Fish consumption, low-level mercury, lipids, and inflammatory markers in children

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.

Race, cortisol, and subclinical cardiovascular disease in 9- to 11-year-old children

BACKGROUND

Non-Hispanic Black Americans have a greater risk for certain subtypes of cardiovascular disease (CVD; e.g., stroke and heart failure) relative to non-Hispanic White Americans. Moreover, Black relative to White adults consistently show elevated cortisol, a CVD risk. The impact of race, environmental stress, and cortisol on subclinical CVD has yet to be fully researched in children.

METHOD

We assessed diurnal salivary cortisol slopes and hair cortisol in a sample of 9- to 11-year-old children (N = 271; 54% female) with roughly half self-identifying as either Black (57%) or White (43%). Two subclinical CVD indicators were assessed: carotid-femoral pulse wave velocity (cfPWV) and carotid intima-media thickness (cIMT). We assessed numerous environmental stress indicators.

RESULTS

After adjusting for covariates, we found that Black children had significantly flatter diurnal cortisol slopes, higher hair cortisol, and thicker IMT than White children. Significant pathways were found: race → salivary cortisol slope → cfPWV (effect = -0.059, 95% CI [-0.116, -0.002]) and race → hair cortisol → cIMT (effect = -0.008, [-0.016, -0.002]). Black children also experienced significantly more environmental stress than White children; however, only income inequality served as a significant indirect pathway from race to salivary cortisol (effect = 0.029, [0.003, 0.060]).

CONCLUSIONS

Relative to White children, Black children had significantly greater hair cortisol and flatter diurnal slopes which, in turn, were associated with greater subclinical CVD. As suggested by a significant indirect pathway, income inequality might partially explain the race-cortisol association. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Association of Blood Total Mercury with Dyslipidemia in a sample of U.S. Adolescents: Results from the National Health and Nutrition Examination Survey Database, 2011-2018

Background

Abnormal lipid profiles in adolescents predict metabolic and cardiovascular diseases in adulthood. While seafood consumption is the primary source of mercury exposure, it also provides beneficial nutrients such as omega-3 fatty acids (O3FA). Prior studies indicate that blood total mercury (TBHg) has endocrine disrupting effects and may be associated with abnormal lipid profiles in adolescents. However, the impact of beneficial nutrients on this relationship has not been examined. Our study investigated the relationship of TBHg with dyslipidemia and lipid profiles and potential confounding and modification of these relationships by sex, body mass index (BMI), selenium and O3FA from seafood consumption.

Methods

We examined 1,390 National Health and Nutrition Examination Survey participants 12-19 years of age from the 2011-2018 cycles. Using logistic and linear regression adjusted for survey design variables and stratified by sex a priori, we estimated the associations of TBHg and methylmercury with dyslipidemia, and with total cholesterol (TC), high (HDL-C) and low-density lipoprotein cholesterol (LDL-C) and triglycerides.

Results

The geometric mean of TBHg in this adolescent population was 0.44 μg/L. After controlling for socio-demographic covariates, BMI, serum selenium, age at menarche (females only) and average daily intake of O3FA; TBHg was significantly associated with higher TC levels (β=3.34, 95% CI: 0.19, 6.50; p<0.05) in females but not males. Methyl Hg was also associated with increased TC, as well as decreased HDL-C in females but not males. We did not find significant associations of Hg exposure with dyslipidemia, LDL-C or triglycerides levels in either male or female adolescents. However, we observed evidence of effect modification by BMI and serum selenium for associations of TBHg with TC levels in male and female adolescents, respectively.

Conclusion

Our findings of elevated TC levels in females but not males necessitates further research to better understand the underlying mechanisms driving these sex-specific associations.

ERICA: prevalence of fish consumption and its association with cardiovascular risk factors and healthy behavior in Brazilian adolescents

OBJECTIVE

To describe the prevalence of fish consumption and its association with cardiovascular risk factors and healthy behavior in Brazilian adolescents.

METHOD

The authors investigated data from 71,533 participants of the Study of Cardiovascular Risk in Adolescents (Estudo de Riscos Cardiovasculares em Adolescentes - ERICA), a nationwide, cross-sectional, school-based study. Of these, 37,815 adolescents were included for blood analyses. All prevalence estimates were presented proportionally with their 95% confidence intervals. Bivariate relationships were evaluated with Pearson's Chi-square test, and a multinomial logistic regression model was applied, considering p < 0.05.

RESULTS

Prevalence of fish consumption in the 7 days prior to the interview was 28.6% (95%CI 26.9-30.3), significantly higher among male adolescents (p = 0.0049), Asian descendants (p = 0.0270), private and rural school students (p < 0.001), and who resided in the Northern region (p < 0.001). A positive association between fish consumption and healthy behavior (breakfast consumption: OR=1.16; 95%CI 1.10-1.22; meals with family members: lunch: OR = 1.07; 95%CI 1.01-1.13; dinner: OR = 1.13; 95%CI 1.04-1.23; physical activity: OR = 1.14; 95%CI 1.02-1.28) and an inverse association with hypertriglyceridemia (OR = 0.84; 95%CI 0.73-0.98) remained significant even after adjustment for possible confounding factors.

CONCLUSION

This study demonstrated that fish consumption was associated with lower cardiovascular risk and may represent a marker of a healthy lifestyle in Brazilian adolescents.

Physical activity is associated with lower pulsatile stress but not carotid stiffness in children

The cardiovascular disease (CVD) process may begin early in life when accompanied by atherosclerotic risk factors. CVD risk factors in children are associated with stiffening of the large elastic arteries, a reflection of subclinical atherosclerosis. Physical activity is a preventative lifestyle strategy that may benefit arterial stiffness by attenuating the hemodynamic stress on the artery wall. This study examined the relations between physical activity, carotid pulsatile stress, and carotid stiffness in children. One hundred and forty children (9-11 yrs; 50.0% male, 57.9% African American, 42.10% Caucasian, body mass index (BMI) 20.1±4.7 kg/m²) participated in this study. Physical activity counts were measured using a wrist-worn accelerometer and averaged over 7 days. Carotid artery β-stiffness and pulse pressure (calibrated to brachial mean and diastolic pressure) were assessed as via ultrasound and tonometry, respectively. Pulsatile stress was calculated as the product of carotid pulse pressure and heart rate. Physical activity counts were correlated with pulsatile stress (r= -0.27), and BMI (r= -0.23), but were unrelated to carotid stiffness. In multivariate models, associations between physical activity counts and pulsatile stress remained (B= -1.3 [95%CI, -2.4, -0.2], β= -0.20, p<0.05) after covariate adjustment for age, race, sex, pubertal stage and BMI. Carotid pulsatile stress was related to regional carotid stiffness (r=0.45, p<0.05). These data suggest that higher levels of physical activity at young age are associated with lower hemodynamic stress in the carotid artery. Findings are discussed in the context of an inverse relationship between hemodynamic pulsatile stress and carotid stiffness in children.

SCREENED: A Multistage Model of Thyroid Gland Function for Screening Endocrine-Disrupting Chemicals in a Biologically Sex-Specific Manner

Endocrine disruptors (EDs) are chemicals that contribute to health problems by interfering with the physiological production and target effects of hormones, with proven impacts on a number of endocrine systems including the thyroid gland. Exposure to EDs has also been associated with impairment of the reproductive system and incidence in occurrence of obesity, type 2 diabetes, and cardiovascular diseases during ageing. SCREENED aims at developing in vitro assays based on rodent and human thyroid cells organized in three different three-dimensional (3D) constructs. Due to different levels of anatomical complexity, each of these constructs has the potential to increasingly mimic the structure and function of the native thyroid gland, ultimately achieving relevant features of its 3D organization including: 1) a 3D organoid based on stem cell-derived thyrocytes, 2) a 3D organoid based on a decellularized thyroid lobe stromal matrix repopulated with stem cell-derived thyrocytes, and 3) a bioprinted organoid based on stem cell-derived thyrocytes able to mimic the spatial and geometrical features of a native thyroid gland. These 3D constructs will be hosted in a modular microbioreactor equipped with innovative sensing technology and enabling precise control of cell culture conditions. New superparamagnetic biocompatible and biomimetic particles will be used to produce "magnetic cells" to support precise spatiotemporal homing of the cells in the 3D decellularized and bioprinted constructs. Finally, these 3D constructs will be used to screen the effect of EDs on the thyroid function in a unique biological sex-specific manner. Their performance will be assessed individually, in comparison with each other, and against in vivo studies. The resulting 3D assays are expected to yield responses to low doses of different EDs, with sensitivity and specificity higher than that of classical 2D in vitro assays and animal models. Supporting the "Adverse Outcome Pathway" concept, proteogenomic analysis and biological computational modelling of the underlying mode of action of the tested EDs will be pursued to gain a mechanistic understanding of the chain of events from exposure to adverse toxic effects on thyroid function. For future uptake, SCREENED will engage discussion with relevant stakeholder groups, including regulatory bodies and industry, to ensure that the assays will fit with purposes of ED safety assessment. In this project review, we will briefly discuss the current state of the art in cellular assays of EDs and how our project aims at further advancing the field of cellular assays for EDs interfering with the thyroid gland.

Toxicity of mercury: Molecular evidence

Minamata disease in Japan and the large-scale poisoning by methylmercury (MeHg) in Iraq caused wide public concerns about the risk emanating from mercury for human health. Nowadays, it is widely known that all forms of mercury induce toxic effects in mammals, and increasing evidence supports the concern that environmentally relevant levels of MeHg could impact normal biological functions in wildlife. The information of mechanism involved in mercurial toxicity is growing but knowledge gaps still exist between the adverse effects and mechanisms of action, especially at the molecular level. A body of data obtained from experimental studies on mechanisms of mercurial toxicity in vivo and in vitro points to that disruption of the antioxidant system may play an important role in the mercurial toxic effects. Moreover, the accumulating evidence indicates that signaling transduction, protein or/and enzyme activity, and gene regulation are involving in mediating toxic and adaptive response to mercury exposure. We conducted here a comprehensive review of mercurial toxic effects on wildlife and human, in particular synthesized key findings of molecular pathways involved in mercurial toxicity from the cells to human. We discuss the molecular evidence related mercurial toxicity to the adverse effects, with particular emphasis on the gene regulation. The further studies relying on Omic analysis connected to adverse effects and modes of action of mercury will aid in the evaluation and validation of causative relationship between health outcomes and gene expression.

Guarana improves behavior and inflammatory alterations triggered by methylmercury exposure: an in vivo fruit fly and in vitro neural cells study

Methylmercury (MeHg) is a well-known environmental pollutant associated with neurological and developmental deficits in animals and humans. However, epidemiological data showed that people living in the Amazon region although exposed to MeHg do not present these effects probably due to the protective effect of certain foods. We hypothesized here if guarana, a highly caffeinated fruit and consumed on a daily basis by Amazon people, could have some protective effect against MeHg toxicity using two complementary approaches. To assess locomotor impairment and sleep disruption, we used fruit fly (Drosophila melanogaster) model, and to evaluate neuroinflammation, we used human SH-SY5Y neural cells by measuring inflammatory cytokines levels. Results showed that guarana had a protective effect on the locomotor activity of male fruit flies reducing the excessive sleepiness caused by MeHg and increasing daily activity. Also, guarana increased the viability of flies and attenuated neural cells mortality. In addition, guarana reduced all pro-inflammatory cytokines levels increased by MeHg, along with caspase-1, caspase -3, caspase-8, and 8-dOHG levels, whereas increased the anti-inflammatory (IL-10) cytokine levels, which was decreased by MeHg. Our study provides new insights on the protective effects of guarana on the viability, locomotor activity, sleep, and activity patterns in vivo and the in vitro neuronal anti-inflammatory effect against MeHg toxicity.

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.

Spatial, Temporal, and Dietary Variables Associated with Elevated Mercury Exposure in Peruvian Riverine Communities Upstream and Downstream of Artisanal and Small-Scale Gold Mining

Artisanal and small-scale gold mining (ASGM) is a primary contributor to global mercury and its rapid expansion raises concern for human exposure. Non-occupational exposure risks are presumed to be strongly tied to environmental contamination; however, the relationship between environmental and human mercury exposure, how exposure has changed over time, and risk factors beyond fish consumption are not well understood in ASGM settings. In Peruvian riverine communities (n = 12), where ASGM has increased 4–6 fold over the past decade, we provide a large-scale assessment of the connection between environmental and human mercury exposure by comparing total mercury contents in human hair (2-cm segment, n = 231) to locally caught fish tissue, analyzing temporal exposure in women of child bearing age (WCBA, 15–49 years, n = 46) over one year, and evaluating general mercury exposure risks including fish and non-fish dietary items through household surveys and linear mixed models. Calculations of an individual’s oral reference dose using the total mercury content in locally-sourced fish underestimated the observed mercury exposure for individuals in many communities. This discrepancy was particularly evident in communities upstream of ASGM, where mercury levels in river fish, water, and sediment measurements from a previous study were low, yet hair mercury was chronically elevated. Hair from 86% of individuals and 77% of children exceeded a USEPA (U.S. Environmental Protection Agency) provisional level (1.2 µg/g) that could result in child developmental impairment. Chronically elevated mercury exposure was observed in the temporal analysis in WCBA. If the most recent exposure exceeded the USEPA level, there was a 97% probability that the individual exceeded that level 8–10 months of the previous year. Frequent household consumption of some fruits (tomato, banana) and grains (quinoa) was significantly associated with 29–75% reductions in hair mercury. Collectively, these data demonstrate that communities located hundreds of kilometers from ASGM are vulnerable to chronically elevated mercury exposure. Furthermore, unexpected associations with fish mercury contents and non-fish dietary intake highlight the need for more in-depth analyses of exposure regimes to identify the most vulnerable populations and to establish potential interventions.

Marble industry effluents cause an increased bioaccumulation of heavy metals in Mahaseer (Tor putitora) in Barandu River, district Buner, Pakistan

The present study was conducted to evaluate the impact of marble industry effluents on the accumulation of heavy metals in selected tissues of mahaseer (Tor putitora) in Barandu River. Fish samples were collected from three selected sites (upstream (US), effluents/industrial (IS), and downstream (DS) sites) on monthly basis for 8 months. Heavy metal concentrations were determined in fish tissues using Atomic Absorption Spectrophotometer. Liver accumulated the highest level of metal concentrations while the lowest concentrations were found in muscles in T. putitora. Among metals, Fe was reported in the highest amount whereas the lowest was Cd in all the fish organs. In all the months, the metal concentrations were significantly higher (P < 0.05) at IS than the other two selected sites and also very often the metal concentrations at DS were found significantly higher (P < 0.05) compared to the US. The obtained results revealed that discharging industrial effluents caused an increased accumulation of heavy metals in fish tissues at IS compared to US and DS. Furthermore, in many cases, the concentrations at DS were also found significantly higher (P < 0.05) compared to US. It is further confirmed by skewness z-score which was found to be higher than 1.96 suggesting the hazardous effects of marble industries on the collective health of the river. It is therefore recommended that all these industries either should be moved away from the bank of River Barandu or must be bound to properly treat their effluents prior to discharge into the river in order to protect the biota of River Barandu from the pollution caused by these marble industries.

Consumption of seafood and its estimated heavy metals are associated with lipid profile and oxidative lipid damage on healthy adults from a Spanish Mediterranean area: A cross-sectional study

The association between the consumption of seafood and its benefits on cardiovascular (CVD) risk can be challenged by its heavy metal (HM) content. This study aimed to explore the association of seafood consumption and its estimated HM contents with the lipid profile and lipid oxidation biomarkers in adults from a Spanish Mediterranean area who do not present risk factors for CVD. In this cross-sectional study, the clinical history, three-day dietary record, lipid profile (LDLc, HDLc, APOB/A, and triglyceride levels), plasma oxidised LDL (oxLDL) and 8-isoprostane levels of 81 adults without risk factors for CVD [43% men, with a mean age of 43.6 years (95%CI: 40.1-47.1)] were assessed. The HM [arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb)] contents of seafood were estimated according to data from analyses of marine species in the same Mediterranean area. Moderate adherence to the Mediterranean diet (score: 4.6 of 9) with a mean seafood consumption of 74.9g/day (95%CI: 59.9-89.9), including 22.7g of shellfish per day (95%CI: 13.5-31.9), was observed. The estimated HM contents were lower than the provisional tolerable weekly intakes (PTWIs): 21.12µg/kg/week As, 0.57µg/kg/week InAs, 0.15µg/kg/week Cd, 1.11µg/kg/week Hg and 0.28µg/kg/week Pb. After adjusting by confounder variables, an increase in shellfish consumption was associated with increases in the levels of LDLc (P=0.013), non-HDLc (P=0.015), APOB/A (P=0.02) and plasma oxLDL (P=0.002). Moreover, an increase in the estimated As and Hg levels in shellfish was associated with an increase in LDLc (P=0.015 and P=0.018, respectively), non-HDLc (P<0.008 and P<0.008, respectively), APOB/A ratio (P=0.008 and P=0.009, respectively), and oxLDL (P≤0.001 and P≤0.001, respectively) levels. In conclusion, in adults without risk factors for CVD, increasing shellfish consumption, even by a moderate amount, could favour a pro-atherogenic lipid profile and a higher level of oxidised LDL. These associations are likely influenced by the estimated exposure to As and Hg from shellfish despite these values are lower than the PTWIs.

Impact of fetal and childhood mercury exposure on immune status in children

BACKGROUND

Mercury exposure have been shown to affect immune status in animals as reflected by cytokine expression. It is unclear whether low levels of exposure during fetal and/or childhood periods could impact on immune status in humans.

OBJECTIVES

To test the hypothesis that fetal and childhood mercury exposure is associated with childhood cytokine profiles and to investigate whether childhood selenium levels interact with any of the associations found.

METHODS

Children were recruited from a previously established birth cohort between the ages of 6-9 years for assessment and measurement of blood mercury, selenium and cytokine profile (interleukin (IL)-4, IL-6, IL-8, IL-10, IL-13 and TNF-alpha). Multivariable linear regression models were used to assess the adjusted association of cord blood mercury concentration and current mercury concentrations with levels of the cytokine levels. We tested whether the association with current mercury level varied by current selenium level and cord blood mercury level.

RESULTS

IL-10 was negatively associated with current blood mercury concentration. The effect was greatest in cases with low cord blood mercury and low current selenium concentrations. None of the other cytokine levels were associated with either cord blood or current blood mercury concentrations, except that cord blood mercury was negatively associated with IL-6.

CONCLUSIONS

Childhood mercury exposure was negatively associated with childhood IL-10 levels. It is postulated that while selenium is protective, low levels of fetal mercury exposure may increase the degree of this negative association during childhood. Further studies into the clinical significance of these findings are required.

Consensus document on the prevention of methylmercury exposure in Spain: Study group for the prevention of Me-Hg exposure in Spain (GEPREM-Hg)

The beneficial effects of fish consumption in both children and adults are well known. However, the intake of methylmercury, mainly from contaminated fish and shellfish, can have adverse health effects. The study group on the prevention of exposure to methylmercury (GEPREM-Hg), made up of representatives from different Spanish scientific societies, has prepared a consensus document in a question and answer format, containing the group's main conclusions, recommendations and proposals. The objective of the document is to provide broader knowledge of factors associated with methylmercury exposure, its possible effects on health amongst the Spanish population, methods of analysis, interpretation of the results and economic costs, and to then set recommendations for fish and shellfish consumption. The group sees the merit of all initiatives aimed at reducing or prohibiting the use of mercury as well as the need to be aware of the results of contaminant analyses performed on fish and shellfish marketed in Spain. In addition, the group believes that biomonitoring systems should be set up in order to follow the evolution of methylmercury exposure in children and adults and perform studies designed to learn more about the possible health effects of concentrations found in the Spanish population, taking into account the lifestyle, eating patterns and the Mediterranean diet.

Mercury and psychosocial stress exposure interact to predict maternal diurnal cortisol during pregnancy

BACKGROUND

Disrupted maternal prenatal cortisol production influences offspring development. Factors influencing the hypothalamic-pituitary-adrenal axis include social (e.g., stressful life events) and physical/chemical (e.g., toxic metals) pollutants. Mercury (Hg) is a common contaminant of fish and exposure is widespread in the US. No prior study has examined the joint associations of stress and mercury with maternal cortisol profiles in pregnancy.

OBJECTIVES

To investigate potential synergistic influences of prenatal stress and Hg exposures on diurnal cortisol in pregnant women.

METHODS

Analyses included 732 women (aged 27.4 ± 5.6 years) from a Mexico City pregnancy cohort. Participants collected saliva samples on two consecutive days (mean 19.52 ± 3.00 weeks gestation) and reported life stressors over the past 6 months. Hg was assessed in toe nail clippings collected during pregnancy.

RESULTS

There were no main effects of Hg or psychosocial stress exposure on diurnal cortisol (ps > .20) but strong evidence of interaction effects on cortisol slope (interaction B = .006, SE = .003, p = .034) and cortisol at times 1 and 2 (interaction B = -.071, SE = .028, p = .013; B = -.078, SE = .032, p = .014). Women above the median for Hg and psychosocial stress exposure experienced a blunted morning cortisol response compared to women exposed to higher stress but lower Hg levels.

CONCLUSIONS

Social and physical environmental factors interact to alter aspects of maternal diurnal cortisol during pregnancy. Research focusing solely on either domain may miss synergistic influences with potentially important consequences to the offspring.

Blood mercury can be a factor of elevated serum ferritin: analysis of Korea National Health and Nutrition Examination Survey (KNHANES 2008-2012)

Serum ferritin as well as blood mercury are reported to be associated with chronic inflammation. However, the relation between serum ferritin and blood mercury has not yet been established. We utilized the Korea National Health and Nutrition Examination Survey (KNHANES, 2008-2012) 10,977 subjects (5433 males and 5544 females). To evaluate the association of serum ferritin and blood mercury cross-sectionally, complex sample analysis was conducted after adjustment for the relevant variables. Serum concentrations of ferritin and blood mercury were higher in males than in females (115.7 ± 1.7 vs. 40.9 ± 0.7 ng/mL and 5.0 ± 0.1 vs. 3.6 ± 0.1 μg/L, respectively). Serum ferritin and blood mercury concentrations had significant correlations in both genders after adjustment (r = 0.062, P < 0.001 in males; r = 0.055, P < 0.001 in females). The analysis of covariance (ANCOVA) test showed significantly higher serum ferritin according to the tertile of blood mercury (P = 0.007) in males. The adjusted odds ratio of having the highest tertile of serum ferritin in the top tertile of blood mercury in males was 1.52 (95 % confidence interval (CI), 1.05-2.21). Thus, the current study indicates that blood mercury concentration can be a factor for the elevated serum ferritin concentration.

Urine cortisol concentration as a biomarker of stress is unrelated to IVF outcomes in women and men

PURPOSE

Our primary objective was to assess associations between urine cortisol as a biomarker of psychological stress and in vitro fertilization (IVF) outcomes. A secondary objective was to assess associations between toxic metals and cortisol.

METHODS

Urine and blood specimens were collected from 52 women and 28 male partners completing a first IVF procedure, on the day of oocyte retrieval. Urine cortisol was measured with an enzyme-linked immunosorbent assay. Mercury (Hg), cadmium (Cd), and lead (Pb) were determined in blood and Cd in urine by inductively coupled plasma-mass spectrometry.

RESULTS

No associations were indicated for cortisol with IVF outcomes in multivariable regression models adjusted for covariates. However, we detected positive linear associations for cortisol and urine Cd (β = 9.96, 95%CI 1.52, 21.44) and blood Hg (β = 1.44, 95%CI 0.31, 3.18). An exploratory stratified analysis suggested a potential inverse association between urine cortisol and oocyte fertilization among women with low, but not high blood Hg.

CONCLUSION

While limited, these preliminary data suggest that psychological stress may not play a major role in IVF outcomes, which therefore could be one less concern for couples and their clinicians. Our data also raise the possibility for toxic metals to modify associations between cortisol and IVF outcomes among women. However, these preliminary results require corroboration in an experimental animal model and confirmation in a larger, more definitive observational study.

Low-level mercury in children: associations with sleep duration and cytokines TNF-α and IL-6

There is a sizeable literature suggesting that mercury (Hg) exposure affects cytokine levels in humans. In addition to their signaling role in the immune system, some cytokines are also integrally associated with sleep behavior. In this cross-sectional study of 9-11 year old children (N=100), we measured total blood Hg in whole blood, serum levels of tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6), and objectively measured sleep and activity using actigraphy. Increasing blood Hg was associated with significantly shorter sleep duration and lower levels of TNF-α. IL-6 was not associated with sleep or blood Hg. This study is the first to document an association between total blood Hg and sleep (albeit a small effect), and the first to consider the associations of total blood Hg with cytokines TNF-α and IL-6 in a pediatric sample. Further research using alternative designs (e.g., time-series) is necessary to determine if there is a causal pathway linking low-level Hg exposure to sleep restriction and reduced cytokines.

Assessment of dietary fish consumption in pregnancy: comparing one-, four- and thirty-six-item questionnaires

OBJECTIVE

Fish consumption influences a number of health outcomes. Few studies have directly compared dietary assessment methods to determine the best approach to estimating intakes of fish and its component nutrients, including DHA, and toxicants, including methylmercury. Our objective was to compare three methods of assessing fish intake.

DESIGN

We assessed 30 d fish intake using three approaches: (i) a single question on total fish consumption; (ii) a brief comprehensive FFQ that included four questions about fish; and (iii) a focused FFQ with thirty-six questions about different finfish and shellfish.

SETTING

Obstetrics practices in Boston, MA, USA.

SUBJECTS

Fifty-nine pregnant women who consumed ≤2 monthly fish servings.

RESULTS

Estimated intakes of fish, DHA and Hg were lowest with the one-question screener and highest with the thirty-six-item fish questionnaire. Estimated intake of DHA with the thirty-six-item questionnaire was 4·4-fold higher (97 v. 22 mg/d), and intake of Hg was 3·8-fold higher (1·6 v. 0·42 μg/d), compared with the one-question screener. Plasma DHA concentration was correlated with fish intake assessed with the one-question screener (Spearman r = 0·27, P = 0·04), but not with the four-item FFQ (r = 0·08, P = 0·54) or the thirty-six-item fish questionnaire (r = 0·01, P = 0·93). In contrast, blood and hair Hg concentrations were similarly correlated with fish and Hg intakes regardless of the assessment method (r = 0·35 to 0·52).

CONCLUSIONS

A longer questionnaire provides no advantage over shorter questionnaires in ranking intakes of fish, DHA and Hg compared with biomarkers, but estimates of absolute intakes can vary by as much as fourfold across methods.

Effect of water quality on mercury toxicity to Photobacterium phosphoreum: Model development and its application in natural waters

Mercury (Hg) compounds are widely distributed toxic environmental and industrial pollutants and they may bring danger to growth and development of aquatic organisms. The distribution of Hg species in the 3 percent NaCl solution was calculated using the chemical equilibrium model Visual MINTEQ, which demonstrated that Hg was mainly complexed by chlorides in the pH range 5.0-9.0 and the proportions of HgCl4(2-), HgCl3(-) and HgCl2(aq) reached to 95 percent of total Hg. Then the effects of cations (Ca(2+), Mg(2+), K(+) and H(+)), anions (HCO3(-), NO3(-), SO4(2-) and HPO4(2-)) and complexing agents (ethylene diamine tetraacetic acid (EDTA) and dissolved organic matter (DOM)) on Hg toxicity to Photobacterium phosphoreum were evaluated in standardized 15min acute toxicity tests. The significant increase of 6.3-fold in EC50 data with increasing pH was observed over the tested pH range of 5.0-8.0, which suggested the possible competition between hydroxyl and the negatively charged chloro-complex. By contrast, it was found that major cations (Ca(2+), Mg(2+) and K(+)) have little effect on Hg toxicity to P. phosphoreum. An interesting finding was that the addition of HPO4(2-) significantly increased Hg toxicity, which may imply that the addition of phosphate increased the soluble Hg-chloro complex species. Additions of complexing agents (EDTA and DOM) into the exposure water increased Hg bioavailability via complexation of Hg. Finally, a model which incorporated the effect of pH, HPO4(2-), HCO3(-), SO4(2-) and DOM on Hg toxicity was developed to predict acute Hg toxicity for P. phosphoreum, which may be a useful tool in setting realistic water quality criteria for different types of water.

Identification of Potential Serum Biomarkers in Mercury-Treated Mice Using a Glycoproteomic Approach

Mercury is a well-recognized health hazard and a deleterious environmental contaminant. Exposure to mercury can cause neurotoxic manifestations, nephrotoxicity, and immune function alterations; however, the mechanisms and related proteins responsible for these effects are still unclear. Our goal is to understand the relationship between the toxicity of mercury and the proteins affected by this toxic heavy metal and to define biomarkers for mercury intoxication. Two different forms of mercury, organic methylmercury or inorganic mercury sulfide, were orally administered to the mice for 4 weeks. To reduce complexity of the serum proteome, we enriched glycoproteins from mice serum with lectin concanavalin A resin, and the tryptic peptides of the purified glycoproteins were subjected to nanoultra performance liquid chromatography-Quadrupole time-of-flight for identification and label-free quantification. In this study, we characterized approximately 209 proteins from mice serum, and, among them, 21 proteins were differentially expressed in organic methylmercury-treated mice serum compared with the control group. Two proteins, serum amyloid P component (SAP) and inter α-trypsin inhibitor heavy chain 4 (ITI-H4), were upregulated in organic methylmercury-treated mice and confirmed with different doses of both types of mercury by Western blot analysis. Results of immunohistochemistry also confirmed the validity of SAP and ITI-H4 as biomarker candidates for organic methylmercury exposure. Findings of this study may assist in understanding the relationship between toxicity of mercury and upregulated proteins in mouse serum. Furthermore, the proteins identified here might be used as biomarker candidates in mercury intoxication.

Immobilized metal affinity chromatography and human serum proteomics

Metal-binding proteins have a pivotal role in normal and diseased states. We used metal affinity chromatography to enrich a fraction of human serum proteins on immobilized columns loaded with cadmium, nickel, zinc, copper, or lead in bis-Tris saline and these proteins were identified using LC-MS/MS. Tens of enriched proteins were identified and we here present the 20 most abundant for binding each metal. The binding of various proteins (complement C3, alpha-2-macroglobulin, serum albumin, apolipoprotein B-100, complement component 4B preproprotein, apolipoprotein A-I, serotransferrin, alpha-1-antitrypsin, ceruloplasmin, 47kDa protein, uncharacterized protein DKFZp686P15220, transthyretin, hemopexin, inter-alpha-trypsin inhibitor heavy chain H2, and histidine-rich glycoprotein) to different metals using immobilized metal affinity chromatography was compared to the literature. Although many metal-binding properties of these proteins have been confirmed, new metal-binding proteins have also been identified. The metal array use in the proteomic biomarker search technologies gives this data particular importance.

Chronic exposure of adult rats to low doses of methylmercury induced a state of metabolic deficit in the somatosensory cortex

Because of the ever-increasing bioaccumulation of methylmercury (MeHg) in the marine food chain, human consumers are exposed to low doses of MeHg continually through seafood consumption. Epidemiological studies strongly suggest that chronic prenatal exposure to nanomolar of MeHg has immense negative impacts on neurological development in neonates. However, effects of chronic exposure to low doses (CELDs) of MeHg in adult brains on a molecular level are unknown. The current study aims to investigate the molecular effects of CELD of MeHg on adult somatosensory cortex in a rat model using proteomic techniques. Young adult rats were fed with a low dose of MeHg (40 μg/kg body weight/day) for a maximum of 12 weeks. Whole proteome expression of the somatosensory cortex (S1 area) of normal rats and those with CELD to MeHg were compared. Levels of MeHg, total calcium, adenosine triphosphate (ATP), and pyruvate were also measured. Comparative proteomic studies of the somatosensory cortexes revealed that 94 proteins involved in the various metabolic processes (including carbohydrate metabolism, generation of precursors for essential metabolites, energy, proteins, cellular components for morphogenesis, and neurotransmission) were down-regulated. Consequently, levels of important end products of active metabolism including ATP, pyruvate, and total calcium were also found to be significantly reduced concomitantly. Our results showed that CELD of MeHg induced a state of metabolic deficit in the somatosensory cortex of adult rats.