Hg Levels In Liver Research Articles

Distribution of mercury in leg muscle and liver of game birds from Serbia

The purpose of this study was to determine the distribution of Hg levels in leg muscle and liver of game birds collected within the Serbian National residue monitoring program from 2013 to 2016. Hg levels in samples (n=464) of: pheasants (n=182), mallard (n=25), Eurasian jay (n=7), partridges (n=5) and woodcocks (n=8) were determined by ICPMS. The highest mean Hg levels were observed in leg muscle samples of woodcocks (0.071 mg/kg) and mallard (0.059 mg/kg). The lowest mean Hg level in liver was determined in partridges (0.008 mg/kg) while the highest was in pheasants (0.262 mg/kg) and mallard (0.161 mg/kg). Statistical analysis showed significantly differences between Hg levels in liver of woodcocks and mallard, as well as between them and livers of other analysed game birds. During the four years (2013-2016), 87.5% of leg muscle and 50% of woodcock livers had Hg levels that exceeded the MRL, while in mallard muscle and liver those percentages were 36% and 40%, respectively.

Total mercury concentrations in white and striped Mullet (Mugil curema and M. cephalus) from a coastal lagoon in the SE Gulf of California

ABSTRACTThe White and Striped mullets (Mugil curema and M. cephalus) are highly abundant and commercially important estuarine fish in northwest (NW) Mexico. Because of their feeding habits and habitat, they are likely to accumulate mercury (Hg) in their muscle and liver. The objectives of this study were to determine total Hg distribution in the tissues of interest, to correlate Hg levels between tissues and with length and weight of fish, to estimate the percentage weekly intake (PWI) of total Hg and methyl Hg (MeHg) through consumption of both mullet species, and to compare total Hg levels with mullets from other areas. The highest total Hg concentration (1.031 µg g−1 dry weight) was measured in liver of White mullet. In both species, the order of averaged Hg concentrations (M. curema liver 0.272, muscle 0.184; M. cephalus liver 0.211, muscle 0.129 µg g−1 dry weight) were liver>muscle. Correlations of Hg in muscle and liver with total weight of M. curema were significant. In M. cephalus, Hg levels in liver were significantly correlated with total length and weight. The PWI of THg (<4%) and MeHg (<10%) were not elevated for both species. Concentration of Hg in the studied mullets was comparable to levels in similar species from Mexican waters but lower than results in mugilids from other coastal areas.

Food preferences and Hg distribution in Chelonia mydas assessed by stable isotopes

Mercury (Hg) is a highly toxic pollutant that poses in risk several marine animals, including green turtles (Chelonia mydas). Green turtles are globally endangered sea turtle species that occurs in Brazilian coastal waters as a number of life stage classes (i.e., foraging juveniles and nesting adults). We assessed total Hg concentrations and isotopic signatures (13C and 15N) in muscle, kidney, liver and scute of juvenile green turtles and their food items from two foraging grounds with different urban and industrial development. We found similar food preferences in specimens from both areas but variable Hg levels in tissues reflecting the influence of local Hg backgrounds in food items. Some juvenile green turtles from the highly industrialized foraging ground presented liver Hg levels among the highest ever reported for this species. Our results suggest that juvenile foraging green turtles are exposed to Hg burdens from locally anthropogenic activities in coastal areas.

Impact of dietary selenium on methylmercury toxicity in juvenile Atlantic cod: A transcriptional survey

Selenium (Se) and its derivatives are known to have protective effects against mercury (Hg) toxicity in mammals. In this study we wanted to evaluate whether Se co-exposure affect the transcription of methylmercury (MeHg) toxicity-relevant genes in early life stages of fish. Juvenile Atlantic cod were exposed to regular feed (control), Se-spiked feed (3mg Sekg−1), MeHg-spiked feed (10mg Hgkg−1) or to Se- and MeHg-spiked feed (3mg Sekg−1 and 10mg Hgkg−1, respectively) for ten weeks. Liver tissue was harvested for transcriptional analysis when the fish were weighing 11.4±3.2g. Accumulated levels of Hg in liver of the two groups of fish exposed to MeHg were 1.5mg Hgkg−1 wet weight, or 44-fold higher than in the control group, while the Se concentrations differed with less than 2-fold between the fish groups. Selenium co-exposure had no effect on the accumulated levels of Hg in liver tissue; however, MeHg co-exposure reduced the accumulated level of Se. Dietary exposure to MeHg had no effect on fish growth. Interaction effects between Se and MeHg exposure were observed for the transcriptional levels of CAT, GPX1, GPX3, NFE2L2, UBA52, SEPP1 and DNMT1. Significant effects of MeHg exposure were seen for DNMT1 and PPARG, while effects of Se exposure were seen for GPX4B and SEPP1A, as well as for DNA methyltransferase activity. The transcriptional results suggest, by considering up-regulation as a proxy for negative impact and at the tested concentrations, a pro-oxidative effect of Se co-exposure with MeHg, rather than an antioxidative effect.

Distinct Response of Lactating and Nonlactating Rats Exposed to Inorganic Mercury on Hepatic δ-Aminolevulinic Acid Dehydratase Activity

This study investigated if lactating and nonlactating rats presented differences in relation to hepatic sensitivity to HgCl2 and the potential preventive role of ZnCl2. Lactating (days 3-12 of lactation) and nonlactating rats received 27 mg/kg ZnCl2 for five consecutive days and 5 mg/kg HgCl2 for five subsequent days. Lactating and nonlactating rats exposed to HgCl2 presented a decrease in food intake, a decrease in plasma alanine aminotransferase (ALT), and an increase in hepatic Hg levels when compared to the control group. Only lactating rats exposed to HgCl2 presented an increase in hepatic δ-aminolevulinic acid dehydratase activity. On the other hand, only nonlactating rats exposed to HgCl2 presented an increase in plasma aspartate aminotransferase (AST). ZnCl2 pre-exposure partially protected the increase in plasma AST activity presented by nonlactating rats and potentiated the liver Hg accumulation in lactating rats. Pups from the Sal-Hg and Zn-Hg groups showed a decrease in absolute liver weight and an increase in liver Hg levels. Summarizing, this study demonstrated that lactating rats presented distinct biochemical responses compared to nonlactating rats exposed to HgCl2 when hepatic parameters were evaluated.

Heavy metal and trace element bioaccumulation in target tissues of four edible fish species from the Danube River (Serbia)

Pikeperch (Sander lucioperca), European catfish (Silurus glanis), burbot (Lota lota), and common carp (Cyprinus carpio) were collected from the Danube River (Belgrade section, Serbia), and samples of liver, muscle, and gills were analyzed for Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Mo, Ni, Pb, Se, Sr, and Zn using inductively coupled plasma optical emission spectrometry (ICP-OES) to highlight the importance of species and tissue selection in monitoring research, contaminant studies, and human health research. The Kruskal–Wallis test revealed significant differences between fish species in regard to metal levels in liver, muscle, and gills. The principal component analysis (PCA) indicated that the studied fish species could be grouped on the basis of the level of analyzed elements in liver and gills. The Mann–Whitney test showed two subsets (one comprising two piscivorous species, pikeperch and catfish, and the other, two polyphagous species, burbot and carp) in regard to Cr and Hg levels in liver (higher levels in piscivorous species), as well as B, Fe, and Hg in gills (B and Fe with higher levels in polyphagous and Hg in piscivorous species), and As in muscle (higher levels in polyphagous species). Carp had distinctly higher levels of Cd, Cu, and Zn in liver in comparison to other three species. None of the elements exceeded the maximum acceptable concentrations (MAC). However, since Hg levels are close to the prescribed MAC levels, the consumption of these fishes can be potentially hazardous for humans.

Levels of Mercury in Muscle and Liver of Star-Spotted Dogfish (Mustelus manazo) from the Northern Region of Japan: A Comparison with Spiny Dogfish (Squalus acanthias)

We analyzed mercury (Hg) concentrations in muscle and liver samples of star-spotted dogfish (Mustelus manazo) caught off the northern region of Japan and compared them with those of spiny dogfish (Squalus acanthias) caught in the same region. The average body length of male star-spotted dogfish specimens was significantly smaller than that of female specimens, reflecting the slower growth rate of male fish. Hg concentrations in liver and muscle increased with increases in body length and estimated age of both male and female star-spotted dogfish specimens. However, the relationships between Hg concentration in liver or muscle and body length or estimated age of male specimens differed markedly from those of female specimens, reflecting differences in growth rate and cessation of growth on reaching maturity. Marked increases in Hg concentration in liver of male and female star-spotted dogfish specimens were observed slightly later than increases in Hg concentration in muscle of those specimens due to growth cessation. These marked increases in Hg in liver may reflect increases in Hg due to the formation of mercury selenide. Similar results were previously reported in spiny dogfish specimens, except spiny dogfish showed only trace levels of Hg in liver (Endo et al., Chemosphere 77:1333-1337, 2009). The greater lipid content in liver and the larger liver size in spiny dogfish may explain the much lower levels of Hg observed in liver of spiny dogfish compared with those in the star-spotted dogfish.

Mercury bioacumulation in four tissues of Podocnemis erythrocephala (Podocnemididae: Testudines) as a function of water parameters

A number of environmental factors influence the dynamics of Hg in aquatic ecosystems, yet few studies have examined these factors for turtles, especially from South America. Red-headed river turtle ( Podocnemis erythrocephala) is easy to capture in the black waters of Rio Negro, making it the turtle species that is consumed most often by people of the region. In this study, environmental factors and turtle size were investigated to determine their influence on the Hg concentration in blood, muscle, liver and carapace of the red-headed river turtle. Factors investigated included turtle length, pH, dissolved organic carbon and availability of potential methylation sites (floodplain forests and hydromorphic soils). The study was conducted in the Rio Negro basin, where we collected water and turtle blood, muscle, liver and carapace samples from 12 tributaries for chemical analysis. Through radar imagery and existing soil maps with GIS, the percentage of alluvial floodplains and hydromorphic soils (potential methylation sites) was estimated for each drainage basin at sampling points. The mean Hg concentration in blood of P. erythrocephala was 1.64 ng g − 1 (SD = 1.36), muscle 33 ng g − 1 (SD = 11), liver 470 ng g − 1 (SD = 313) and carapace 68 ng g − 1 (SD = 32). Sex or length did not influence the Hg concentration in P. erythrocephala blood, muscle and liver, but Hg increased in carapace tissue when length size increased (ANCOVA p = 0.007). In the multiple regression analysis, none of the environmental factors studied had a significant relation with blood, muscle, liver and carapace. P. erythrocephala moves among habitats and in the open and interconnected aquatic systems of the Amazon basin, characterized by high levels of limnological variability, a good bioindicator of Hg concentration needs to be relatively sedentary to represent a specific habitat. However, the levels of Hg in liver were sufficient to pose a potential risk to humans that consume them, suggesting the usefulness of P. erythrocephala as a bioindicator.

Mercury concentrations in wild mink (Mustela vison) and river otters (Lontra canadensis) collected from eastern and Atlantic Canada: Relationship to age and parasitism

Total mercury (Hg) concentrations were measured in the fur, brain and liver of wild mink (Mustela vison) and river otters (Lontra canadensis) collected from eastern and Atlantic Canada. Total Hg concentrations in fur were strongly correlated with levels in the brain and liver. There was no difference in tissue concentrations between male and female mink; however, female otters had significantly higher fur, brain and liver Hg levels than males. Similarly, there was not a significant relationship between Hg concentration and age of mink, whereas in otters, Hg concentrations in all three tissues decreased significantly with age. In both species, only a very small percentage of the variability in Hg concentration was explained by age. After adjusting the data for site-to-site differences in Hg levels, Hg concentrations in the fur of mink infected by the parasite, Dioctophyma renale, were found to be significantly higher than Hg levels in uninfected mink.

Trace Elements in Three Marine Birds Breeding on Reunion Island (Western Indian Ocean): Part 1—Factors Influencing Their Bioaccumulation

This work aimed to use seabirds as bioindicators of trace element levels in the tropical waters and food webs of the Western Indian Ocean. The accumulation patterns of selected toxic (Cd and Hg) and essential (Cu, Fe, Mn, Se, and Zn) elements were determined in liver, kidney, and pectoral muscle of 162 marine birds belonging to 3 species collected in Reunion Island between 2002 and 2004. These pelagic seabirds belong to the following species: Barau's Petrel (Pterodroma baraui), Audubon's Shearwater (Puffinus lherminieri bailloni), and White-Tailed Tropicbird (Phaethon lepturus). Hg levels were also measured in breast feathers. Highest mean kidney Cd and liver Hg levels (respectively, 27.79 +/- 13.78 microg x g (-1) dry weight (dw) and 24.31 +/- 14.13 microg x g (-1) dw) were found in the squid-eating Barau's Petrel. Barau's Petrel feather Hg levels fell in the range of 0.6 to 2.7 microg x g(-1) dw previously reported for other petrels and shearwaters. The values of the other elements were also in the same range as those previously reported in the published literature concerning related seabirds, although Se and Zn burdens in the Reunion birds were among the highest values. Levels of Zn, Fe, and, to a lesser extent, Cu appeared to be regulated in seabird tissues. Uptake and pathways of metabolism and storage seemed to be similar for the five essential elements. The reproductive status of the bird did not seem to affect element levels, which, moreover, were not significantly different between male and female birds. However, trace elements in sampled birds varied according to the tissue considered, the age of the animal, and its species. Diet was seemingly a major influencing factor. Health status also appeared to have an impact on element levels.

Trace element accumulation in hawksbill turtles (Eretmochelys imbricata) and green turtles (Chelonia mydas) from Yaeyama Islands, Japan

Concentrations of 18 trace elements (V, Cr, Mn, Co, Cu, Zn, Se, Rb, Sr, Zr, Mo, Ag, Cd, Sb, Ba, Hg, Tl, and Pb) were determined in the liver, kidney, and muscle of green turtles (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) from Yaeyama Islands, Okinawa, Japan. Accumulation features of trace elements in the three tissues were similar between green and hawksbill turtles. No gender differences in trace element accumulation in liver and kidney were found for most of the elements. Significant growth-dependent variations were found in concentrations of some elements in tissues of green and hawksbill turtles. Significant negative correlations (p < 0.05) were found between standard carapace length (SCL) and the concentrations of Cu, Zn, and Se in the kidney and V in muscle of green turtles and Mn in the liver, Rb and Ag in kidney, and Hg in muscle of hawksbill turtles. Concentrations of Sr, Mo, Ag, Sb, and Tl in the liver, Sb in kidney, and Sb and Ba in muscle of green turtles and Se and Hg in the liver and Co, Se, and Hg in kidney of hawksbill turtles increased with an increase in SCL (p < 0.05). Green and hawksbill turtles accumulated extremely high concentrations of Cu in the liver and Cd in kidney, whereas the levels of Hg in liver were low in comparison with those of other higher-trophic-level marine animals. High accumulation of Ag in the liver of green turtles was also observed. To evaluate the trophic transfer of trace elements, concentrations of trace elements were determined in stomach contents of green and hawksbill turtles. A remarkably high trophic transfer coefficient was found for Ag and Cd in green turtles and for Cd and Hg in hawksbill turtles.

Mercury exposure to passerine birds in areas close to local emission sources in Slovakia and Norway

Mercury concentrations in vegetation, insects and insectivorous birds were studied in the vicinity of a mercury production plant at Rudnany, Slovakia and a zinc smelter at Odda, Norway. Comparison was made with pristine reference sites in both countries. Sampling of eggs and juvenile birds was facilitated through the use of nest boxes. In Norway the migrating species Ficedula hypoleuca was studied, whereas in Slovakia both migrating and resident birds were represented. While the Hg levels in vegetation and insects corresponded well to the expectations based on previous knowledge of contamination levels, the levels in passerine bird eggs seemed to depend mainly on whether the bird was migratory or resident. In chicks liver Hg levels at different sites in Norway showed no clear correspondence with egg levels at the same sites. At the background site an initial Hg burden provided through the egg was rapidly reduced, probably through excretion during feather development, whereas at the most contaminated site intake of Hg through contaminated food outweighed the excretion effect.

Influence of Dietary Levels of Protein and Sulfur Amino Acids on the Subacute Toxicity of Methylmercury in Mice.

The influence of diet on the subacute toxicity of methylmercury (MeHg) was investigated using C57BL/6N male mice, each fed a 24.8% protein diet (normal protein diet, NPD), a 7.5% protein diet (low protein diet, LPD) or LPD supplemented by methionine and cystine to NPD level (amino acid supplemented diet, ASD). When MeHg was consecutively administered to each group of mice (20 μmol/kg per day), median survival times were 11, 18 and 30 d in ASD-, LPD- and NPD-fed mice, respectively. Toxic symptoms including ataxia and loss of body weight were in that order. Hg accumulation rate in brain was faster in LPD-fed mice than in NPD-fed mice, and was further enhanced in ASD-fed mice. The fact that Hg in plasma low molecular weight (LMW) fraction was in the order of ASD->LPD->NPD-fed mice, would be one reason for the difference in the brain Hg accumulation. Hg levels in liver, blood and plasma showed a monotonous increase, and their terminal Hg levels were similar in the three groups. Renal Hg levels increased rapidly and almost never changed from the 7th d in the three groups. Urinary excretion of Hg in LPD-fed mice was markedly lower than in NPD-fed mice throughout the experimental period ; that in ASD-fed mice, which was the highest at least for the first few days, began to decline earliest. No difference was observed in fecal Hg levels during the early part of the experiment. Our results suggest that diet is an important factor determining the susceptibility to subacute MeHg toxicity, and that accelerated Hg accumulation rate in the brain caused by diet would result in higher susceptibility to subacute MeHg toxicity.

Changes in mercury levels in harbor porpoises from the Bay of Fundy, Canada, and adjacent waters during 1969?1977

Mercury levels were studied in a sample of 146 harbor porpoises taken in the Bay of Fundy, Canada, and adjacent waters during 1969–77. Mean concentrations of total mercury recorded in 5-year old males (exemplifying sexually mature adults) were 1.12 ppm in axial muscle, 0.38 in cerebrum, 0.31 in cerebellum, 2.00 in kidney, and 15.7 in liver. Respective means in tissues of 5-year old females were 1.46, 0.42, 0.21 2.77 and 16.2 ppm. There was a clear correlation of increase in total Hg with age in the tissues examined. Except in the liver, mercury levels were less well correlated with weight and body length than with age. Hg levels were not significantly correlated (p > 0.05) with weight and lengthwithin age classes, except marginally in the case of liver (P ⩾0.10). Hg in muscle was virtually all in the methylated form, but in liver only about 17% was methylated. The proportions in other tissues were intermediate (kidney about 41%, mam-mary gland about 46%, brain about 8 to 52%). Levels in liver were thought to be those giving the best indication of changes in background levels of mercury in the food chain. Significant changes in Hg tissue levels appear to have occurred during the 9-year study period. Liver Hg levels in both sexes decreased from 1970 to 1971, remained low for 3 years, increased again in 1974, and continued to do so in the years following. Data are presented suggesting that this also occurred in other tissues. Since there is no evidence of a change in diet in this period, we speculate that the decline in Hg levels could be correlated with a dominance of relatively mercury-poor Gulf Stream water in the Bay of Fundy approaches in 1971–73, as opposed to the usual dominance by waters of the Nova Scotia current.