M.M. Storelli

Total and methylmercury residues in tuna-fish from the Mediterranean sea

This study was carried out to determine the current levels of total mercury and methylmercury in the muscle tissue of albacore (Thunnus alalunga) and bluefin tuna (Thunnus thynnus) caught in the Mediterranean sea with the purpose of ascertaining whether the concentrations exceeded the maximum level fixed by the European Commission Decision. Total mercury concentrations ranged from 0.84 to 1.45 mg kg-1 w.w. (av. 1.17 mg kg-1 w.w.) and from 0.16 to 2.59 mg kg-1 (av. 1.18 mg kg-1 w.w.) in the muscle of albacore and bluefin tuna, respectively. In 78.6% of albacore and in 61.1% of bluefin tuna analysed, total mercury concentrations exceeded the maximum level fixed by the European Commission Decision (Hg = 1 μg g-1 wet wt). In the two species, mercury was present almost completely in the methylated form, with percentages between 77 and 100% (av. 91.3%) in albacore and between 75 and 100% (av. 91%) in bluefin-tuna. In order to assess the potential health impact, the estimated weekly intake was calculated. The estimated weekly intake was far above the established Provisional Tolerable Weekly Intake for both species.

Total mercury in muscle of benthic and pelagic fish from the South Adriatic Sea (Italy)

Total mercury concentrations were measured from the muscle of different kinds of fish: yellow gurnard (Trigla lucerna), red gurnard (Aspitrigla cuculus) red fish (Helicolenus dactylopterus), skate spp. (Raje spp.), goldline (Sarpa salpa), atlantic bonito (Sarda sarda), mackerel (Scomber scombrus), chub mackerel (Scomber japonicus) caught in the South Adriatic Sea (south Italy) in the period June/August 1995. The highest total mercury levels were found in the benthic marine organisms and particularly in skates (Raje spp.) whose values ranged from 0.05 to 2.65 mg/kg wet wt with a mean value of 1.02 mg/kg wet wt. As for pelagic species, the highest mean levels were observed in Atlantic bonito (0.34 mg/kg wet wt), while in goldline the mean content of total mercury was the lowest (0.07 mg/kg wet wt). According to the rules in force (Official Journal of the European Communities 1994) 53% of skate and Atlantic bonito samples showed concentrations exceeding the peak value of 1 mg/kg, while for the other species, only 28% of samples exceeded the peak value fixed at 0.5 mg/kg. Correlations between total mercury concentration and specimen weight were evident in all examined species except for goldline and skates.

Mercury in fish: Concentration vs . fish size and estimates of mercury intake

Total mercury concentrations were determined in different fish size classes of commercial importance such as, conger eel (Conger conger), starry ray (Raja asterias), forkbeard (Phycis blennoides), frostfish (Lepidopus caudatus), striped mullet (Mullus barbatus), red gurnard (Aspitrigla cuculus) and yellow gurnard (Trigla lucerna) in order to evaluate variations in consumer exposure to mercury as a function of fish consumption of a spectrum of different sizes. The highest mean levels of total mercury were detected in conger eel (0.80 µg g−1) and starry ray (0.75 µg g−1). Forkbeard (0.67 µg g−1), frostfish (0.59 µg g−1) and striped mullet (0.55 µg g−1) showed slightly lower levels, while red gurnard (0.33 µg g−1) and yellow gurnard (0.22 µg g−1) exhibited the lowest concentrations. The results of linear regression analysis showed a significant relationship between mercury concentrations and fish size for all species. Consequently, dietary consumption of larger size specimens leads to an increase in the exposure level for consumers. Understanding by consumers of all factors leading to an increase of exposure to mercury is the first step to enable them to make decisions about eating fish.

Survey of total mercury and methylmercury levels in edible fish from the Adriatic Sea

Total mercury and methylmercury concentrations were measured in the muscle tissue of different fish species from the Adriatic Sea to ascertain whether the concentrations exceeded the maximum level fixed by the European Commission. Large species-dependent variability was observed. The highest total mercury mean concentrations were in benthic (0.20–0.76 μg g−1 wet wt) and demersal fish (0.22–0.73 μg g−1 wet wt), while pelagic species showed the lowest levels (0.09–0.23 μg g−1 wet wt). In 15% of frost fish, in 42% of skate and in 30% of angler fish samples total mercury concentrations exceeded the maximum level fixed by the European Commission (Hg = 1 μg g−1 wet wt); for the species for which the maximum level was set to 0.5 μg g−1 wet wt, concentrations exceeding the prescribed legal limit were observed in 6.4% of bokkem, in 6.6% of pandora, in 20% of megrin, in 12.5% of four-spotted megrim, in 16% of striped mullet, in 5.0% of forkbeard and in 5.3% of picarel samples. In all the different species, mercury was present almost completely in the methylated form, with mean percentages between 70 and 100%. Weekly intake was estimated and compared with the provisional tolerable weekly intake recommended by the FAO/WHO Expert Committee on Food Additives. A high exposure was associated with the consumption of only skates, frost fish and angler fish, thought the consumption of the other species, such as, megrim, four spotted megrim, red fish striped mullet and forkbeard, resulted in a weekly intake slightly below the established provisional tolerable weekly intake.

Total mercury and methylmercury content in edible fish from the Mediterranean Sea.

The objective of this study was to determine the current levels of total mercury and methylmercury in the muscle tissues of different fish species caught in the Mediterranean Sea to ascertain whether these concentrations exceed the maximum level stipulated by the European Commission Decision. Total mercury concentrations in the muscles of skates ranged from 0.18 to 1.85 mg/kg (wet weight) (average, 1.00 mg/kg) while levels of 0.11 to 1.92 mg/kg (wet weight) (average, 0.70 mg/kg) and 0.21 to 1.74 mg/kg (wet weight) (average, 0.70 mg/kg) were recorded for blue whiting and red mullet, respectively. For 66.7% of long nose skate samples, 61.4% of thornback ray samples, 42.8% of winter skate samples, and 38% of starry ray samples, the total mercury concentrations exceeded the prescribed legal limit (1.0 mg/kg [wet weight]). Concentrations exceeding the maximum total mercury level stipulated by the European Commission Decision (0.5 mg/kg [wet weight]) were observed in 63.6 and 40% of blue whiting and striped mullet samples, respectively. Mercury was present in the different species almost completely in the methylated form at 55 to 100%. Weekly intakes were estimated and compared with the provisional tolerable weekly intake recommended by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives.

Consumption of bivalve molluscs in Italy: estimated intake of cadmium and lead

Concentrations of cadmium and lead were determined in nine different species of mollusc bivalves(Modiolus barbatus, Venus verrucosa, Scapharca inaequivalvis, Tapes decussatus, Callista chione, Pecten jacobeus, Ensis siliqua, Venus gallina, Cardium tubercolata)collected from different coastal areas of the Adriatic Sea (north, middle and south Adriatic). The levels of cadmium and lead found in bivalves from the north Adriatic Sea were significantly (P<lt; 0.001) higher than those detected in those from the middle and south Adriatic Sea. In some species of molluscan bivalves(M. barbatus and T. decussatus)from the north Adriatic Sea, concentrations of cadmium and lead exceeded the maximum limit (2mg/kg w.w.) established by the Italian legislation. Weekly intakes were estimated and compared with the Provisional Tolerable Weekly Intake (PTWI) recommended by the FAO/WHO Expert Committee on Food Additives.

Cadmium and mercury in cephalopod molluscs: Estimated weekly intake

Cadmium and mercury concentrations were measured in the flesh and hepatopancreas of different species of cephalopod molluscs (European squid, common octopus, curled octopus, horned octopus, pink cuttlefish, common cuttlefish) in order to establish whether the concentrations exceeded the maximum levels fixed by the European Commission. In hepatopancreas, the levels of cadmium were substantially higher than those in flesh (flesh 0.11–0.87 µg g−1 wet weight, hepatopancreas 2.16–9.39 µg g−1 wet weight), whilst the levels of mercury (flesh 0.13–0.55 µg g−1 wet weight, hepatopancreas 0.23–0.79 µg g−1) were approximately double those in flesh. Concentrations exceeding the maximum permitted limit of cadmium were found in 39.8 and 41.0% of common octopus and pink cuttlefish flesh, respectively. For mercury, concentrations above the limit were found only in octopuses, and precisely in 36.8, 50.0 and 20.0% of flesh samples of common, curled and horned octopus, respectively. In the hepatopancreas, concentrations of cadmium and mercury were above the proposed limits in all the samples examined. The estimated weekly intake of between 0.09 and 0.49 µg kg−1 body weight for cadmium and between 0.05 and 0.24 µg kg−1 body weight for mercury made only a small contribution to the provisional tolerable weekly intake (cadmium 1.3–7.0%, mercury 1.0–4.8%) set by the WHO.

Cadmium in Cephalopod Molluscs: Implications for Public Health

Cadmium concentrations were measured in the flesh and hepatopancreas (digestive gland) of 1,392 specimens of different species of cephalopod molluscs (broadtail squid, spider octopus, curled octopus, horned octopus, elegant cuttlefish, and pink cuttlefish) to determine whether maximum levels fixed by the European Commission were exceeded. In all species, mean cadmium concentrations were higher in hepatopancreas than in flesh. Large differences among the different species were also observed. Pink cuttlefish and spider octopus had the highest concentrations for both flesh (spider octopus, 0.77 microg g(-1); pink cuttlefish, 0.87 microg g(-1)) and hepatopancreas (spider octopus, 9.65 microg g(-1); pink cuttlefish, 18.03 microg g(-1)), and the lowest concentrations were encountered in broadtail squid (flesh, 0.13 microg g(-1); hepatopancreas, 2.48 microg g(-1)). The other species had intermediate concentrations of 0.20 to 0.30 microg g(-1) in flesh and 5.46 to 8.01 microg g(-1) in hepatopancreas. Concentrations exceeding the limit proposed by the European Commission (1.00 microg g(-1)) were observed in 44.4 and 40.0% of flesh samples of spider octopus and pink cuttlefish, respectively. The estimated weekly intake, 0.09 to 0.66 microg/kg body weigh, was below the provisional tolerable weekly intake set by the World Health Organization.

Intake of essential and non-essential elements from consumption of octopus, cuttlefish and squid

Total concentrations of essential (Cu, Zn, Se and Cr) and non-essential (Hg, Cd, Pb and As) trace elements were measured in the flesh and hepatopancreas of Octopodidae (Eledone moschata, Eledone cirrhosa, Octopus salutii), Sepiidae (Sepia elegans, Sepia orbignyana) and Loliginidae (Illex coindeti, Loligo vulgaris) from the Mediterranean Sea. As expected, the hepatopancreas showed higher metal concentrations than flesh; the only exceptions were Hg and As, which were equally distributed in the two tissues. Regarding the edible portion, the highest toxic metal concentrations were in Octopodidae (Hg: 0.44, Cd: 0.49, Pb: 0.10 µg g−1 wet weight) and Sepiidae (Hg: 0.27, Cd: 0.50, Pb: 0.12 µg g−1 wet weight), while Loliginidae tended to accumulate less metal, especially Hg (Hg: 0.11, Cd: 0.30, Pb: 0.05 µg g−1 wet weight). The other elements showed a heterogeneous distribution among the different cephalopod families. Loliginidae showed the highest Se concentrations (1.18 µg g−1 wet weight), Octopodidae of Cu (37.37 µg g−1 wet weight) and Zn (42.00 µg g−1 wet weight) and Sepiidae of As (61.43 µg g−1 wet weight), while Cr was uniformly distributed among the various families (0.38–0.43 µg g−1 wet weight). In these seafoods, the concentrations of essential and non-essential elements were within the prescribed limits set by various authorities, except for Cu and As. Health risks posed by toxic elements to humans via dietary intake of these mollusks were assessed on the basis on Provisional Tolerable Weekly Intake (PTWI), while the estimated intakes of essential elements were compared to Dietary Reference Intakes (RDIs). A 70-g serving of these mollusks was shown to provide a large contribution to Cd intake (0.89 µg kg−1 body weight), corresponding to 35.6% of PTWI. Concerning the essential elements, the consumption of these mollusks made an important contribution to daily dietary intake of Se, Cu and Zn.

Levels and profiles of DDTs and PCBs in a gadiform fish (Phycis blennoides) from Mediterranean Sea

Cac ador, I., Vale, C., Catarino, F., 1996. Accumulation of Zn, Pb, Cu, Cr and Ni in sediments between roots of the Tagus Estuary salt marshes, Portugal. Estuarine Coastal Shelf Science 42 (3), 393–403. Cac ador, I., Costa, A.L., Vale, C., 2005. Nitrogen sequestration capacity of two salt marshes from the Tagus Estuary. Hydrobiologia 587 (1), 137–145. Caetano, M., Vale, C., Cesário, R., Fonseca, N., 2008. Evidence for preferential depths of metal retention in roots of salt marsh plants. Science of the Total Environment 390, 466–474. Canário, J., Vale, C., Caetano, M., 2005. Distribution of monomethylmercury and mercury in surface sediments of the Tagus Estuary (Portugal). Marine Pollution Bulletin 50, 1142–1145. Canário, J., Vale, C., 2007. Monitoring program for the Tagus Estuary and tributaries, Scientific Report, IPIMAR, June 2007, p. 78. Canário, J., Vale, C., Nogueira, M., 2008. The pathway of mercury in contaminated waters determined by association with organic carbon (Tagus Estuary, Portugal). Applied Geochemistry. doi: 10.1016/j.apgeochem.2007.12.019. Cohen, T., Hee, S., Ambrose, R., 2001. Trace metals in fish and Invertebrates of three California Coastal Wetlands. Marine Pollution Bulletin 42 (3), 232–242. Cotté-Krieff, M.H., Guieu, C., Thomas, A.J., Martin, J.M., 2000. Sources of Cd, Cu, Ni and Zn in Portuguese coastal waters. Marine Chemistry 49 (3), 279–290.