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ABSTRACT: The bivalve Scrobicularia plana has been proposed as a sentinel species for the assessment of estuarine sediment quality. The aim of this study was to test the responsiveness of a set of biomarkers in bivalves originating from a moderately contaminated site (Loire estuary, France) and a comparatively cleaner site (Bay of Bourgneuf, France) used as reference. Temporal fluctuations were examined in animals collected on eight occasions from March 2008 to October 2009 for the determination of biochemical (MTs, GST, AChE), physiological (energy reserves as glycogen and lipids, condition, hepato-somatic and gonado-somatic indices), and behavioural biomarkers (burrowing). Metals in clams were examined with the aim of understanding the variations in MT concentrations. The current findings indicate that among biochemical markers MTs must be used in a precautionary fashion, and comparison with a reference site remains indispensable together with an appreciation of any salinity effects. Clearer responses were obtained for GST activity which contributes to defence against organic compounds. However, any such defence was not sufficient to ensure total protection since a number of impairments were observed at the individual level (burrowing behaviour, condition index, gonado-somatic index). The integrated biomarker response (IBR) illustrated higher levels of stress in clams collected from the Loire estuary compared to those gathered from the reference site at most of the sampling periods. The interpretation of responses involved in the cascade of energetic events (from available food, digestive enzyme activities, energy reserves to condition and reproductive status) is complex but did reveal disturbances in the Loire estuary which is far from being the most contaminated estuary in France and over the world. However, no links can be established between effects at individual and supra-individual levels in organisms in the Loire estuary, even in the case of a small oil spill which occurred at the beginning of this study.
Ecotoxicology and Environmental Safety 12/2012; · 2.29 Impact Factor
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ABSTRACT: The bivalve Scrobicularia plana, an important species for the structure and functioning of estuarine and coastal mudflats, was studied in thirteen sites from NW France differing by their degree of contamination to document the presence of reproduction impairments (intersex, sex ratio, gonadosomatic indices) in relation to the condition revealed by using hepatosomatic and condition indices. In agreement with recent studies in other European estuaries, intersex was revealed in all the studied estuaries, including sites the chemical and ecological status of which is considered "good" according to the criteria of the European Water Framework Directive. The presence of endocrine disrupting chemicals (EDCs) could result in such disturbances. Our results re-inforce the concern linked to the subtle effects of EDCs, which are active at very low doses, often in the absence of any major sign of toxicity. However at this stage, no clear link may be established between intersex and population effects.
Environmental pollution (Barking, Essex: 1987) 04/2012; 167:70-7. · 3.43 Impact Factor
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ABSTRACT: The ragworm Nereis diversicolor has been proposed as a sentinel species for the assessment of estuarine sediment quality. The aim of this study was to test the responsiveness of the worms using a battery of biomarkers in specimens from a moderately contaminated site (Loire estuary, Fr.) and a comparatively cleaner site (Bay of Bourgneuf, Fr.) as a reference site. Ragworms were collected on 7 occasions from April 2008 to October 2009 for the determination of biochemical (GST, AChE, digestive enzymes), physiological (energy reserves (glycogen, lipids and proteins), relationship between length and weight), and behavioural (feeding and burrowing) biomarkers. The biomarker responses were tentatively interpreted in terms of the concept of cascading events potentially responsible for local depletion/extinction of populations submitted to chemical stress. Impairments of AChE and amylase activities, feeding rate, energy reserve concentrations (glycogen and lipids), and the relationship between length and weight showed up differences between the reference site and the Loire estuary despite the latter being far from the most contaminated estuary in France or internationally. However, no links could be established in the Loire estuary ragworms between effects at infra-individual and individual levels, nor with worm population density, even though a small oil spill had occurred in the Loire estuary only one month before the beginning of sampling.
Aquatic toxicology (Amsterdam, Netherlands) 02/2012; 114-115:96-103. · 3.12 Impact Factor
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ABSTRACT: Cadmium (Cd) and metallothionein (MT) concentrations were analysed in the gills and digestive gland of clams Ruditapes decussatus collected from two sites of the Gulf of Gabès (Tunisia) which differ by their degree of pollution. The effect of biotic (maturity stages, protein, sex and body mass) and abiotic factors (temperature, salinity, site and season) on Cd and MT concentrations showed that in the reference site "Bordj d'Ungha" physiological changes caused by gamete development and maturity contributed more to changes in MT concentrations than the bioavailable Cd concentrations; whereas, in the contaminated site "El Hofra", MT induction responded to raised Cd bioavailabilities rather than to physiological changes. With a view to using MTs as metal exposure biomarker in monitoring program, our results show that the analysis in the digestive gland seem to be more relevant than in gills, and that males appear as the most promising candidates compared to females in the determination of this biomarker.
Ecotoxicology and Environmental Safety 04/2009; 72(5):1489-98. · 2.29 Impact Factor
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ABSTRACT: The effect of cadmium (Cd) on the reproduction of Ruditapes decussatus was monitored over a period of 12 months, from June 2001 to June 2002. Two sites "Bordj d'Ungha" and "El Hofra" differing by their degree of cadmium contamination were chosen in the Gulf of Gabès area (Tunisia). Annual mean concentrations of Cd in the whole soft tissues of clams from the site El Hofra were more than 4 times higher than those from the site Bordj d'Ungha (reference site). The gametogenic cycle of the clam R. decussatus was also investigated by histological examination and monthly observations of gonadal sections in a population of clams from both sites. The results show that gametogenesis occurred from March to December in clams from both sites. Nevertheless, spawning and emission of gametes were synchronized in both sexes from only the clams of the reference site. Although this species is considered as gonochoristic, 6.6% of hermaphroditic cases were observed in clams from both sites in which gametes of both males and females were in ripe stage. Moreover, the period of ripening of sexual products led to an increase of condition index and to a decrease of Cd concentrations in the whole soft tissues of clams from both sites, hence reflecting the phenomenon of "biological dilution".
Comparative Biochemistry and Physiology Part C Toxicology & Pharmacology 07/2006; 143(2):252-61. · 2.62 Impact Factor
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ABSTRACT: Oysters, as very popular food items in France, are subject to rules concerning the maximum acceptable contents of trace metals in foods. The food standards for the quantities of metals permitted are always based on total metal concentrations, and not on the metal concentrations that are potentially bioavailable to the consumer (man). In order to estimate the percentages of accumulated trace metals (i.e. Ag, Cd, Cu and Zn) that are potentially bioavailable during consumption, we have used a simple chemical digestion simulation on the insoluble fraction of oysters. These quantities have been added to the soluble fraction, assuming that metals in this fraction are completely bioavailable. Our experiments were conducted on oysters Crassostrea gigas sampled from five sites on the French Atlantic coast and on oysters Ostrea edulis sampled from Restronguet Creek in the United Kingdom. These sites are characterised by various degrees of metal contamination. This study has allowed us to gain a better estimate of the real concentrations of metals bioavailable to the consumer. Only a part of the total metal present is bioavailable: 36-68% for silver, 44-75% for cadmium, 26-80% for copper and 50-80% for zinc. These new estimates have the potential to contribute to any re-evaluation of the food standards for metals.
Food and Chemical Toxicology 12/2004; 42(11):1893-902. · 3.00 Impact Factor
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Bulletin of Environmental Contamination and Toxicology 12/2003; 71(5):961-70. · 1.02 Impact Factor
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ABSTRACT: Bioaccumulation of cadmium, copper, and zinc was examined in common ragworms Hediste diversicolor from control (Bay of Somme, Blackwater) and metal-rich (Seine estuary, Boulogne harbor, Restronguet Creek) sites in France and the United Kingdom. The degree of exposure in the field was assessed by considering both total concentrations in superficial sediment and the quantities of metals which may be released in vitro at different pH levels. Among the three contaminated sites, release of the three metals was not detectable in Boulogne harbor, in correlation with limited enhancement of the metal concentrations in the common ragworms from this site. Even at those sites where zinc could be released in vitro from the sediment, zinc concentrations were not enhanced in common ragworms, in agreement with previous findings indicating that the body content of this metal is regulated in H. diversicolor. At all the studied sites, bioaccumulated zinc was mainly in cytosolic form. The distribution of cadmium and copper varied according to the origin of the common rag-worms, the insoluble fraction increasing with the degree of contamination (cadmium in the Restronguet Creek, copper in the Seine estuary, and even more in Restronguet Creek). In the cytosolic fraction, metals were partly linked to cytosolic heat-stable thiolic compounds (CHSTC) with molecular masses (5-6 kDa and about 12 kDa) consistent with metallothionein-like proteins (MTLP). Metal-binding to MTLP varied with the degree of contamination and with the metal studied. In contrast to many invertebrates, the presence of metal-binding CHSTC (MM about 2 kDa) other than MTLP seems to be a peculiar feature of H. diversicolor.
Archives of Environmental Contamination and Toxicology 12/2003; 45(4):468-78. · 1.93 Impact Factor
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ABSTRACT: Alternative methodologies have been applied to the study of cadmium transfer in a food chain: water, microalgae (Skeletonema costatum and Tetraselmis suecica), oysters (Crassostrea gigas). The potential bioavailability of Cd in organisms was assessed through partitioning at the cell or tissue levels, and the predictive value of this method was evaluated by determining directly the metal transfer in an experimental food chain model. Cd concentrations were lower in S. costatum than T. suecica, in controls as well as in contaminated algae. In both algal species, Cd was firmly bound to the cell wall or had entered the cell. Cytosolic Cd was bound to intracellular ligands, the biochemical characteristics of which were not consistent with the hypothesis of detoxification via phytochelatins. In both algal species, Cd was predominantly present in the insoluble fraction, but at pHs such as those existing in the digestive tract of bivalves, it was easily extracted from the cells. Thus, exposure to Cd through phytoplanktonic food induced a significant uptake of this metal in soft tissues of bivalves. Due to the difference in Cd accumulation in algae, Cd doses associated with S. costatum were lower than those bound to T. suecica. Moreover, oysters retained a lower percentage of the metal associated with S. costatum compared to T. suecica (9 and 20%, respectively, after 21 days of exposure). Cd doses potentially available to oysters exposed directly in sea water were considerably higher, and direct uptake induced the highest levels of Cd incorporation but only 2% of dissolved Cd was actually retained by oysters over 21 days of exposure. In the soft tissues of oysters, Cd was distributed equally between soluble and insoluble fractions. Cytosolic Cd was present predominantly in the heat-stable fraction and mainly bound to compounds of molecular weight equal to 13.5 kDa. Moreover, a positive correlation was observed between metallothionein-like protein (MTLP) levels and gross concentrations of Cd in the soft tissues of oysters. These data are consistent with the hypothesis of an important role of metallothioneins in Cd metabolism in oysters and suggest a potential availability of MT-bound fraction of Cd to the consumers. These data are in agreement with the response of oysters exposed to Cd in the field.
Archives of Environmental Contamination and Toxicology 03/2001; 40(2):209-21. · 1.93 Impact Factor
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ABSTRACT: This work aimed to validate the relationship between metallothioneins (MTs) and metals (Cd, Cu and Zn) in field conditions. Specimens of the marine bivalve Ruditapes decussatus (Linné, 1758) from Gargour were transferred in two sites: Gargour and Sidi Mansour, both situated along the south-eastern coast of Tunisia. The bivalves were removed from pairs of cages at day 0 (date of transplantation), day 62 and day 132. Metals (Cd, Cu and Zn) and MTs were determined in the subcellular fractions of the digestive gland. In Gargour, metal and MT levels increased significantly after 62 days of transplantation. However, they showed modest and non-significant variations in Sidi Mansour. Zn was mainly associated with the insoluble fraction, whereas Cd and Cu percentages in the soluble and the insoluble fractions were equivalent. Simple correlation analysis showed a positive and significant relationship between MTs and each metal. If all metals were taken together, multiple correlations showed that MTs were significantly correlated with Cd and Zn, with an important coefficient for Cd, but no significant relationship was observed for Cu. Gel filtration chromatography showed that in the heat stable fraction, the only cytosolic SH rich compounds have an apparent low molecular mass (about 15 kDa), which could correspond to metallothioneins. In the digestive gland of R. decussatus MTs responded to moderate increases of metal contamination, without interference with other factors, and could be a promising biochemical indicator of metal exposure.
Comparative Biochemistry and Physiology Part C Toxicology & Pharmacology 10/2000; 127(2):185-97. · 2.62 Impact Factor
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ABSTRACT: Metal transfer in marine food chains may be examined at different scales from field studies to cellular level. Some years ago, the major question was to verify the existence of metal biomagnification, a phenomenon which seems in fact to be limited to mercury and the radionuclide cesium-137. In numerous cases, metal incorporation is not determined chiefly by the trophic level in the food chain. It is also controlled by both the metabolic characteristics of species or populations and the biological role of each element. The most accurate assessment of trophic transfer may be by determining the physico-chemical state of metals in marine organisms, a methology which can be used for both field and experimental samples. Some species exhibiting high detoxication ability may be interpreted as highly contamined links in food chains but according to the nature of the detoxifying ligands--in outline, mineral granules or metalloproteins--the bioavailability to the next trophic level may vary widely.
Acta Biologica Hungarica 02/1993; 44(4):387-409. · 0.59 Impact Factor
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ABSTRACT: The accumulation and physico-chemical forms of metals were determined by atomic absorption spectrometry in the whole soft tissues of oysters, by histological and microanalytical techniques in tissue sections, by gel permeation chromatography of soft tissue homogenates. Oysters were reared according to four types of experimental conditions: exposed to silver (20 micrograms Ag/l) or unexposed, in sea water (33%) or brackish water (8%). Copper, zinc and silver accumulation in oysters are inversely related to salinity. Amoebocytes, which play a key role in accumulating copper and zinc in natural sea water, are able to sequester an important part of added silver as Ag2S. In brackish water an increase of the number of amoebocytes may be considered as responsible for the enhancement of Cu and Zn concentrations in the whole soft tissues. In such conditions, additional silver is concentrated in these cells rather than in the basement membranes which are target structures for Ag2S accumulation in sea water. If the global fluctuations of metal concentrations in the soft tissue are ascribable mainly to changes at the histological level, the fate of metals in the soluble fraction must not be neglected since the speciation of metals influences their toxicity. The freshening of sea water induced a change in the distribution of cytosolic silver and zinc but in no case were the molecular masses of compounds associated with each metal perfectly identical. From these results, it is concluded that the accumulation of silver by oysters is not mediated by the same mechanisms as those for copper and zinc.
Biology of Metals 02/1991; 4(3):144-50.
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ABSTRACT: Dans une zone peu pollue, des prlvements mensuels d'eau de mer, d'Algues et de Gastropodes brouteurs ont t effectus pendant plus de deux ans. Dans de nombreux cas (variables selon les espces et les mtaux) les diffrences de concentrations d'origine naturelle seront voisines des variations dues des pollutions modres.Les diffrences inter-taxons des concentrations de Cd et Pb tant aussi importantes que les diffrences entre niveaux trophiques, on peut considrer qu'il n'intervient pas de biomagnification de ces mtaux dans la chane alimentaire Algues Gastropodes. De plus, les contaminations exprimentales par Cd montrent que la Littorine accumule fortement le mtal en solution. L'origine des fortes concentrations de Cu observes in situ chez les Gastropodes par rapport aux Algues reste inconnue. Les niveaux de Zn dans les consommateurs primaires sont gaux ou suprieurs ceux rencontrs dans leur nourriture. Toutefois les expriences de contamination rapportes dans la prsente tude et les donnes bibliographiques indiquent que les mtaux essentiels Cu et Zn sont rguls, an moins pour une contamination modre de l'eau et/ou de la nourriture.En consquence, dans les zones modrment pollues, les niveaux de Cu et Zn dans les Gastropodes seront relativement indpendants de la concentration de ces mtaux dans l'environnement. Des pollutions aigus pourraient mme ne pas tre dtectes, de fortes contaminations par le zinc ne perturbant pas court terme sa bioaccumulation.
Water Air and Soil Pollution 04/1987; 34(1):11-30. · 1.63 Impact Factor
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ABSTRACT: A regulation of internal levels of some essential metals has been observed in various animals, whereas the bioaccumulation of several non-essential metals parallels their overloads in water. In the mussel Mytilus edulis L., we have attempted to determine if such a phenomenon exists by comparing the patterns of accumulation of copper and zinc vs cadmium. With this aim, mussels collected in the Bay of Bourgneuf (France) in November 1983 were exposed to these metals for 16 d. At external levels of zinc as high as 100 gl-1, mussels were able to maintain a normal concentration in all groups of organs for 4 d. The ability of mussels to limit the bioaccumulation of copper and zinc varied from organ to organ, and decreased with higher levels of contamination and longer periods of exposure. In contrast, at the lowest experimental concentration and the lowest period of exposure, a significant increase of cadmium in mussel tissues was generally observed. Even at the highest sub-lethal doses, the levels of copper and zinc in mussel tissues were not much higher than the natural levels (contaminated:background ratios= 2.3 to 6.1), whereas the bioaccumulation of cadmium was less well restricted (contaminated:background ratios=136 to 192). The use of mussels as a bioindicator of pollution seems doubtful for essential metals, particularly as regards short-term pollution, since the levels of these trace elements in the organisms are largely independent of their concentration in the ambient seawater.
Marine Biology 06/1986; 92(1):7-13. · 2.28 Impact Factor
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ABSTRACT: The understanding of natural fluctuations of metal concentrations in mussels used as bio-indicators is indispensable for a good assessment of the disturbances due to pollution. We have studied thoroughly the factors which condition bioaccumulation by using controlled populations of mussels, Mytilus edulis L., sampled monthly over more than two years (March 1982–May 1984) in the Bay of Bourgneuf, France. Seasonal changes in metal levels have been recognized, maximum values being observed in winter and early spring and minimum in later spring and summer. Depending on metal and size group, the ratios between these maximum and minimum values varied between 1.56 and 3.43. The fluctuations in soft-tissue weight appear to be the main explanatory factor of seasonal variations in metal concentrations in mussels. Fluctuations in metal levels related to size of mussels were observed. Except for cadmium in mussels with a mean dry weight of soft tissues >0.2 g, a slight decrease in metal concentrations was observed for growing individuals: the regression coefficient b was -0.10, -0.11, -0.13 and -0.27 for Cd, Cu, Zn and Pb, respectively. The metals examined were rather uniformly distributed among the different groups of organs (visceral mass, gills and palps, remainder) and, consequently, several analyses of metals in different organs do not provide much more information than one analysis on the whole soft tissues. It is concluded that fluctuations related to size or season are reflected by only moderate differences in the maximum and minimum concentrations of metals in the mussels, but that they are nevertheless sufficient to conceal low chronic or short-term pollution, except at those sites where the normal environmental conditions are well-documented.
Marine Biology 01/1986; 90(3):425-431. · 2.28 Impact Factor
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ABSTRACT: In order to appraise the relation between the physico-chemical forms of Zn and its availability to plants or water, we introduced various forms of this element in experimental systems according to whether it was associated with soil, mineral fertilizers or sewage sludges. These sludges were rich in organic matter and carbonates and one of them contained iron and aluminium oxides and hydroxides.The physico-chemical forms of Zn in soils and sludges were determined following a selective extraction procedure which showed that only a small amount of this metal was associated with the easily available phase. In accordance with these results, the exportsvia vegetables and leached waters were very low, regardless of the treatment.
Plant and Soil 05/1984; 82(2):231-246. · 2.73 Impact Factor
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ABSTRACT: The physico-chemical forms of Pb and its circulation through water or air, condition its biological accumulation. In order to appraise the relative importance of each vector, we have used this element in experimental systems under various forms according as it was associated with the soil, with mineral fertilizers or with sewage sludges. These sludges contained important quantities of organic matter and carbonate and, for some of them, of Fe and Al oxides and hydroxides. The cultural systems were submitted to natural atmospheric conditions.Selective extraction procedures showed the very small availability of Pb in the sewage sludges and in the soils. That is in accordance with the insignificant exports via vegetables and leached waters. Whatever the treatment may be, the Pb falls out particularly on the green parts of vegetables and, in a lesser extent, in the non-tuberous roots, showing the predominance of atmospheric pollutions. No appreciable migration to reproductive and reserve organs have been observed.
Water Air and Soil Pollution 12/1983; 21(1):447-460. · 1.63 Impact Factor
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ABSTRACT: The patterns of accumulation of essential and non-essential trace metals have been studied comparatively in worms, molluscs, crustaceans, and fish exposed to short-term experimental contaminations and low chronic contaminations in a polluted environment.In short-term contaminations, the concentrations X of the non-essential metals cadmium and lead in the organisms depend mainly on their environmental level Y according to the power function Y = aXb. For copper - an essential metal - this equation is also suitable to describe the bioaccumulation in some species (Nereis diversicolor O.F. Müller, Scrobicularia plana (da Costa), Gammarus zaddachi Sexton) for a large range of experimental overloads. As for the mussel Mytilus edulis L., this equation is accurate for medium or high overloads only. All the species are able to control the level of the essential zinc in their tissues but for both copper and zinc the best regulators are the more highly evolved forms including decapod crustaceans and fish. The in situ chronic contaminations support the same conclusions. In one fish and one decapod crustacean species it has been shown that the regulation mechanisms may be functional since early life stages. When the duration of exposure to essential metals increases, the regulation mechanism is, however, disturbed by more and more low additional concentrations in sea water.
Journal of Experimental Marine Biology and Ecology.
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ABSTRACT: The toxicity and bioaccumulation of silver have been studied comparatively in the freshwater bivalve Dreissena polymorpha and in four marine species: the oyster Crassostrea gigas, the mussel Mytilus galloprovincialis, the scallop Chlamys varia and the clam Scrobicularia plana. In the freshwater and marine mussels, the silver absorption was very limited but M. galloprovincialis was more susceptible than D. polymorpha. The oysters and scallops were silver accumulators but the effect of the metal was much more noxious in the second species. These data have demonstrated that no direct relationships exist between the global concentration in soft tissues and the susceptibility of the different bivalves. Thus the physico-chemical forms of storage of silver (silver sulphide, metal-binding proteinic compounds) were determined in each species and related to the high variability of biological responses. The modes of exposure (through food or water) influenced the binding of silver with cytosolic compounds (in oysters) and its biological effects (in scallops). Changes in salinity had only a moderate effect on silver bioaccumulation in oysters, a fact which is interesting since pollutions due to this metal often affect estuarine and coastal areas.In the light of these data, the potential injuries due to silver pollution may be attributable: (1) to noxious effects on susceptible species with a resulting imbalance of biocoenosis structure; and (2) to the existence of silver accumulation with a risk of transfer to the food web. However, the knowledge of the chemical speciation of silver in organisms permit to predict the importance of this risk.
Science of The Total Environment.
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ABSTRACT: Oysters, as very popular food items in France, are subject to rules concerning the maximum acceptable contents of trace metals in foods. The food standards for the quantities of metals permitted are always based on total metal concentrations, and not on the metal concentrations that are potentially bioavailable to the consumer (man). In order to estimate the percentages of accumulated trace metals (i.e. Ag, Cd, Cu and Zn) that are potentially bioavailable during consumption, we have used a simple chemical digestion simulation on the insoluble fraction of oysters. These quantities have been added to the soluble fraction, assuming that metals in this fraction are completely bioavailable. Our experiments were conducted on oysters Crassostrea gigas sampled from five sites on the French Atlantic coast and on oysters Ostrea edulis sampled from Restronguet Creek in the United Kingdom. These sites are characterised by various degrees of metal contamination. This study has allowed us to gain a better estimate of the real concentrations of metals bioavailable to the consumer. Only a part of the total metal present is bioavailable: 36–68% for silver, 44–75% for cadmium, 26–80% for copper and 50–80% for zinc. These new estimates have the potential to contribute to any re-evaluation of the food standards for metals.
Food and Chemical Toxicology.
