Selenium with Mercury

A summary of the influence of selenium on deposition of mercury in rat tissues is presented in Table III. In the injection experiments, selenium caused a reduction in mercury deposition in the kidneys of rats given either inorganic or organic mercury. The reduction in kidney mercury is dependent upon the level of selenium injected and the chemical form of selenium (Fang, 1977). Selenomethionine was most effective in reducing the renal mercury content, followed by selenocystine, selenate, and selenite. In contrast to the kidneys, selenium usually resulted in an increased deposition of mercury in other tissues. It is of particular interest that selenium appears to be very effective in increasing methylmercury deposition in the brain. When included in the diet, selenium also causes an increased deposition of hepatic mercury. This is consistent with the results of selenium injection experiments. Deposition in the kidney may depend upon the level in the diet. At low mercury levels, selenium resulted in decreased levels in the kidneys but in increased levels at 

Some work has been done on the deposition of selenium and mercury in eggs. When included in the diet (20 ppm mercury as methylmercury) of laying hens, dietary selenium (8 ppm) was shown to increase the mercury content of egg white with simultaneous reduction of the mercury content of egg yolk (Magat and Sell, 1979). More than 97% of the total mercury in egg white was associated with ovalbumin, and selenium had very little influence on this amount. In contrast, the largest proportion of selenium in egg white was found in globulin. This preferential binding of 

There is substantial evidence that some animals may accumulate mercury and selenium at molar increment ratios in their tissues. When doses of mercury and selenium are varied in rats, the molar ratios of these elements in a plasma protein remained fairly close to unity (Burk et al., 1974). The selenium content of high mercury tuna was observed to be greater than in low mercury tuna (Ganther and Sunde, 1974). On a molar basis, selenium increases in an approximate 1 1 ratio with mercury. Mercury levels in the livers of 56 specimens of nine different species of marine mammals were highly correlated (r 0.99) with their selenium content, and 1 1 mercury-selenium molar increment ratios were found (Koeman et al., 1975). The authors suggested that marine mammals are 

Weanling rats were fed a basal Torula yeast diet with 15 ppm methylmercury (control) or this diet plus additions of BHT (0.2%), DPPD (0.2%), vitamin E (500 ppm), ascorbic acid (0.2%), or 0.5 ppm selenium as either selenite (inorganic) or high selenium wheat (organic). 

The mercury-selenium ratio may have significance in human health. Mercury and selenium levels were determined in post-mortem samples from workers in the mercury mine at Idrija, Yugoslavia and from inhabitants of this town (Kosta et al, 1975). Although the kidney has been considered the prime accumulator of inorganic mercury, the accumulation was highest (ppm basis) in the thyroid, followed by the pituitary, kidney, brain, and liver. The correlation coefficient between mercury and selenium in the organs of the miners was 0.998, with two virtually identical regression equations of the form Se (ppm) = 0.41 Hg (ppm) + 0.21. In molar terms, the ratio of mercury to selenium was 0.96. 

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Ganther HE. 1980. Interactions of vitamin E and selenium with mercury and silver. Ann NY Acad Sci 355 212-226. 

Parizek, J., Kalouskova, J., Babicky, A., Benes, J., and Pavlik, L., 1974, Interaction of selenium with mercury, cadmium and other toxic metals, in Trace Elements Metabolism in Animals, Vol. 2 (W. G. Hoekstra, J. W. Suttie, H. E. Ganther, and W. Mertz, eds.), pp. 119-131, University Park Press, Baltimore, Maryland. 

Sodium selenite has also been incorporated into styrene—butadiene mbber and used in a pellet form which results in the slow release of selenium into water. These pellets have been placed in lakes in Sweden which have fish contaminated with mercury owing to high levels of that element in the water. The selenium released by the pellets reacts with mercury to form insoluble, heavy mercury selenide which setties to the lake bottom and removes mercury from the ecosystem (126). 

The preparation of Pans-1,2-cyclohexanediol by oxidation of cyclohexene with peroxyformic acid and subsequent hydrolysis of the diol monoformate has been described, and other methods for the preparation of both cis- and trans-l,2-cyclohexanediols were cited. Subsequently the trans diol has been prepared by oxidation of cyclohexene with various peroxy acids, with hydrogen peroxide and selenium dioxide, and with iodine and silver acetate by the Prevost reaction. Alternative methods for preparing the trans isomer are hydroboration of various enol derivatives of cyclohexanone and reduction of Pans-2-cyclohexen-l-ol epoxide with lithium aluminum hydride. cis-1,2-Cyclohexanediol has been prepared by cis hydroxylation of cyclohexene with various reagents or catalysts derived from osmium tetroxide, by solvolysis of Pans-2-halocyclohexanol esters in a manner similar to the Woodward-Prevost reaction, by reduction of cis-2-cyclohexen-l-ol epoxide with lithium aluminum hydride, and by oxymercuration of 2-cyclohexen-l-ol with mercury(II) trifluoro-acetate in the presence of ehloral and subsequent reduction. ... 

Hoffman DJ, Ohlendorf HM, Mam CM, Pendleton GW. 1998. Association of mercury and selenium with altered glutathione metabolism and oxidative stress in diving ducks from the San Francisco Bay region, USA. Environ Toxicol Chem 17 167-172. 

In the Boliden process, developed by Boliden Kemi Company in Sweden, filter beds containing amorphous selenium are used to filter the gases. Mercury in the gas is deposited in the filter as mercury selenide (HgSe). Alternatively, the gases can be scrubbed with a slurry of amorphous selenium, whereupon mercury is precipitated as HgSe. Activated carbon filters are also useful for absorbing mercury vapor from the gas. 

Phenylnaphthalene has been prepared by the reaction of a-halonaphthalenes with mercury diphenyl3 6 or with benzene in the presence of aluminum chloride,6 and by means of the Gri-gnard synthesis, starting with either bromobenzene, cyclohexyl chloride, and a-tetralone 7 or with a-bromonaphthalene and cyclohexanone.6 8 9 Dehydrogenation of the reduced naphthalene has been accomplished by the use of sulfur,6 bromine,8 platinum black, or selenium.7 The formation of the hydrocar-... 

Selenium lessens the toxicity of divalent mercury in animals, the protection being less at continuous mercury exposure. Selenium has been found to affect the distribution of mercuric mercury in mice [134], rats [135], rabbits [136, 137] and pigs [ 138]. Mercury forms a mercury-selenium protein complex with selenium with little biological activity [139]. Mercury is thus retained longer in the blood, liver and spleen and as a consequence lessens accumulation in the kidney. In fish, selenium pretreatment probably retarded mercury uptake rather than promoting mercury excretion [140]. 

At emulsion crumb rubber facilities, a well-operated biological treatment facility permits compliance with BPT limitations and reduces organic toxic pollutant levels. Toxic metals that may not be reduced include chromium, cadmium, copper, selenium, and mercury. Tables 16 and 17 show pollutant removal efficiencies at two emulsion cmmb plants. 

Oxidation of the sulfur- or selenium-bridged azepines (171 X=S or Se) with mercury(II) oxide in methanol yields ultimately the 4f/-azepine (68JCS(C)23ll) with hydrogen peroxide as oxidant, the sulfur compound furnishes the sulfoxide (171 X=SO). Selenium dioxide oxidation of 7,8-dimethyl-lf/-l-benzazepin-2-one affords the 2,3-dioxo derivative (173) that displays no evidence of enol tautomers or heteroaromaticity (7ici(L)1439). 

After combustion of the sample and carriers in an oxygen stream, reducing conditions are achieved by a flow of carbon monoxide over the sample ash. Arsenic, zinc, cadmium, and any remaining selenium and mercury are reduced to elemental form. When the sample is heated to 1150°C in a slow carbon monoxide stream in a quartz tube in a furnace, recovery of all five elements in the liquid nitrogen trap is complete in 30 min. The recovery trap is washed with nitric acid to dissolve all the metals, and the radioactivity of a nitric acid solution of the products is counted with a Ge(Li) detector. 

A special subroutine, incorporating this correction and the tests for when it should be used, was added to SPECTRA. We checked it by irradiating and analyzing mixtures with known amounts of ytterbium, selenium, and mercury. The true values and the values calculated by the computer agreed within 15% for mercury. The method allowed the determination of mercury in the presence of ytterbium and selenium when their concentration ranged up to 10 times greater than mercury. 

High mercury levels in terminal food chain predators hke tuna fish have caused considerable worry. It has been found that tuna contain larger than average amounts of selenium.1- 10 Discuss the possible role of selenium with respect to the presence of mercury. ... 

The following compounds 1 are prepared in a similar manner to the corresponding thiophenes, fusion of sulphur or selenium with acetophenone anil giving rise respectively to 2 4-diphenylthiophene and 2 4-diphenylsdencpkene. The melting-points of these compounds and their derivatives are as follows 2 4-diphenylthiophene, M.pt. 122-5° C., 2 4-diphenylselenophene, M.pt. 112-3° C., 5-chloro-mercuri-2 4-diphenylthiophene, M.pt. 223° C., o-chloromercuri-2 4-diphenylselenophene, M.pt. 224° C. 

Ridlington JW, Whanger PD. 1981. Interactions of selenium and antioxidants with mercury, cadmium and silver. Fundam Appl Toxicol 1 368-375. 

Whanger PD. 1985. Metabolic interactions of selenium with cadmium, mercury, and silver. Adv Nutr Res 7 221-250. 

In a further study of routes to steroids with an aromatic ring C, 18-norandrost-13-enes (273) were found to give 7a-hydroxy-18-norandrosta-8,l 1,13-trienes (274) on reaction with selenium dioxide, while the 18-norandrosta-7,13-dienes reacted with mercury(n) acetate to give the 7a-acetate (276), as well as its 7j8-epimer. Mechanisms, including stepwise dehydrogenations, are discussed.226... 

A combination of IPC and inductively coupled plasma (ICP) MS was extensively explored for the speciation of phosphorus, arsenic, selenium, cadmium, mercury, and chromium compounds [108-118] because it provides specific and sensitive element detection. Selenium IPC speciation was joined to atomic fluorescent spectrometry via an interface in which all selenium species were reduced by thiourea before conventional hydride generation [119], Coupling IPC separation of monomethyl and mercuric Hg in biotic samples by formation of their thiourea complexes with cold vapor generation and atomic fluorescence detection was successfully validated [120]. The coupling of IPC with atomic absorption spectrometry was also used for online speciation of Cr(III) and Cr(VI) [121] and arsenic compounds employing hydride generation [122]. 

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