Subchronic mercury exposure in coturnix and a method of hazard evaluation

Hill, Elwood F.; Soares, Joseph H.

doi:10.1002/etc.5620030311

Cited by 23 publications

(4 citation statements)

References 25 publications

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“…There have been some instances of declines in bird populations attributed to Hg contamination, in places such as southern Florida (Spalding et al 1994), Northwestern Ontario ( Fimreite 1974), and Sweden ( Wallin 1984). The experimental dietary dose of methylmercury lethal to birds ranges from 4 to 40 μg/g ( Finley et al 1979; Hill & Soares 1984; Solonen & Lodenius 1984). Among sensitive avian species, sublethal effects, predominantly on reproduction, have been reported at concentrations of more than 0.1 μgHg/g in the diet and 5 μgHg/g in feathers ( Heinz 1979; Solonen & Lodenius 1984; Eisler 1987 ).…”

Section: Discussionmentioning

confidence: 99%

Mercury Contamination of Fish and Its Implications for Other Wildlife of the Tapajós Basin, Brazilian Amazon

Uryu

Malm

Thornton

et al. 2001

Conservation Biology

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Since 1979 the gold rush in the Brazilian Amazon has caused serious environmental damage to one of the most complex ecosystems on Earth. Mainly due to the toxicity of mercury to humans, this problem has received wide public attention and prompted many studies. Although these studies have involved sampling of fish, the negative effect of mercury contamination to fish themselves and other wildlife has been largely ignored. To assess the present level of mercury contamination of fish, and its implication for fish and other animals, we collected and examined data on mercury concentration in fish of the Brazilian Amazon, especially for the Tapajós basin, between 1991 and. We conclude that omnivores and piscivores that live nearer to gold mining areas in the Tapajós basin are already at high risk of mercury toxification, especially reproductive failure. Mercury concentrations in these fish are also high enough to have detrimental effects on animals at higher trophic levels. The same conclusion applies to other mercury-contaminated areas in the Brazilian Amazon. Because most Amazonian rivers or their tributaries have favorable conditions for mercury contamination, we can expect the problem to persist in the Amazon for a long time, and the consequences are likely to become more significant in the future. These conclusions have important implications for all tropical rainforests where gold mining operations have caused extensive mercury pollution.Contaminación de Peces por Mercurio y sus Implicaciones para Otras Especies de Vida Silvestre de la Cuenca Tapajós, del Amazonas Brasileño Resumen: Desde 1979, la extracción del oro en el Amazonas brasileño ha ocasionado un daño ambiental serio a uno de los ecosistemas más complejos del mundo. Principalmente debido a la toxicidad del mercurio para los humanos, este problema ha recibido una atención pública amplia y ha impulsado muchos estudios. A pesar de que estos estudios han involucrado el muestreo de peces, el efecto negativo de la contaminación por mercurio en los mismos peces y otras especies de vida silvestre ha sido ignorado. Para evaluar los niveles actuales de contaminación por mercurio en peces y sus implicaciones en otros animales, colectamos y examinamos datos sobre la concentración de mercurio en peces del Amazonas brasileño, especialmente en la cuenca Tapajós, entre 1991 y 1996. Concluimos que los omnívoros y piscívoros que viven más cerca de las áreas de minas de oro en la cuenca Tapajós ya se encuentran en un alto riesgo de intoxicación por mercurio, especialmente en riesgo de falla reproductiva. Las concentraciones de mercurio en estos peces son lo suficientemente altas como para causar un efecto dañino en animales de niveles tróficos más altos. Las mismas conclusiones son válidas para otras áreas del Amazonas brasileño contaminadas con mercurio. Debido a que la mayoría de los ríos del Amazonas o sus tributarios tienen condiciones favorables para la contami- † † Uryu et al. Mercury Contamination of Amazon Fish 439nación por mercurio, podemos esperar que el probl...

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Section: Discussionmentioning

confidence: 99%

Mercury Contamination of Fish and Its Implications for Other Wildlife of the Tapajós Basin, Brazilian Amazon

Uryu

Malm

Thornton

et al. 2001

Conservation Biology

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“…However, Se at 10 ppm as sodium selenite resulted in a much greater increase in GSH peroxidase than did methylmercury in quail, in keeping with our observations in the laboratory and the field with mallards and diving ducks. Hill and Soares [22] reported on subchronic maturational and physiological effects of methylmercury up to 8 ppm in the diet of Japanese quail during the first 9 weeks after hatching. At 8 ppm, approx.…”

Section: Discussionmentioning

confidence: 99%

“…The toxicity of Hg to birds and wildlife has been reviewed in detail [17–19]. Significant sublethal effects of Hg in birds have included altered glutathione and thiol status as well as activities of related enzymes [20,21], depression of brain acetylcholinesterase (AChE), and elevated plasma enzyme levels [22]. Cuvin‐Aralar and Furness [23] reviewed Hg and Se interactions; these interactions are normally antagonistic, but additivity and synergism have also been reported.…”

Section: Introductionmentioning

confidence: 99%

Effects of mercury and selenium on glutathione metabolism and oxidative stress in mallard ducks

Hoffman¹,

Heinz²

1998

Enviro Toxic and Chemistry

121

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Earlier studies have reported on the toxicity and related oxidative stress of different forms of Se, including seleno-D,Lmethionine, in mallards (Anas platyrhynchos). This study compares the effects of Se (seleno-D,L-methionine) and Hg (methylmercury chloride) separately and in combination. Mallard drakes received one of the following diets: untreated feed (controls), or feed containing 10 ppm Se, 10 ppm Hg, or 10 ppm Se in combination with 10 ppm Hg. After 10 weeks, blood, liver, and brain samples were collected for biochemical assays. The following clinical and biochemical alterations occurred in response to Hg exposure: hematocrit and hemoglobin concentrations decreased; activities of the enzymes glutathione (GSH) peroxidase (plasma and liver), glutathione-S-transferase (liver), and glucose-6-phosphate dehydrogenase (G-6-PDH) (liver and brain) decreased; hepatic oxidized glutathione (GSSG) concentration increased relative to reduced glutathione (GSH); and lipid peroxidation in the brain was detected by increased thiobarbituric reactive substances (TBARS). Effects of Se alone included increased hepatic GSSG reductase activity and brain TBARS concentration. Selenium in combination with Hg partially or totally alleviated effects of Hg on GSH peroxidase, G-6-PDH, and GSSG. These findings are compared in relation to field observations for diving ducks and other aquatic birds. It is concluded that since both Hg and excess Se can affect thiol status, measurement of associated enzymes in conjunction with thiol status may be a useful bioindicator to discriminate between Hg and Se effects. The ability of Se to restore the activities of G-6-PDH, GSH peroxidase, and glutathione status involved in antioxidative defense mechanisms may be crucial to biological protection from the toxic effects of methylmercury.

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“…The toxicity of inorganic Hg forms (for example HgCl 2 ) is, at least in part, explained by the great affinity for SH groups biomolecules (Salgado et al 1987;Goyer 1996), and for less affinity for phosphate, carboxyl, amide and amine groups (WHO 1991). The consequence of these effects is the inhibition or inactivation of various enzymes such as Na π /K π -ATPase (Clarkson 1972), Ca 2π -ATPase (Freitas et al 1996), aspartate aminotransferase, a-hidroxibutirate dehydrogenase, lac-tate dehydrogenase (Hill & Soares 1984), carbonic anhydrase (Suzuki et al 1994), porphobilinogen synthase (Rocha et al 1993(Rocha et al & 1995Emanuelli et al 1996;Peixoto et al 2003).…”

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confidence: 99%

2,3‐Dimercapto‐1‐propanol does Not Alter the Porphobilinogen Synthase Inhibition but Decreases the Mercury Content in Liver and Kidney of Suckling Rats Exposed to HgCl₂

Roza¹,

Peixoto²,

Welter³

et al. 2005

Basic Clin Pharma Tox

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Heavy metals have received great attention as environmental pollutants mainly because once introduced in the biological cycle they are incorporated in the food chain. Especially the mercury toxicity due to a diversity of effects caused by different chemical species should be emphasized. Heavy metal intoxication has been treated with chelating agents such as 2,3-dimercapto-1-propanol (BAL). However, the efficacy of this treatment is questionable due to the lack of specific effect on the toxic metal. The present study examined the effects of HgCl 2 exposure (five doses of 5.0 mg/kg between ages 8 to 12 days) on physiological parameters, on porphobilinogen synthase activity, and on mercury content in liver, kidneys and brain from suckling rats. The effect of BAL (one dose of 12.5-75 mg/kg) applied 24 hr after mercury intoxication on these parameters was also investigated. The results demonstrate that HgCl 2 intoxication induced a decrease of corporal weight gain as well as brain weight and an increase in renal weight. The inhibition of porphobilinogen synthase from liver and kidney, is still significant and was not modified by subsequent BAL treatment. However, BAL altered two effects induced by mercury: increase in death percentage and decrease in mercury contents in liver and kidney. The increase of mortality induced by mercury was not promoted by metal redistribution to brain nor by the increase of porphobilinogen synthase inhibition induced by metal. More investigations are necessary to determine if the different effects of BAL on intoxication by metals are possibly related to other tissues and/or if the probable metal-chelating complex formed is more toxic than the metal itself.

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Subchronic mercury exposure in coturnix and a method of hazard evaluation

Cited by 23 publications

References 25 publications

Mercury Contamination of Fish and Its Implications for Other Wildlife of the Tapajós Basin, Brazilian Amazon

Mercury Contamination of Fish and Its Implications for Other Wildlife of the Tapajós Basin, Brazilian Amazon

Effects of mercury and selenium on glutathione metabolism and oxidative stress in mallard ducks

2,3‐Dimercapto‐1‐propanol does Not Alter the Porphobilinogen Synthase Inhibition but Decreases the Mercury Content in Liver and Kidney of Suckling Rats Exposed to HgCl₂

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Subchronic mercury exposure in coturnix and a method of hazard evaluation

Cited by 23 publications

References 25 publications

Mercury Contamination of Fish and Its Implications for Other Wildlife of the Tapajós Basin, Brazilian Amazon

Mercury Contamination of Fish and Its Implications for Other Wildlife of the Tapajós Basin, Brazilian Amazon

Effects of mercury and selenium on glutathione metabolism and oxidative stress in mallard ducks

2,3‐Dimercapto‐1‐propanol does Not Alter the Porphobilinogen Synthase Inhibition but Decreases the Mercury Content in Liver and Kidney of Suckling Rats Exposed to HgCl2

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2,3‐Dimercapto‐1‐propanol does Not Alter the Porphobilinogen Synthase Inhibition but Decreases the Mercury Content in Liver and Kidney of Suckling Rats Exposed to HgCl₂