Silver accumulation

Silver is a normal trace constituent of many organisms (Smith and Carson 1977). In terrestrial plants, silver concentrations are usually less than 1.0 mg/kg ash weight (equivalent to less than 0.1 mg/kg DW) and are higher in trees, shrubs, and other plants near regions of silver mining. Seeds, nuts, and fruits usually contain higher silver concentrations than other plant parts (USEPA 1980). Silver accumulations in marine algae (max. 14.1 mg/kg DW) are due mainly to adsorption rather than uptake bioconcentration factors of 13,000 to 66,000 are not uncommon (USPHS 1990 Ratte 1999). 

Season of collection (Fowler and Oregioni 1976 Sanders etal. 1991) and latitude (Anderlini 1974) also influenced silver accumulations. Seasonal variations in silver concentrations of Baltic clams (Macoma balthica) were associated with seasonal variations in soft tissue weight and frequently reflected the silver content in the sediments (Cain and Luoma 1990). Oysters from the Gulf of Mexico vary considerably in whole-body concentrations of silver and other trace metals. Variables that modify silver concentrations in oyster tissues include the age, size, sex, reproductive stage, general health, and metabolism of the animal water temperature, salinity, dissolved oxygen,... 

Hogstrand, C., F. Galvez, and C.M. Wood. 1996. Toxicity, silver accumulation and metallothionein induction in freshwater rainbow trout during exposure to different silver salts. Environ. Toxicol. Chem. 15 1102-1108. 

Silver accumulation, natural defenses against, 22 655 Silver acetate, 22 669 Silver acetylide, 22 670 Silver acetylides, 1 180 Silver alloys, 22 636... 

During immersion, the maximum whole body silver concentration was 22.1 mg/kg DW vs. 0.8 in controls main sites of accumulation were the connecting tissues of nephridia and gut. No histopathology. A constant elimination of silver in urine occurs simultaneously with silver accumulation. During depuration, new connective tissue formed and silver concentrations were reduced by 88%... 

Silver has been demonstrated in the brains of neonatal rats whose mothers received injections of silver lactate on days 18 and 19 of gestation (Rungby and Danscher 1984). As mentioned above, treatment of neonatal rats has also been found to reduce the volumes of certain cell groups within the hippocampus (Rungby et al. 1987). However, functional tests were not performed on these rats, and therefore, neither the significance of the silver accumulation, nor the decrease in regional hippocampal volume can be determined. 

Silver accumulation in marine algae appears to result from adsorption rather than uptake bioconcentration factors of 13,000-66,000 have been reported (Fisher et al. 1984). 

George SG, Pirie BJS, Calabrese A, et al. 1986. Biochemical and ultrastructural observations of long-term silver accumulation in the mussel, Mytilus edulis. Marine Environmental Research 18 255-265. 

As shown in Table V, silver significantly depressed plasma copper levels and ceruloplasmin activity but had no influence on plasma zinc levels. As expected, silver accumulated in the plasma. The depressing effect of silver on ceruloplasmin activity is in agreement with earlier work (Whanger and Weswig, 1970). These workers found silver to have the most depressing effect on plasma ceruloplasmin activity, followed by cadmium, molybdenum, zinc, and sulfate in descending order. 

Silver accumulated in the liver with each increase of dietary silver, and this significantly increased hepatic copper and iron content (Table VI). However, silver had no influence on the zinc content of the liver. Dietary selenium significantly increased the silver content of the liver, consistent with the results of Wagner et al. (1975). The metabolic interaction of silver with copper in the rat is in agreement with findings by others using the chick (Hill et al, 1964 Peterson and Jensen, 1975b). 

Slightly different effects of silver on the renal mineral content were observed (Table VII). In contrast to the liver, silver had no significant effect on renal copper and iron levels. As for the liver, silver had no effect on renal zinc levels. Also consistent with the liver, silver accumulated in the kidneys, and selenium caused a significant increase in this accumulation. However, in contrast to the liver, there was a significant interaction between selenium and silver with respect to the accumulation of silver in this organ. This indicates that only a combination of selenium and silver brings about this effect. 

Glover, C.N., and C.M. Wood. 2004. Physiological interactions of silver and humic substances in Daphnia magna Effects on reproduction and silver accumulation following an acute silver challenge. Comp. Biochem. Physiol. C Toxicol. Pharmacol. 139 273-280. 

Morgan, T.P., M. Grosell, R.C. Playle, et al. 2004. The time course of silver accumulation in rainbow trout during static exposure to silver nitrate Physiologieal regulation or an artifact of the exposure conditions Aquat. Toxicol. 66 55—72. 

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