Essentiality, and Toxicity

Copper is one of the several heavy metals that have essential as well as toxic properties. Copper is toxic to many bacteria and viruses but for plants copper toxicity is virtually 

Selected reference values for copper in various human tissue of healthy subjects range, according to Versieck (1985) for liver from 2.6 to approx. 14 mg/kg, for kidney cortex from 1.4 to approx. 3.9 mg/kg, and for muscle tissue from 0.6 to 1.0 mg/kg. All data were given for wet weight. 

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M. Abdulla, B. M. Nait, and R. K. Chandra, eds.. Proceedings of An International Symposium, Health Effects and Interactions of Essential and Toxic Elements, Nutrition Research, Suppl. 1, Peigamon Press, New York, 1985. 

D.L. Grunes Service, Ithaca, NY interaction of essential and toxic mineral... 

Falchuk, K. 1988. Zinc deficiency and the E. gracilis chromatin. Pages 75-91 in A.S. Prasad (ed.). Essential and Toxic Trace Metals in Human Health and Disease. Alan R. Liss, NY. 

The metabolic cycle of an element can be represented by the simple Scheme 1. As will be shown each of these phases involves specific chelation. Passage between the phases is also under the control of chelates. On a more extensive scale an ecological cycle, as shown in Scheme 2, is of significance to both essential and toxic elements. Of particular importance is the interface between any two phases, the interface requiring water for effective transport of elements. Here again, chelation or mischelation can have a serious impact on the ecological cycle of an element. 

Disease. Volume II. Essential and Toxic Elements" Prasad,... 

O Flaherty EJ. 1993b. Chromium as an essential and toxic metal. Scand J Work Environ Health 19( 1) 124-124. 

Wagley D, Schmiedel G, Mainka E, et al. 1989. Direct determination of some essential and toxic elements in milk and milk powder by graphite furnace atomic absorption spectrometry. Atmos Spectrosc 10(4) 106-111. 

Mussels (Mytilus edulis) have a content of trace elements, both essential and toxic (As, Cd, Hg, Ni, and Pb), that is tightly correlated to the geographic zone, water salinity, and degree of sea contamination [15]. 

TABLE 10.6. Essential and Toxic Element Daily Intakes in the Population of Northern Italy... 

E. Coni, P. Falconieri, E. Ferrante, P. Semerano, E. Beccaloni, A. Stacchini, S. Caroli, Reference values for essential and toxic elements in human milk, Ann. 1st. Super. Sanitd, 26 (1990), 119-130. 

F. A. Rivero Martino, M. L. Fernandez Sanchez, A. Sanz-Medel, Total determination of essential and toxic elements in milk whey by double focusing ICP-MS, J. Anal. Atom. Spectrom., 15 (2000), 163-168. 

Twenty-three elements, including almost all the essential and toxic metals or metalloids such as As, Ag, Cd, Hg, Pd, and Tl, were quantified in 35 types of bottled and canned Polish beers by double-focusing SF-ICP-MS with ultrasonic nebulization after MW-assisted digestion of the samples [121]. Negligible levels... 

Enzymatic extraction carried out using in vitro models of the gastrointestinal tract is cheaper, faster, more reproducible, and ethically easier than the alternative of studies involving people and animals. Estimation of nutrient bioavailability (including trace elements, both essential and toxic) is particularly important for nutritionists, pharmacists, and toxicologists. Application of sequential procedures allows analyte fractionation (metals usually), but enzyme selectivity allows leaching of certain speciation forms of the determined elements. Table 6.9 gives examples of application of enzymatic extraction procedures for trace element analysis and speciation analysis [71, 72]. 

With this technique both essential and toxic elements in food can be detected at lower levels than is the case with FAAS. GF AAS is highly sensitive and selective, and samples can be analysed without prior preparation. Microsamples can be analysed, and the limit of detection is of the order of micrograms per litre. The drawbacks of GF AAS include poor repeatability, the determination of only single elements, and matrix effects, which can significantly lower the quality of the analytical results [72]. 

Kwoczek, M., Szefer, P., Had, E., Grembecka, M. Essential and toxic elements in seafood available in Poland from different geographical regions. J. Agric. Food Chem. 54, 3015-3024 (2006)... 

Mohamed, A.E., Rashed, M.N., Mofty, A. Assessment of essential and toxic elements in some kinds of vegetables. Ecotoxicol. Environ. Safety 55, 251-260 (2003)... 

Otherwise abundances of all essential, non-essential and toxic elements in different plant species were measured and compared (Bowen 1979 Kabata-Pendias and Pendias 1984 Markert 1996) with the latter author calling the inter-species abundance correlations derived from these analyses the Biological System of Elements (Markert 1994a). Besides the REEs and Y, abundances of yet other metals (Al, Ti, V and essential Fe) are linked to each by very highly positive correlation coefficients (Markert 1996). 

Ongoing investigations into selenium metabolism include state-of-the-art methods such as HPLC/ICPMS in combination with MS/MS. Data on the profile of selenium metabolites will elucidate the element s essential and toxic roles and relate individual Se species with observed health effects. 

There are numerous variables that can affect trace element determinations before the analysis of the sample is undertaken and these require careful control. Guidelines giving details of sample collection procedures, and procedures for limitation of contamination in a range of sample types, are available for essential and toxic trace elements. Age, sex, ethnic origin, time of sampling in relation to food intake, time of day and year, history of medication, tobacco usage, and other factors should be recorded when establishing reference intervals from healthy control populations. 

Table 7.3 Formation ( = Stability) constants for EDTA and DTP A complexes with some essential and toxic metals (from Smith and Martell, 1974)...

Tinggi, U. (2003). Essentiality and toxicity of selenium and its status in Australia a review. Toxicol. Lett. 137, 103-110. 

Osman, K., A. Schutz, B. Akesson, A. Maciag, and M. Vahter. 1998. Interactions between essential and toxic elements in lead exposed children in Katowice, Poland. Clin. Biochem. 31... 

Combs GF. 1993. Essentiality and toxicity of selenium with respect to recommended daily allowances and reference doses. Scand J Work Environ Health 19(suppl 1) 119-121. 

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