Differences In Hg Levels Research Articles

Mercury stable isotopes in seabirds in the Ebro Delta (NE Iberian Peninsula): Inter-specific and temporal differences

Mercury (Hg) is a global pollutant, which particularly affects aquatic ecosystems, both marine and freshwater. Top-predators depending on these environments, such as seabirds, are regarded as suitable bioindicators of Hg pollution. In the Ebro Delta (NE Iberian Peninsula), legacy Hg pollution from a chlor-alkali industry operating in Flix and located ca. 100 km upstream of the Ebro River mouth has been impacting the delta environment and the neighboring coastal area. Furthermore, levels of Hg in the biota of the Mediterranean Sea are known to be high compared to other marine areas. In this work we used a Hg stable isotopes approach in feathers to understand the processes leading to different Hg concentrations in three Laridae species breeding in sympatry in the area (Audouin's gull Ichthyaetus audouinii, black-headed gull Chroicocephalus ridibundus, common tern Sterna hirundo). These species have distinct trophic ecologies, exhibiting a differential use of marine resources and freshwater resources (i.e., rice paddies prey). Moreover, for Audouin's gull, in which in the Ebro Delta colony temporal differences in Hg levels were documented previously, we used Hg stable isotopes to understand the impact of anthropogenic activities on Hg levels in the colony over time. Hg stable isotopes differentiated the three Laridae species according to their trophic ecologies. Furthermore, for Audouin's gull we observed temporal variations in Hg isotopic signatures possibly owing to anthropogenic-derived pollution in the Ebro Delta. To the best of our knowledge this is the first time Hg stable isotopes have been reported in seabirds from the NW Mediterranean.

Analysis of Mercury in Aquifers in Gold Mining Areas in the Ecuadorian Amazon and Its Associated Risk for Human Health.

Gold mining activity is a source of supply in many areas of the world, and especially in developing countries, it is practiced illegally and by applying unsafe techniques. Particularly in Ecuador, artisanal and small-scale gold mining (ASGM) is widespread, and it is based on the use of toxic substances, such as mercury (Hg), in gold recovery. Hg is a heavy metal that is water-insoluble, which, once mobilized, poses a threat to both the environment and human health. This study analyzes Hg concentrations in the six provinces of Napo, Sucumbíos, Orellana, Pastaza, Morona Santiago, and Zamora Chinchipe of the Ecuadorian Amazon region to conduct a human health risk assessment. Significant differences in Hg levels were found between provinces, but concentrations were below MPL imposed by Ecuadorian regulations everywhere. Nevertheless, a worrisome picture emerges, especially with regard to the most vulnerable receptors represented by the child population. There are multiple factors of incidence that may affect the possible future development of the phenomenon, and with reference to the social, economic, and environmental context of the region, it can be concluded that it may be appropriate to plan further investigation to arrive at a more comprehensive assessment. The results of this study can be used by decision makers to plan further investigation and to implement monitoring networks, risk mitigation strategies, and groundwater protection measures.

Mercury and Autism Spectrum Disorder: Exploring the Link through Comprehensive Review and Meta-Analysis.

Mercury (Hg) is a non-essential trace metal with unique neurochemical properties and harmful effects on the central nervous system. In this study, we present a comprehensive review and meta-analysis of peer-reviewed research encompassing five crucial clinical matrices: hair, whole blood, plasma, red blood cells (RBCs), and urine. We assess the disparities in Hg levels between gender- and age-matched neurotypical children (controls) and children diagnosed with autism spectrum disorder (ASD) (cases). After applying rigorous selection criteria, we incorporated a total of 60 case-control studies into our meta-analysis. These studies comprised 25 investigations of Hg levels in hair (controls/cases: 1134/1361), 15 in whole blood (controls/cases: 1019/1345), 6 in plasma (controls/cases: 224/263), 5 in RBCs (controls/cases: 215/293), and 9 in urine (controls/cases: 399/623). This meta-analysis did not include the data of ASD children who received chelation therapy. Our meta-analysis revealed no statistically significant differences in Hg levels in hair and urine between ASD cases and controls. In whole blood, plasma, and RBCs, Hg levels were significantly higher in ASD cases compared to their neurotypical counterparts. This indicates that ASD children could exhibit reduced detoxification capacity for Hg and impaired mechanisms for Hg excretion from their bodies. This underscores the detrimental role of Hg in ASD and underscores the critical importance of monitoring Hg levels in ASD children, particularly in early childhood. These findings emphasize the pressing need for global initiatives aimed at minimizing Hg exposure, thus highlighting the critical intersection of human-environment interaction and neurodevelopment health.

Mercury Exposure and Risk of Type 2 Diabetes: A Systematic Review and Meta-Analysis.

Methods Scopus and PubMed databases were systematically searched from their inception to November 2021 to obtain pertinent studies. Standardized mean differences (SMDs) with corresponding 95% confidence intervals (CIs) were calculated to evaluate the difference in Hg levels between people with and without T2DM. The association of the Hg exposure with T2DM was assessed using a random-effects model by pooling the odds ratios (ORs) and 95% CIs. Results A total of 17 studies, with 42,917 participants, aged ≥18 years, were analyzed. Overall, Hg levels were significantly higher in T2DM patients compared with non-T2DM controls (SMD = 1.07; 95%CI = 0.59 to 1.55, P ≤ 0.001), with significant heterogeneity across studies (I2 = 96.1%; P=≤0.001). No significant association was found between Hg exposure and risk of T2DM in the overall analysis and subgroup analysis based on the source of sample and study design. However, higher exposure to Hg was related to reduced risk of T2DM in men (OR = 0.71; 95%CI = 0.57 to 0.88), but not in women. No significant evidence for publication bias was detected. Conclusions Although the Hg level in T2DM is significantly higher than that of nondiabetics, there was no association between Hg exposure and the overall risk of T2DM. Nevertheless, our study shows that higher exposure to Hg might reduce the risk of T2DM in men.

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Mercury (Hg) is one of the most important environmental pollutants with endocrinedisrupting properties. There is little data from epidemiological studies describing the doseresponse relationship between toxic metal levels and hormone levels. The aim of this study was to use the nearest neighbor matching analysis to determine the difference in Hg concentration in healthy/sick subjects with thyroid disease and to use Benchmark modeling to determine the doseresponse relationship between Hg levels in the blood and thyroid-stimulating hormone (TSH) and thyroid hormones in serum. Blood samples were collected and used for Hg measurement using the ICP-MS method, and separated serum was used for hormone analysis. The study showed the existence of a statistically significant difference in Hg levels measured in healthy and sick subjects and the existence of a dose-response relationship between Hg and all measured hormones, with a narrow interval obtained for the Hg-TSH pair. The results of this research support the use of the Benchmark dose approach for the purpose of analyzing data from human studies, and our further research will be focused on examining the impact of low doses on animal models in order to determine more precise effects of low doses on the organism.

Mercury Exposure in Birds Linked to Marine Ecosystems in theWestern Mediterranean.

Mercury (Hg), particularly as methylmercury (MeHg), is a nonessential, persistent, and bioaccumulative toxic element with high biomagnification capacity and is considered a threat to marine environments. We evaluated total Hg concentrations in liver, kidney, and brain in 62 individuals of 9 bird species linked to marine ecosystems from western Mediterranean admitted in a Wildlife Rehabilitation Center (WRC) (Alicante, Spain, 2005-2020). Age- and sex-related differences in Hg levels, as well as the cause of admission to the WRC, were alsoevaluated in certain species. The species studied were: northern gannet (Morus bassanus), European shag (Phalacrocorax aristotelis), great cormorant (Phalacrocorax carbo), osprey (Pandion haliaetus), Balearic shearwater (Puffinus mauretanicus), yellow-legged gull (Larus michahellis), razorbill (Alca torda), common tern (Sterna hirundo), and black-headed gull (Chroicocephalus ridibundus). Concentrations in feathers of 27 individuals, and concentrations in internal tissues in 7 other individuals of 7 different species were alsoreported but not statistically evaluated due to the limited number of samples. Results suggest that individuals were chronically exposed to Hg through diet. The differences in Hg concentrations among speciesmay beexplained by theirdiet habits. Mercury concentrations strongly correlated between tissues (r = 0.78-0.94, p < 0.001, n = 61-62). Some individuals of certain species (i.e., European shag, northern gannet, and great cormorant) showed Hg concentrations close to or above those described in the literature as causing reproductive alterations in other avian species. Consequently, certain individuals inhabiting western Mediterranean could be at risk of suffering long-term, Hg-related effects. Some of the species evaluated are listed within different categories of threat according to the International Union forConservation of Nature (IUCN) and are endangered at a national level, so this study will provide valuable information for assessors and authorities in charge of the management of the environment and pollution.

Rhamphotheca as a useful indicator of mercury in seabirds

The evaluation of mercury (Hg) toxicity in wildlife species has prompted a search for sensitive indicators to accurately measure the body burden of Hg. Despite the extensive use of feathers as an indicator of Hg in birds, they do not appear to be an entirely suitable indicator of the extent of contamination in certain conditions and bird species since Hg levels are influenced by the growth period, timing of the last moult and migration. This research aimed to evaluate rhamphotheca as a potential indicator of environmental Hg concentrations in seabirds. We used culled yellow-legged gulls (Larus michahellis) (n = 20) and determined THg in rhamphotheca and feathers. We distinguished between upper and lower rhamphotheca, and divided each one into 16 equal portions along the culmen to analyse their THg content spatially. In each bird, THg was also determined in primary (P1) and secondary (S8) feathers and compared with rhamphotheca. The median (25th, 75th percentile) rhamphotheca Hg concentration was 13.44 (9.63, 17.46) μg/g, which was twofold higher than in the feathers 7.56 (4.88, 12.89) μg/g. Median THg in rhamphotheca was significantly higher (p < 0.05) in females 15.05 (10.35, 23.04) μg/g than in males 12.34 (8.57, 15.19) μg/g, whereas no differences (p > 0.05) were found in the feathers. No significant differences in Hg levels were found between upper and lower beak mandibles or along either. In contrast, significant differences in Hg concentrations were found between the P1 and S8 feathers (mean, 12.04 vs. 6.04 μg/g). No correlation was found between Hg content in rhamphotheca and feathers. Mercury levels in rhamphotheca exhibited stronger significant relationships with weight (R2 = 0.568), length (R2 = 0.524) and culmen (R2 = 0.347) than the levels in the feathers, which showed no correlation. Overall, our results suggest that rhamphotheca is a suitable tissue indicator for Hg monitoring in gulls; however, further studies are needed to extend our research to other bird species.

Mercury Exposure Among Artisanal and Small-Scale Gold Miners in Four Regions in Uganda.

Background.Artisanal and small-scale gold mining is a human health concern, especially in low-income countries like Uganda due to the use of mercury (Hg) in the mining process.Objective.The aim of the present study was to assess Hg exposure among artisanal and small-scale gold miners in Uganda through biologic monitoring parameters and Hg-related clinical manifestations.Methods.A cross-sectional study was conducted from June to July 2018 among 183 miners from Ibanda (Western region), Mubende (Central region), Amudat (Karamoja region) and Busia (Eastern region) in Uganda. An interviewer-administered questionnaire and health assessment were used to collect socio-demographic, exposure and self-reported Hg poisoning symptoms. In addition, 41 urine, 41 blood and 26 environment samples were assessed. Descriptive statistics, Kruskal-Wallis test and Wilcoxon signed-rank test for comparison of Hg levels in urine and blood among miners were performed while logistic regression was used to assess associations between exposure and Hg poisoning-related symptoms.Results:The miners ranged from 15 to 65 years old and were primarily male (72.6%). The majority (73.3%) had worked directly with Hg for an average duration of 5.3 years. Symptoms associated with working directly with Hg included chest pain (odds ratio (OR)=9.0, confidence interval (CI)=3.3 to 24.6), numbness (OR=8.5, CI=2.1 to 34.4), back pain (OR=6.2, CI= 2.2 to 17.5), fatigue and stress (OR=5.4, 2.0 to CI=14.9), headache (OR=4.7, CI=1.9 to 11.3), dizziness (OR=3.8, CI=1.5 to 9.7) joint pain (OR=3.2, CI=1.3 to 8.3) and respiratory problems (3.2, 1.0 to 10.1). Statistically significant differences in Hg levels with p-values less than 0.05 were observed across district, gender and type of work. Mubende had the highest blood and urine levels (136 μg/l and 105.5 μg/l) in comparison with Busia (60 μg/l and 70.6 μg/l) and Ibanda (43 μg/l and 58 μg/l). Females (84.7 μg/l), panners (109 μg/l) and those with knowledge of occupational health and safety measures (95.6 μg/l) reported higher levels of Hg in urine. The average levels of Hg in water and soil samples were 23.79 μg/l and 0.21 μg/l, respectively.Conclusions.Variation in Hg levels were attributed to varied duration of exposure across geographical sites. There was considerable exposure to Hg as indicated by both clinical manifestations and biologic parameters among miners in Uganda with Hg in urine exceeding the recommended thresholds.Participant Consent.ObtainedEthics Approval.Ethical approval was obtained from the Makerere University School of Health Science Institutional Review Board (reference number SHSREC REF 2018–2019) and Uganda National Council for Science and Technology (reference number SS 4577)Competing Interests.The authors declare no competing financial interests.

Variation in mercury concentration in juvenile Magellanic penguins during their migration path along the Southwest Atlantic Ocean

The vulnerability of seabirds related to their migratory dynamics is frequently linked to environmental problems along the migration path. In this context, Magellanic penguins (Sphenicus magellanicus) seem to be vulnerable to an extensive range of environmental disturbances during their northward migration along the Atlantic waters of South America, which include by catch, marine debris ingestion, overfishing and environmental contamination. In this study, we investigate mercury accumulation in muscle and hepatic tissues of juveniles penguins collected along the Brazilian coast during three migratory seasonal years (2006, 2008 and 2012) and three areas along a latitudinal gradient. We found significant differences in Hg levels across the years, with higher hepatic Hg levels found in tissues of penguins sampled in 2008. The higher Hg levels in samples of penguins from 2008 might be attributed to variations in body condition or Hg uptake, associated with the trophic imbalance linked to an extreme El Niño event during that year. Significant differences in Hg accumulation across the latitudinal areas were also observed. The penguins sampled at the farthest area from the breeding ground presented the higher levels of Hg and also the poorest body condition. Body condition and other traits may influence the levels of chemical pollutants and decrease the migratory success rate in the juvenile age phase, compromising population dynamics.

Mercury in Forage Fish from Mexico and Central America: Implications for Fish-Eating Birds.

Mercury (Hg) is a global contaminant of aquatic food chains. Aquatic birds, such as the osprey (Pandion haliaetus), with migratory populations breeding in Canada and the northern United States and wintering in the Central and South America, can be exposed to mercury on both the breeding and wintering ranges. We examined Hg levels in 14 fish taxa from 24 osprey wintering sites identified from satellite telemetry. Our main goal was to determine whether fish species that feature in the diet of overwintering and resident fish-eating birds reached toxicity thresholds for Hg. Mean Hg levels in fish whole carcasses ranged from a high of 0.18µgg(-1) (wet weight) in Scomberomorus sierra to a low of 0.009µgg(-1) in Catostomidae. Average Hg levels were within published toxicity threshold values in forage fish for only two sites in Mexico (Puerto Vallarta and San Blas Estuary), and all were marine species, such as mackerel (Scomberomorus sierra), sea catfish (Ariopus spp.), and sardinas species (Centropomus spp.). Except for one sample from Nicaragua, sea catfish from Puerto Morazan, none of the fish from sites in Central America had Hg levels which exceeded the thresholds. Nonmetric multidimensional scaling revealed geographical differences in Hg levels with significant pairwise differences between sites along the Pacific Ocean (Mexico) versus the Bay of Campeche, partly due to differences in species composition of sampled fish (and species distributions). Hg increased with trophic level, as assessed by nitrogen stable isotope ratios (δ(15)N but not δ(13)C), in freshwater and marine, but not estuarine, environments. Hg concentrations in forage fish do not account for the elevated Hg reported for many osprey populations on the breeding grounds, thus primary sources of contamination appear to be in the north.

Mercury bioaccumulation in cartilaginous fishes from Southern New England coastal waters: Contamination from a trophic ecology and human health perspective

This study examined total mercury (Hg) concentrations in cartilaginous fishes from Southern New England coastal waters, including smooth dogfish (Mustelus canis), spiny dogfish (Squalus acanthias), little skate (Leucoraja erinacea), and winter skate (Leucoraja ocellata). Total Hg in dogfish and skates were positively related to their respective body size and age, indicating Hg bioaccumulation in muscle tissue. There were also significant inter-species differences in Hg levels (mean ± 1 SD, mg Hg/kg dry weight, ppm): smooth dogfish (3.3 ± 2.1 ppm; n = 54) > spiny dogfish (1.1 ± 0.7 ppm; n = 124) > little skate (0.4 ± 0.3 ppm; n = 173) ∼ winter skate (0.3 ± 0.2 ppm; n = 148). The increased Hg content of smooth dogfish was attributed to its upper trophic level status, determined by stable nitrogen (δ15N) isotope analysis (mean δ15N = 13.2 ± 0.7‰), and the consumption of high Hg prey, most notably cancer crabs (0.10 ppm). Spiny dogfish had depleted δ15N signatures (11.6 ± 0.8‰), yet demonstrated a moderate level of contamination by foraging on pelagic prey with a range of Hg concentrations, e.g., in order of dietary importance, butterfish (Hg = 0.06 ppm), longfin squid (0.17 ppm), and scup (0.11 ppm). Skates were low trophic level consumers (δ15N = 11.9–12.0‰) and fed mainly on amphipods, small decapods, and polychaetes with low Hg concentrations (0.05–0.09 ppm). Intra-specific Hg concentrations were directly related to δ15N and carbon (δ13C) isotope signatures, suggesting that Hg biomagnifies across successive trophic levels and foraging in the benthic trophic pathway increases Hg exposure. From a human health perspective, 87% of smooth dogfish, 32% of spiny dogfish, and <2% of skates had Hg concentrations exceeding the US Environmental Protection Agency threshold level (0.3 ppm wet weight). These results indicate that frequent consumption of smooth dogfish and spiny dogfish may adversely affect human health, whereas skates present minimal risk.

Does trophic structure dictate mercury concentrations in top predators? A comparative analysis of pelagic food webs in the Pacific Ocean

Large pelagic predators in the marine environment accumulate relative high levels of mercury (Hg), yet it is difficult to identify the ecological factors that control the fate and flow of contaminants in marine systems, in part due to the difficulty in experimenting with large, dynamic ecosystems. By comparing the eastern tropical Pacific (ETP) and central north Pacific (CNP) pelagic food webs, we determined how differences in trophic pathways, versus differences in baseline Hg conditions, might translate into varying levels of Hg contamination in upper trophic levels. We developed coupled contaminant-trophic mass balance models to estimate Hg concentrations or Hg-elimination rates for species groups in each region finding generally higher Hg concentrations in the ETP model. Specifically we found Hg concentrations of yellowfin, skipjack, bigeye, and albacore tunas were two- to four-fold greater in the ETP than the CNP. These estimated differences reflected previous empirical observations of Hg concentrations in tunas across these regions. Regional differences in tuna Hg concentrations can be solely explained by differences in diets of tuna and their prey, although changes in Hg input at the base of the food web can strongly influence Hg concentrations in top predators as well. The coupled models allowed us to test hypotheses on the sources of Hg variation in top predators at a food web scale, incorporating the indirect effects of different food web structures into our regional Hg estimates. Our ability to draw firm conclusions regarding causal effects underlying known differences in Hg levels across ocean regions is restricted by data limitations that led to different assumptions made to construct the food web models.

Mercury exposure and neurochemical biomarkers in multiple brain regions of Wisconsin River Otters (Lontra canadensis)

River otters are fish-eating wildlife that bioaccumulate high levels of mercury (Hg). Mercury is a proven neurotoxicant to mammalian wildlife, but little is known about the underlying, sub-clinical effects. Here, the overall goal was to increase understanding of Hg's neurological risk to otters. First, Hg values across several brain regions and tissues were characterized. Second, in three brain regions with known sensitivity to Hg (brainstem, cerebellum, and occipital cortex), potential associations among Hg levels and neurochemical biomarkers [N-methyl-D-aspartic acid (NMDA) and gamma-aminobutyric acid (GABAA) receptor] were explored. There were no significant differences in Hg levels across eight brain regions (rank order, highest to lowest: frontal cortex, cerebellum, temporal cortex, occipital cortex, parietal cortex, basal ganglia, brainstem, and thalamus), with mean values ranging from 0.7 to 1.3 ug/g dry weight. These brain levels were significantly lower than mean values in the muscle (2.1 ± 1.4 ug/g), liver (4.7 ± 4.3 ug/g), and fur (8.8 ± 4.8 ug/g). While a significant association was found between Hg and NMDA receptor levels in the brain stem (P = 0.028, rp = -0.293), no relationships were found in the cerebellum and occipital cortex. For the GABA receptor, no relationships were found. The lack of consistent Hg-associated neurochemical changes is likely due to low brain Hg levels in these river otters, which are amongst the lowest reported.

Mercury in Different Feather Types from Great Cormorants (Phalacrocorax carbo L.) Inhabiting the Vistula Lagoon Ecosystem in Poland

Total mercury levels in different feather types (down, contour, tail and flight) in Great Cormorants (Phalacrocorax carbo L.) were determined using CV-AAS. Feathers from Great Cormorants inhabiting the Vistula Lagoon ecosystem have an average Hg level of 7.14 ± 3.99 (μg/g w.w.). Age-dependent concentrations of Hg were statistically significant (ANOVA Kruskal–Wallis, p < 0.0001). There were also significant differences in Hg levels in different parts of feathers from adults and immature birds (ANOVA Kruskal–Wallis, p < 0.0001). Cormorant chick feathers appear to be a potential biomonitor of Hg pollution in the Vistula Lagoon ecosystem, but this subject requires further research.

Fate of mercury in tree litter during decomposition

Abstract. We performed a controlled laboratory litter incubation study to assess changes in dry mass, carbon (C) mass and concentration, mercury (Hg) mass and concentration, and stoichiometric relations between elements during decomposition. Twenty-five surface litter samples each, collected from four forest stands, were placed in incubation jars open to the atmosphere, and were harvested sequentially at 0, 3, 6, 12, and 18 months. Using a mass balance approach, we observed significant mass losses of Hg during decomposition (5 to 23 % of initial mass after 18 months), which we attribute to gaseous losses of Hg to the atmosphere through a gas-permeable filter covering incubation jars. Percentage mass losses of Hg generally were less than observed dry mass and C mass losses (48 to 63 % Hg loss per unit dry mass loss), although one litter type showed similar losses. A field control study using the same litter types exposed at the original collection locations for one year showed that field litter samples were enriched in Hg concentrations by 8 to 64 % compared to samples incubated for the same time period in the laboratory, indicating strong additional sorption of Hg in the field likely from atmospheric deposition. Solubility of Hg, assessed by exposure of litter to water upon harvest, was very low (&lt;0.22 ng Hg g−1 dry mass) and decreased with increasing stage of decomposition for all litter types. Our results indicate potentially large gaseous emissions, or re-emissions, of Hg originally associated with plant litter upon decomposition. Results also suggest that Hg accumulation in litter and surface layers in the field is driven mainly by additional sorption of Hg, with minor contributions from "internal" accumulation due to preferential loss of C over Hg. Litter types showed highly species-specific differences in Hg levels during decomposition suggesting that emissions, retention, and sorption of Hg are dependent on litter type.

Locational Differences in Mercury and Selenium Levels in 19 Species of Saltwater Fish from New Jersey

Individuals who fish, and their families that ingest self-caught fish, make decisions about where to fish, what type of fish to eat, and the quantity of fish to eat. While federal and state agencies often issue consumption advisories for some fish with high mercury (Hg) concentrations, advisories seldom provide the actual metal levels to the general public. There are few data for most saltwater fish, and even less information on variations in Hg levels in fish within a state or geographical region. The objective of this study was to provide Hg concentrations from 19 species of fish caught in different locations in New Jersey to (1) test the hypothesis that mean metal levels vary geographically, (2) provide this information to individuals who fish these coastal waters, and (3) provide a range of values for risk assessors who deal with saltwater fish exposure in the Northeastern United States. Selenium (Se) was also examined because of its purported moderating effect on the toxicity of Hg. Hg levels showed significant geographical variation for 10 of 14 species that were caught in more than one region of New Jersey, but there were significant locational differences for Se in only 5 of the fish. Mercury levels were significantly lower in fish collected from northern New Jersey (except for ling, Molva molva), compared to other regions. As might be expected, locational differences in Hg levels were greatest for fish species with the highest Hg concentrations (shark, Isurus oxyrinchus; tuna, Thunnus thynnus and T. albacares; striped bass, Morone saxatilis; bluefish, Pomatomus saltatrix). Fishers and their families might reduce their risk from Hg exposure not only by selecting fish generally lower in Hg, but by fishing predominantly in some regions over others, further lowering the potential risk. Health professionals might use these data to advise patients on which fish are safest to consume (in terms of Hg exposure) from particular geographical regions.

Evaluation of the suitability of application of golden jackal (Canis aureus) hair as a noninvasive technique for determination of body burden mercury

An evaluation of suitability of applying hair as a noninvasive indicator for determination of the body burden mercury in mammals was carried out by determining the concentration of mercury in hair and liver tissue of the golden jackal, Canis aureus . Nineteen jackals killed on the roads along the Caspian Sea in the central region of Mazandaran Province, Iran were collected. The mercury measurements were carried out by AMA254 LECO and the standard method ASTM-D6722. SPSS and Excel were used for analytical statistics. There was a significant difference in Hg levels between the hair and liver tissue (P < 0.001). The average concentration of mercury was 187.3 + or - 22.7 and 53.3 + or - 7.3 ng/g, respectively. No significant differences were seen either between the sexes or in correlation between the tissues. But a significant and positive relation was seen between the mercury content in hair and body weight and length (P < 0.005). In general, the mercury concentration was less than the deleterious, effective limit on the species. It seems that this is the first study of Hg concentrations in jackals and demonstrates on easy and noninvasive sampling method.

Mercury Levels in Muscle of Six Species of Turtles Eaten by People Along the Rio Negro of the Amazon Basin

Mercury levels in the Amazon River are generally high, but there are no published studies on Hg levels in turtles from the region. In this study, levels of Hg were examined in the muscle of six species of turtles in the Rio Negro in the Amazon basin of Brazil, including Podocnemis unifilis, Podocnemis expansa, Podocnemis erythrocephala, Podocnemis sextuberculata, Peltocephalus dumerilianus, and Chelus fimbriatus. It is important to analyze Hg levels in chelonians in this region because of the potential health risk to humans and other receptors that eat them, as well as their potential use as bioindicators. The effect of sex, weight, and carapace length on Hg concentrations in turtle muscle was examined to determine if the levels represent a health risk to riverine people. There was a significant interspecific difference in Hg levels but no differences as a function of size or gender. The highest Hg level was found in Chelus fimbriatus (mean = 432 ppb, standard deviation +/- 196 ppb), followed by Peltocephalus dumerilianus (106 +/- 41 ppb), Podocnemis expansa (62 +/- 49 ppb), P. sextuberculata (61 +/- 40 ppb), P. unilifis (35 +/- 17 ppb), and P. erythrocephala (33.1 +/- 17 ppb). Of the species studied, the piscivorous C. fimbriatus had the highest Hg level. Hg levels in turtles were similar to the levels found in fish from the same basin. Levels of Hg in the muscle of C. fimbriatus are sufficiently high to pose a potential risk to humans who consume them. This study represents the first comparative study of Hg levels in muscle of six species of turtles.

Factors Affecting Mercury and Selenium Levels in New Jersey Flatfish: Low Risk to Human Consumers

Some fish contain high levels of mercury (Hg), which could pose a risk to fish eaters themselves or their children. In making decisions about fish consumption, people must decide whether to eat fish, how much to eat, what species to eat, and what size fish to eat, as well as suitable (or unsuitable) locations, among other factors. Yet to make sound decisions, people need to know the levels of Hg in fish as a function of species, size, and location of capture. Levels of Hg and selenium (Se) were examined in three species of flatfish (fluke or summer flounder [Paralichthys dentatus], winter flounder [Pseudopleuronectes americanus], and windowpane [Scophthalmus aquosus]) from New Jersey as a function of species, fish size, season, and location. Flatfish were postulated to have low levels of Hg because they are low on the food chain and are bottom feeders, and data were generated to provide individuals with information on a species that might be safe to eat regularly. Although there were interspecific differences in Hg levels in the 3 species, total Hg levels averaged 0.18, 0.14, and 0.06 ppm (μg/g, wet weigh) in windowpane, fluke, and winter flounder, and selenium levels averaged 0.36, 0.35, and 0.25 ppm, respectively. For windowpane, 15% had Hg levels above 0.3 ppm, but no individual fish had Hg levels over 0.5 ppm. There were no significant seasonal differences in Hg levels, although Se was significantly higher in fluke in summer compared to spring. There were few geographical differences among New Jersey locations. Correlations between Hg and Se levels were low. Data, based on 464 fish samples, indicate that Hg levels are below various advisory levels and pose little risk to typical New Jersey fish consumers. A 70-kg person eating 1 meal (8 oz or 227 g) per week would not exceed the U.S. Environmental Protection Agency reference dose of 0.1 μg/kg body weight/d of methylmercury (MeHg). However, high-end fish eaters consuming several such meals per week may exceed recommended levels.

Spatial and temporal variation of mercury load in surface water and sediments around an integrated steel plant in India

Coal burning in the steel industry is the chief source of mercury presence in surrounding environment. About 20 water-storage ponds and three natural water streams are located in adjoining areas of an integrated steel plant in Bhilai, India. Hundreds of hospital admissions with chronic ailments due to hazardous emissions from the steel industry are frequently reported. Many of these ailments are related to reported mercury-poisoning diseases. Measurements of mercury levels in various environmental matrices around this industrial area was started early in the 1990s. From 1990–1995, few environmental samples were analyzed for mercury content but from 1995 onwards, comprehensive assessment of mercury load along with other toxic metals in various environmental matrices were begun. This work synthesizes and compares data of mercury in the surface water from three major field programs, in 1997, 2002, and 2006. The focus is on both spatial and temporal variation. In the present survey (2006), mercury levels are significantly higher compared to subsequent surveys and have shown 10–18 times higher values compared to 2001 and 1997 surveys. The differences in Hg levels between downwind and other sites in three survey programs are found to be in order: 1997 > 2001 > 2006. Regression between water and sediment mercury levels has shown variation in correlation values and higher in winter season.