Hair THg Research Articles

Mercury Levels in Hair of Pregnant Women in Tumbes, Peru: A Cross-Sectional Study

Mercury, a potent toxin that poses serious risks to human health, particularly for pregnant women and young children, is widely present due to artisanal and small-scale gold mining (ASGM), which impacts water quality. The objective of this study was to evaluate methylmercury exposure among pregnant women in communities downstream from ASGM sites. We characterized hair total mercury (THg) concentrations among 148 pregnant women across 24 communities in the Tumbes region of Peru, downstream from ASGM sites in Ecuador. Using purposeful sampling, we classified communities into three exposure risk zones: Puyango-Tumbes River watershed, Coast, and Zarumilla. The mean THg concentration was 2.08 µg/g ± 1.36, with 45% of participants (67/148) exceeding UNEP/WHO exposure limits (>2.0 µg/g). The median was 1.84 with an interquartile range (IQR) from 1.01 to 2.83. Median THg levels were significantly higher in the Puyango-Tumbes River region (2.72 µg/g; IQR: 1.66–3.55) compared with Zarumilla (1.61 µg/g; IQR: 0.67–2.63; P = 0.001) and to the Coast (1.71 µg/g; IQR: 1.13–2.50; P = 0.01), suggesting that living close to the Puyango-Tumbes River may be associated with a higher mercury exposure risk. After controlling for potential confounders, individuals in the Puyango-Tumbes watershed exhibited a significant 57% higher expected geometric mean of hair THg compared with Zarumilla (95% CI: 0.1–146.2%). These findings underscore the importance of identifying high-risk regional populations and ongoing biomonitoring of the Puyango-Tumbes River watershed.

Dietary intake of methylmercury by 0-5 years children using the duplicate diet method in Japan.

The developing brains are sensitive to methylmercury (MeHg). However, the exposure to MeHg in baby foods and toddler meals remains unknown. This study aimed to determine MeHg intake from baby food or toddler meals, and to investigate the relationship with child hair total mercury (THg). A total of 3 days of 24-hour dietary diet and hair samples were collected from 260 consenting children aged 0-5 years. We measured the concentrations of THg and MeHg in the diet and THg in the hair. The results of measuring THg were below both the method detection and method quantification limits or either of both in powdered milk (93.8%), 5-6 months (53.3%), and 7-8 months (39.5%). The median daily THg intake was 20.3 (95% confidence interval 0.72-232.5) ng/kgbw. MeHg was not detected in 213 samples with dietary THg concentrations below 1 ng/g. The MeHg concentration with THg concentrations of 1 ng/g or higher was 1.70 (0.87-6.21) ng/g, and MeHg percentage in THg was 90.0%. To estimate MeHg intake, we multiplied the THg concentration by 90.0%, resulting in an estimated MeHg intake of 18.3 (0.65-209.2) ng/kgbw/day. The THg in children's hair was 1.05 (0.31-3.96) ppm, and a weak positive correlation was observed between hair THg and dietary MeHg (r = 0.170). This study highlights the accurate estimation of MeHg intake in children using a duplicate method. Japanese children consume fish, the MeHg intakes exceeded the reference dose and/or provisional tolerable weekly intake in several children. Further discussion based on epidemiological data is required.

Exposure to mercury among Spanish adolescents: Eleven years of follow-up

The toxic effects of mercury exposure on human health are a public health concern. The most important source of this exposure is the consumption of fish and marine mammals. This study aims to describe hair mercury concentrations and their evolution from birth until eleven years of age in adolescents from the INMA (Environment and Childhood) birth cohort study, and to assess the association of hair mercury concentrations at eleven years of age with sociodemographic and dietary factors.The sample comprised 338 adolescents from the sub-cohort of Valencia (in eastern Spain). Total mercury (THg) was measured in hair samples collected at 4, 9 and 11 years old and in cord blood at birth. The equivalent of hair for cord-blood THg concentrations was calculated. Fish consumption and other characteristics at 11 years old were collected through questionnaires. Multivariate linear regression models were conducted to explore the association between THg concentrations, fish consumption and covariates.The geometric mean of hair THg concentrations at 11 years of age was 0.86 μg/g (95%CI: 0.78–0.94) and 45.2% of the participants presented concentrations above the equivalent RfD proposed by the US EPA (1 μg/g). Consumption of fish such as swordfish, canned tuna and other large oily fish was associated with higher levels of hair mercury at 11 years of age. Swordfish had the highest effect with an increase of 125% in hair mercury (95%CI: 61.2–214.9%) given a 100 g/week increase in its consumption, and, taking into account the frequency of consumption, canned tuna was the main contributor to Hg exposure among our population. The hair THg concentrations at 11 years of age represented a reduction of around 69% with respect to that estimated at childbirth. Even though THg exposure shows a sustained decreasing trend, it can still be considered elevated. INMA birth cohort studies provide a longitudinal assessment of mercury exposure in a vulnerable population, its associated factors and temporal trends, and this information could be used to adjust recommendations about this issue.

Efficacy of Hair Total Mercury Content as a Biomarker of Methylmercury Exposure to Communities in the Area of Artisanal and Small-Scale Gold Mining in Madre de Dios, Peru

Total mercury content (THg) in hair is an accepted biomarker for chronic dietary methylmercury (MeHg) exposure. In artisanal and small-scale gold mining (ASGM) communities, the validity of this biomarker is questioned because of the potential for contamination from inorganic mercury. As mining communities may have both inorganic and organic mercury exposures, the efficacy of the hair-THg biomarker needs to be evaluated, particularly as nations begin population exposure assessments under their commitments to the Minamata Convention. We sought to validate the efficacy of hair THg for public health monitoring of MeHg exposures for populations living in ASGM communities. We quantified both THg and MeHg contents in hair from a representative subset of participants (N = 287) in a large, population-level mercury exposure assessment in the ASGM region in Madre de Dios (MDD), Peru. We compared population MeHg-THg correlations and %MeHg values with demographic variables including community location, sex, occupation, and nativity. We observed that hair MeHg-THg correlations were high (r > 0.7) for all communities, regardless of location or nativity. Specifically, for individuals within ASGM communities, 81% (121 of 150 total) had hair THg predominantly in the form of MeHg (i.e., >66% of THg) and reflective of dietary exposure to mercury. Furthermore, for individuals with hair THg exceeding the U.S. EPA threshold (1.0 μg/g), 88 out of 106 (83%) had MeHg as the predominant form. As a result, had urine THg solely been used for mercury exposure monitoring, approximately 59% of the ASGM population would have been misclassified as having low mercury exposure. Our results support the use of hair THg for monitoring of MeHg exposure of populations in ASGM settings where alternative biomarkers of MeHg exposure are not feasible.

CoNaMad-Cohorte de Nacimiento de Madre de Dios/Madre de Dios Birth Cohort to Study Effects of in-utero Trace Metals Exposure in the Southern Peruvian Amazon.

Background:In-utero exposure to mercury and other trace metals pose a significant threat to child health and development, but exposures and health impacts in artisanal and small-scale gold mining (ASGM) environments are poorly defined.Objectives:We describe the CONAMAD study design, a prospective birth cohort consisting of multiparous women (18 and over) living in rural and peri-urban Peruvian Amazon communities exposed to ASGM.Methods:Pregnant women are enrolled from health posts across four zones of Madre de Dios, Peru. Data are collected at enrollment, childbirth, and (planned) 36-48 months. At enrollment, hair samples for mercury assessment, demographic and clinical data are obtained. At birth, we obtain venous and cord blood, placenta, hair, toenails, and saliva.Findings:Two hundred seventy mothers were enrolled at an average 20 weeks gestational age with no differences in maternal characteristics across zones. Two hundred fifteen mothers were successfully followed at birth. We obtained 214 maternal and cord blood samples, 211 maternal and 212 infant hair samples, 212 placenta samples, 210 infant saliva samples, and 214 infant dried blood spots. Data collected will allow for testing our primary hypotheses of maternal malnutrition modifying ratios of cord:maternal blood total mercury (tHg), cord blood:maternal hair tHg, and infant:maternal hair tHg, and whether chemical mixtures (Hg, Pb, Cd) have synergistic effects on infant neurodevelopment.Conclusions:CONAMAD is designed to collect and store samples for future processing and hypothesis testing associated with in-utero mercury exposure and child development. We have completed the exposure assessments and will conduct a follow-up of mothers to evaluate early child development outcomes, including developmental delay and growth. These data offer insights into disease mechanisms, exposure prevention, and policy guidance for countries where ASGM is prevalent.

Maternal methylmercury exposure through rice ingestion and child neurodevelopment in the first three years: a prospective cohort study in rural China

BackgroundRice is an important dietary source for methylmercury; however, rice does not contain the same beneficial nutrients as fish. Our main objective was to assess associations of prenatal methylmercury exposure through rice ingestion with child neurodevelopment in rural China.MethodsEligible peripartum women were enrolled (n = 391), provided peripartum hair samples, and children’s neurodevelopment was assessed at 12 months (n = 264, 68%) and 36 months (n = 190, 48%) using the Bayley Scales of Infant Development, 2nd Edition, including the Mental Developmental Index (MDI) and the Psychomotor Developmental Index (PDI). Associations between prenatal methylmercury exposure during the third trimester [log2 maternal hair total mercury (THg)] and child’s neurodevelopment were assessed using linear mixed models for repeated measures.ResultsIn adjusted models, a doubling in maternal hair THg corresponded to a 1.3-point decrement in the MDI score [95% confidence interval (CI): − 2.6, − 0.14], and a 1.2-point decrement in the PDI score (95% CI: − 2.6, 0.14). Overall, adverse associations between maternal hair THg and MDI scores attenuated over time. However, associations were robust and stable over time among children whose primary caregiver was their parent(s). During the study follow-up, an increasing proportion of children were raised by grandparents (12 months: 9% versus 36 months: 27%), a trend associated with rural-to-urban parental migration for work.ConclusionsFor young children living in rural China, a biomarker of prenatal methylmercury exposure was associated with decrements in cognitive function assessed between 12 and 36 months of age. Changes in the family structure over the study follow-up time interval potentially impacted children’s sensitivity to prenatal methylmercury exposure.

Prenatal low-level methyl mercury exposure and child development in an Italian coastal area

Environmental studies have identified mercury pollution in the Northern Adriatic Sea (Italy). High- level methyl mercury exposure is a known cause of neurodevelopmental disorders. However, the exposure-effect relation at levels <10ppm is controversial. To assess the possible health effects of prenatal methyl mercury exposure through maternal fish consumption, we conducted an epidemiologic cohort study in a mercury polluted area of the Adriatic Sea. We identified all the children born between 1999 and 2001 to women who were resident in two coastal fishing towns. A comparison group was identified inland. A total of 243 children were enrolled. Their mothers were interviewed approximately two months after delivery to determine a variety of covariates and the type, quantity and origin of fish consumed during pregnancy. Total mercury (THg) and methyl mercury (MeHg) were assessed in maternal hair and breast milk and in the child's hair. The children were evaluated after age 18 months with a physical examination and the Denver Developmental Screening Test II (DDST II). Statistical analyses matched by residential area are not presented since they were not associated with fresh fish consumption, THg or MeHg exposure level or neurodevelopmental outcomes. To date 52 children have been evaluated. After adjustment for a number of potential confounders, preliminary results indicate that the fine motor adaptive score on the Denver Developmental test is inversely related to maternal hair THg. These pilot findings are suggestive of an association between children's fine motor skills and their prenatal methyl mercury exposure from maternal fish consumption. However, only a small number of the cohort have been tested and more extensive testing with more sensitive and specific tests is needed to determine if these findings persist.

Mercury exposure in mammalian mesopredators inhabiting a brackish marsh.

Bioaccumulation of environmental contaminants in mammalian predators can serve as an indicator of ecosystem health. We examined mercury concentrations of raccoons (Procyon lotor; n=37 individuals) and striped skunks (Mephitis mephitis; n=87 individuals) in Suisun Marsh, California, a large brackish marsh that is characterized by contiguous tracts of tidal marsh and seasonally impounded wetlands. Mean (standard error; range) total mercury concentrations in adult hair grown from 2015 to 2018 were 28.50μg/g dw (3.05μg/g dw; range: 4.46-81.01μg/g dw) in raccoons and 4.85μg/g dw (0.54μg/g dw; range: 1.53-27.02μg/g dw) in striped skunks. We reviewed mammalian hair mercury concentrations in the literature and raccoon mercury concentrations in Suisun Marsh were among the highest observed for wild mammals. Although striped skunk hair mercury concentrations were 83% lower than raccoons, they were higher than proposed background levels for mercury in mesopredator hair (1-5μg/g). Hair mercury concentrations in skunks and raccoons were not related to animal size, but mercury concentrations were higher in skunks in poorer body condition. Large inter-annual differences in hair mercury concentrations suggest that methylmercury exposure to mammalian predators varied among years. Mercury concentrations of raccoon hair grown in 2017 were 2.7 times greater than hair grown in 2015, 1.7 times greater than hair grown in 2016, and 1.6 times greater than hair grown in 2018. Annual mean raccoon and skunk hair mercury concentrations increased with wetland habitat area. Furthermore, during 2017, raccoon hair mercury concentrations increased with the proportion of raccoon home ranges that was wetted habitat, as quantified using global positioning system (GPS) collars. The elevated mercury concentrations we observed in raccoons and skunks suggest that other wildlife at similar or higher trophic positions may also be exposed to elevated methylmercury bioaccumulation in brackish marshes.

A Study on Hair Mercury Levels of University Students.

Total mercury (THg) and methylmercury (MeHg) concentrations were measured in hair of 98 Chinese university students to study their levels of Hg exposure and influencing factors. The results showed that Hg exposure for university students was at a low level with concentrations lower than the USEPA recommended reference level (1µg/g) across all hair samples. The percentage of MeHg to THg (%MeHg) in hair was about 50%, lower than the previously reported value of 70-100%, probably associated with the low %MeHg in the diet of university students. Fish and rice consumption were not a primary factor affecting hair Hg levels of university students, while smoking could be one main pathway of Hg exposure. In addition, the similarly dietary structure in the studied university narrowed the difference of Hg exposure levels among students.

Climate-associated drivers of plasma cytokines and contaminant concentrations in Beaufort Sea polar bears (Ursus maritimus)

Assessing polar bear (Ursus maritimus) immune function in relation to environmental stressors, including habitat change, nutritional stress, pathogen prevalence, and pollution, has been identified as critical for improved understanding of the species' health. The objectives of this study were two-fold: 1) to assess the role of climate-associated factors (habitat use, body condition) in explaining the plasma concentrations of contaminants in southern Beaufort Sea (SB) polar bears, and 2) to investigate how climate-associated factors, contaminant concentrations, and pathogen sero-prevalence influence the plasma concentrations of immune-signaling proteins called cytokines. A commercially available multiplex canine cytokine panel was validated for the quantification of five pro- and anti-inflammatory cytokines in polar bear plasma: tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), IL-8, IL-10, and interferon gamma-induced protein 10 (IP-10). This panel was then used to measure cytokine concentrations in 49 SB polar bears sampled in the springs of 2013 and 2014. Mean ∑PCBs (plasma), ∑OCs (plasma), and THg (hair) were 13.01 ± 1.52 ng g−1 w.w. (range: 0.17–52.63), 19.46 ± 1.17 ng g−1 w.w. (range: 6.63–45.82), and 0.49 μg g−1 d.w. (range: 0.99–15.18), respectively. Top models explaining variation in concentrations of plasma PCBs, plasma OC pesticides, and hair THg in SB polar bears included body mass index and/or habitat use (onshore versus offshore), with higher contaminant concentrations in leaner and/or offshore bears. Plasma cytokine concentrations were influenced most strongly by plasma PCBs and age, with little to no influence found for plasma OCs or hair THg concentrations, habitat use, or pathogen sero-prevalence. The lack of association between cytokines and these latter variables is likely due to a temporal disconnect between measured endpoints. The change of polar bear habitat use, feeding ecology, and body condition with ongoing climate warming is affecting exposure to contaminants and pathogens, with potential adverse consequences on a well-balanced immune system.

Association between genetic variations in GSH-related and MT genes and low-dose methylmercury exposure in children and women of childbearing age: a pilot study

BackgroundGenetic variations in glutathione (GSH)-related and metallothionein (MT) genes, which are involved in producing enzymes in the methylmercury (MeHg) metabolism pathway, have been proposed as one of the reasons for the individual variability in MeHg toxicokinetics. ObjectiveTo investigate the impact of genetic variations in MT and GSH-related genes on the association of fish consumption with body burden of MeHg, as measured by hair Hg concentrations among young children and women of childbearing age. MethodsA total of 179 unrelated children and 165 mothers with either high or low fish consumption were recruited from the community. Their hair total Hg (tHg) and MeHg levels and genotypes for SNPs located on the GCLC, GCLM, GPX1, GSTA1, GSTP1, MT1A, MT2A, and MT4 genes were determined. Based on their 14-day food records, the amounts of fish consumed and their MeHg intakes were estimated. The impact of genetic variations on hair Hg concentrations was examined by using Mann-Whitney tests and multivariable linear regression analyses. ResultsThe presence of minor alleles of GCLC-129 (rs17883901), GPX1-198 (rs1050450) and MT1M (rs9936741) were associated with significantly lower hair tHg levels in mothers whereas mothers with minor alleles of GSTP1-105(rs1695) and MT1M (rs2270836) have significantly higher hair tHg levels. After adjustment for fish consumption and other confounding factors, apart from MT1M (rs2270836), all of the above SNPs remain significant in the multivariable linear regression models. ConclusionsOur results in a group of children and women show that genetic variants of GSH-related and MT genes are associated with hair Hg concentrations. These genetic variations are likely to significantly affect MeHg metabolism and thus influence the accumulation of Hg in the human body.

BIOACCUMULATION OF MERCURY IN A TERRESTRIAL CARNIVORE, AMERICAN MARTEN (MARTES AMERICANA).

Studies that assess mercury bioaccumulation in small carnivores in terrestrial habitats are limited. We quantified total mercury (THg) in American marten (Martes americana) that were harvested for fur in Michigan, US, during 2013 and 2014. We quantified THg (dry weight) in hair, kidney, and liver samples and further analyzed hair for potential demographic and ecological factors that influence THg bioaccumulation. We found THg concentrations to be the highest in hair (1.228±0.475 µg/g, n=40), followed by kidney (0.922±0.651 µg/g, n=29) and liver (0.344±0.219 µg/g, n=26). Total mercury distributed predictably and significantly between tissue types, and hair was moderately predictive at modeling THg in kidney (R2=0.50, P<0.001, n=29) and weakly predictive in liver (R2=0.35, P<0.001, n=26), suggesting that hair, which is easily obtained, could be a useful sample type for future biomonitoring programs. The concentrations of THg in hair were higher in adults relative to juveniles, and adult female martens had the highest levels of THg (1.980±0.188 µg/g), as compared to juveniles and adult males. Results of generalized linear modeling suggested that THg hair concentrations were positively associated with marten age and trophic position (stable isotope ratio, δ15N). An interaction between δ15N and the year marten carcasses were collected showed that δ15N alone could be highly predictive of THg in some years but not in others. Annual changes in diet could lead to differing rates of mercury bioaccumulation and alter the usefulness of δ15N to predict THg in marten tissues. Further research should explore the connections between changes in prey availability, types of prey consumed, and the influence on bioaccumulation rates of mercury in terrestrial system mesocarnivores.

Mercury exposure, risk factors, and perceptions among women of childbearing age in an artisanal gold mining region of the Peruvian Amazon

Recent studies from the Madre de Dios region of Peru report elevated mercury exposure among the general population. Our objective was to assess mercury exposure, risk factors, risk perceptions, and knowledge among women of childbearing age, a population of concern due to risks to infant and fetal health. We collected hair samples and administered a survey among 200 women aged 18–49 years residing in Madre de Dios. Hair total mercury (THg) concentrations were analyzed in accordance with EPA Method 7473. Associations between exposures and potential risk factors were analyzed using generalized linear mixed models. Geometric mean hair THg concentration (±standard deviation) for all participants was 1.62 ± 2.54 μg/g (range: 0.01–30.12 μg/g), and 67 participants (33.5%) had concentrations above the 2.2 μg/g reference dose established by the World Health Organization (WHO). Higher exposure was significantly associated with higher fish consumption (p = 0.03) and less mercury knowledge (p < 0.0001), but not with age or educational attainment. Most participants (86.2%) expressed concern about mercury contamination, but few (26.2%) had knowledge of the health risks associated with exposure. Many residents consumed fish species previously found to have low mercury concentrations, but more than 25% of participants reported consuming fish species with high mercury concentrations. We did not observe cross-sectional differences in fish intake among women who were pregnant or breastfeeding at the time of data collection.

Exposure to mercury among 9-year-old Spanish children: Associated factors and trend throughout childhood

Mercury is considered a neurotoxicant and human exposure occurs mainly from the consumption of marine species. We aimed to describe total mercury concentrations (THg) and associated factors in 9-year old children, as well as to explore the trend in THg from 4 to 9 years of age. The study population consisted of 9-year-old children participating in the INMA (Environment and Childhood) birth cohort study in Valencia, Spain (n = 405, 2013–2014). THg in hair samples was measured by atomic absorption spectrometry at the age of 4 and 9 years. Sociodemographic and dietary data was obtained through questionnaires. Multiple linear regression was used to explore the association between THg and covariates.The geometric mean (95% confidence interval) of hair THg at 9 years old was 0.89 μg/g (0.81, 0.98). Thirteen percent of children had THg above the equivalent to the Provisional Tolerable Weekly Intake proposed by the World Health Organization. THg were higher among children whose mothers had a healthy body mass index before pregnancy. Children with non-smoker mothers and worker fathers had also higher THg. Children's fish intake at 9 years-old was positively associated with THg, being swordfish, canned tuna and lean fish (i.e. hake, sea bream and sole) the most associated categories. Levels decreased by around 22% between 4 and 9 years old.Birth cohort studies, such as the INMA Project, allow the longitudinal evaluation of Hg exposure and the possible effects on children's health. This information can be used to formulate diet recommendations in vulnerable populations.

Assessment of Total Mercury in Hair, Urine and Fingernails of Small-Scale Gold Miners in the Amansie West District, Ghana.

Background.Mercury (Hg) is a heavy metal that can cause several adverse health effects based on its form (organic, inorganic or elemental), duration and pathway of exposure. Measurement of mercury present in human biological media is often used to assess human exposure to mercury at mining sites.Objectives.The aim of the present study was to measure the concentrations of total mercury in urine, hair, and fingernails of miners and inhabitants of Amansie West District, Ghana.Methods.Concentrations of total mercury were measured in sixty–eight miners and twelve non–miners in the study area using cold vapor atomic absorption spectrophotometry with an automatic mercury analyzer (HG 5000).Results.Total mercury in nails and hair of smelter miners was 3.32 ± 0.36 and 6.59 ± 0.01 μg/g, respectively. Total mercury concentrations in hair samples obtained from smelter miners were above the 1 μg/g guideline set by the United States Environmental Protection Agency (USEPA). Moreover, the total mercury concentration in urine samples was 6.97 ± 0.06 μg/L, far below the >25 μg/L level considered to be a high level of mercury contamination. The total mercury accrued by the individuals was not dependent on age, but was positively associated with duration of stay.Conclusions.Based on the total mercury (THg) levels analyzed in the biological media, artisanal gold mining activities in Amansie West District are on the increase with a potential risk of developing chronic effects. However, the majority of the population, particularly those engaged in artisanal small–scale gold mining, are unmindful of the hazards posed by the use of mercury in mining operations. The results showed that THg in urine, hair, and fingernails more efficiently distinguished mercury exposure in people close to mining and Hg pollution sources than in people living far from the mining sites. Further education on cleaner artisanal gold mining processes could help to minimize the impact of mercury use and exposure on human health and the environment.Participant Consent.ObtainedEthics Approval.This study was approved by the Ghana Environmental Protection Agency and the Ministry of Local Government and Rural Development in Manso Nkwanta.Competing Interests.The authors declare no competing financial interests.

Dietary human exposure to mercury in two artisanal small-scale gold mining communities of northwestern Colombia

Artisanal and small-scale gold mining (ASGM) is the largest anthropogenic source of mercury pollution worldwide, posing a grave threat to human health. The present study identifies current levels of mercury in the human population from mining areas of the Chocó Department, Colombia, through total mercury (THg) and methylmercury (MeHg) measurements in human hair. Mercury exposure of the local population was assessed in two towns affected by ASGM and was related to different variables of interest. Concentrations of THg in human hair ranged from 0.06 to 17.54ppm and the mean value for the subjects under study was 2.48ppm. Men had significantly higher levels than women in both towns (3.29ppm vs. 0.77ppm). Fish consumption was related to a marked increase of THg in hair, with mean values close to five times higher in frequent fish consumers (5–7 times/week) than in non-fish consumers (4.80ppm vs. 0.90ppm). A multiple linear regression model was fitted successfully (R=0.671) and reveals that gender, fish consumption and location of residence were significant indicators of Hg levels in hair, while no significant relationship was found for age. Approximately 60% of subjects tested had THg levels that exceeded the U.S. Environmental Protection Agency reference dose of 1.0ppm, while 25% surpassed that of the World Health Organization (2.2ppm).

Ecological Change Drives a Decline in Mercury Concentrations in Southern Beaufort Sea Polar Bears.

We evaluated total mercury (THg) concentrations and trends in polar bears from the southern Beaufort Sea subpopulation from 2004 to 2011. Hair THg concentrations ranged widely among individuals from 0.6 to 13.3 μg g-1 dry weight (mean: 3.5 ± 0.2 μg g-1). Concentrations differed among sex and age classes: solitary adult females ≈ adult females with cubs ≈ subadults > adult males ≈ yearlings > cubs-of-the-year ≈ 2 year old dependent cubs. No variation was observed between spring and fall samples. For spring-sampled adults, THg concentrations declined by 13% per year, contrasting recent trends observed for other Western Hemispheric Arctic biota. Concentrations also declined by 15% per year considering adult males only, while a slower, nonsignificant decrease of 4.4% per year was found for adult females. Lower THg concentrations were associated with higher body mass index (BMI) and higher proportions of lower trophic position food resources consumed. Because BMI and diet were related, and the relationship to THg was strongest for BMI, trends were re-evaluated adjusting for BMI as the covariate. The adjusted annual decline was not significant. These findings indicate that changes in foraging ecology, not declining environmental concentrations of mercury, are driving short-term declines in THg concentrations in southern Beaufort Sea polar bears.

Total mercury levels in hair of children aged 7 years before and after the Great East Japan Earthquake

The Great East Japan Earthquake on March 11, 2011 caused severe damage to the Sanriku coastal area, where we have been conducting a birth cohort study. The disaster occurred in the middle of 7-year-old examination. The mother-child pairs who participated in our study were compulsorily divided into two groups: the examination was finished for 157 children before the disaster, and for 335 after the disaster. We examined whether the disaster affected total mercury (THg) levels of the cohort, as well as a relationship between the THg levels at birth and at present. Although there was no significant difference between the predisaster and postdisaster groups for THg levels in cord blood (16.3 and 16.1ngg−1, respectively) or maternal hair at parturition (2.57 and 2.55μgg−1, respectively), the THg in hair of the 7-year-old children was significantly lower in the postdisaster group (1.79μgg−1) than in the predisaster group (2.51μgg−1). The difference remained significant after adjusting for the prenatal exposure level of THg. In the 492 mother-child pairs, the cord-blood THg was significantly correlated with the THg in maternal hair at parturition (r=0.846) and in hair of the 7-year-old children (r=0.147). In conclusion, the 29% decrease in hair THg after the disaster appears to have been due to the fact that children in the affected area could not consume fish/seafood as usual, probably because of destructive damage to the fishery. Nevertheless, the THg levels at 7years of age reflected the prenatal exposure levels to some extent.

Prenatal exposure to mercury and child fine motor development in an Eastern Mediterranean cohort

Introduction. We argue that the evidence about a relation between maternal total mercury (THg) and child fine motor (FM) neurodevelopmental scores remains insufficient. To fill this gap, we analyzed data from a prospective mother-child cohort recruited in Italy, Slovenia, Croatia and Greece within PHIME, EU Sixth FP. Methods. Study design and rationale of the study is described in Valent F et al J Epidemiol 2013;23(2):146-152. Varying by country, mothers were recruited during pregnancy or at child’s birth. Metals were measured in maternal hair and blood during pregnancy and in umbilical cord blood and breast milk. FM scores were calculated by a psychologist using Bayley III at 18 months. For this analysis we defined the exposure as higher quintiles of mother’s hair THg levels (ng/g) and the outcome as the lowest quintile of the scaled FM score (&lt;=10). Lifestyle, dietary and socioeconomic factors assessed by questionnaires were considered as potential confounders or effect modifiers. Multivariate logistic regression models were run against FM as binary outcome. Results. 2189 mothers were enrolled in the study during pregnancy. 1729 mother-child pairs provided information at child’s birth. Follow-up at 18 months was 85%. Mother’s hair THg quintiles cut-offs were 337, 566, 881,1456 ng/g. The odds ratio (OR) of an FM score &lt;= 10 for THg ≥ 337 ng/g was 2.04 (95% confidence interval: 1.33-3.21), adjusted for country, sex, breastfeeding duration and earlier introduction of fresh fish in the child’s diet. Results were consistent by country but did not show clear trends. Earlier introduction of fresh fish in child’s diet was linked with higher FM scores (p&lt;0.0245). Conclusions. Absence of a trend for THg level and use of a dichotomous FM outcome variable require caution. However, these results suggest further testing of this hypothesis in existing child cohorts that consider the relation of mercury with FM scores separately from gross psychomotor assessments.

Hair and bone as predictors of tissular mercury concentration in the Western Alaska Red Fox, Vulpes vulpes

We evaluated if total mercury (THg) concentrations of keratin-based and bone-based tissues can predict THg concentrations in skeletal muscle, renal medulla, renal cortex, and liver. The THg concentration in matched tissues of 65 red foxes, Vulpes vulpes, from western Alaska was determined. Hair THg concentration had a significant positive correlation with liver, renal medulla, renal cortex, and muscle. The THg concentration for males and females is moderately predictive of THg concentration in the renal cortex and liver for these foxes based on R2 values (R2=0.61 and 0.63, respectively). Bone is weakly predictive of THg concentration in muscle (R2=0.40), but not a reliable tissue to predict THg concentration in liver (R2=0.24), renal cortex (R2=0.35), or renal medulla (R2=0.25). These results confirm the potential use of trapped animals, specifically foxes, as useful Arctic sentinel species to inform researchers about patterns in THg levels over time as industrialization of the Arctic continues.