Blood Mercury Concentrations Research Articles

Variation in blood mercury concentrations in brown skuas (Stercorarius antarcticus) is related to trophic ecology but not breeding success or adult body condition

Mercury is a pervasive environmental contaminant that can negatively impact seabirds. Here, we measure total mercury (THg) concentrations in red blood cells (RBCs) from breeding brown skuas (Stercorarius antarcticus) (n = 49) at Esperanza/Hope Bay, Antarctic Peninsula. The aims of this study were to: (i) analyse RBCs THg concentrations in relation to sex, year and stable isotope values of carbon (δ13C) and nitrogen (δ15N); and (ii) examine correlations between THg, body condition and breeding success. RBC THg concentrations were positively correlated with δ15N, which is a proxy of trophic position, and hence likely reflects the biomagnification process. Levels of Hg contamination differed between our study years, which is likely related to changes in diet and distribution. RBC THg concentrations were not related to body condition or breeding success, suggesting that Hg contamination is currently not a major conservation concern for this population.

Effectiveness of Morelet's crocodile as a bioindicator of metal pollution and metallothionein response to spatial variations of metal exposure

• Significant differences for mercury between the factors tissue:site were detected. • Significant differences for zinc between the factors tissue:site were detected. • Metallothioneins in blood plasma were detected in all sites but in erythrocytes detection frequency was lower than 20%. Several studies have assessed the potential of crocodylians as bioindicators of environmental contamination. In this study, the Morelet's crocodile ( Crocodylus moreletii ) was used as a bioindicator of metal pollution across five locations in southeastern Mexico classified as having high, medium, and low anthropogenic impact. Total length and sex were determined for each animal and concentrations of metals and metallothioneins (MTs) were determined by using non-destructive tissues. Mercury (Hg) concentrations in crocodile blood and scutes generally exhibited a decreasing pattern from the higher impacted site to the lower impacted site ( x 2 (14) = 185.42, p < 0.001), suggesting that concentrations in these samples are sensitive enough to identify difference in the bioavailability of Hg within crocodile populations. The highest concentrations were detected in scutes from Laguna Guerrero (Hg = 0.60 ± 0.217 µg/g w.w.) and Nichupté-Bojorquez (Cd = 14.99 ± 2.95 µg/g w.w., Cu = 58.66 ± 11.29 µg/g w.w., Zn = 80.86 ± 80.54 µg/g w.w.). MTs in blood plasma were detected at all sites (27.48 ± 4.78 µg/mL) but was low in erythrocytes detection frequency, suggesting this latter fraction may not be useful for MTs analysis. In general, our study supports the utility of crocodiles as bioindicators of xenobiotic metal pollution. However, it is necessary for such studies to perform assays for specific MT isoforms and the effective concentrations of metals bound to this protein, and to determine metal concentrations in multiple environmental matrices from the sites under evaluation.

Blood mercury concentrations in four sympatric gull species from South Western France: Insights from stable isotopes and biologging

Mercury (Hg) is a toxic trace element widely distributed in the environment, which particularly accumulates in top predators, including seabirds. Among seabirds, large gulls (Larus sp) are generalist feeders, foraging in both terrestrial and marine habitats, making them relevant bioindicators of local coastal Hg contamination. In the present study, we reported blood Hg concentrations in adults and chicks of four different gull species breeding on the French Atlantic coast: the European herring gull (Larus argentatus), the Lesser black-backed gull (L. fuscus), the Great black-backed gull (L. marinus) and the Yellow-legged gull (L. michahellis). We also investigated the potential role of foraging ecology in shaping Hg contamination across species, using the unique combination of three dietary tracers (carbon, nitrogen and sulfur stable isotopes) and biologging (GPS tracking). A high concentration of Hg was associated with high trophic position and a marine diet in gulls, which was corroborated by birds’ space use strategy during foraging trips. Adults of all four species reached Hg concentrations above reported toxicity thresholds. Specifically, adults of Great black-backed gulls had a high trophic marine specialized diet and significantly higher Hg concentrations than the three other species. Blood Hg was 4–7 times higher in adults than in chicks, although chicks of all species received mainly marine and high trophic position prey, which is expected to be the cause of blood Hg concentrations of toxic concern. By using both stable isotopes and GPS tracking, the present study provides compelling insights on the main feeding habits driving Hg contamination in a seabird assemblage feeding in complex coastal environments.

Mercury concentrations in tuna blood and muscle mirror seawater methylmercury in the Western and Central Pacific Ocean

Understanding the relationship between mercury in seafood and the distribution of oceanic methylmercury is key to understand human mercury exposure. Here, we determined mercury concentrations in muscle and blood of bigeye and yellowfin tunas from the Western and Central Pacific. Results showed similar latitudinal patterns in tuna blood and muscle, indicating that both tissues are good candidates for mercury monitoring. Complementary tuna species analyses indicated species- and tissue- specific mercury patterns, highlighting differences in physiologic processes of mercury uptake and accumulation associated with tuna vertical habitat. Tuna mercury content was correlated to ambient seawater methylmercury concentrations, with blood being enriched at a higher rate than muscle with increasing habitat depth. The consideration of a significant uptake of dissolved methylmercury from seawater in tuna, in addition to assimilation from food, might be interesting to test in models to represent the spatiotemporal evolutions of mercury in tuna under different mercury emission scenarios.

Analysis of Whole Blood and Urine Trace Elements in Children with Autism Spectrum Disorders and Autistic Behaviors

The relationship between trace elements and neurological development is an emerging research focus. We performed a case–control study to explore (1) the differences of 13 trace elements chromium (Cr), manganese (Mn), cobalt (Co), zinc (Zn), arsenic (As), selenium (Se), molybdenum (Mo), cadmium (Cd), stannum (Sn), stibium (Sb), mercury (Hg), titanium (TI), and plumbum (Pb) concentration in whole blood and urine between autism spectrum disorder (ASD) children and their typical development peers, and (2) the association between the 13 trace elements and core behaviors of ASD. Thirty ASD subjects (cases) and 30 age-sex-matched healthy subjects from Baise City, Guangxi Zhuang Autonomous Region, China, were recruited. Element analysis was carried out by inductively coupled plasma-optical emission spectrometry. Autistic behaviors were assessed using Autism Behavior Checklist (ABC), Childhood Autism Rating Scale (CARS), and Children Neuropsychological and Behavior Scale (CNBS). The whole blood concentrations of Mo (p = 0.004), Cd (0.007), Sn (p = 0.003), and Pb (p = 0.037) were significantly higher in the ASD cases than in the controls. Moreover, Se (0.393), Hg (0.408), and Mn (− 0.373) concentrations were significantly correlated between whole blood and urine levels in ASD case subjects. There were significant correlations between whole blood Sb (0.406), Tl (0.365), Mo (− 0.4237), Mn (− 0.389), Zn (0.476), and Se (0.375) levels and core behaviors of ASD. Although the mechanism of trace element imbalance in ASD is unclear, these data demonstrate that core behaviors of ASD may be affected by certain trace elements. Further studies are recommended for exploring the mechanism of element imbalance and providing corresponding clinical treatment measures.

Heavy Metals Content in Whole Blood (Literature Review and Case Study)

Heavy metals content in whole blood was analyzed for Kyiv city residents, who were tested in 2019-2020 years. According to obtained results, the metals were divided into three group. 1) with elevated concentration in statistical sample and elevated threshold (mercury and arsenic); 2) with elevated concentrations for several patients while average concentration for sample did not exceed threshold (lead); 3) with single cases of increased concentrations that are not a risk to the health of the population, but pose a threat to a particular patient (Bi, Cd, Cr, Mo, Cs, Va). Some metals never exceeded the maximum allowable concentrations Al, Ba, Be, Au, Co, Cu, Mn, Ni, Pd, Pt, Sr, Ti, U, Zr). We recommend regular check-up for the concentrations of mercury and arsenic in blood, because these metals are the factors of population risk. When the metals concentrations in blood are elevated, the diagnosis should be established taking into account clinical history of the patient.

Association of Seafood Consumption and Mercury Exposure With Cardiovascular and All-Cause Mortality Among US Adults

Although seafood is known to contain heart-healthy omega-3 fatty acids, many people choose to limit their seafood consumption because of fear of mercury exposure from seafood. It is imperative to clarify the potential health effects of current mercury exposure in contemporary populations. To examine the association of seafood consumption and mercury exposure with all-cause and cardiovascular disease (CVD)-related mortality in the US general population. This prospective cohort study included adults 20 years or older who participated in the 2003 to 2012 cycles of the National Health and Nutrition Examination Survey; data were linked to mortality records through December 31, 2015. Data analysis was performed from January to March 10, 2021. Seafood consumption was assessed through two 24-hour dietary recalls, and mercury exposure was assessed by blood mercury levels. All-cause and CVD-related mortality. Multivariable Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% CIs of mortality associated with usual seafood consumption and blood mercury concentration quartiles. This study included 17 294 participants (mean [SD] age, 45.9 [17.1] years; 9217 [53.3%] female) with a mean (SD) blood mercury concentration of 1.62 (2.46) μg/L. During 131 276 person-years of follow-up, 1076 deaths occurred, including 181 deaths from CVD. The multivariable-adjusted HR for an increase in seafood consumption of 1 oz equivalent per day and all-cause mortality was 0.84 (95% CI, 0.66-1.07) and for CVD-related mortality was 0.89 (95% CI, 0.54-1.47). Blood mercury level was not associated with all-cause or CVD-related mortality. Comparing the highest with the lowest quartile of blood mercury concentration, the multivariable-adjusted HRs were 0.82 (95% CI, 0.66-1.05) for all-cause mortality and 0.90 (95% CI, 0.53-1.52) for CVD-related mortality. In this cohort study of US adults, seafood consumption and mercury exposure with the current seafood consumption level were not significantly associated with the risk of all-cause or CVD-related mortality. These findings may inform future public health guidelines regarding mercury exposure, seafood consumption, and cardiovascular health promotion.

Health effects of selected trace elements in hairdressing cosmetics on hairdressers in Enugu, Nigeria

Could trace elements in hairdressing cosmetics prove carcinogenic to hairdressers, who use them regularly as raw materials in hairdressing business? The toxic effects of selected trace elements contained in hairdressing cosmetics on hairdressers were investigated by regressing the quality of life values for hairdressers with their blood/urine levels of the toxic metals A hundred subjects were randomly drawn from a cluster of hairdressers. Blood lead level, 17.47 ± 4.59 µg/dL, confirmed that the hairdressers were regularly exposed to lead. Mean blood mercury level, 25.06 ± 4.11 ng/dL, was above the normal blood mercury concentration of less than 10–20 ng/mL. Mean blood cadmium level, 3.64 ± 1.87 µg/dL, was within the normal range, < 5.0 µg/dL. Mean urine arsenic level, 96.16 ± 38.34 µg/L, was above normal range, ≤ 50 μg/dL, but within high normal range, > 50 to < 200 μg/dL. Blood nickel level, 0.49 ± 0.20 µg/dL, was above both the healthy range, 0.14–0.65 µg/dL, and the most reliable value of 0.2 µg/dL. Negative correlations existed between the quality of life and levels for lead (R = − .017), mercury (R = − .008), arsenic (R = − .072) and nickel (R = − .168), but there was positive correlation with cadmium level (R = .123). At 0.096, the probability value (p value) for nickel was significant at 10%. P value as insignificant at 1%, 5% and 10% for lead (0.868), mercury (0.940), cadmium (0.224) and arsenic (0.475). Therefore, Ni contained in hairdressing cosmetics might have carcinogenic effects that affected the quality of life of hairdressers, unlike other trace elements tested, namely, lead, mercury, cadmium and arsenic. Further research with the tumor markers assessment is recommended to confirm the carcinogenic effect of Ni.

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

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

Methylmercury: A Human Biomonitoring Study of Portuguese Women of Childbearing Age

BACKGROUND AND AIM: Methylmercury (MeHg) is a toxic compound that undergoes bioaccumulation in the aquatic food chain. Predatory fish species are an important human exposure source. Portugal has the highest consumption of fishery products in the European Union (EU), above the EU and world average. The main target of MeHg is the central nervous system and the prenatal period represents a period of greatest vulnerability regarding neurodevelopmental effects on the foetus. Human biomonitoring (HBM) allows direct exposure assessment of human exposure to chemical compounds. Total mercury (THg) concentration in blood is usually considered an appropriate biomarker for estimating short-term internal exposure to MeHg in individuals with regular fish consumption. The aim of the present study was to evaluate the exposure of Portuguese women of childbearing age to MeHg through HBM. METHODS: Three hundred Portuguese women of childbearing age (25 to 44 years) were randomly selected among the participants in a cross-sectional epidemiological study carried out in Portugal (INSEF) in 2015. THg content was determined in whole blood samples by thermal decomposition and amalgamation atomic absorption spectrophotometry (TDA/AAS). RESULTS:Two samples had THg levels below LOQ (0.5 µg/L), and in the remaining (n=298), THg levels ranged from 0.6 to 35.0 µg/L. About 52% of the samples had values below 5 µg/L, a HBM value below which no adverse health effects are expected. However, 48% of samples revealed levels above 5 µg/L and therefore presented risk of adverse health effects. Blood mercury concentration values were higher in older women, in higher education level and residents in the Autonomous Region of Madeira, with statistically significant differences compared to the other groups (p0.05). CONCLUSIONS:This study reinforces the need to develop and implement in Portugal strategies regarding risk communication focused on the selection of fish species with lower MeHg concentration in order to reduce human exposure to this compound. KEYWORDS: Biomarkers of exposure, Exposure assessment, Food/nutrition, Heavy metals, Risk assessment

Associations of total blood mercury and blood methylmercury concentrations with diabetes in adults: An exposure-response analysis of 2005-2018 NHANES

ObjectiveTo examine the exposure-response relationship between mercury exposure and diabetes in adults, and to explore the possible effect modifications by selenium and omega-3 fatty acids. MethodsBiomarker data (total blood mercury and blood methylmercury) from individuals ≥20 years of age were obtained from the 2005–2018 NHANES. Diabetes was defined through questionnaires, fasting plasma glucose, 2 -h plasma glucose and hemoglobin A1c levels. The exposure-response relationship between mercury exposure and diabetes was assessed with logistic regression and restricted cubic splines. ResultsComparing the highest to lowest quartile of exposure, the multivariable-adjusted odds ratio (95 % CI) of diabetes was 0.76 (0.63−0.92) with total blood mercury and 0.82 (0.66−1.00) with blood methylmercury. The inverse associations between total blood mercury [0.55 (0.40−0.77)] and blood methylmercury [0.61 (0.38−0.97)] and diabetes were observed among individuals having higher intakes of selenium (Pfor interaction<0.05). Trends toward lower odds of diabetes with mercury exposure were mainly confined to individuals having higher intakes of omega-3 fatty acid, but the interactions were not significant. The inverse associations between total blood mercury and blood methylmercury and diabetes remained in sensitivity analyses after excluding patients with hypertension that may change their dietary intake of fish. Exposure-response analyses showed an initial decrease in odds of diabetes followed by a platform or a weaker decrease beyond 3 μg/L of total blood mercury and methylmercury concentrations, respectively. ConclusionsTotal blood mercury and blood methylmercury concentrations were inversely associated with diabetes in adults, and the associations were modified by selenium.

Concentrations of Lead, Mercury, Selenium, and Manganese in Blood and Hand Grip Strength among Adults Living in the United States (NHANES 2011–2014)

Exposure to lead and mercury can cause deficits in neuromotor function. Selenium and manganese are essential elements, hence both deficiency and excess could result in decreased neuromotor function. We aimed to examine hand grip strength, a marker of neuromotor function, and blood concentrations of lead, mercury, selenium, and manganese in the general U.S. population. We used data from the National Health and Nutrition Examination Survey (NHANES, 2011–2014) on 6199 participants ages 20–79 years. We assessed associations of blood concentration for these elements and grip strength with generalized regression models, and cubic splines to detect possible nonlinear relations, adjusting for confounders. The results showed that mercury and manganese were not associated with grip strength. Lead was associated with weaker grip strength in women (for 10-fold increase in lead, −2.4 kg; 95% CI: −4.2, −0.5), but not in men. Higher selenium was associated with stronger grip strength in women (8.5 kg; 95% CI: 1.9, 15.1) and men (4.6; 95% CI: −11.9, 21.0), although the association was not significant in the latter. In conclusion, lead exposure was associated with weaker grip strength in women, even at the low exposure levels in the population. Furthermore, low blood selenium level was associated with weaker grip strength, suggesting that some individuals might have selenium deficiency manifesting with poorer neuromotor function.

Hair to blood mercury concentration ratios and a retrospective hair segmental mercury analysis in the Northwest Territories, Canada

Concentrations of total mercury were measured in blood and hair samples collected as part of a human biomonitoring project conducted in First Nations communities of the Mackenzie Valley, Northwest Territories, Canada. Hair (n = 443) and blood (n = 276) samples were obtained from six communities in the Dehcho region and three communities in the Sahtú region of the Mackenzie Valley. The aim of this paper was to calculate hair to blood mercury ratios (for matched samples) and determine if: 1) ratios differed significantly between the two regions; 2) ratios differed from the 250:1 ratio proposed by the WHO; and, 3) point estimates of hair to blood mercury ratios could be used to estimate blood mercury concentrations. In addition, this paper aims to determine if there were seasonal patterns in hair mercury concentrations in these regions and if so, if patterns were related to among-season variability in fish consumption.The majority of mercury levels in hair and blood were below relevant health-based guidance values. The geometric mean hair (most recent segment) to blood mercury ratio (stratified by region) was 619:1 for the Dehcho region and 1220:1 for the Sahtú region. Mean log-transformed hair to blood mercury ratios were statistically significantly different between the two regions. Hair to blood ratios calculated in this study were far higher (2–5 times higher) than those typically reported in the literature and there was a large amount of inter-individual variation in calculated ratios (range: 114:1 to 4290:1). Using the 250:1 ratio derived by the World Health Organisation to estimate blood mercury concentrations from hair mercury concentrations would substantially over-estimate blood mercury concentrations in the studied regions. However, geometric mean site-specific hair to blood mercury ratios can provide estimates of measures of central tendency for blood mercury concentrations from hair mercury concentrations at a population level.Mercury concentrations were determined in segments of long hair samples to examine exposure of participants to mercury over the past year. Hair segments were assigned to six time periods and the highest hair mercury concentrations were generally observed in hair segments that aligned with September/October and November/December, whereas the lowest hair mercury concentrations were aligned with March/April and May/June. Mean log-transformed hair mercury concentrations were statistically significantly different between time periods. Between time periods (e.g., September/October vs. March/April), the geometric mean mercury concentration in hair differed by up to 0.22 μg/g, and the upper margins of mercury exposure (e.g., 95th percentile of hair mercury) varied by up to 0.86 μg/g. Results from self-reported fish consumption frequency questionnaires (subset of participants; n = 170) showed total fish intake peaked in late summer, decreased during the winter, and then increased during the spring. Visual assessment of results indicated that mean hair mercury concentrations followed this same seasonal pattern. Results from mixed effects models, however, indicated that variability in hair mercury concentrations among time periods was not best explained by total fish consumption frequency. Instead, seasonal trends in hair mercury concentrations may be more related to the consumption of specific fish species (rather than total wild-harvested fish in general). Future work should examine whether seasonal changes in the consumption of specific fish species are associated with seasonal changes in hair mercury concentrations.

Role of MT1A Polymorphism and Environmental Mercury Exposure on the Montreal Cognitive Assessment (MoCA).

PurposeMany age-related structural and functional changes in the brain have important consequences. Long-term exposure to mercury and the impact of functional polymorphisms of metal-regulating proteins such as metallothioneins (MTs) can result in neurological-neurobehavioral effects in elderly individuals. Therefore, the aims of this study are to examine the associations between biomarkers of mercury exposure and cognitive impairment and to investigate the effect of the rs8052394 single nucleotide polymorphism (SNP) of the potential modifier gene MT1A on different domains of the Montreal Cognitive Assessment (MoCA).Materials and MethodsWe studied 436 participants aged ≥55 years from the Electricity Generating Authority of Thailand study. They underwent a physical examination, an extensive cognitive assessment with the MoCA (cutoff <26 points), and a biochemical analysis related to diabetes and dyslipidemia. The blood mercury level was determined by inductively coupled plasma mass spectrometry. Genotyping of the MT1A rs8052394 SNP was performed by the restriction fragmentation length polymorphism method.ResultsThe mean age of the study population was 58.8±3.01 years, and most had ≥12 years of education (75.7%). The primary study finding was that the prevalence of mild cognitive impairment (MCI) in older Thai adults was 39.7%. The frequency distributions of the G allele of the rs8052394 SNP of the MT1A gene were significantly associated with the total and sub-domain MoCA scores. The prevalence of MCI was significantly associated with increased age, hypertriglyceridemia, hyperhomocysteinemia, the third tertile of blood mercury concentration, and the rs8052394 variant genotype of MT1A (P values for all odds ratios <0.05).ConclusionThese findings suggested that neurocognitive effects associate with mercury exposure and genetic susceptibility in toxicokinetics. Public health strategies can be used to implement as a comprehensive action plan to educate vulnerable populations on how to reduce mercury exposure. Concurrently, impact of such genetic predisposition requires replication for identifying and protecting susceptible individuals from mercury toxicity.

Impact of environmental mercury exposure on the blood cells oxidative status of fishermen living around Mundaú lagoon in Maceió – Alagoas (AL), Brazil

Mercury in the aquatic environment can lead to exposure of the human population and is a known toxic metal due to its capacity for accumulation in organs. We aimed to evaluate the mercury level in the blood and urine of fishermen and correlate it with the level of oxidative stress in blood cells. We show in this case-control study that the fishermen of the exposed group (case) of Mundaú Lagoon (Maceió - Alagoas, Brazil) have higher concentrations of total mercury in the blood (0.73–48.38 μg L−1) and urine (0.430–10.2 μg L−1) than the total mercury concentrations in blood (0.29–17.30 μg L−1) and urine (0.210–2.65 μg L−1) of the control group. In the blood cells of fishermen, we observed that the lymphomononuclear cells produced high levels of reactive oxygen species (61.7%), and the erythrocytes presented increased lipid peroxidation (151%) and protein oxidation (41.0%) and a decrease in total thiol (36.5%), GSH and the REDOX state (16.5%). The activity of antioxidant system enzymes (SOD, GPx, and GST) was also reduced in the exposed group by 26.9%, 28.3%, and 19.0%, respectively. Furthermore, hemoglobin oxygen uptake was decreased in the exposed group (40.0%), and the membrane of cells presented increased osmotic fragility (154%) compared to those in the control group. These results suggest that mercury in the blood of fishermen can be responsible for causing impairments in the oxidative status of blood cells and is probably the cause of the reduction in oxygen uptake capacity and damage to the membranes of erythrocytes.

Foraging in marine habitats increases mercury concentrations in a generalist seabird

Methylmercury concentrations vary widely across geographic space and among habitat types, with marine and aquatic-feeding organisms typically exhibiting higher mercury concentrations than terrestrial-feeding organisms. However, there are few model organisms to directly compare mercury concentrations as a result of foraging in marine, estuarine, or terrestrial food webs. The ecological impacts of differential foraging may be especially important for generalist species that exhibit high plasticity in foraging habitats, locations, or diet. Here, we investigate whether foraging habitat, sex, or fidelity to a foraging area impact blood mercury concentrations in western gulls (Larus occidentalis) from three colonies on the US west coast. Cluster analyses showed that nearly 70% of western gulls foraged primarily in ocean or coastal habitats, whereas the remaining gulls foraged in terrestrial and freshwater habitats. Gulls that foraged in ocean or coastal habitats for half or more of their foraging locations had 55% higher mercury concentrations than gulls that forage in freshwater and terrestrial habitats. Ocean-foraging gulls also had lower fidelity to a specific foraging area than freshwater and terrestrial-foraging gulls, but fidelity and sex were unrelated to gull blood mercury concentrations in all models. These findings support existing research that has described elevated mercury levels in species using aquatic habitats. Our analyses also demonstrate that gulls can be used to detect differences in contaminant exposure over broad geographic scales and across coarse habitat types, a factor that may influence gull health and persistence of other populations that forage across the land-sea gradient.

Health measures of Eeyouch (Cree) who are eligible to participate in the on-the-land Income Security Program in Eeyou Istchee (northern Quebec, Canada)

BackgroundParticipation in on-the-land programs that encourage traditional cultural activities may improve health and well-being. The Income Security Program (ISP) − a financial incentive-based on-the-land program − for Eeyouch (Cree) hunters and trappers in Eeyou Istchee was created as a result of the 1975 James Bay and Northern Quebec Agreement to help mitigate the effects of hydroelectric development on the Cree people of northern Quebec, Canada. Beyond the ISP’s financial incentives, little is known about the health measures of those who are eligible to participate in the ISP (i.e. spent ≥120 days on-the-land during the previous year). Therefore, this paper’s objective was to assess the health measures of northern Quebec Cree, who were eligible for participation in the ISP.MethodsUsing participant data (n = 545) compiled from the Nituuchischaayihtitaau Aschii Multi-Community Environment-and-Health Study, we assessed 13 different health measures in generalized linear models with the independent variable being the eligibility to participate in the ISP.ResultsParticipants in the present study who were eligible for the ISP had significantly higher levels of vigorous and moderate activity per week, and higher concentrations of omega-3 polyunsaturated fatty acids in the blood compared to those ineligible for the ISP (i.e. spent ≤119 days on-the-land during the previous year). Encouragingly, following model adjustment for age and sex, participants eligible for the ISP did not have higher blood concentrations of mercury than those who were not eligible for the ISP.ConclusionsOur results suggest that the participants eligible for participation in the ISP are likely to be healthier than those who are ineligible to participate − and are promising for on-the-land programs for Indigenous peoples beyond a financial incentive − with no apparent higher risk of increasing contaminant body burden through traditional on-the-land-activities (e.g. fish consumption).

Mercury offloading in gametes and potential adverse effects of high mercury concentrations in blood and tissues of Atlantic Goliath Grouper Epinephelus itajara in the southeastern United States

Mercury (Hg) is a ubiquitous and non-essential heavy metal that is highly toxic to aquatic organisms. Few studies examine Hg and its effects on wild fish populations. Here, we investigated the potential effects of Hg exposure on a large and long-lived marine species of conservation concern, the vulnerable Atlantic Goliath Grouper Epinephelus itajara. Our objectives were (1) to measure Hg (methyl-Hg; and total Hg = combined methyl-Hg and inorganic-Hg) concentrations in whole blood (WB) and gametes (eggs and sperm); (2) to investigate the relationships between Hg concentrations in muscle and liver with WB and gametes; (3) to investigate the relationships between Hg concentrations in liver, muscle, and WB with hematological and plasma biochemical analytes; and (4) to investigate the relationship between liver Hg and pigmented macrophage aggregates in liver tissue sections. We found several lines of evidence for potential adverse effects on Goliath Grouper health and reproduction by high Hg concentrations in liver, muscle, WB, and gametes, including (1) Hg concentrations in all tissues and gametes were well above observable ranges of marine and freshwater fishes from experimental exposure studies; (2) gamete Hg concentrations were among the highest recorded in wild fishes, with seasonal patterns suggesting females offload significant amounts of Hg into their eggs during the spawning season; (3) Methyl-Hg was highest in muscle, followed by sperm, liver, eggs, and WB; (4) there were significant correlations between liver, muscle, and WB Hg concentrations with various blood analytes; (5) vitellogenin positively correlated with female liver methyl-Hg concentrations, and was abnormally high in males, suggesting direct endocrine effects; and (6) liver total Hg positively correlated with pigmented macrophage aggregate count and percent area. This work will help guide future research examining the potential adverse effects of Hg and its role as an additional stressor on wild fish populations.

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

BackgroundMaternal seafood intake during pregnancy and prenatal mercury exposure may influence children’s growth trajectories.MethodsThis study, based on the Norwegian Mother, Father and Child Cohort Study (MoBa), includes 51 952 mother-child pairs recruited in pregnancy during 2002–08 and a subsample (n = 2277) with maternal mercury concentrations in whole blood. Individual growth trajectories were computed by modelling based on child’s reported weight and length/height from 1 month to 8 years. We used linear mixed-effects regression analysis and also conducted discordant-sibling analysis.ResultsMaternal lean fish was the main contributor to total seafood intake in pregnancy and was positively but weakly associated with child body mass index (BMI) growth trajectory. Higher prenatal mercury exposure (top decile) was associated with a reduction in child’s weight growth trajectory, with the estimates ranging from -130 g [95% Confidence Intervals (CI) = -247, -12 g] at 18 months to -608 g (95% CI = -1.102, -113 g) at 8 years. Maternal fatty fish consumption was positively associated with child weight and BMI growth trajectory, but only in the higher mercury-exposed children (P-interaction = 0.045). Other seafood consumption during pregnancy was negatively associated with child weight growth compared with no intake, and this association was stronger for higher mercury-exposed children (P-interaction = 0.004). No association was observed between discordant maternal seafood intake and child growth in the sibling analysis.ConclusionsWithin a population with moderate seafood consumption and low mercury exposure, we found that maternal seafood consumption in pregnancy was associated with child growth trajectories, and the direction of the association varied by seafood type and level of prenatal mercury exposure. Prenatal mercury exposure was negatively associated with child growth. Our findings on maternal seafood intake are likely non-causal.

Feathers accurately reflect blood mercury at time of feather growth in a songbird

Methylmercury (MeHg) is a globally distributed pollutant that can negatively affect wildlife. Bird feathers are often used as a monitoring tool of contaminant exposure, but variability in total mercury (THg) content in flight feathers has raised concerns over their utility. The objective of this study was to quantify blood and feather THg depuration through the progression of primary feather molt in order to clarify the relationship between blood and feather mercury concentration, and test the reliability of feather THg measurements as a monitoring tool in wild songbirds. Song sparrows (Melospiza melodia) were experimentally exposed to dietary MeHg and their blood and primary feather THg concentrations were measured during exposure and post-exposure periods of three months each. A rapid decrease in feather and blood THg concentration through molt progression was observed. Primary feather THg content was higher in feathers grown during the MeHg exposure period compared to those grown during the post-exposure period. Primary feather THg concentration was highly correlated with blood THg measured at the time of feather growth (R = 0.98), indicating that, although THg concentration is variable among flight feathers, this reflects temporally sequential molting patterns and declining blood concentration during depuration. Primary flight feathers thus provide an accurate and useful tool for estimating the mercury burden of birds at the time a chosen feather was grown, and have the potential to be an effective and reliable biomonitoring tool for species with well-characterized molt patterns.