Blood mercury concentration, fish consumption and anthropometry in Chinese children: A national study

Fish intake and mercury exposure in young children

Fish consumption is one of the main sources of mercury (Hg) exposure, but few studies have examined Hg exposure from fish consumption among children. This study aimed to assess the frequency of fish intake and associations with Hg and other element concentrations among 700 three-year-old children from the New Hampshire Birth Cohort Study. Usual fish intake was derived from a validated food frequency questionnaire (Block Questionnaire for ages 2-7) and toenail element concentrations were determined using ICP-MS. Multiple linear regression analysis was used to assess the association between fish intake and toenail element concentrations. A mixture analysis, using Weighted quantile sum (WQS) regression, was used to estimate the relative contribution of fish consumption to element exposures. Twenty-three percent of children were reported to consume at least one fish meal/week on average during the previous 6 months. In adjusted linear regression models, children with any type of fish consumption versus no consumption had 108% (95% confidence interval (CI: 68%, 153%)) higher toenail Hg concentrations. To a lesser extent, children consuming "other fish (not fried) including tuna" and "fried fish or fish sticks" had 120% (95% CI: 82%, 164%), and 23% (95% CI: 2%, 51%) higher toenail concentrations, respectively, than those consuming no fish. Using WQS regression, Hg was the element most strongly related to fish consumption. Fish intake among young children was related to Hg exposure even at low levels of consumption. Future studies will need to determine the health consequences of this exposure.

Blood mercury mediates the associations between fish consumption and serum uric acid levels among Chinese adults: A nationally representative study

Fish consumption can increase purine load in human body, and the enrichment of mercury in fish may affect the glomerular filtration function, both resulting in increased serum uric acid (SUA) levels. The data of blood mercury (BHg), fish consumption frequency and SUA levels of 7653 participants aged 18 years or older was from China National Human Biomonitoring (2017-2018). The associations between fish consumption frequency, ln-transformed BHg and SUA levels were explored through weighted multiple linear regressions. The mediating effect of BHg levels between fish consumption frequency and SUA levels was evaluated by mediation analysis. We found that both the fish consumption frequency and BHg were positively associated with SUA levels in both sexes. Compared to participants who had never consumed fish, participants who consumed fish once a week or more had higher SUA levels [β (95% confidence interval, CI): 20.39 (2.16, 38.62) in males; β (95% CI): 10.06 (0.76, 19.37) in females] and ln-transformed BHg [β (95% CI): 0.97 (0.61, 1.34) in males; β (95% CI): 0.84 (0.63, 1.05) in females]. Each 1-unit increase in ln-transformed BHg, the SUA levels rose by 4.78 (95% CI: 0.01, 9.54) μmol/L for males and 3.81 (95% CI: 1.60, 6.03) μmol/L for females. The association between fish consumption with SUA levels was mediated by ln-transformed BHg with the percent mediated of 34.66% in males and 26.58% in females. It revealed that BHg played mediating roles in the elevation of SUA levels caused by fish consumption. This study's findings could promote the government to intervene in mercury pollution in fish, so as to ensure the safety of fish consumption.

Mercury sources, transport, and transformation in rainfall-runoff processes: Mercury isotope approach

Mercury (Hg) in runoff water poses significant ecological risks to aquatic ecosystems that can affect organisms. However, accurately identifying the sources and transformation processes of Hg in runoff water is challenging due to complex natural conditions. This study provides a comprehensive investigation of Hg dynamics in water from rainfall to runoff. The Hg isotope fractionation in water was characterized, which allows accurate quantification of Hg sources, transport, and transformations in rainfall-runoff processes. Δ200Hg and corrected Δ199Hg values can serve as reliable tracers for identifying Hg sources in the runoff water and the variation of δ202Hg can be explained by Hg transformation processes. During runoff migration processes, Hg from rainfall is rapidly absorbed on the land surface, while terrestrial Hg entering the water by the dissolution process becomes the primary component of dissolved mercury (DHg). Besides the dissolution and adsorption, microbial Hg(II) reduction and demethylation of MeHg were dominant processes for DHg in the runoff water that flows through the rice paddies, while photochemical Hg(II) reduction was the dominant process for DHg in the runoff water with low water exchange rates. Particulate Hg (PHg) in runoff water is dominantly originated by the terrestrial material and derived from the dissolution and adsorption process. Tracking sources and transformations of Hg in runoff water during the rainfall-runoff process provides a basis for studying Hg pollution in larger water bodies under complex environmental factors.

Environmental exposure and child health in China

Chinese children are exposed to broad environmental risks ranging from well-known hazards, such as pesticides and heavy metals, to emerging threats including many new man-made chemicals. Although anecdotal evidence suggests that the exposure levels in Chinese children are substantially higher than those of children in developed countries, a systematic assessment is lacking. Further, while these exposures have been linked to a variety of childhood diseases, such as respiratory, endocrine, neurological, behavioral, and malignant disorders, the magnitude of the associations is often unclear. This review provides a current epidemiologic overview of commonly reported environmental contaminants and their potential impact on children's health in China. We found that despite a large volume of studies on various topics, there is a need for more high-quality research and better-coordinated regional and national data collection. Moreover, prevention of such diseases will depend not only on training of environmental health professionals and enhanced research programs, but also on public education, legislation, and networking.

The Association Between Blood Mercury and Lipid Biomarkers in US Hypertensive Adults

Mercury (Hg) is detrimental to human health, but its impact on lipid biomarkers remains a subject of controversy. This study sought to delineate a clear link between blood Hg and lipid biomarkers correlated with cardiovascular disease (CVD), including total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG), in hypertensive adults in the USA.

METHODS

This cross-sectional research gathered data from a total of 4415 participants sourced from the National Health and Nutrition Examination Survey (NHANES). The Holm-Bonferroni stepdown procedure was utilized to control the type I error rate in multiple comparisons. We employed multivariable linear regression models to assess the correlation between blood Hg and lipid biomarkers. Subsequently, subgroup analyses were conducted, categorized by both gender and race. Additionally, we used smooth curve fittings and generalized additive models to confirm the presence of non-linear relationships. When non-linearity was detected, we applied a recursive algorithm to calculate the inflection points. Finally, we established a weighted two-piecewise linear regression model to illustrate the associations on either side of the inflection point.

RESULTS

In our multivariable linear regression models, clear associations emerged. Specifically, positive correlations were observed between blood mercury and TC (β = 0.025; 95% CI 0.009 to 0.041; corrected P = 0.011), LDL-C (β = 0.022; 95% CI 0.007 to 0.036; corrected P = 0.012), and HDL-C (β = 0.007; 95% CI 0.001 to 0.013; corrected P = 0.058). However, there was no significant correlation with TG (β =  - 0.007; 95% CI - 0.018 to 0.004; corrected P = 0.526). Notably, it has been demonstrated that distinct inverted U-shaped and U-shaped curves exist when stratified by gender in our analysis.

CONCLUSIONS

Blood Hg exhibited a positive correlation with TC, LDL-C, and HDL-C in hypertensive adults in the USA. Nonetheless, no significant association was observed with TG.

Mollusc and crustacean consumption in the first 1000 days: a scoping review

Mollusc and crustacean consumption in the first 1000 d may improve maternal and child health by providing essential nutrients. However, in some contexts, molluscs and crustaceans have been associated with allergies and environmental contamination, potentially leading to adverse health and development outcomes. It is unclear whether the health benefits of consuming molluscs and crustaceans, collectively classified as shellfish in nutrition, are outweighed by the potential risks to pregnant women and children. We conducted a scoping review (PROSPERO: CRD42022320454) in PubMed, Scopus and EBSCO Global Health of articles published between January 2000 and March 2022 that assessed shellfish consumption during pregnancy, lactation or childhood (0-2 years) in relation to maternal health, child health or child development. A total of forty-six articles were included in this review. Overall, shellfish consumption was associated with higher biomarkers of environmental contaminants, with mercury being the most studied and having the strongest evidence base. The limited research on nutritional biomarker status shows an association between shellfish consumption and iodine status. Preterm birth was not associated with shellfish consumption, but newborn anthropometry showed mixed results, with several studies reporting lower birth weight with higher shellfish consumption. The few studies that examined child development and maternal health outcomes reported no significant associations. This review revealed trade-off health risks and benefits with inclusion of molluscs and crustaceans in the dietary patterns of mothers and young children. More research is needed to understand how these aquatic animal-source foods may be safely consumed and leveraged for improving human nutrition.

Factors associated with blood mercury concentrations and their interactions with three glutathione S-transferase genes (GSTT1, GSTM1, and GSTP1): an exposure assessment study of typically developing Jamaican children

BACKGROUND

Jamaican soil is abundant in heavy metals including mercury (Hg). Due to availability and ease of access, fish is a traditional dietary component in Jamaica and a significant source of Hg exposure. Mercury is a xenobiotic and known neuro-toxicant that affects children's neurodevelopment. Human glutathione S-transferase (GST) genes, including GSTT1, GSTM1, and GSTP1, affect Hg conjugation and elimination mechanisms.

METHODS

In this exposure assessment study we used data from 375 typically developing (TD) 2-8-year-old Jamaican children to explore the association between environmental Hg exposure, GST genes, and their interaction effects on blood Hg concentrations (BHgCs). We used multivariable general linear models (GLMs).

RESULTS

We identified the child's age, consumption of saltwater fish, canned fish (sardine, mackerel), string beans, grain, and starches (pasta, macaroni, noodles) as the environmental factors significantly associated with BHgCs (all P < 0.05). A significant interaction between consumption of canned fish (sardine, mackerel) and GSTP1 in relation to BHgC using either a co-dominant or recessive genetic model (overall interaction P = 0.01 and P < 0.01, respectively) indicated that consumption of canned fish (sardine, mackerel) was significantly associated with higher mean BHgC only among children with the GSTP1 Ile105Val, Ile/Ile [Ratio of mean Hg (95% CI) = 1.59 (1.09, 2.32), P = 0.02] and Ile/Val [Ratio of mean Hg (95% CI) = 1.46 (1.12, 1.91), P = 0.01] genotypes.

CONCLUSIONS

Since this is the first study from Jamaica to report these findings, replication in other populations is recommended.

Exposure to metal mixtures and young children's growth and development: A biomonitoring-based study in Eastern China

Exposure to metal mixtures may affect children's health but the conclusions are controversial. We aimed to investigate the associations of metal mixture exposure with children's physical and behavioral development. 15 metals were detected in the urine samples of 278 preschoolers aged 3-6 years from eastern China. Multiple linear models and restricted cubic splines were used to evaluate dose-response relationships between single metal and children's physical and behavioral development. The Bayesian Kernel Machine Regression (BKMR) models, the weighted quantile sum (WQS) models and Quantile G-Computation were applied to evaluate the joint effects of metal mixtures. The results showed that arsenic (As) was negatively associated with z score of height for age (HAZ) in individual-metal models [β (95%CI): - 0.22 (-0.38, -0.06), P = 0.006]. Concerning children's behavioral development, multiple-metal models demonstrated a negative association with strontium (Sr) [β (95%CI): - 0.82 (-1.38, -0.26), P = 0.004], and a positive association with tin (Sn) [β (95%CI): 0.69 (0.16, 1.21), P = 0.010]. Notably, these associations remained significant or suggestive even after adjustments for multiple tests, sensitivity analyses, and application of different statistical models, including BKMR, WQS, and Quantile G-Computation. Furthermore, the study identified a negative joint effect of the metal mixture on HAZ, as demonstrated by BKMR and Quantile G-Computation models, with As playing an irreplaceable role in this observed impact. In summary, exposure to As appears to have adverse effects on HAZ, while exposure to Sn may hinder children's behavioral development. Conversely, exposure to Sr may have a protective effect on children's behavioral development. Additionally, the combined impact of metal mixtures is implicated in potentially impairing children's physical development, particularly in terms of HAZ.

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.

Association between mercury exposure and lung function in young adults: A prospective cohort study in Shandong, China

BACKGROUND

Mercury has been associated with many adverse health outcomes. However, limited studies have explored the association between blood mercury concentrations and lung function.

OBJECTIVE

To examine the association between blood mercury concentrations and lung function among young adults.

METHODS

We conducted a prospective cohort study among 1800 college students based on the Chinese Undergraduates Cohort in Shandong, China during August 2019 and September 2020. Lung function indicators including forced vital capacity (FVC, ml), forced expiratory volume in 1 s (FEV₁, ml) and peak expiratory flow (PEF, ml) were collected with a spirometers (Chestgraph Jr. HI-101, Chest M.I., Tokyo, Japan). The blood mercury concentration was measured using inductively coupled plasma mass spectrometry. We divided participants into low (≤25 percentiles), intermediate (25-75 percentiles), and high (≥75 percentile) subgroups according to blood mercury concentrations. The multiple linear regression model was used to examine the associations between blood mercury concentrations and lung function changes. Stratification analyses by sex and fish consumption frequency were also conducted.

RESULTS

The results showed that each 2-fold increase in blood mercury concentrations was significantly associated with -70.75 ml [95 % confidence interval (CI): -122.35, -19.15] change in FVC, -72.68 ml (95%CI: -120.36, -25.00) in FEV₁, and -158.06 ml (95%CI: -283.77, -32.35) in PEF. The effect was more pronounced among participants with high blood mercury and male participants. Participants who consumed fish more than once a week more likely to be affected by mercury.

CONCLUSION

Our study indicated that blood mercury was significantly associated with decreased lung function in young adults. It is necessary to implement corresponding measures to reduce the effect of mercury on the respiratory system, especially for men and people who consumed fish more than once a week.

Cognitive outcomes caused by low-level lead, cadmium, and mercury mixture exposure at distinct phases of brain development

Contaminated water and food are the main sources of lead, cadmium, and mercury in the human body. Long-term and low-level ingestion of these toxic heavy metals may affect brain development and cognition. However, the neurotoxic effects of exposure to lead, cadmium, and mercury mixture (Pb + Cd + Hg) at different stages of brain development are rarely elucidated. In this study, different doses of low-level Pb + Cd + Hg were administered to Sprague-Dawley rats via drinking water during the critical stage of brain development, late stage, and after maturation, respectively. Our findings showed that Pb + Cd + Hg exposure decreased the density of memory- and learning-related dendritic spines in the hippocampus during the critical period of brain development, resulting in hippocampus-dependent spatial memory deficits. Only the density of learning-related dendritic spines was reduced during the late phase of brain development and a higher-dose of Pb + Cd + Hg exposure was required, which led to hippocampus-independent spatial memory abnormalities. Exposure to Pb + Cd + Hg after brain maturation revealed no significant change in dendritic spines or cognitive function. Further molecular analysis indicated that morphological and functional changes caused by Pb + Cd + Hg exposure during the critical phase were associated with PSD95 and GluA1 dysregulation. Collectively, the effects of Pb + Cd + Hg on cognition varied depending on the brain development stages.

Temporal changes of blood mercury concentrations in Chinese newborns and the general public from 1980s to 2020s

Mercury (Hg) is a global pollutant that threatens the environment and human health. As a major producer, emitter and consumer of Hg, China is currently taking different measures to curb mercury pollution in accordance with the requirements of the Minamata Convention on Mercury. Blood Hg can reflect the human body's recent exposure to Hg. This review summarized the temporal changes in blood Hg concentrations in newborns and the general public in China from 1980 s to 2020 s. It was shown that the blood Hg concentrations of newborns showed the downward trend, although it was not significant. The general public Hg concentrations showed a trend of first increase and then decrease trend. Most of the cord blood Hg and venous blood Hg concentrations in China were lower than the USEPA reference concentration of 5.8 µg/L. Since low-dose prenatal Hg exposure can affect fetal and neonatal development, continuous attention needs to be paid to reduce maternal and neonatal Hg exposure. The information provided in this review may lay a basis for the effectiveness evaluation on the implementation of Minamata Convention on Mercury.

Dam cascade unveils sediment methylmercury dynamics in reservoirs

Methylmercury (MeHg) can be bioaccumulated through food chains and adversely affect human health. Reservoirs are reported to stimulate MeHg production, however, the characteristics of MeHg dynamics in cascade reservoirs and the associated relations to sedimentation as well as reservoir properties remained unclear. Here we investigated sediment MeHg dynamics in eight cascade reservoirs in the upper Mekong River. We found significant differences in sediment MeHg concentration between the reservoirs, showing an increase with fluctuations along the reservoirs cascade. However, a novel relationship was found between sediment%MeHg (MeHg/Hg) and the ratio of reservoir hydraulic residence time (HRT) to reservoir age. This relationship is formed by the joint effects of the original deposit of Hg and organic carbon (OC) before impoundment and the subsequent sedimentation of Hg and OC after impoundment. The original deposit is continuously transformed as the reservoir ages, whereas the latter is driven by the annual hydrological cycle and HRT, of which the HRT is dominant. This finding cannot be easily revealed in a single reservoir or by comparing multiple reservoirs in different rivers. The discovery is of great significance to understand Hg geochemical cycling in reservoirs, which is quickly increasing in rivers worldwide.

Heavy Metals and Human Health: Possible Exposure Pathways and the Competition for Protein Binding Sites

Heavy metals enter the human body through the gastrointestinal tract, skin, or via inhalation. Toxic metals have proven to be a major threat to human health, mostly because of their ability to cause membrane and DNA damage, and to perturb protein function and enzyme activity. These metals disturb native proteins’ functions by binding to free thiols or other functional groups, catalyzing the oxidation of amino acid side chains, perturbing protein folding, and/or displacing essential metal ions in enzymes. The review shows the physiological and biochemical effects of selected toxic metals interactions with proteins and enzymes. As environmental contamination by heavy metals is one of the most significant global problems, some detoxification strategies are also mentioned.

Mercury Chloride Impacts on the Development of Erythrocytes and Megakaryocytes in Mice

Inorganic mercury (Hg²⁺) is a highly toxic heavy metal. The aim of this study was to investigate the impact of Hg²⁺ on the development of erythrocytes and megakaryocytes. B10.S mice (H-2^s) and DBA/2 mice (H-2^d) were administrated with 10 μM HgCl₂ or 50 μM HgCl₂ via drinking water for four weeks, and erythro-megakaryopoiesis was evaluated thereafter. The administration of 50 μM HgCl₂ increased the number of erythrocytes and platelets in B10.S mice, which was not due to a reduced clearance for mature erythrocytes. The administration of 50 μM HgCl₂, but not 10 μM HgCl₂, increased the number of progenitors for erythrocytes and megakaryocytes in the bone marrow (BM) of B10.S mice, including erythroid-megakaryocyte progenitors (EMPs), burst-forming unit-erythroid progenitors (BFU-Es), colony-forming unit-erythroid progenitors (CFU-Es), and megakaryocyte progenitors (MkPs). Moreover, 50 μM HgCl₂ caused EMPs to be more proliferative and possess an increased potential for differentiation into committed progenies in B10.S mice. Mechanistically, 50 μM HgCl₂ increased the expression of the erythropoietin receptor (EPOR) in EMPs, thus enhancing the Jak2/STAT5 signaling pathway to promote erythro-megakaryopoiesis in B10.S mice. Conversely, 50 μM HgCl₂ did not impact erythro-megakaryopoiesis in DBA/2 mice. This study may extend our current understanding for hematopoietic toxicology of Hg.

Association between Blood Mercury Concentration and Prevalence of Borderline Hypercholesterolemia among Adolescents: The Korea National Health and Nutrition Examination Survey (KNHANES) 2010-2013 and 2016

There is limited evidence on the association between blood mercury (Hg) concentration and the risk of borderline dyslipidemia in adolescents. Here, we investigated the association between blood Hg concentration and the prevalence of borderline dyslipidemia among Korean adolescents. A total of 1559 participants (806 boys and 753 girls) aged 10–18 years who cross-sectionally enrolled in the Korea National Health and Nutrition Examination Survey (KNHANES) 2010–2013 and 2016 were included in this study. Hg concentrations (µg/L) in whole blood samples were measured. The geometric mean (GM) of the blood Hg concentration was 1.88 µg/L. It showed a 63% higher prevalence of borderline hypercholesterolemia (total cholesterol (TC) 170–199 mg/dL) per unit of natural log-transformed blood Hg concentration in boys (95% CI = 1.10–2.41), but not in girls. When a categorical model was applied, the positive association with the prevalence of borderline hypercholesterolemia was also persistant in boys (OR (95% CI) for 2nd and 3rd tertiles (Hg concentration 1.532–11.761 µg/L) vs. 1st tertile (Hg concentration 0.192–1.531 µg/L): 1.92 (1.19–3.10)), but not in girls. This finding suggests that blood Hg concentration might result in a higher prevalence of borderline hypercholesterolemia among adolescents and more stringent public health actions should be taken for the reduction of Hg exposure to prevent dyslipidemia from early-childhood, despite the need of further study to evaluate a causal relationship between blood Hg concentration and the risk of dyslipidemia.

Exposure to a mixture of metals and growth indicators in 6-11-year-old children from the 2013-16 NHANES

Lead (Pb), mercury (Hg) and fluoride (F) exposure during childhood is of concern owing to their toxicity. Also, evidence suggests that high and low exposure levels to manganese (Mn) and selenium (Se) during this vulnerable period are associated with an increased risk of adverse health effects. A reduced growth is associated with high Pb and F exposure; however, little is known about their impact on children's body size, and there is a lack of consensus on the effects of Hg, Mn, and Se exposure on children's anthropometric measures. This is particularly true for childhood metal co-exposures at levels relevant to the general population. We investigated the joint effects of exposure to a metal mixture (Pb, Mn, Hg, and Se in blood and F in plasma) on 6-11-year-old US children's anthropometry (n = 1,634). Median F, Pb, Mn, Hg, and Se concentrations were 0.3 μmol/L, 0.5 μg/dL, 10.2 μg/L, 0.3 μg/L, and 178.0 μg/L, respectively. The joint effects of the five metals were modeled using Bayesian kernel machine and linear regressions. Pb and Mn showed opposite directions of associations with all outcome measured, where Pb was inversely associated with anthropometry. For body mass index and waist circumference, the effect estimates for Pb and Mn appeared stronger at high and low concentrations of the other metals of the mixture, respectively. Our findings suggest that metal co-exposures may influence children's body mass and linear growth indicators, and that such relations may differ by the exposure levels of the components of the metal mixture.

Food quality score and anthropometric status among 6-year-old children: A cross-sectional study

OBJECTIVE

Weight status and growth during childhood are indicative of healthy development throughout the lifespan. It is well understood that dietary patterns and overall quality of diet can prevent disease, improve health status and optimise growth and development. The current study investigates the relationship between overall diet quality and measures of childhood development including body mass index and height-for-age in 6-year-old children.

METHODS

This cross-sectional study was conducted across 788 6-year-old children from Tehran, Iran, in 2018. Food quality score (FQS) was used to assess overall diet quality, in addition to a modified food-based diet quality score specific to children (modified FQS) developed by our group.

RESULTS

Participants in the highest tertile using the modified FQS had the highest height-for-age z-score (HAZ) (-0.509 ± 0.028 vs -0.605 ± 0.028; P = .048). In contrast, participants in the highest tertile assessed using the original FQS had a higher BMI for age z-score (BAZ) compared to participants in the first tertile (0.391 ± 0.072 vs 0.266 ± 0.072; P = .023). Children within the highest tertile, according to the original FQS, compared to those within the lowest tertile were 49% less likely to be categorised as severely underweight (OR: 0.51; 95% CI: 0.47-0.98).

CONCLUSIONS

Findings presented in this study demonstrate that FQS was significantly associated with participants characterised as severely underweight; however, FQS was not associated with other anthropometric parameters. Therefore, future well-designed cohort studies are required to address limitations of the current study.

Effects of low-level mercury exposure on brain-derived neurotrophic factor in preschool children

OBJECTIVES

Mercury (Hg), a ubiquitous heavy metal, could affect the neurodevelopment of the children, however, these associations are still equivocal. Brain derived neurotrophic factor (BDNF) plays an essential role in the central nervous system development in children. This study aimed to investigate the effects of low-level mercury exposure on serum BDNF levels and the influence of sex and dietary intake on these relationships in children.

METHODS

In this cross-sectional study, a total of 541 pre-school children were recruited, the blood mercury concentrations and serum BDNF levels were measured. The background information on demographic characteristics and dietary habits of the children was collected through questionnaires. Multivariable linear models after adjustment for potential confounders were used to evaluate the associations between mercury exposure and levels of BDNF in children.

RESULTS

The GMs of blood mercury concentrations and serum BDNF levels were 1.06 μg/L, 20.4 ng/mL, respectively. A significant positive association between blood mercury concentrations and serum BDNF levels was found. After stratification by sex, the blood mercury concentrations in children were positive associated with serum BDNF levels in girls but not in boys. However, these associations were attenuated when we further adjusted the children's dietary intake variables.

CONCLUSIONS

Our findings suggest that low-levels of mercury exposure may have sex-specific effects on BDNF levels in young children and that dietary intake may be potential confounders in these relationships. However, further studies are warranted to investigate the role of BDNF in the effects of mercury on neurodevelopment.

Impact of low-level mercury exposure on intelligence quotient in children via rice consumption

Wanshan is a city in southwest China that has several inactive mercury (Hg) mines. The local population are exposed to methylmercury (MeHg) due to the consumption of Hg contaminated rice. The relationship between Hg exposure and the cognitive functions of local children is unknown. This study investigated the relationship between hair Hg concentrations and the intelligence quotient (IQ) of 314 children aged 8-10 years, recruited from three local primary schools in Wanshan area in 2018 and 2019. IQ was evaluated using Wechsler Intelligence Scale for Children - Fourth Edition (WISC-IV). The average THg concentration in children's hair samples was 1.53 μg g^-1 (range: 0.21-12.6 μg g^-1), and 65.6% exceeded the United States Environment Protection Agency (USEPA) recommended value of 1 μg g^-1. Results of logistic regression analysis showed that children with hair Hg ≥ 1 μg g^-1 were 1.58 times more likely to have an IQ score <80, which is the clinical cut-off for borderline intellectual disability (R² = 0.20, p = 0.03). Increasing of 1 μg g^-1 hair Hg resulted in 1 point of IQ loss in Wanshan children, which was.much higher than that via fish consumption. The economical cost due to Hg exposure was estimated to be $69.8 million (9.43% of total GDP) in the Wanshan area in 2018.

Inflammasome/NF-κB translocation inhibition via PPARγ agonist mitigates inorganic mercury induced nephrotoxicity

Mercury (Hg) pollution poses global human health and environmental risks. However, still knowledge gaps exist on both exposures and health effects. Here, we combined transcriptome sequencing technique to further investigate the specific mechanisms of inorganic Hg toxicity in the kidney. Strikingly, transcriptomic analysis revealed that 4174 unigenes (including 2646 upregulated and 1528 downregulated unigenes) were differentially expressed under acute HgCl₂ (5 mg/kg) exposure in the kidney. Additionally, we observed that HgCl₂ selectively induced tumor necrosis factor superfamily (TNFSF) to participate in renal damage, which was consistent with the high-throughput sequencing data. The phenomenon is accompanied by NLRP3 inflammasome and NF-κB signal activation in the kidney. Simultaneously, ELISA results shown that TNF-α, IL-1β and IL-6 concentrations in the kidney were significant increased. KEGG enrichment analysis showed that peroxisome proliferators-activated receptors (PPAR) signaling pathway might be vital toxic mechanism of Hg in the kidney. Then, our data showed that PPARγ agonist (GW 1929) attenuated HgCl₂ (15 μg/ml)-induced apoptosis and NLRP3 inflammasome activation via decreasing translocation of NF-κB and increasing Bcl2 levels in vitro. Along with this, we demonstrated that PPARγ antagonists (GW9662) effectively aggravated HgCl₂-induced nephrotoxicity. Overall, our results suggested that PPARγ signaling pathway is considered to be a protective mechanism to combat against HgCl₂-triggered NLRP3 inflammasome activation and apoptosis.

Status of mercury accumulation in agricultural soils across China (1976-2016)

Soil contamination with mercury (Hg) is a serious and widespread issue in China, with particularly severe effects on the quality of agricultural soils. To analyse long-term, nation-wide trends in Hg contamination of agriculture soil, we conducted a review of Hg concentrations in agricultural soils over four decades, based on 791 studies comprising 1411 sites, published between 1976 and 2016. We assessed spatiotemporal variations in Hg concentration, along with ecological and health risks. While Hg concentrations in agricultural soils showed an increasing trend between 1979 and 2010, they declined thereafter. Moreover, Hg concentrations in agricultural soils were generally high in western (e.g. Guizhou), southern (e.g. Hunan) and north-eastern provinces (e.g. Liaoning), where mining activities were concentrated. Using the geoaccumulation index (I_geo) and other ecological and health risk indices, we found most sampling sites to be uncontaminated, or to have a low level of contamination, although some mining sites showed moderate to extreme Hg contamination. The noncarcinogenic risk to exposure groups followed the order of children (4.42) > adult females (2.71) > adult males (2.45). Therefore, children were identified as the priority risk group. Noncarcinogenic risk values exceeded 100 in some areas in Guizhou and Hunan provinces; these areas should be prioritised for Hg control measures. This review examined Hg pollution in Chinese agricultural soils to provide insight to policymakers for the development of targeted contamination prevention measures.

Blood Mercury Levels in Children with Kawasaki Disease and Disease Outcome

The risk of ethnic Kawasaki disease (KD) has been proposed to be associated with blood mercury levels in American children. We investigated the blood levels of mercury in children with KD and their association with disease outcome. The mercury levels demonstrated a significantly negative correlation with sodium levels (p = 0.007). However, data failed to reach a significant difference after excluding the child with blood mercury exceeding the toxic value. The findings indicate that KD patients with lower sodium concentrations had a remarkably higher proportion of intravenous immunoglobulin (IVIG) resistance (p = 0.022). Our patients who had lower mercury levels (<0.5 μg/L) had more changes in bacille Calmette-Guerin. Mercury levels in 14/14 patients with coronary artery lesions and 4/4 patients with IVIG resistance were all measured to have values greater than 1 μg/L (while average values showed 0.92 μg/L in Asian American children). Mercury levels had no correlations with IVIG resistance or coronary artery lesion (CAL) formation (p > 0.05). CAL development was more common in the incomplete group than in the complete KD group (p = 0.019). In this first report about mercury levels in KD patients, we observed that the juvenile Taiwanese had higher mercury concentration in blood compared to other populations.

Effects of Lead, Mercury, and Cadmium Co-exposure on Children's Pulmonary Function

Accumulating evidence has shown that toxic metals exposure can have adverse effects on children, but the effects of blood Pb, Hg, and Cd co-exposure on pulmonary function in children remains to be clarified. This cross-sectional multicenter study was conducted in Wuxi City, China. A total of 221 healthy children free from chronic obstructive pulmonary disease were recruited. The blood samples were collected while blood Pb, Hg, and Cd levels were determined. The forced vital capacity volume (FVC) and forced expiratory volume in the 1 s (FEV1) were measured. The associations between metals concentration and pulmonary function were analyzed by multiple linear regression models. The geometric means of the blood Pb, Hg, and Cd levels in our study were 37.27 μg/L, 1.41 μg/L, and 0.28 μg/L, respectively. After adjusting for age, sex, maternal education, annual family income, fish consumption, and second-hand smoking exposure, only the blood Pb levels were significantly negatively associated with the pulmonary function. In addition, a significantly positive interaction between blood Pb and blood Cd on pulmonary function were also detected. Although causal relationship cannot be confirmed in this study, at least higher levels of Pb in blood are associated with decreased pulmonary parameters in children.

Prenatal and Early Postnatal Exposure to Total Mercury and Methylmercury from Low Maternal Fish Consumption

The aim of this study was to investigate the influence of low fish consumption on prenatal and early postnatal exposure to mercury species. The samples of umbilical cord blood and maternal milk as well as interviewer-administered questionnaires were collected from 142 Slovak mother-child pairs. The mean total mercury (THg) concentrations in cord blood and milk were 0.949 μg/L and 0.376 μg/kg, respectively. The mean methylmercury (MeHg) concentration in cord blood was 0.504 μg/L. Fish eaters had significantly higher cord blood MeHg concentrations than non-fish eaters (p = 0.030); no difference was found in milk or cord blood THg concentrations. The bivariate analysis showed a positive correlation between cord blood MeHg and consumption of sea fish and shellfish (r_s = 0.320, p < 0.001); after adjustment for the potential confounders, the association was weakened (β = 0.173, p = 0.059). Nevertheless, the decision tree method showed sea fish and shellfish consumption to be the best predictor of cord blood MeHg. Furthermore, a negative association was found between THg concentrations in maternal milk and freshwater fish consumption (β = - 0.193, p = 0.017), which might indicate a beneficial effect of freshwater fish consumption. The results suggest there is a need for future research to investigate the benefits versus the adverse effects of low maternal fish consumption on child development.

Kinetic Study of Biodangerous Methylmercury Degradation under Various Light Conditions

Methylmercury (MeHg) has remarkable toxicological effects on humans, plants, and other lives in the environment, which may restrict the comprehensive utilization of biomass source in view of possibly forming biohazardous waste. In this study, a kinetic study of MeHg degradation under UVB, UVA, natural light, and dark was carried out. The result showed that light radiation enhanced MeHg degradation but had no significant influence on the final balance between MeHg and inorganic mercury (Hg2+) in pure water. The balance is of great importance and can be used as a key fundamental to estimate MeHg cycling in other complicated aquatic environments. MeHg degradation was identified to be second-order reaction using the fitting optimization level of the regression equation, and the second-order rate constants were 1.61, 0.82, and 0.91 L·ng−1·d−1, half-lives were calculated to be 0.62, 1.3, and 1.08 d for UVB, UVA, and natural light, respectively. A possible MeHg degradation mechanism was proposed, and it could perfectly explain the results obtained in this paper and some previous studies.

The three 'B' of fish mercury in China: Bioaccumulation, biodynamics and biotransformation

Mercury (Hg) is a global toxic pollutant and has raised the world's attention for decades. In this study, we reviewed the fish mercury levels in China (both marine and freshwater, as well as wild and farmed) documented over the past decade and their controlling environmental and biological factors. China is the largest contributor of global Hg cycling and the largest nation for the consumption and export of fish and fish product, thus Hg level in fish becomes a critical issue for food safety and public health. In China, Hg in fish is generally accumulated at a low level, but significant geographical differences were evident and formed the "hot spots" from the north to the south. For marine fish, the east (median: 70 ng g^-1 ww, range: 5.0-330 ng g^-1 ww) and southeast (median: 72 ng g^-1 ww, range: 0.3-329 ng g^-1 ww) of China have higher total Hg concentrations than the other coastal areas. For freshwater fish, Tibetan Plateau exhibited the highest total Hg levels (median: 104 ng g^-1 ww, range: 5.0-868 ng g^-1 ww). Risk assessment of the exposure of low-Hg-level fish to China's population deserves more attention and detailed fish consumption advisories to specific populations are urgently needed. The biokinetic model is a useful tool to characterize the underlying processes involved in Hg accumulation by fish. The diet (Hg concentration, speciation, food quality and quantity) and growth appear to be the important factors affecting the Hg levels of fish in China. The Hg biotransformation can also make contributions to Hg speciation and overall accumulation in fish. The intestinal microbes play an important role in Hg biotransformation and the potential for minimizing Hg contamination in fish deserves further investigation.

Relation of prenatal low-level mercury exposure with early child neurobehavioral development and exploration of the effects of sex and DHA on it

BACKGROUND

The extent to which low-level, in utero mercury exposure affects child neurobehavioral development during early childhood has been inconclusive. In addition, the effects of sex and docosahexaenoic acid (DHA) on these relationships remain unclear and controversial.

OBJECTIVES

This study aimed to explore the associations between prenatal low-level mercury exposure and child neurobehavioral development during the neonatal and toddler periods and to examine the potential confounding or interactive effects of sex and DHA status on these relationships.

METHODS

This longitudinal study included 286 mother-child pairs in Shanghai, China, whose cord blood samples were analyzed for total mercury, DHA, other nutrients and coexposure contaminants possibly due to maternal consumption of seafood. Children's neurobehavioral development was assessed with the Neonatal Behavioral Neurological Assessment (NBNA) three days after birth and the Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III) at 18 months of age.

RESULTS

Cord blood mercury concentration, with geometric mean of 2.00 μg/l, was related to poorer NBNA performance but unrelated to BSID-III scores with adjustment for DHA and other covariates. Cord serum DHA was positively associated with motor development assessed by the BSID-III. The interaction was found between mercury and DHA on the NBNA score, and the inverse relation of cord blood mercury with NBNA was significant only among the children with lower DHA levels (<45.54 μg/ml). Additional adjustment for DHA didn't change the associations between cord blood mercury and neurodevelopmental outcomes substantially. The mercury by sex interaction for language of BSID-III was borderline significant.

CONCLUSIONS

Our research provides initial evidence for the negative effects of prenatal low-level mercury exposure on neonates' neurobehavioral development. Prenatal DHA status may modify the relationship between cord blood mercury level and neonatal neurobehavioral development, but the confounding effects of DHA were not observed. Further studies are warranted before the causality of the observed associations can be determined.

Impact of hydrotechnical works on outflow of mercury from the riparian zone to a river and input to the sea

The aim of this research was to assess the impact of hydrotechnical works within the riverbed and riparian zone on the mobility of mercury in soil and its outflow to the river and the sea. Deepening and reconstruction of the riverbed or the cutting of reeds, influenced the fate of mercury in the river system. However, only activitis that disturbed the riperian zone increased mobilization of Hg in soils. Hg transformations in these places were controled by inflow of fresh organic matter in soil and sediments as well as by oxidation-reduction potential. In areas where reducing conditions occurred, mercury released from the soil was incorporated into the sediment. However, in areas where oxidizing conditions prevailed in the sediment, mercury flowing out of the soil occurred mainly in dissolved form and most of it was transported downstream from where it could reach the sea.

Prenatal thallium exposure and poor growth in early childhood: A prospective birth cohort study

BACKGROUND

Thallium (Tl) exposure remains a public health problem with potential impacts on humans. Studies have suggested that prenatal exposure to thallium may be associated with fetal growth, but no studies are known have explored its association with early childhood anthropometry.

OBJECTIVE

To investigate the effects of prenatal Tl exposures on early child growth and development aged 0-2 years in a prospective birth cohort study.

METHODS

3080 pregnant women and their children participated in the study, which were recruited from a birth cohort in China. Serum samples collected in the first and second trimester of pregnant subjects and umbilical cord blood of infants were analyzed for Tl exposure assessment. Infant length or standing height and weight were obtained from medical records and 2 years planned visits. We used length/height and weight to calculate z-scores for weight-for-age (WAZ), height-for-age (HAZ), weight-for-height (WHZ), and body mass index-for-age (zBMI) based on World Health Organization standards. Linear mixed model was used to investigate the association between serum concentrations of Tl and the children's anthropometric characteristics (WAZ, HAZ, WHZ, and zBMI), and stratification analysis by sex was also examined.

RESULTS

The median (P₂₅-P₇₅) of Tl levels in the first trimester, second trimester and umbilical cord serum were 61.7 (50.7-77.0), 60.1 (50.9-74.8) and 38.4 (33.6-43.9) ng/L, respectively. Paired Mann-Whitney tests found Tl concentrations in umbilical cord serum were significantly less than that in maternal serum during the first and second trimesters (all p < 0.01). Using adjusted linear mixed model, no significant relationships were observed between maternal Tl exposure and child growth parameters. However, the umbilical cord serum Tl levels may contributed to decreased WAZ (β = -0.382, 95% confidence interval (CI): -0.670, -0.095) and HAZ (β = -0.427, 95% CI: -0.702, -0.152). When stratified by sex, the umbilical cord serum Tl levels were negatively related to WAZ (β = -0.450, 95% CI: -0.853, -0.048) and HAZ (β = -0.775, 95% CI: -1.160, -0.391) for girls. Among boys, overall Tl exposures were not significantly associated with early children anthropometric outcomes.

CONCLUSIONS

In the present study, our results suggested that prenatal Tl exposures may have a sex specific effect on child anthropometric measurements in the first 2 years of life. Umbilical cord serum Tl levels tended to be reduced child's stature and weight in young girls.

Effects of lead, mercury, aluminium and manganese co-exposure on the serum BDNF concentration of pre-school children in Taizhou, China

Previous studies have shown that toxic metal exposure can have adverse effects on the nervous system of children, but the toxicology of metal co-exposure on neurodevelopment remains to be clarified. Brain derived neurotrophic factor (BDNF) plays an important role in nervous system development, but the possible effects of metal co-exposure on the serum BDNF concentrations of children remain unknown. A total of 561 children living in Taizhou City, China were recruited to participate in our cross-sectional multicenter survey. We measured their blood Pb, Hg, Al and Mn levels and serum BDNF concentrations as well as determined their associations in the total and within sex subgroups. The geometric means of the blood Pb, Hg, Al and Mn levels in all the participants were 67.18 μg/L, 1.01 μg/L, 52.03 μg/L and 18.26 μg/L, respectively. The serum BDNF concentration in children was 19.45 ng/mL. After adjusting for confounders, the blood Pb levels were significantly negatively associated with the serum BDNF concentrations in all the subjects and boys but not in girls. In addition, a significantly negative interaction between blood Pb and blood Hg and a positive interaction between blood Pb and blood Al on serum BDNF concentrations were also observed in boys but not in girls. Our findings highlight the toxic effects of metal co-exposure on serum BDNF levels in pre-school children and indicate that these effects might differ by gender, which suggest that special attention should be paid to the sex-specific effects of metal exposure.

Impacts of farmed fish consumption and food trade on methylmercury exposure in China

The global pollutant mercury (Hg), especially as methylmercury (MeHg), threatens human and ecosystem health. But major contributors of MeHg exposure to people in China remain highly debated. We developed the China Mercury Exposure Assessment (CMEA) model, which incorporates human exposure pathways for MeHg and total Hg (THg), the interregional, including international and interprovincial, food trading as well as human physiology to provide a comprehensive system that can evaluate the pathway of Hg forms to human consumers in China. Based on the CMEA model that employed the most comprehensive and recent data, we have found that the Probable Daily Intake (PDI) of MeHg for the Chinese population was 0.057 (range: 0.036-0.091 as 60% confidence interval) μg·kg^-1·day^-1, while that of THg was 0.35 (range: 0.22-0.55) μg·kg^-1·day^-1. MeHg exposure was dominated by fish intake, especially by farm-raised freshwater fish due to higher consumption of these fish. In 2011, fish intake contributed to 56% to the total MeHg exposure, followed by rice (26%). Consumption of farm-raised fish reduced human exposure to MeHg by 33%. On the other hand, interregional food trading increased MeHg exposure of the Chinese population, as a whole, by 7.6%. The international and interprovincial food trades contributed to 5.1% and 22% of MeHg intake, respectively. For the whole China, fish intake related exposure to MeHg was highest for the Eastern and Northeastern populations, while Tibetans were chronically exposed to the highest MeHg from other sources. Our findings highlight the importance of farmed fish and food trade for MeHg exposure.

Influence of Maternal Fish Intake on the Anthropometric Indices of Children in the Western Amazon

We studied trends in fish intake among pregnant women living in the Madeira River Basin in Rondônia State, Brazil, to investigate the influence of maternal fish intake on anthropometric indices of children followed up to 5 years. Maternal fish intake was assessed using hair mercury concentrations of mothers and children at delivery and 6, 24, and 59 months. Data analysis was performed using a linear mixed-effect model. Mothers were predominantly young, had low incomes and limited schooling, and breastfed for >6 months. Only 1.9% of children had low birth weight. Anthropometric indices in approximately 80% of the study population showed Z-score values ranging from ≥-2 to ≤1. The influence of maternal fish intake on anthropometric indices, including height-to-age (H/A), weight-to-age (W/A), and weight-to-height (W/H) were not statistically significant after model adjustments. However, higher income and larger birth weight had a positive influence on H/A and W/A, whereas W/H gain was favored by higher maternal educational status and breastfeeding duration. Other variables (hemoglobin concentration and maternal age) had a positive significant influence on anthropometric indices. Maternal fish intake (or its attendant MeHg exposure) did not affect children growth. Nevertheless, it is advisable to avoid mercury-contaminated fish during pregnancy and childhood.

Mercury impact on hematopoietic stem cells is regulated by IFNγ-dependent bone marrow-resident macrophages in mice

, but not MeHg, affects HSC through regulating IFNγ-dependent BM-resident macrophages in mice. These findings reveal a previously unknown toxicity of Hg.