In utero exposure to mercury and childhood overweight or obesity: counteracting effect of maternal folate status

Food, nutrition, and autism: from soil to fork

Food and nutrition-related factors have the potential to impact development of autism spectrum disorder (ASD) and quality of life for people with ASD, but gaps in evidence exist. On 10 November 2022, Tufts University's Friedman School of Nutrition Science and Policy and Food and Nutrition Innovation Institute hosted a 1-d meeting to explore the evidence and evidence gaps regarding the relationships of food and nutrition with ASD. This meeting report summarizes the presentations and deliberations from the meeting. Topics addressed included prenatal and child dietary intake, the microbiome, obesity, food-related environmental exposures, mechanisms and biological processes linking these factors and ASD, food-related social factors, and data sources for future research. Presentations highlighted evidence for protective associations with prenatal folic acid supplementation and ASD development, increases in risk of ASD with maternal gestational obesity, and the potential for exposure to environmental contaminants in foods and food packaging to influence ASD development. The importance of the maternal and child microbiome in ASD development or ASD-related behaviors in the child was reviewed, as was the role of discrimination in leading to disparities in environmental exposures and psychosocial factors that may influence ASD. The role of child diet and high prevalence of food selectivity in children with ASD and its association with adverse outcomes were also discussed. Priority evidence gaps identified by participants include further clarifying ASD development, including biomarkers and key mechanisms; interactions among psychosocial, social, and biological determinants; interventions addressing diet, supplementation, and the microbiome to prevent and improve quality of life for people with ASD; and mechanisms of action of diet-related factors associated with ASD. Participants developed research proposals to address the priority evidence gaps. The workshop findings serve as a foundation for future prioritization of scientific research to address evidence gaps related to food, nutrition, and ASD.

Independent and Joint Effects of Prenatal Incense-Burning Smoke Exposure and Children's Early Outdoor Activity on Preschoolers' Obesity

Incense burning is a significant source of indoor air pollution in many Asian regions. There is emerging evidence that maternal prenatal exposure to incense-burning smoke may be a risk factor for childhood obesity. We aimed to extend this new line of research by investigating the independent and joint effect of incense-burning smoke exposure, and children's outdoor activity in early life, on preschoolers' obesity. A total of 69,637 mother-child dyads were recruited from all kindergartens in the Longhua District of Shenzhen, China. Information on sociodemographic characteristics, maternal exposure to incense-burning smoke (IBS) during pregnancy, and frequency and duration of outdoor activity at the age of 1-3 years was collected by a self-administered questionnaire. In addition, the heights and weights of the children were measured by the research team. Logistic regression models and cross-over analyses were conducted to investigate the independent and combined effects of maternal exposure to incense-burning smoke during pregnancy and children's early outdoor activity on obesity in preschoolers. We found that prenatal exposure to incense-burning smoke increased the risk of the presence of obesity in preschoolers' (AOR = 1.13, 95% CI = 1.03-1.23). Additionally, lower frequencies (<3 times/week) or shorter durations (<60 min/time) of outdoor activity from the age of 1-3 years were significantly associated with the presence of obesity, with AORs of 1.24 (95% CI =1.18-1.32) and 1.11 (95% CI = 1.05-1.17), respectively. Furthermore, the cross-over analysis showed that prenatal exposure to IBS combined with a lower frequency of early outdoor activity (AOR = 1.47, 95% CI = 1.31-1.66) or a shorter duration of outdoor activity during ages of 1-3 years (AOR = 1.22, 95% CI = 1.07-1.39) increased the risk of obesity in preschoolers. Finally, additive interactions between prenatal exposure to IBS and postnatal outdoor activity on obesity were identified. Our study indicates that maternal exposure to incense-burning smoke during pregnancy and early lower postanal outdoor activity may independently and jointly increase the risk of obesity among preschoolers.

Association between Heavy Metals, Metalloids and Metabolic Syndrome: New Insights and Approaches

Metabolic syndrome (MetS) is an important public health issue that affects millions of people around the world and is growing to pandemic-like proportions. This syndrome is defined by the World Health Organization (WHO) as a pathologic condition characterized by abdominal obesity, insulin resistance, hypertension, and hyperlipidemia. Moreover, the etiology of MetS is multifactorial, involving many environmental factors, including toxicant exposures. Several studies have associated MetS with heavy metals exposure, which is the focus of this review. Environmental and/or occupational exposure to heavy metals are a major risk, contributing to the development of chronic diseases. Of particular note, toxic metals such as mercury, lead, and cadmium may contribute to the development of MetS by altering oxidative stress, IL-6 signaling, apoptosis, altered lipoprotein metabolism, fluid shear stress and atherosclerosis, and other mechanisms. In this review, we discuss the known and potential roles of heavy metals in MetS etiology as well as potential targeted pathways that are associated with MetS. Furthermore, we describe how new approaches involving proteomic and transcriptome analysis, as well as bioinformatic tools, may help bring about an understanding of the involvement of heavy metals and metalloids in MetS.

Why Do People Gain Belly Fat in Rural Areas? A Study of Urinary Metal(loid)s and Abdominal Obesity in China

Obesity is prevalent in rural areas of China, and there are inconsistent findings regarding the association between metal(loid) exposure and the risk of obesity. Abdominal obesity (AOB), which reflects visceral fat abnormity, is a crucial factor in studying obesity-related diseases. We conducted a study measuring 20 urinary metal(loid)s, 13 health indicators, and the waist circumference (WC) in 1849 participants from 10 rural areas of China to investigate their relationships. In the single exposure models, we found that urinary chromium (Cr) was significantly associated with the odds of having AOB [adjusted odds ratio (OR) = 1.81 (95% confidence interval (CI): 1.24, 2.60)]. In the mixture exposure models, urinary Cr consistently emerged as the top contributor to AOB, while the overall effect of mixed metal(loid)s was positive toward the odds of having AOB [adjusted OR: 1.33 (95% CI: 1.00, 1.77)], as revealed from the quantile g-computation model. After adjusting for the effects of other metal(loid)s, we found that the elevation of apolipoprotein B and systolic blood pressure significantly mediated the association between urinary Cr and the odds of having AOB by 9.7 and 19.4%, respectively. Our results suggest that exposure to metal(loid)s is a key factor contributing to the prevalence of AOB and WC gain in rural areas of China.

Longitudinal trajectories and determinants of plasma per- and polyfluoroalkyl substance (PFAS) levels from birth to early childhood and metabolomic associations: A pilot study in the Boston Birth Cohort

Background

Per- and polyfluoroalkyl substances (PFAS) are a major public health concern worldwide due to their ubiquitous exposures, environmental persistence, maternal-to-fetal transfer, and multi-organ toxicity. This pilot study aimed to generate preliminary data to inform future studies to address data gaps in the field, including early life PFAS exposure levels, longitudinal changes, determinants, and associated metabolomic alterations in understudied Black and Hispanic children in the United States (U.S.).

Methods

This study leveraged existing biosamples and data in the Boston Birth Cohort and measured 12 legacy and emerging PFAS, including Me-PFOSA-AcOH, PFDA, PFDoA, PFHxS, PFNA, PFOA, PFOS, PFUnA, GenX, ADONA, 9Cl-PF3ONS, and PFHpS, in paired cord and early childhood plasma samples. Summary statistics and graphic plots were used to depict PFAS levels at the two time points and their longitudinal changes. Linear regression models were used to identify the early-life factors associated with cord and early childhood PFAS levels. Associations of cord PFAS with cord metabolites were explored using a metabolome-wide association approach and a targeted approach.

Results

This study included 39 children, of whom 25 (64%) were Black, 14 (36%) were Hispanic, and 15 (38%) were female. PFOA, PFOS, PFNA, and PFHpS were detectable in all cord and early childhood plasma samples, while GenX and ADONA were not detectable in any sample. Cord PFAS levels were weakly-to-moderately correlated with early childhood PFAS levels (r = -0.03 to 0.40). Several maternal and child factors, including gestational age, year at blood collection, and race/ethnicity, were associated with cord and early childhood PFAS levels. The metabolome-wide association study and the targeted study identified several cord metabolites that may have been affected by in utero PFAS exposure.

Conclusions

This pilot study found ubiquitous exposure to multiple PFAS in cord plasma (reflects in utero exposure) and in early childhood plasma (reflects both prenatal and postnatal exposure) among U.S. Black and Hispanic children. Metabolomic analysis suggests that in utero PFAS exposures may alter fetal metabolism. Future large-scale studies are needed to replicate the findings and further examine the associations of fetal PFAS exposure with long-term health outcomes and underlying metabolic pathways.

In-utero co-exposure to toxic metals and micronutrients on childhood risk of overweight or obesity: new insight on micronutrients counteracting toxic metals

BACKGROUND/OBJECTIVES:

Low-level, in-utero exposure to toxic metals such as lead (Pb) and mercury (Hg) is widespread in the US and worldwide; and, individually, was found to be obesogenic in children. To address the literature gaps on the health effects of co-exposure to low-level toxic metals and the lack of intervention strategy, we aimed to investigate the association between in-utero co-exposure to Hg, Pb, cadmium (Cd) and childhood overweight or obesity (OWO) and whether adequate maternal micronutrients (selenium (Se) and folate) can be protective.

SUBJECTS/METHODS:

This study included 1442 mother-child pairs from the Boston Birth Cohort, a predominantly urban, low-income, Black, and Hispanic population, who were enrolled at birth and followed prospectively up to age 15 years. Bayesian kernel machine regression (BKMR) was applied to estimate individual and joint effects of exposures to metals and micronutrients on childhood OWO while adjusting for pertinent covariables. Stratified analyses by maternal OWO and micronutrient status were performed to identify sensitive subgroups.

RESULTS:

In this sample of understudied US children, low-level in-utero co-exposure to Hg, Pb, and Cd was widespread. Besides individual positive associations of maternal Hg and Pb exposure with offspring OWO, BKMR clearly indicated a positive dose-response association between in-utero co-exposure to the three toxic metals and childhood OWO. Notably, the metal mixture-OWO association was more pronounced in children born to mothers with OWO; and in such a setting, the association was greatly attenuated if mothers had higher Se and folate levels.

CONCLUSIONS:

In this prospective cohort of US children at high-risk of toxic metal exposure and OWO, we demonstrated that among children born to mothers with OWO, low-level in-utero co-exposure to Hg, Pb, and Cd increased the risk of childhood OWO; and that adequate maternal Se and folate levels mitigated the risk of childhood OWO.

Developmental Exposure to Endocrine Disrupting Chemicals and Its Impact on Cardio-Metabolic-Renal Health

Developmental origin of health and disease postulates that the footprints of early life exposure are followed as an endowment of risk for adult diseases. Epidemiological and experimental evidence suggest that an adverse fetal environment can affect the health of offspring throughout their lifetime. Exposure to endocrine disrupting chemicals (EDCs) during fetal development can affect the hormone system homeostasis, resulting in a broad spectrum of adverse health outcomes. In the present review, we have described the effect of prenatal EDCs exposure on cardio-metabolic-renal health, using the available epidemiological and experimental evidence. We also discuss the potential mechanisms of their action, which include epigenetic changes, hormonal imprinting, loss of energy homeostasis, and metabolic perturbations. The effect of prenatal EDCs exposure on cardio-metabolic-renal health, which is a complex condition of an altered biological landscape, can be further examined in the case of other environmental stressors with a similar mode of action.

A metabolome-wide association study of in utero metal and trace element exposures with cord blood metabolome profile: Findings from the Boston Birth Cohort

BACKGROUND

Exposure to metals lead (Pb), mercury (Hg), and cadmium (Cd) and trace elements selenium (Se) and manganese (Mn) has been linked to the developmental origins of cardiometabolic diseases, but the mechanisms are not well-understood.

OBJECTIVE

Conduct a metabolome-wide association study to understand how in utero exposure to Pb, Hg, Cd, Se, and Mn affects the metabolic programming of fetuses.

METHODS

We used data from the Boston Birth Cohort, which enrolled mother-child pairs from Boston, MA. We measured metals and trace elements in maternal red blood cells (RBCs) collected 24-72 h after delivery, and metabolites in cord blood collected at birth. We used multivariable linear regression to examine associations of metals and trace elements with metabolites and Bonferroni correction to account for multiple comparisons. We assessed non-linear associations of metals and trace elements with metabolites using restricted cubic spline plots.

RESULTS

This analysis included 670 mother-child pairs (57% non-Hispanic Black and 24% Hispanic). After Bonferroni correction, there were 25 cord metabolites associated with at least one of the metals or trace elements. Pb was negatively associated with the xenobiotic piperine, Cd was positively associated with xenobiotics cotinine and hydroxycotinine, and Hg was associated with 8 lipid metabolites (in both directions). Se and Mn shared associations with 6 metabolites (in both directions), which mostly included nucleotides and amino acids; Se was additionally associated with 7 metabolites (mostly amino acids, nucleotides, and carnitines) and Mn was additionally associated with C36:4 hydroxy phosphatidylcholine. Restricted cubic spline plots showed that most associations were linear.

DISCUSSION

Maternal RBC metal and trace element concentrations were associated in a dose-dependent fashion with cord blood metabolites. What remains to be determined is whether these metals- and trace elements-associated changes in cord metabolites can influence a child's risk of cardiometabolic diseases.

Association of Blood Mercury Levels with the Risks of Overweight and High Waist-to-Height Ratio in Children and Adolescents: Data from the Korean National Health and Nutrition Examination Survey

A previous study in adults demonstrated the substantial role of mercury exposure in the development of overweight and obesity. Although children and adolescents are more susceptible to the toxic effects of mercury than adults, studies on the association of overweight and obesity with mercury exposure is limited. This study aimed to investigate the association of blood mercury levels with the body mass index (BMI) and waist-to-height ratio (WHtR) as obesity indices in Korean children and adolescents. The analyzed cross-sectional data were obtained from 1327 participants (age: 10–18 years; 672 male and 655 female) who completed the Korean National Health and Nutrition Examination Survey 2010–2013. The covariates included sociodemographic factors (age, sex, and household income), dietary factors (fish, shellfish, and seaweed consumption), lifestyle factors (alcohol consumption, smoking status, and exercise), and blood hematocrit levels. The adjusted geometric mean blood mercury level was 2.19 µg/L, and the level of mercury was significantly higher in the overweight (BMI ≥ 85th gender and age-specific percentiles) and high WHtR (cutoff: ≥0.5) groups than in the normal group. In all the participants, the blood mercury levels were significantly positively associated with the BMI and WHtR after adjusting for all covariates (p < 0.05). All the participants in the highest blood mercury level quartile were at a higher risk for overweight and a high WHtR than those in the lowest quartile after adjusting for all covariates (p < 0.05). Our study suggests a significant association between mercury exposure and the risks of overweight and high WHtR in Korean children and adolescents.

Exposome and foetoplacental vascular dysfunction in gestational diabetes mellitus

A balanced communication between the mother, placenta and foetus is crucial to reach a successful pregnancy. Several windows of exposure to environmental toxins are present during pregnancy. When the women metabolic status is affected by a disease or environmental toxin, the foetus is impacted and may result in altered development and growth. Gestational diabetes mellitus (GDM) is a disease of pregnancy characterised by abnormal glucose metabolism affecting the mother and foetus. This disease of pregnancy associates with postnatal consequences for the child and the mother. The whole endogenous and exogenous environmental factors is defined as the exposome. Endogenous insults conform to the endo-exposome, and disruptors contained in the immediate environment are the ecto-exposome. Some components of the endo-exposome, such as Selenium, vitamins D and B₁₂, adenosine, and a high-fat diet, and ecto-exposome, such as the heavy metals Arsenic, Mercury, Lead and Copper, and per- and polyfluoroakyl substances, result in adverse pregnancies, including an elevated risk of GDM or gestational diabesity. The impact of the exposome on the human placenta's vascular physiology and function in GDM and gestational diabesity is reviewed.

Prenatal exposure to mercury and precocious puberty: a prospective birth cohort study

STUDY QUESTION

Is in utero exposure to mercury associated with the risk of precocious puberty?

SUMMARY ANSWER

Prenatal exposure to high levels of mercury was associated with increased risk of precocious puberty, which was strengthened by concomitant maternal cardiometabolic conditions and adverse birth outcomes.

WHAT IS KNOWN ALREADY

The developing fetus is sensitive to mercury, a well-known endocrine disruptor which impacts the endocrine and reproductive system.

STUDY DESIGN, SIZE, DURATION

This study included 1512 mother-child pairs from the Boston Birth Cohort, a longitudinal cohort which recruited at birth and followed prospectively up to 21 years of age.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Mother-child pairs, from a predominantly urban minority population, were enrolled from 2002 to 2013. Prenatal exposure was assessed by maternal mercury concentration in red blood cells (RBCs) collected at 1-3 days after delivery. Precocious puberty was defined based on International Classification of Disease codes. Cox proportional hazards models were applied to the association between maternal mercury concentrations and the risk of precocious puberty.

MAIN RESULTS AND THE ROLE OF CHANCE

The median (interquartile range) of maternal mercury concentrations among children with and without precocious puberty were 3.4 (1.9-4.6) µg/l and 2.0 (1.0-3.7) µg/l, respectively. Compared to those in the lowest tertile for mercury, the highest tertile was associated with increased risk of precocious puberty, with an adjusted hazard ratio (HR) of 2.41, 95% CI: 1.16-5.03. In addition, concomitant maternal cardiometabolic conditions and adverse birth outcomes strengthened the effects of mercury on the risk of precocious puberty. The highest risk of precocious puberty was observed among children who had adverse birth outcomes and whose mothers had high RBC-mercury concentrations along with cardiometabolic conditions, with an HR of 4.76 (95% CI: 1.66-13.60) compared to children with favorable profiles of all three risk factors.

LIMITATIONS, REASONS FOR CAUTION

Precocious puberty was defined based on medical records, not on a direct assessment, which may have led to underdiagnosis and the inability to make a subclassification. The study included a predominately urban, low-income, minority population and as such our findings may not be widely generalizable.

WIDER IMPLICATIONS OF THE FINDINGS

Prenatal Hg exposure was associated with an increased risk of precocious puberty. This risk was strengthened by concomitant maternal cardiometabolic conditions during pregnancy and adverse birth outcomes.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the NIH/National Institute of Environmental Health Sciences, NIH/Eunice Kennedy Shriver National Institute of Child Health and Human Development and the Health Resources and Services Administration of the U.S. Department of Health and Human Services. The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Plasma and red blood cells distribution of total mercury, inorganic mercury, and selenium in maternal and cord blood from a group of Japanese women

Fetuses are a high-risk group for methylmercury (MeHg) exposure. The main objective of this study was to compare the characteristic profiles of total mercury (THg), inorganic mercury (IHg), MeHg, and selenium in plasma and red blood cells (RBCs) between maternal and cord blood at parturition collected from a group of Japanese women. Furthermore, correlations of THg in RBCs, which is a biomarker of MeHg, and THg in plasma, which is an IHg exposure biomarker, were examined in maternal and cord blood. Fifty-five pairs of maternal and cord blood samples obtained at parturition were collected from pregnant women in Fukuoka, Japan. THg in RBCs and plasma were significant correlated between maternal and cord blood. THg in RBCs was 13.9 ng/mL for cord and 9.16 ng/mL for maternal blood, with a cord:maternal RBCs ratio for THg of 1.58, suggesting that MeHg is actively transferred from the mother to the fetus via the placenta. THg in plasma showed a positive correlation with THg in RBCs for maternal and cord blood. This result suggests that measuring THg in plasma can overestimate the exposure level to IHg in fish-eating populations. The percentages of IHg in cord plasma and RBCs were 31% and 1.7%, respectively, and those in maternal plasma and RBCs were 46% and 5.9%, respectively. These results suggest that cord blood is rich in MeHg and can easily transfer to the fetal brain. Selenium in cord plasma was 67 ng/mL and that in maternal plasma was 97 ng/mL, with a cord:maternal plasma ratio for Se of 0.69, suggesting that the protective effects of Se against MeHg toxicity in fetuses may be weaker than those expected in adult mothers.

Maternal seafood intake during pregnancy, prenatal mercury exposure and child body mass index trajectories up to 8 years

Background

Maternal seafood intake during pregnancy and prenatal mercury exposure may influence children’s growth trajectories.

Methods

This study, based on the Norwegian Mother, Father and Child Cohort Study (MoBa), includes 51 952 mother-child pairs recruited in pregnancy during 2002–08 and a subsample (n = 2277) with maternal mercury concentrations in whole blood. Individual growth trajectories were computed by modelling based on child’s reported weight and length/height from 1 month to 8 years. We used linear mixed-effects regression analysis and also conducted discordant-sibling analysis.

Results

Maternal lean fish was the main contributor to total seafood intake in pregnancy and was positively but weakly associated with child body mass index (BMI) growth trajectory. Higher prenatal mercury exposure (top decile) was associated with a reduction in child’s weight growth trajectory, with the estimates ranging from -130 g [95% Confidence Intervals (CI) = -247, -12 g] at 18 months to -608 g (95% CI = -1.102, -113 g) at 8 years. Maternal fatty fish consumption was positively associated with child weight and BMI growth trajectory, but only in the higher mercury-exposed children (P-interaction = 0.045). Other seafood consumption during pregnancy was negatively associated with child weight growth compared with no intake, and this association was stronger for higher mercury-exposed children (P-interaction = 0.004). No association was observed between discordant maternal seafood intake and child growth in the sibling analysis.

Conclusions

Within a population with moderate seafood consumption and low mercury exposure, we found that maternal seafood consumption in pregnancy was associated with child growth trajectories, and the direction of the association varied by seafood type and level of prenatal mercury exposure. Prenatal mercury exposure was negatively associated with child growth. Our findings on maternal seafood intake are likely non-causal.

A Nonlinear Relation Between Maternal Red Blood Cell Manganese Concentrations and Child Blood Pressure at Age 6-12 y: A Prospective Birth Cohort Study

BACKGROUND

Although manganese (Mn) is an essential trace element and a common component of most multivitamins on the market, an adverse effect on blood pressure (BP) has been reported in adults. In addition, the longitudinal relation between prenatal Mn status and childhood BP is still unknown.

OBJECTIVE

This study investigated the association between prenatal Mn concentrations and risk of elevated BP at ages 3-12 y.

METHOD

The analyses included 1268 mother-child dyads who were enrolled at birth and followed prospectively at the Boston Medical Center. Maternal RBC Mn concentrations were measured by inductively coupled plasma mass spectrometry, using RBCs collected within 1-3 d after delivery (reflecting late-pregnancy Mn exposure). Child elevated BP was defined as systolic or diastolic BP ≥90th percentile for a given age, sex and height. Multivariate logistic regression models were conducted. Path analysis was applied to mediation estimation.

RESULTS

The median (IQR) maternal RBC Mn concentration was 37.5 (29.2-48.5) μg/L. The rate of child elevated BP at ages 3-12 y was 25%. Both the lowest and highest quartiles of maternal RBC Mn concentrations were associated with higher risk of elevated BP among children aged 6-12 y (OR: 1.52; 95% CI: 1.04, 2.21 and OR: 1.65; 95% CI: 1.13, 2.40, respectively) compared with those in the second and third quartiles. Gestational age and fetal growth mediated the association between low maternal RBC Mn (first quartile) and child elevated BP, explaining 25% of the association, but not for high (fourth quartile) maternal RBC Mn concentrations. No association was found between maternal RBC Mn concentrations and BP among children aged 3-5 y.

CONCLUSION

We found a nonlinear association between maternal RBC Mn concentrations and elevated BP among children aged 6-12 y from a high-risk, predominantly minority population. Our findings warrant further investigation.

Toenail mercury levels positively correlate with obesity and abdominal obesity among Korean adults

BACKGROUND

Although previous studies have shown that short-term exposure to mercury is associated with obesity, it should be noted that mercury is not easily released and that it constantly accumulates in the body. However, few studies have explored the association between chronic mercury exposure and obesity. This study aimed to examine the association between chronic mercury exposure and obesity in Korean adults.

METHODS

The study used baseline data from the Trace Element Study of Korean Adults in Yeungnam area. A total of 495 participants aged 40-69 years who provided the required information (demographic, diet, lifestyle, toenail mercury levels, and health examination results) were included. Toenail mercury levels were measured using neutron-activation analysis. Body mass index and waist circumference were obtained from medical examination. Multivariable-adjusted logistic regression and restricted cubic spline regression were used in the analysis.

RESULTS

In the fully adjusted logistic regression models, participants with the highest toenail mercury levels had a higher prevalence of obesity (odds ratio [OR]: 3.26, 95 % confidence interval [CI]: 1.79-5.93) and abdominal obesity (OR: 2.30, 95 % CI: 1.15-4.59). In the cubic spline regression model, linear relationships were confirmed between increased toenail mercury levels and higher prevalence of obesity and abdominal obesity (all p > 0.05 for nonlinearity).

CONCLUSIONS

In summary, chronic mercury exposure was associated with higher prevalence of obesity and abdominal obesity in Korean adults. Therefore, the development of public health interventions against environmental exposure of foods is required to manage and prevent obesity.

Adverse effects of prenatal mercury exposure on neurodevelopment during the first 3 years of life modified by early growth velocity and prenatal maternal folate level

BACKGROUND AND AIMS

Previous studies have suggested that mercury exposure and folate levels during pregnancy may influence early childhood neurodevelopment. Rapid catch-up growth in children is associated with an increased risk of pathological nervous system development. We evaluated whether the association between prenatal folate and mercury-related neuropsychological dysfunction was modified by growth velocity during childhood.

METHODS

The Mothers and Children's Environmental Health (MOCEH) birth cohort study began in 2006 and by 2010, 1751 women had been enrolled before the second trimester of their pregnancy along with their partners. Participants visited the research center at birth and 6, 12, 24, and 36 months. We measured mercury levels in maternal and cord blood and folate in maternal serum. Questionnaires to evaluate the environment and health of their child were administered and anthropometric factors including body weight and height were measured. Certified investigators used the Bayley test to measure neurobehavioral outcomes. We calculated postnatal growth change as the change in infant weight for-age z-score between birth and 3 years. Multiple linear regression and mixed models were used to examine the association between mercury exposure and children's neurodevelopment as well as the modifying effects of folate and growth velocity.

RESULTS

A total of 30.6% of children experienced rapid growth during the first 3 years of life. Median values of mercury in the low folate group were significantly higher in rapid growers (3.41 μg/L in maternal blood and 5.63 μg/L in cord blood) than in average/slow growers (3.05 μg/L in maternal blood and 5.19 μg/L in cord blood). Rapid growers were also significantly associated with decreased psychomotor development scores during the first 3 years of life and with having mothers who had low prenatal folate levels, even after adjusting for potential confounders.

CONCLUSION

Prenatal mercury exposure adversely affects infant neurodevelopment and is associated with rapid growth during the first 3 years of life. This effect was limited to children whose mothers had low prenatal folate levels, suggesting a protective effect of folate against developmental neurotoxicity due to mercury exposure and rapid catch-up growth.

Endocrine Disruptors in Food: Impact on Gut Microbiota and Metabolic Diseases

Endocrine disruptors (EDCs) have been associated with the increased incidence of metabolic disorders. In this work, we conducted a systematic review of the literature in order to identify the current knowledge of the interactions between EDCs in food, the gut microbiota, and metabolic disorders in order to shed light on this complex triad. Exposure to EDCs induces a series of changes including microbial dysbiosis and the induction of xenobiotic pathways and associated genes, enzymes, and metabolites involved in EDC metabolism. The products and by-products released following the microbial metabolism of EDCs can be taken up by the host; therefore, changes in the composition of the microbiota and in the production of microbial metabolites could have a major impact on host metabolism and the development of diseases. The remediation of EDC-induced changes in the gut microbiota might represent an alternative course for the treatment and prevention of metabolic diseases.