Metals and organochlorine compounds in eel (Anguilla anguilla) from the Lesina lagoon, Adriatic Sea (Italy)

The muscle tissue of eels was analysed for metals (Hg, Cd, Cu and Zn), polychlorinated biphenyls (PCBs) and organochlorine pesticides (DDTs) to ascertain whether the concentrations exceeded the maximum levels fixed by the European Commission. Zinc showed the highest concentrations (mean: 20.2 μg g⁻¹ wet wt), followed by copper (mean: 0.58 μg g⁻¹ wet wt), mercury (mean: 0.18 μg g⁻¹ wet wt) and cadmium (mean: 0.03 μg g⁻¹ wet wt). None of the fish samples analysed presented metal concentrations exceeding the proposed limits. Among the organochlorine pesticides, only p,p′-DDE and p,p′-DDT were found with mean values of 19.2 and 3.0 ng g⁻¹ wet wt, respectively, while mean concentrations of PCBs were 94.0 ng g⁻¹ wet wt. With regard to DDT and its metabolites the concentrations were well below the maximum residue limit (MRL), while the mean PCB concentrations, calculated as the sum of the seven “target” congeners indicated by the European Union, exceeded the established limit. From an ecotoxicological point of view, the concentrations of metals and organochlorine compounds reflect a comparatively clean and pollution-free environment. These concentrations may be, thus, considered as useful background levels to which to refer for comparison within the Adriatic Sea.     

Cadmium and total mercury in some cephalopods from the South Adriatic Sea (Italy)

In the framework of a wide monitoring programme on the presence of heavy metals in marine organisms caught in the South Adriatic Sea, cadmium and total mercury concentrations were determined in flesh and hepatopancreas of 512 specimens of two species of cephalopods. The aim of the study was to establish the quality of the marine food with respect to the health of consumers and to investigate cadmium and mercury distribution in organisms representing different habitats. For both elements, higher levels were found in spider octopus (Octopus salutii) than in broadtail squid (Illex coindeti). Between the two different tissues analysed, higher concentrations were observed in hepatopancreas than flesh. According to the rules in force, no flesh sample showed cadmium and total mercury concentrations exceeding the peak permitted values of 2mg/kgwetwt and 0.5mg/kgwetwt respectively.     

Organochlorine pesticides and polychlorinated biphenyls in 12 edible marine organisms from the Adriatic Sea, Italy, Spring 1997.

Edible portions of 12 marine organisms from several areas of the Adriatic Sea, Italy, were collected during Spring 1997 and analysed for 32 organochlorine pesticides residues and 27 polychlorobiphenyl congeners. Only eight organochlorine pesticides - hexachlorobenzene (HCB), hexachlorocyclohexane (HCH) isomers, diphenyl-dichloro-trichloroethane (DDT) group, dieldrin - were determined at levels in the range <0.01-19.88 ng g(-1) wet weight, with 1,1'-dichloro-2,2'-bis(4-chlorophenyl)ethylene (DDE) being the more relevant single organochlorine. The contamination by organochlorine pesticides was comparable in organisms from the North, Centre and South Adriatic. Polychlorinated biphenyls (PCBs) were determined at levels in the range <0.05-14.46 ng g(-1), with CB 101, 118, 138, 153, 180 and 187 being more relevant (penta-, hexa- and hepta-chlorinated congeners). The sum of PCBs congeners determined were in the range 1.18-69.05 ng g(-1). The contamination by PCBs is more relevant in organisms from the North Adriatic Sea owing to the antropic discharge from major rivers such as Po and Adige that flow through highly industrialized and densely populated areas.     

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 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.     

Residues of polychlorinated biphenyls in edible fish of the Adriatic Sea: assessment of human exposure

ABSTRACT:  Food consumption is an important route of human exposure to polychlorinated biphenyls (PCBs). To assess the potential health risks associated with these contaminants due to fish consumption, the muscle tissue of edible species of fish was analyzed. Contamination levels among the different species varied from 134 to 1210 ng/g lipid weight. Isomer-specific analysis revealed a profile dominated by hexa- (57.9% to 82.9%) and pentachlorobiphenyls (10.3% to 23.9%), followed by hepta- (9.0% to 19.2%) and tetrachlorobiphenyls (0.7% to 17.5%). Other congeners, including those with less than 4 or more than 9 chlorine atoms, were below the instrumental limit of detection in all samples. Risk evaluation for human health was carried out by comparing the experimental data with the new European Commission legal level and a new approach proposed by the U.S. EPA to protect population-segments who repeatedly consume fish. The dietary intake of PCBs, as WHO-TEQ per kg body weight (b.w.), was below 8 pg TEQ/kg body weight/week, while the new EPA approach suggested that the chronic effects do not represent any type of danger for human health, while the possible rise in the carcinogenic risk connected with consumption of some type of fish is more worrisome.     

Occurrence of Vibrio and other pathogenic bacteria in Mytilus galloprovincialis (mussels) harvested from Adriatic Sea, Italy.

Sixty-two samples of Mytilus galloprovincialis (mussels) harvested from approved shellfish waters in the Adriatic Sea were examined for the presence of Vibrio, Salmonella, Campylobacter, and verocytotoxin producing Escherichia coli. Vibrio spp. were isolated from 48.4% of samples; the species most frequently found were V. alginolyticus (32.2%) and V. vulnificus (17.7%), followed by V. cincinnatiensis (3.2%), V. parahaemolyticus (1.6%), V. fluvialis (1.6%) and V. cholerae non-O1 (1.6%). V. parahaemolyticus resulted negative to Kanagawa-phenomenon and to PCR amplification of tdh gene. V. cholerae resulted negative to PCR amplification of sto gene. No Salmonella, Campylobacter, or E. coli verocytotoxin-producing strains were isolated. The results of this study suggest the potential risk of ingesting raw or undercooked mussels due to the frequent presence of potentially pathogenic Vibrio species.     

Monitoring of perfluorinated compounds in edible fish from the Mediterranean Sea

Perfluorooctanoic acid (PFOA) and perfluorooctane sulphonate (PFOS) are environmental contaminants belonging to a chemical group known as perfluorinated compounds (PCFs). The United States Environmental Protection Agency (US EPA) considers both compounds to be carcinogenic. The goal of the present study was to evaluate the contamination levels of PFOS and PFOA in edible fish of the Mediterranean Sea. Twenty six fish muscles, 17 fish livers, five series of cephalopods (each composed of ten specimens) and thirteen series of bivalves (each composed of about 50 specimens) were used for the investigation. A fast sample treatment, followed by an LC–ESI–MS/MS method is described for the identification, and quantification of PFOA and PFOS in fish. The method was in-house-validated through the determination of precision, accuracy, specificity, calibration curve, decision limit (CCα), and detection capability (CCβ). The results showed PFOA and PFOS levels in fishes and molluscs lower than those reported for analogue matrices in different geographic areas. Therefore, our biomonitoring results did not show that the Mediterranean Sea had any particularly alarming pollution by PFCs, although it is located in a semi-closed basin with scarce water change. Nonetheless, a worrying element is that a few fish showed extremely high contamination by PFOA and PFOS. This finding needs further clarification in order to assess whether such unusual contamination is linked to “dot-like” pollutant release, which could explain the anomaly.     

Assessment of edible marine species in the Adriatic Sea for contamination from polychlorinated biphenyls and organochlorine insecticides

It is estimated that 90% of human exposure to persistent organic pollutants is through food, and fish and shellfish represent an important source of contamination for polychlorinated biphenyls (PCBs) and organochlorine insecticides. To evaluate the levels of seafood contamination coming from the central Adriatic Sea, Italy, a study involving several pools of shellfish, crustaceans, and fish was carried out. Several marine species were selected by their abundance, wide distribution, and common use in the Italian diet and sampled and analyzed during 2004. The concentration of total (sigma) PCBs exceeded that of total dichlorodiphenyltrichloroethanes (DDTs) in all samples. Atlantic mackerel showed the highest concentrations of PCBs, ranging from 514 to 1772 ng/g of fat weight, and DDTs, ranging from 52 to 656 ng/g of fat weight. The lowest concentrations of PCBs and DDTs were found in cephalopods and mussels. Despite this, to protect human health from these pollutants, legal limits have been established for fish and shellfish for DDTs but not PCBs. The most common representative PCB congeners, in all species, were PCB 153 and PCB 138; the most common DDT was p,p'-dichlorodiphenyldichloroethylene.     

Presence of pathogenic Vibrio parahaemolyticus strains in mussels from the Adriatic Sea, Italy

Samples of mussels (Mytilus galloprovincialis) collected from approved coastal sites located on the Adriatic Sea (Central Italy) were examined for the presence of Vibrio parahaemolyticus and the occurrence of pathogenic strains. The isolation of the micro-organisms was performed using a standard method. A biochemical protocol was applied for the identification of the isolates. Polymerase chain reaction (PCR) was used to confirm the identification of the strains and to detect the tdh and trh genes. The Kanagawa phenomenon was assayed as phenotypic marker of thermostable direct hemolysin (TDH) toxin. The urease activity was assayed as phenotypic marker of trh gene. The protease activity and the cytotoxicity of strains were examined to identify other potential virulence factors. Thirty-five V. parahaemolyticus strains were isolated out of 144 samples. The tdh and trh genes were in one and three isolates, respectively. All strains, independent of the presence of tdh and trh genes, showed protease activity and cytotoxicity. Due to the occurrence of pathogenic V. parahaemolyticus, the potential risk of eating raw or undercooked mussels is envisaged.     

Organic and inorganic arsenic and lead in fish from the South Adriatic Sea, Italy.

Total, organic and inorganic arsenic and lead were measured from the muscle of different kinds of fish: skate (Raje spp.), hake (Merluccius merluccius) and blue whiting (Micromesistius poutassou), caught in the South Adriatic Sea (South Italy) in the period June-August 1995. The highest levels of total arsenic were found in skate (Raje spp.) whose values ranged from 14.4 to 61.5 mg/kg ww, followed by blue whiting (M. poutassou) and hake (M. merluccius) that showed lower levels ranging from 8.5 to 21.5 mg/kg ww and from 5.9 to 16.1 mg/kg ww, respectively. In all the species examined most of this element was present as organic compounds while inorganic arsenic was only a very modest percentage (0.47-3.5%) of the total arsenic present. Lead in all species analysed was at small concentrations with mean values ranging from 0.12 to 0.15 mg/kg ww. According to the rules in force in Italy no samples showed concentrations of lead exceeding the peak value of 2 mg/kg.     

Occurrence of toxigenic Clostridium difficile in edible bivalve molluscs

Clostridium difficile is an anaerobic bacterium commonly considered to be responsible for antibiotic-associated gastrointestinal diseases, ranging from diarrhea of varying severity to pseudomembranous colitis. The aim of this study was to assess the occurrence of C. difficile in marine edible bivalve molluscs, which, as filter feeding organisms, are able to accumulate particles suspended in water, including microorganisms. Samples of Mytilus galloprovincialis, Tapes philippinarum, and Venus verrucosa were collected from mussel farms and fishmongers in the province of Naples (Southern Italy). C. difficile was found in 49% of the 53 samples investigated. Sixteen isolates were grouped in 12 known different PCR ribotypes (001, 002, 003, 010, 012, 014/020, 018, 045, 070, 078, 106, and 126), whereas 10 additional isolates were grouped in 8 new PCR riboprofiles. Two toxinotypes (0 and V) were found. Fifty eight percent of the isolates were toxigenic. These findings indicate that toxigenic C. difficile strains can be isolated in bivalve molluscs. Marine filter feeding organisms, therefore, may be considered as reservoir of toxigenic strains of C. difficile. The ingestion of raw or poorly cooked contaminated seafood and the high temperature resistance of the spore-forming C. difficile could represent an important source of exposure and pose human health concern.     

Selenium content in the pilchard of the Adriatic Sea

The selenium content was determined in the muscle tissue (M. longissimus dorsi) of the pilchard (Clupea pilchardus). The fishes originated from catches at two localities, the mid-and northern Adriatic Sea, during two seasons—spring and autumn. The selenium content was determined by the hydride procedure of atomic absorption spectrophotometry, with the results being expressed as wet weight (ww). Four groups of the analysed samples indicated differences in the selenium content, depending on the location and time (season) of the catch. The highest selenium content was found in the pilchard of the mid-Adriatic Sea in spring (712.7 ±23.7 ng/g wet weight) and the lowest in the pilchard of the northern Adriatic Sea caught in autumn (472.7± 34.7 ng/g ww.). Regardless of seasonal differences and/or geographical aspects, the pilchard of the Adriatic Sea contains on average 580 ng Se/g ww and may be considered a significant source of this essential micronutrient.     

Selenium content in sea bass of the Adriatic Sea

The present work was aimed at establishing the presence of selenium in the muscle tissue (M. longissimus dorsi) of the sea bass (Dicentrarchus labrax). Free-living sea bass was compared with cage-farmed sea bass, fed with and without selenium feed supplement. The highest levels of selenium in muscle (397.3±18.3 ng/g wet weight) were recorded in the farmed sea bass, at 250–300 g of table weight, aged 28 months and fed with selenium supplement. Selenium contents in the muscle tissue of free-living sea bass of equal weight and/or equal age, and in the cage-farmed sea bass fed on feed without selenium addition were significantly lower i.e. in the range 235.0±25.1 to 286.7±24.4 ng/g (w/w).     

Heavy metals in mussels (Mytilus galloprovincialis) from the lonian Sea, Italy

Concentrations of six heavy metals (Hg, Pb, Cd, Cr, Zn, and Sn) were determined in mussels (Mytilus galloprovincialis) collected between June and September 1997 from 10 locations along a sound formed by two inlets (Mar Piccolo) near the Gulf of Taranto (Ionian Sea, Italy). The average concentrations of the heavy metals found in mussels samples were 0.15 mg/kg for Hg, 1.19 mg/kg for Pb, 0.64 mg/kg for Cd, 0.31 mg/kg for Cr, 5.15 mg/kg for Zn, and 0.54 mg/kg for Sn. The concentrations of heavy metals in mussels from the first inlet did not differ greatly from those observed in mussels from the second inlet. The concentrations of heavy metals in the mussels analyzed were below acceptable levels for human consumption.     

Heavy metals in edible mushrooms in Italy

The distribution of arsenic, cadmium, lead, mercury, and selenium was investigated in 1194 samples of 60 species of common, edible mushrooms collected mainly in the province of Reggio Emilia, Italy. The quantitative determination of heavy metals (mg/kg dry weight) was carried out by spectrophotometry, with the exception of Hg, which was determined by atomic absorption spectroscopy.     

Carcass evaluation and nutritive value of some popular edible molluscs in Nigeria

The carcass characteristics and nutritive value of the giant African land snails (A. achatina and A. marginata), the common garden snail (V. quadrata) and periwinkles (P. aurita and T. fuscatus) were assessed. The edible portions account for less than 42% of the live weight in all molluscs. Protein content was generally high: 74.9% in A. achatina, 71.6% in A. marginata, 76.2% in V. quadrata, 82.5% in P. aurita and 61.3% in T. fuscatus. Fat level was low in the molluscs (1.0-1.5%). Amino acid analysis indicated that all species were particularly rich in lysine (7.4-10.0 g/16 g N). All, except P. aurita were low in methionine (0.92-1.95 g/16 g N). A. achatina gave the highest PER (4.0) followed by A. marginata (3.7), T. fuscatus (2.9), V. quadrata (2.0) and P. aurita (1.9). Rats in each group gained weight during the experimental period. TD, BV and NPU generally followed the same trend.     

The microflora of fresh and spoiled sardines (Sardina pilchardus) caught in Adriatic (Mediterranean) Sea and stored in ice

A total of 1500 strains were isolated from the skin and gills of fresh, ice-stored (4 days) and spoiled (8 days) Adriatic sardines, and were identified at different taxonomic levels. Fresh sardine microflora found included mostly non-fermenting Gram-negative bacteria, (Pseudomonas, Flavobacterium, Psychrobacter, Acineobacter, Shewanella), and a minor proportion of Enterobacteriaceae and Gram-positive bacteria. The highest increase in microflora frequency, after 8 days in ice, was observed for thePseudomonas fragigroup (8–30·8%) andShewanella putrefaciens(1·8–11%). A significant presence was also noted for fluorescentPseudomonas(15·6–18·4%) andPsychrobacter immobilis(16·4–23·4%). The isolation frequency of the other groups decreased during storage. The most important proteolytic species werePseudomonas fluorescensandShewanella putrefaciensand the most lipolytic bacteria werePsychrobacter immobilisand again,P. fluorescensandS. putrefaciens. A total of 288 isolates, representative of the main groups, were tested for potential spoiling activity (H₂S and off-odour production, TMAO reduction).Shewanella putrefacienswas the strongest spoiler, followed byPseudomonas fluorescens. A weaker activity was observed for strains ofPseudomonas fragi, enterobacteriaceae and non-saccharolytic pseudomonads. The contribution of weak spoiler bacteria can be undermined by the activity of the strongest spoilers, but in some cases the considerable incidence of the former group suggests their effective role.Morganella morganiiwas the only histamine-producing species among 57 screened strains representative of different taxa.     

Polycyclic aromatic hydrocarbons in mussels (Mytilus galloprovincialis) from the Ionian Sea, Italy

Concentrations of eight polycyclic aromatic hydrocarbons (PAHs) (phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, benzo[a]pyrene, dibenz[a,h]anthracene, benzo[ghi]perylene) were determined in mussels (Mytilus galloprovincialis) collected between June and September 1995 from 10 locations along a sound of sea formed by two inlets (Mar Piccolo) close to the Gulf of Taranto (Ionian Sea, Italy). In mussels the concentrations of total PAHs were between 14.8 and 645.3 microg/kg wet weight. Among the single identified compounds, the predominance of phenanthrene (29.5 microg/kg wet weight) and anthracene (64.7 microg/kg wet weight) was evident. Another relevant pollutant was pyrene (18.4 microg/kg wet weight) followed by fluoranthene (7.2 microg/kg wet weight), whereas the other compounds showed low levels. The mussels that showed the highest total concentrations of PAHs were collected from stations affected by stronger human activities (industrial fallout, urban wastewaters, and contaminants transported via riverine discharge). Our results were similar to those found in areas classified as moderately polluted. This observation suggests the need for an increased effort in controlling sources of pollution in this area recognized as one of the most productive mussel-farming areas in the Italy.     

Triacylglycerols and their fatty acid composition in edible Mediterranean molluscs and crustacean

The triacylglycerol (TAG) composition of edible Mediterranean molluscs (Eledone moschata, Sepia officinalis, Todarodes sagittatus) and crustacean (Penaeus kerathurus) was studied using a combination of preparative RP–HPLC and GC/MS. In S. officinalis and T. sagittatus mantle TAG, the main fatty acids were C16:0 and C18:0 while in E. moschata they were C18:1ω-9, C16:0, C20:5ω-3 and C22:6ω-3. In P. kerathurus muscle and cephalothorax TAG, the main fatty acids were C16:0, C18:0, C18:1ω-9, C20:4ω-6, C20:5ω-3, C22:6ω-3 and C16:0, C18:1ω-9, C20:4ω-6, C20:5ω-3, C22:6ω-3, respectively.