10) was measured in children's homes using personal modular impactors. Neurobehavioral symptoms were assessed using the Child Behavior Checklist (CBCL). Multiple regression models were performed to test the hypothesized associations between proximity/exposure and neurobehavioral symptoms. Geospatial statistical methods were used to map the spatial patterns of exposure and neurobehavioral symptoms.

RESULTS

A small proportion of the variations of neurobehavioral problems (social problems, affective problems, and anxiety problems) were explained by the regression models in which distance to power plants, traffic proximity, and neighborhood poverty was statistically associated with the neurobehavioral health outcomes. Statistically significant hot spots of participants who had elevated levels of attention deficit hyperactivity disorder, anxiety, and social problems were observed in the vicinity of the two power plants.

SIGNIFICANCE

Results of this study suggest an adverse impact of proximity to power plants on children's neurobehavioral health. Although coal-fired power plants are being phased out in the US, health concern about exposure from coal ash storage facilities remains. Furthermore, other countries in the world are increasing coal use and generating millions of tons of pollutants and coal ash. Findings from this study can inform public health policies to reduce children's risk of neurobehavioral symptoms in relation to proximity to power plants.

Methylmercury and Polycyclic Aromatic Hydrocarbons in Mediterranean Seafood: A Molecular Anthropological Perspective

Eating seafood has numerous health benefits; however, it constitutes one of the main sources of exposure to several harmful environmental pollutants, both of anthropogenic and natural origin. Among these, methylmercury and polycyclic aromatic hydrocarbons give rise to concerns related to their possible effects on human biology. In the present review, we summarize the results of epidemiological investigations on the genetic component of individual susceptibility to methylmercury and polycyclic aromatic hydrocarbons exposure in humans, and on the effects that these two pollutants have on human epigenetic profiles (DNA methylation). Then, we provide evidence that Mediterranean coastal communities represent an informative case study to investigate the potential impact of methylmercury and polycyclic aromatic hydrocarbons on the human genome and epigenome, since they are characterized by a traditionally high local seafood consumption, and given the characteristics that render the Mediterranean Sea particularly polluted. Finally, we discuss the challenges of a molecular anthropological approach to this topic.

Developmental exposure to methylmercury and ADHD, a literature review of epigenetic studies

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that affects the competence of academic performance and social wellness in children and adults. The causes of ADHD are unclear. Both genetic and environmental factors contribute to the development of ADHD. The behavioral impairments in ADHD are associated with epigenetic changes in genes that are important for neurodevelopment. Among environmental causes of ADHD, the neurotoxin methylmercury (MeHg) is associated with an increased risk for ADHD. Developing children are susceptible to neurotoxic effects of prenatal MeHg exposure. Human epidemiology studies have shown that prenatal MeHg exposure could invoke epigenetic changes in genes that are involved in ADHD. In addition, the pathogenesis of ADHD involves dopaminergic system, which is a target of developmental MeHg exposure. MeHg-induced alterations in the dopaminergic system have a profound impact on behavioral functions in adults. As a trace level of MeHg (around nM) can induce long-lasting behavioral alterations, potential mechanisms of MeHg-induced functional changes in the dopaminergic system may involve epigenetic mechanisms. Here, we review the relevant evidence on developmental MeHg exposures and the risk for ADHD. We also point out research gaps in understanding environmental causes of ADHD.

Sex-specific neurotoxic effects of heavy metal pollutants: Epidemiological, experimental evidence and candidate mechanisms

The heavy metals lead (Pb), mercury (Hg), and cadmium (Cd) are ubiquitous environmental pollutants and are known to exert severe adverse impacts on the nervous system even at low concentrations. In contrast, the heavy metal manganese (Mn) is first and foremost an essential nutrient, but it becomes neurotoxic at high levels. Neurotoxic metals also include the less prevalent metalloid arsenic (As) which is found in excessive concentrations in drinking water and food sources in many regions of the world. Males and females often differ in how they respond to environmental exposures and adverse effects on their nervous systems are no exception. Here, we review the different types of sex-specific neurotoxic effects, such as cognitive and motor impairments, that have been attributed to Pb, Hg, Mn, Cd, and As exposure throughout the life course in epidemiological as well as in experimental toxicological studies. We also discuss differential vulnerability to these metals such as distinctions in behaviors and occupations across the sexes. Finally, we explore the different mechanisms hypothesized to account for sex-based differential susceptibility including hormonal, genetic, metabolic, anatomical, neurochemical, and epigenetic perturbations. An understanding of the sex-specific effects of environmental heavy metal neurotoxicity can aid in the development of more efficient systematic approaches in risk assessment and better exposure mitigation strategies with regard to sex-linked susceptibilities and vulnerabilities.