Impacts of mercury contamination in the southeastern United States

Facemire, Charles F.; Augspurger, Tom; Bateman, Donald V.; Brim, Michael; Conzelmann, P.; Delchamps, S.; Douglas, E.; Inmon, L.; Looney, K.; López, Félix; Masson, G.; Morrison, D.; Morse, N.; Robison, Andrew

doi:10.1007/bf01189745

Cited by 39 publications

(22 citation statements)

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“…In this study, we aimed to investigate the presence of trace metals in an environmental model and interrogate potential associations with global DNA methylation, with a particular focus on mercury, as its impact throughout the southeastern United States has been well-documented (Facemire et al, 1995). Very few studies to date have examined how mercury exposures might affect the epigenome, especially in free-living animals (Basu et al, 2013; Hanna et al, 2012; Pilsner et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Global DNA methylation loss associated with mercury contamination and aging in the American alligator (Alligator mississippiensis)

Nilsen

Parrott

Bowden

et al. 2016

Science of The Total Environment

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Mercury is a widespread environmental contaminant with exposures eliciting a well-documented catalog of adverse effects. Yet, knowledge regarding the underlying mechanisms by which mercury exposures are translated into biological effects remains incomplete. DNA methylation is an epigenetic modification that is sensitive to environmental cues, and alterations in DNA methylation at the global level are associated with a variety of diseases. Using a liquid chromatography tandem mass spectrometry-based (LC-MS/MS) approach, global DNA methylation levels were measured in red blood cells of 144 wild American alligators (Alligator mississippiensis) from 6 sites with variable levels of mercury contamination across Florida’s north-south axis. Variation in mercury concentrations measured in whole blood was highly associated with location, allowing the comparison of global DNA methylation levels across different “treatments” of mercury. Global DNA methylation in alligators across all locations was weakly associated with increased mercury exposure. However, a much more robust relationship was observed in those animals sampled from locations more highly contaminated with mercury. Also, similar to other vertebrates, global DNA methylation appears to decline with age in alligators. The relationship between age-associated loss of global DNA methylation and varying mercury exposures was examined to reveal a potential interaction. These findings demonstrate that global DNA methylation levels are associated with mercury exposure, and give insights into interactions between contaminants, aging, and epigenetics.

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Section: Introductionmentioning

confidence: 99%

Global DNA methylation loss associated with mercury contamination and aging in the American alligator (Alligator mississippiensis)

Nilsen

Parrott

Bowden

et al. 2016

Science of The Total Environment

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“…Methylmercury has been well documented as a bioaccumulated contaminant in aquatic ecosystems (Faber and Hickey, 1973;Fimreite, 1974, Stendell et al, 1976Thomann et al, 1992;Facemire et al, 1995;Meyer et al, 1995;Cleckner et al, 1998;Wolfe and Norman, 1998). Negative effects on the neurological (Chang, 1977;Burbacher et al, 1990;Nagashima, 1997) and immune systems (Ilback, 1991;Ilback et al, 1996) and other tissues (SnelgroveHobson et al, 1988) are well documented in humans and captive mammals.…”

Section: Introductionmentioning

confidence: 99%

“…These studies have focused on non-piscivorous species, whereas the top predators in aquatic systems are often piscivorous mammals and birds. Although the presence of mercury in the tissues of wild fisheaters is commonly reported, the health and behavioral effects have only been sporadically documented (Barr, 1986;Spalding et al, 1994;Facemire et al, 1995, Meyer et al, 1998Scheuhammer et al, 1998;Nocera and Taylor, 1998).…”

Section: Introductionmentioning

confidence: 99%

Histologic, Neurologic, and Immunologic Effects of Methylmercury in Captive Great Egrets

Spalding

Frederick

McGill

et al. 2000

Journal of Wildlife Diseases

115

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Captive great egret (Ardea albus) nestlings were maintained as controls or were dosed with methylmercury chloride at low (0.5), and high doses (5 mg/kg, wet weight) in fish. Low dosed birds were given methylmercury at concentrations comparable to current exposure of wild birds in the Everglades (Florida, USA). When compared with controls, low dosed birds had lower packed cell volumes, dingy feathers, increased lymphocytic cuffing in a skin test, increased bone marrow cellularity, decreased bursal wall thickness, decreased thymic lobule size, fewer lymphoid aggregates in lung, increased perivascular edema in lung, and decreased phagocytized carbon in lung. High dosed birds became severely ataxic and had severe hematologic, neurologic, and histologic changes. The most severe lesions were in immune and nervous system tissues. By comparing responses in captive and wild birds, we found that sublethal effects of mercury were detected at lower levels in captive than in wild birds, probably due to the reduced sources of variation characteristic of the highly controlled laboratory study. Conversely, thresholds for more severe changes (death, disease) occurred at lower concentrations in wild birds than in captive birds, probably because wild birds were exposed to multiple stressors. Thus caution should be used in applying lowest observed effect levels between captive and wild studies.

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“…Mercury has been identified as one of the most serious environmental threats to the well-being of wildlife in the southeastern United States (Facemire et al 1995). The prevalence of Hg in aquatic species has also prompted concerns for the health of subsistence fishermen and the general population who regularly consume fish.…”

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confidence: 99%

Relationship of Blood Mercury Levels to Health Parameters in the Loggerhead Sea Turtle ( Caretta caretta )

Day

Segars

Arendt

et al. 2007

Environ Health Perspect

128

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BackgroundMercury is a pervasive environmental pollutant whose toxic effects have not been studied in sea turtles in spite of their threatened status and evidence of immunosuppression in diseased populations.ObjectivesIn the present study we investigate mercury toxicity in loggerhead sea turtles (Caretta caretta) by examining trends between blood mercury concentrations and various health parameters.MethodsBlood was collected from free-ranging turtles, and correlations between blood mercury concentrations and plasma chemistries, complete blood counts, lysozyme, and lymphocyte proliferation were examined. Lymphocytes were also harvested from free-ranging turtles and exposed in vitro to methylmercury to assess proliferative responses.ResultsBlood mercury concentrations were positively correlated with hematocrit and creatine phosphokinase activity, and negatively correlated with lymphocyte cell counts and aspartate amino-transferase. Ex vivo negative correlations between blood mercury concentrations and B-cell proliferation were observed in 2001 and 2003 under optimal assay conditions. In vitro exposure of peripheral blood leukocytes to methylmercury resulted in suppression of proliferative responses for B cells (0.1 μg/g and 0.35 μg/g) and T cells (0.7 μg/g).ConclusionsThe positive correlation between blood mercury concentration and hematocrit reflects the higher affinity of mercury species for erythrocytes than plasma, and demonstrates the importance of measuring hematocrit when analyzing whole blood for mercury. In vitro immunosuppression occurred at methylmercury concentrations that correspond to approximately 5% of the individuals captured in the wild. This observation and the negative correlation found ex vivo between mercury and lymphocyte numbers and mercury and B-cell proliferative responses suggests that subtle negative impacts of mercury on sea turtle immune function are possible at concentrations observed in the wild.

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Impacts of mercury contamination in the southeastern United States

Cited by 39 publications

References 1 publication

Global DNA methylation loss associated with mercury contamination and aging in the American alligator (Alligator mississippiensis)

Global DNA methylation loss associated with mercury contamination and aging in the American alligator (Alligator mississippiensis)

Histologic, Neurologic, and Immunologic Effects of Methylmercury in Captive Great Egrets

Relationship of Blood Mercury Levels to Health Parameters in the Loggerhead Sea Turtle ( Caretta caretta )

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