Umbilical cord blood mercury levels in China

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.

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.

Co-exposure to lead, mercury, and cadmium induces neurobehavioral impairments in mice by interfering with dopaminergic and serotonergic neurotransmission in the striatum

Humans are exposed to lead (Pb), mercury (Hg), and cadmium (Cd) through various routes, including drinking water, and such exposure can lead to a range of toxicological effects. However, few studies have investigated the toxic effects of exposure to mixtures of metals, particularly in relation to neurotoxicity. In this study, 7-week-old male mice were exposed to Pb, Hg, and Cd individually or in combination through their drinking water for 28 days. The mice exposed to the metal mixture exhibited significantly reduced motor coordination and impaired learning and memory abilities compared to the control group and each of the single metal exposure groups, indicating a higher level of neurotoxicity of the metal mixture. The dopamine content in the striatum was significantly lower in the metal mixture exposure group than in the single metal exposure groups and the control group. Furthermore, compared to the control group, the metal mixture exposure group showed a significantly lower expression level of tyrosine hydroxylase (TH) and significantly higher expression levels of dopamine transporter (DAT), tryptophan hydroxylase 1 (TPH1), and serotonin reuptake transporter (SERT). Notably, there were no significant differences in SERT expression between the single metal exposure groups and the control group, but SERT expression was significantly higher in the metal mixture exposure group than in the single metal and control groups. These findings suggest that the key proteins involved in the synthesis and reuptake of dopamine (TH and DAT, respectively), as well as in the synthesis and reuptake of serotonin (TPH1 and SERT, respectively), play crucial roles in the neurotoxic effects associated with exposure to metal mixtures. In conclusion, this study demonstrates that simultaneous exposure to different metals can impact key enzymes involved in dopaminergic and serotonergic neurotransmission processes, leading to disruptions in dopamine and serotonin homeostasis and consequently a range of detrimental neurobehavioral effects.

Co-exposure to low-dose lead, cadmium, and mercury promotes memory deficits in rats: Insights from the dynamics of dendritic spine pruning in brain development

Lead (Pb), cadmium (Cd), and mercury (Hg) are environmentally toxic heavy metals that can be simultaneously detected at low levels in the blood of the general population. Although our previous studies have demonstrated neurodevelopmental toxicity upon co-exposure to these heavy metals at these low levels, the precise mechanisms remain largely unknown. Dendritic spines are the structural foundation of memory and undergo significant dynamic changes during development. This study focused on the dynamics of dendritic spines during brain development following Pb, Cd, and Hg co-exposure-induced memory impairment. First, the dynamic characteristics of dendritic spines in the prefrontal cortex were observed throughout the life cycle of normal rats. We observed that dendritic spines increased rapidly from birth to their peak value at weaning, followed by significant pruning and a decrease during adolescence. Dendritic spines tended to be stable until their loss in old age. Subsequently, a rat model of low-dose Pb, Cd, and Hg co-exposure from embryo to adolescence was established. The results showed that exposure to low doses of heavy metals equivalent to those detected in the blood of the general population impaired spatial memory and altered the dynamics of dendritic spine pruning from weaning to adolescence. Proteomic analysis of brain and blood samples suggested that differentially expressed proteins upon heavy metal exposure were enriched in dendritic spine-related cytoskeletal regulation and axon guidance signaling pathways and that cofilin was enriched in both of these pathways. Further experiments confirmed that heavy metal exposure altered actin cytoskeleton dynamics and disturbed the dendritic spine pruning-related LIM domain kinase 1-cofilin pathway in the rat prefrontal cortex. Our findings demonstrate that low-dose Pb, Cd, and Hg co-exposure may promote memory impairment by perturbing dendritic spine dynamics through dendritic spine pruning-related signaling pathways.

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.

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.

Developmental Toxicology of Metal Mixtures in Drosophila: Unique Properties of Potency and Interactions of Mercury Isoforms

Mercury ranks third on the U.S. Agency of Toxic Substances and Disease Registry priority list of hazardous substances, behind only arsenic and lead. We have undertaken uncovering the mechanisms underlying the developmental toxicity of methylmercury (MeHg), inorganic mercury (HgCl2), lead acetate (Pb), and sodium arsenite (As). To probe these differences, we used the Drosophila model, taking advantage of three developmental transitions-pupariation, metamorphosis, and eclosion-to differentiate potentially unique windows of toxicity. We elaborated dose response profiles for each individual metal administered in food and accounted for internal body burden, also extending analyses to evaluate combinatorial metal mixture effects. We observed all four metals producing larval lethality and delayed pupariation, with MeHg being most potent. Compared to other metals, MeHg's potency is caused by a higher body burden with respect to dose. MeHg uniquely caused dose-dependent failure in eclosion that was unexpectedly rescued by titrating in HgCl2. Our results highlight a unique developmental window and toxicokinetic properties where MeHg acts with specificity relative to HgCl2, Pb, and As. These findings will serve to refine future studies aimed at revealing tissue morphogenesis events and cell signaling pathways, potentially conserved in higher organisms, that selectively mediate MeHg toxicity and its antagonism by HgCl2.

Analysis of search strategies for evaluating low-dose heavy metal mixture induced cognitive deficits in rats: An early sensitive toxicological approach

Heavy metals such as lead (Pb), cadmium (Cd), and mercury (Hg) are representative neurotoxicological contaminants that can evoke cognitive dysfunctions. Low levels of these contaminants can be detected simultaneously in the human blood. In our previous study, behavioral performances were markedly impaired by exposure to these heavy metal mixtures (MM) at low levels. However, the aspects of cognitive functions involved are not well understood. Here, we further analyzed search strategies using a new algorithm named Morris water maze-unbiased strategy classification (MUST-C). Rat pups were co-exposed to low doses of Pb, Cd, and Hg during the embryonic and lactation stage. MM exposure at low doses, similar to those found in the general population, impaired search strategies even though their latency and path length were not affected in the Morris water maze task. MM-exposed rats preferred to use more directionless repetition strategies and less target orientation strategies than did vehicle-exposed animals in a dose-dependent manner. In addition, thionine staining and electron microscopy further revealed that MM exposure induced dose-dependent search strategy related place cell injures in the hippocampal CA1 and CA3 regions. These results demonstrate that the use of suboptimal search strategies underlies the early cognitive deficits in rats exposed to low doses of MM. The current study determined that search strategy analysis might be a novel sensitive assessment method for evaluating in the neurobehavioral toxicity.

Biomonitoring of maternal and fetal exposure to mercury in Sabzevar and its affecting risk factors

Fetuses and young children are sensitive to even low levels of exposure to Hg, which can damage their brain and adversely affect their central nervous system and cognitive development. This study was conducted to determine the maternal and fetal mercury burden levels in mothers presenting to Shahidan Mobini Hospital for delivery. Eighty-nine mothers were included in this study and 360 samples were taken from their placental tissue and blood (maternal blood) as well as their umbilical cord tissue blood (infant blood). Findings revealed a significant strong correlation (r = 0.890, p < 0.001) in blood mercury between mothers and their infants. According to multiple linear regression analysis, there was a significant positive association between living in rural areas and the level of mercury in the placental tissue (β = 11.09, p < 0.001). This positive association was also found in other samples. In addition, there was a significant association between maternal age and mercury level in the placental tissue (β = 5.56, p = 0.049), placental blood (β = 11.67, p = 0.003), umbilical cord tissue (β = 8.33, p = 0.004) and umbilical cord blood (β = 9.51, p < 0.001).

Insights into cognitive deficits caused by low-dose toxic heavy metal mixtures and their remediation through a postnatal enriched environment in rats

The heavy metals, namely lead (Pb), cadmium (Cd), and mercury (Hg), have been studied extensively in various independent studies. It has been seen that these metals are usually detected simultaneously in the human blood at low levels. However, it is unknown whether exposure to these heavy metal mixtures (MM) can induce neurological damages at these low levels. Therefore, we investigated the influence of the Pb, Cd, and Hg mixture on the nervous system in rats at exposure doses equivalent to those normally found in the human blood. After pregnant rats being exposed to MM via drinking water throughout the gestation and lactation, their offspring were followed-up till adulthood. MM caused cognitive deficits and impairments in a dose-dependent manner. Furthermore, MM disrupted dendritic spines, the structural basis of learning and memory, and induced changes in spine-related pathways. Meanwhile, we explored an early and safe way to remedy these impairments through a postnatal enriched environment. The enriched environment ameliorated MM-impaired cognitive function, synaptic plasticity, and spine-related pathways. This study demonstrated that low-dose co-exposure to Pb, Cd, and Hg can cause cognitive and synaptic plasticity deficits and timely intervention through the enriched environment has a certain corrective effect.

Toxicity assessment due to prenatal and lactational exposure to lead, cadmium and mercury mixtures

The heavy metals lead (Pb), cadmium (Cd) and mercury (Hg) are common environmental pollutants that can be detected simultaneously in blood, serum, and urine samples from the general human population. However, there is limited information regarding toxicity of low-level exposure to Pb, Cd, and Hg mixtures. Our previous research showed the interaction of these three elements at low concentrations in vitro. In this study, we further evaluate early effects of low dose exposure to Pb, Cd, and Hg mixtures on the brain, heart, liver, kidney, and testicle in rats. Pregnant rats were exposed to various concentrations of heavy metal mixtures (MM) in drinking water, during gestation and lactation, and the impacts on offspring were measured at postnatal day 23. Our results showed that the concentrations of Pb, Cd, and Hg in the blood of rat pups were similar to those in the blood of the general human population. Additionally, the MM concentrations in their blood and brain significantly increased in a dose-dependent manner. MM exposure caused histopathological changes in the brain, liver, kidney and testicle. Statistically significant increases in liver CYP450 and PON1, kidney KIM1, and decrease in testicle SDH were observed. In the brain, significant increases were detected in oxidative stress, intracellular free calcium, and cell apoptosis. Further neurobehavioral testing revealed that MM exposure caused dose-dependent impairments in learning and memory as well as sensory perception. MM exposure also disrupted synapse remodeling, which may be associated with pathways involved in dendritic spine growth, maintenance, and elimination. These results suggested that exposure to Pb, Cd, and Hg mixtures, at human environmental exposure related levels, caused damage to multiple organs as well as impairments in neurobehavioral functions of rats. Our findings emphasize the need to control and regulate potential sources of heavy metal contamination.

Effects of environmental contaminants on fertility and reproductive health

Recent research indicates that the human infertility rate is increasing. Although various reasons have been hypothesized for the growing infertility rate, environmental contaminants are potentially important causal agents associated with this change. Chemical contaminants are widespread throughout our environment and human exposure is virtually unavoidable. The overall contribution of environmental exposure to infertility is unknown, but studies involving occupational exposure, together with results from animal experiments, suggest that environmental contaminants may adversely affect fertility. We reviewed the adverse effects of environmental exposure on fertility and related reproductive outcomes. Environmental contaminants covered in this review include heavy metals, organic solvents, pesticides and endocrine disrupting chemicals. It is hoped that this review will highlight the need for further research in this area.

Impact of delivery mode on the levels of essential trace elements in breast milk

Aim: This study investigated whether the parturition mode (vaginal or cesarean [C-] section) affects breast milk concentrations of four essential trace elements (iron, copper, zinc, and manganese).Methods: Women giving birth at seven hospitals in seven different regions of China were enrolled in the study. Each participant provided breast milk, collected on postpartum day 3-5, for determination of iron, copper, zinc, and manganese concentrations. Breast milk concentrations of the subject trace elements were compared between women giving birth vaginally or via C-section.Results: Of the 1243 women enrolled in the study, 617 (49.6%) gave birth via the vaginal route and 626 (50.4%) delivered via C-section. The mean milk concentrations of iron, copper, zinc, and manganese in the milk of women delivering via the vaginal route were higher than those in the milk of women delivering via C-section; only the copper concentration differences were statistically significant, after adjusting for confounding factors (p = .023).Conclusion: Delivery mode impacts breast milk concentrations of essential trace elements, with vaginal delivery being associated with higher essential trace element concentrations than C-sections.

Lead, cadmium, arsenic, and mercury combined exposure disrupted synaptic homeostasis through activating the Snk-SPAR pathway

Lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) are among the leading toxic agents detected in the environment, and they have also been detected simultaneously in blood, serum, and urine samples of the general population. Meanwhile early neurologic effects and multiple interactions of Pb, Cd, As, and Hg had been found in children from environmentally polluted area. However, the current studies of these four metals were mostly limited to the interactions between any two metals, whereas the interaction characteristics between any three and four metals were rarely studied. In our study, we firstly explored the characteristics of the neurotoxic interactions among these four elements in nerve cells with factorial designs. The results showed that Pb+Cd+As+Hg co-exposure had a synergistic neurotoxic effect that was more severe than that induced by any two or three metals, when their individual metals were at human environmental exposure (in the blood of U.S. population) relevant levels and below no observed adverse effect levels (NOAELs). Therefore, Pb+Cd+As+Hg co-exposure at human environmental exposure relevant levels were further selected to examine synaptic homeostasis as the cellular and molecular foundation of learning and memory. We reported for the first time that Pb+Cd+As+Hg co-exposure induced dose-dependent decreases of the dendritic lengths and branching, as well as spine density and mature phenotype in primary hippocampal neurons, and the stimulated neurite outgrowths in NGF-differentiated PC12 cells. And the above synaptic homeostasis disruption was associated with serum induced kinase (Snk)-spine associated Rap GTPase activating protein (SPAR) pathway. Our study suggests that human environmental Pb, Cd, As, and Hg co-exposure has the potential to evoke synergistic neurotoxicity even if their individual metals are below NOAELs, which reinforces the need to control and regulate potential sources of metal contamination.

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

OBJECTIVE

This study sought to obtain national cross-sectional data for blood mercury levels and risk factors for mercury exposure in Chinese children aged 0 to 6years to provide evidence to support preventive measures for reducing childhood blood mercury levels.

METHODS

A multi-stage, stratified, clustered random sampling survey was conducted May 2013-Mar 2015. Shanghai, Jilin, Shanxi, Guangdong, Qinghai, Yunnan and Hubei, which are located in seven different geographical regions in China, were selected as the study field. A total of 14,202 children aged 0-6years participated in the study. Whole-blood venous samples (3ml) were collected from the subjects for mercury exposure assessment. The DMA-80 was applied for mercury detection, and a health questionnaire gathering information on related confounders was completed by the subjects' parents of the subjects after they received guidance from the investigators. A general linear model was used for the primary descriptive statistical analysis. Odds ratios (ORs) and 95%CIs for the risk factors were estimated using unconditional logistic regression.

RESULTS

A total of 14,202 eligible samples were collected. The mean mercury level was 1.39μg/L. Other results were as follows: median 1.23μg/L, p25 0.86μg/L, p75 1.73μg/L, and GM 1.10μg/L. Of the seven geographical regions, Qinghai, in northwestern China, had a median mercury level of 0.37μg/L, which was significantly lower than the mercury level in Guangdong, in southeastern China (2.01μg/L). The median blood mercury level of children in suburban areas was 1.34μg/L, which was remarkably higher than that of children in rural areas (1.09μg/L). Dichotomous subgroups were generated using the median mercury concentration. Unconditional logistic regression analysis revealed that fish consumption may contribute to increased blood mercury levels (p<0.05). Additionally, we observed significantly positive associations between mercury concentrations and the children's anthropometric characteristics (BMI; p<0.05).

CONCLUSIONS

Blood mercury concentrations among Chinese children aged 0-6years were considered low, and children who consumed more marine fish, freshwater fish and shellfish tended to have higher mercury concentrations. Our study suggests that children's growth is likely affected by the positive effects of mercury, which may have implications concerning the positive effects of fish consumption.

Current progress on understanding the impact of mercury on human health

Mercury pollution and its impacts on human health is of global concern. The authors of this paper were members of the Plenary Panel on Human Health in the 12th International Conference on Mercury as a Global Pollutant held in Korea in June 2015. The Panel was asked by the conference organizers to address two questions: what is the current understanding of the impacts of mercury exposure on human health and what information is needed to evaluate the effectiveness of the Minamata Convention in lowering exposure and preventing adverse effects. The authors conducted a critical review of the literature published since January 2012 and discussed the current state-of-knowledge in the following areas: environmental exposure and/or risk assessment; kinetics and biomonitoring; effects on children development; effects on adult general populations; effects on artisanal and small-scale gold miners (ASGM); effects on dental workers; risk of ethylmercury in thimerosal-containing vaccines; interactions with nutrients; genetic determinants and; risk communication and management. Knowledge gaps in each area were identified and recommendations for future research were made. The Panel concluded that more knowledge synthesis efforts are needed to translate the research results into management tools for health professionals and policy makers.

Environmental influences on reproductive health: the importance of chemical exposures

Chemical exposures during pregnancy can have a profound and life-long impact on human health. Because of the omnipresence of chemicals in our daily life, there is continuous contact with chemicals in food, water, air, and consumer products. Consequently, human biomonitoring studies show that pregnant women around the globe are exposed to a variety of chemicals. In this review we provide a summary of current data on maternal and fetal exposure, as well as health consequences from these exposures. We review several chemical classes, including polychlorinated biphenyls, perfluoroalkyl substances, polybrominated diphenyl ethers, phenols, phthalates, pesticides, and metals. Additionally, we discuss environmental disparities and vulnerable populations, and future research directions. We conclude by providing some recommendations for prevention of chemical exposure and its adverse reproductive health consequences.

In vitro evaluation of inorganic and methyl mercury mediated cytotoxic effect on neural cells derived from different animal species

To extend the current understanding of the mercury-mediated cytotoxic effect, five neural cell lines established from different animal species were comparatively analyzed using three different endpoint bioassays: thiazolyl blue tetrazolium bromide, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay (MTT), neutral red uptake assay (NRU), and Coomassie blue assay (CB). Following a 24-hr exposure to selected concentrations of mercury chloride (HgCl2) and methylmercury (II) chloride (MeHgCl), the cytotoxic effect on test cells was characterized by comparing their 50% inhibition concentration (IC50) values. Experimental results indicated that both these forms of mercury were toxic to all the neural cells, but at very different degrees. The IC50 values of MeHgCl among these cell lines ranged from 1.15±0.22 to 10.31±0.70μmol/L while the IC50 values for HgCl2 were much higher, ranging from 6.44±0.36 to 160.97±19.63μmol/L, indicating the more toxic nature of MeHgCl. The IC50 ratio between HgCl2 and MeHgCl ranged from 1.75 to 96.0, which confirms that organic mercury is much more toxic to these neural cells than inorganic mercury. Among these cell lines, HGST-BR and TriG44 derived from marine sea turtles showed a significantly high tolerance to HgCl2 as compared to the three mammalian neural cells. Among these neural cells, SK-N-SH represented the most sensitive cells to both chemical forms of mercury.

Disruption of iron homeostasis and resultant health effects upon exposure to various environmental pollutants: A critical review

Environmental pollution has become one of the greatest problems in the world, and the concerns about environmental pollutants released by human activities from agriculture and industrial production have been continuously increasing. Although intense efforts have been made to understand the health effects of environmental pollutants, most studies have only focused on direct toxic effects and failed to simultaneously evaluate the long-term adaptive, compensatory and secondary impacts on health. Burgeoning evidence suggests that environmental pollutants may directly or indirectly give rise to disordered element homeostasis, such as for iron. It is crucially important to maintain concerted cellular and systemic iron metabolism. Otherwise, disordered iron metabolism would lead to cytotoxicity and increased risk for various diseases, including cancers. Thus, study on the effects of environmental pollutants upon iron homeostasis is urgently needed. In this review, we recapitulate the available findings on the direct or indirect impacts of environmental pollutants, including persistent organic pollutants (POPs), heavy metals and pesticides, on iron homeostasis and associated adverse health problems. In view of the unanswered questions, more efforts are warranted to investigate the disruptive effects of environmental pollutants on iron homeostasis and consequent toxicities.

Low-level prenatal mercury exposure in north China: an exploratory study of anthropometric effects

In order to investigate anthropometric effects of mercury (Hg) exposure, we examined the status of human prenatal exposure to Hg species, including total mercury (THg), methylmercury (MeHg) and inorganic mercury (IHg), in North China, as well as their potential effects on fetal and infant growth. Hg concentrations in various bioindicators were measured from 50 Chinese women and newborns in 2011. The participants were followed for 12 months to collect anthropometric information. Linear and two-level regression analyses were performed to determine the associations between Hg levels and body growth. The geometric mean levels of THg in the placenta, cord blood, fetal hair, and maternal blood, hair, and urine were 25.88 μg/kg dry wt, 2.73 μg/L, 572.98 μg/kg, 2.29 μg/L, 576.54 μg/kg, and 0.58 μg/g creatinine, respectively. Nearly 100% of Hg presented as IHg in urine, and the percentage of IHg in other bioindicators was 14.86-48.73%. We observed significantly negative associations between Hg levels in some matrixes and anthropometry of neonates (weight and height) and infants (height) (p < 0.05). THg levels in maternal hair were also negatively associated with infant growth rate of weight during 12 months after delivery (p = 0.017). This study suggests that low-level prenatal Hg exposure could play a role in attenuating fetal and infant growth, and the effects of MeHg and IHg are different.

Body burden of Hg in different bio-samples of mothers in Shenyang city, China

Hg is an accumulative and neuro-toxic heavy metal which has a wide range of adverse effects in human health. However, few studies are available on body burden of Hg level in different bio-samples of pregnant women in Chinese population. Therefore, this study evaluated Hg levels in different maternal bio-samples in Shenyang city, China and investigated the correlation of Hg levels in different bio-samples. From October to December 2008, 200 pregnant women about to deliver their babies at ShengJing Hospital (Shenyang city, northeast of China) participated in this study. The geometric mean (GM) of Hg levels in cord blood, maternal venous blood, breast milk, and maternal urine were 2.18 µg/L, 1.17 µg/L, 1.14 µg/L, and 0.73 µg/L, respectively, and the GM of maternal hair Hg level was 404.45 µg/kg. There was a strong correlation between cord blood and maternal blood total Hg level (r = 0.713, P<0.001). Frequency of fish consumption more than or equal to 3 times per week during pregnancy was suggested as a significant risk factor of prenatal Hg exposure (unadjusted OR 3.5, adjusted OR 2.94, P<0.05). This study provides evidence about Hg burden of mothers and the risk factors of prenatal Hg exposure in Shenyang city, China.

Levels of prenatal mercury exposure and their relationships to neonatal anthropometry in Wujiang City, China

We determined the levels of prenatal Hg exposure in Wujiang City, located in the southeast of Taihu Lake in China's Jiangsu Province, and analyze the relationship between prenatal exposure to Hg and neonatal anthropometry, including birth weight, body length, and head circumference. From June 2009 to July 2010, a total of 213 mother-infant pairs were enrolled. The geometric means of Hg levels in maternal hair, fetal hair, placentas, and cord blood were 496.76 μg/kg, 233.94 μg/kg, 3.58 μg/kg, and 1.54 μg/L, respectively. The Hg levels detected in our study were significantly lower than those reported by previous studies. In addition, no significant correlations were found between Hg levels in maternal hair, fetal hair, placenta, or cord blood and neonatal anthropometrics. Together, our findings may be important for understanding the effects of prenatal exposure to Hg on newborns' development and have implications concerning the recommended dose for Hg.