Determination of 20 trace elements in fish and other seafood from the French market

Food Chemistry 127 (2011) 934–942

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Determination of 20 trace elements in fish and other seafood from the French market Thierry Guérin ⇑, Rachida Chekri, Christelle Vastel, Véronique Sirot, Jean-Luc Volatier, Jean-Charles Leblanc, Laurent Noël Agence nationale de sécurité sanitaire de l’alimentation, de l’environnement et du travail, unités CIME et AQR-PC, ANSES-LSA 23, Av. du G. de Gaulle, F-94706 Maisons-Alfort, France

a r t i c l e

i n f o

Article history: Received 9 September 2010 Received in revised form 24 November 2010 Accepted 19 January 2011 Available online 25 January 2011 Keywords: Essential trace elements Toxic trace elements Fish Seafood ICPMS

a b s t r a c t The levels of 20 essential or toxic trace elements in 159 fish, other seafood and seafood products on the French coastal market collected between January and April 2005 were measured by ICP-MS. The concentration ranges (mg/kg of fresh mass) for the elements determined were compared with previous studies. The contents of Co, Cu, Fe, Li, Mn, Se, Zn and Pb found in fish are close to or often lower than previous studies. For other seafood, comparison is difficult due to the lack of data on a more global scale. However, it should be noted that the contents of Ag were found considerably higher in this study. Ó 2011 Elsevier Ltd. All rights reserved.

1. Introduction In recent decades, much attention has been paid to the study of essential and toxic trace element content in foodstuffs, as a result of a growing concern about the health benefits and risks of food consumption. The evaluation of risks and benefits of the consumption of fish and other seafood has been particularly controversial. Nutritionists consider these products to be an important source of high-quality proteins, minerals and essential fatty acids such as omega 3. Toxicologists tend to regard seafood as a major vector for toxic substances such as metal trace elements and persistent organic pollutants. The scientific reality is more complex and a reconciliation of these two viewpoints requires that we take into consideration both nutritional and toxic substances contained in food products and also consumer behaviour with regard to these products. As a safeguard for human health, guidelines and regulations stipulating maximum permissible levels of cadmium, lead and mercury in fish and seafood have been set by Regulation (EC) No. 629/2008 to limit dietary exposure of consumers to toxic metals. In France, as regards exposure to trace elements, several recent studies have shown that for the average consumer in the general population the toxicological limits are not exceeded. Nevertheless, the absence of risk for the average consumer does not exclude a

⇑ Corresponding author. Tel.: +33 1 49 77 27 11. E-mail address: [email protected] (T. Guérin). 0308-8146/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2011.01.061

risk for heavy consumers, as underlined previously (Leblanc et al., 2005). Moreover, the absence of French data on the levels of ‘‘indirect’’ or ‘‘direct’’ exposure to certain substances (omega 3 and pollutants in particular) of populations consuming large quantities of seafood does not enable a quantified assessment of the benefits or risks associated with these dietary habits, a situation that is obviously prejudicial to the global health risk evaluation and management process. The objectives of the CALIPSO study (Consommations ALimentaires de produits de la mer et Imprégnation aux éléments traces, PolluantS et Oméga 3) started in 2004 were to assess food exposure and biomarkers of exposure of the main toxic trace elements present in fish and other seafood and products from a group of frequent consumers (Bemrah, Sirot, Leblanc, & Volatier, 2009; Guérin, Sirot, Volatier, & Leblanc, 2007; Leblanc, 2006; Sirot, Guérin, Volatier, & Leblanc, 2009; Sirot, Oseredczuk, BemrahAouachria, Volatier, & Leblanc, 2008a; Sirot, Samieri, Volatier, & Leblanc, 2008c; Sirot et al., 2008b). The study shows that the contaminant levels measured in fish and other seafood are globally satisfactory when compared with currently applicable regulations, with the exception of a few products. As regards risks, only the highest consumers of our study population present a nonnegligible probability of exceeding the reference toxicological values, notably for methylmercury, cadmium, dioxins and PCBs. However, only cadmium, mercury, arsenic and organotin compounds have been studied and discussed in these products (Guérin et al., 2007; Sirot et al., 2008b, 2008c, 2009), the essential trace elements and several toxic trace elements were not taken

T. Guérin et al. / Food Chemistry 127 (2011) 934–942

into account when assessing CALIPSO and therefore it is believed that these samples could be valuably reused to complement the occurrence data in these fishery products (Ersoy & Celik, 2010; Lavilla, Vilas, & Bendicho, 2008; Sivaperumal, Sankar, & Nair, 2007; Tetsuro et al., 2007; Tuzen, 2009; Türkmen, Türkmen, Tepe, Töre, & Ates, 2009). The main goal of this study was to complete the database of occurrence levels of trace elements in fish and other seafood that can be used at national and international levels for future risk assessment of the general population or high consumers of these food products. Thus, in the present study, the concentrations of 20 elements were measured in edible parts of the 159 fish and other seafood and products sampled in four French coastal areas between January and April 2005 for the CALIPSO study. The results were compared with previous French and worldwide studies.

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(In), Rhenium (Re) and Bismuth (Bi) were purchased from Analytika (Prague, Czech Republic) and were used to prepare calibration and internal standards. Working standards were prepared daily in 6% (v/v) HNO3 67% and were used without further purification. A solution of 10 mg l1 multi-element solution (Merck, Darmstadt, Germany) was used to prepare a tuning solution with 29 elements such as Indium (In), Uranium (U), Barium (Ba) and Lithium (Li), capable of covering a wide range of masses. Ultra-pure grade carrier and collision gases (Argon (Ar), Helium (He) and Hydrogen (H2), 99.9995% pure) were supplied from Air Liquide (Nanterre, France). Certified Reference Material (CRM): ERMÒ CE-278 (mussel tissue) from the Institute for Reference Materials and Measurements, and IAEA 407 (fish tissue) from the International Atomic Energy Agency, were all purchased from LGC Standards (Molsheim, France) and used without further grinding. 2.3. Sample selection and preparation

2. Materials and methods 2.1. Apparatus Sample digestion was carried out using a microwave digestion system Multiwave 3000 (Anton-Paar, Courtaboeuf, France), equipped with a rotor for eight sample vessels type X (80 ml quartz tubes, operating pressure 80 bars). ICP-MS measurements were performed by a VG Plasma Quad ExCell (Thermo Electron, Courtaboeuf, France), equipped with Collision Cell Technology (CCT) and a CETAC ASX 500 Model 510 auto-sampler (CETAC, Omaha, Nebraska, USA). Further details of the instrumental settings are given in Table 1.

Based on a validated food frequency questionnaire (FFQ), 63 seafood products including fish, molluscs, crustaceans and seafood-based dishes were selected in four French coastal areas, covering 88–100% of total seafood consumption (Bemrah et al., 2009). Local sampling took into account the frequencies and quantities consumed, and the purchase place of consumers for each species according to the methodology developed previously (Leblanc et al., 2005). Thus, 159 products were sampled between January and April 2005, including 138 fresh and frozen fish, molluscs and crustaceans, along with 21 canned products, smoked fish and seafood-based dishes. All the sample preparation methodology has already been described (Sirot et al., 2008a).

2.2. Reagents

2.4. Analytical methods

All solutions were prepared with analytical reagent-grade chemicals and ultrapure water (18 MX-cm) generated by purifying distilled water with the Milli-QTM PLUS system connected to an Elix 5 pre-system (Millipore S.A., St Quentin en Yvelines, France). Suprapur nitric acid (HNO3 67% (v/v)) was purchased from VWR (Fontenay-sous-Bois, France). Standard stock solutions containing 1000 mg l1 of each element (Li, Al, V, Cr, Fe, Mn, Co, Ni, Cu, Zn, Ga, Ge, Se, Sr, Mo, Ag, Sb, Te, Ba and Pb) and internal standard solutions containing 1000 mg l1 of Scandium (Sc), Yttrium (Y), Indium

The digestion programme was optimised previously (Noël, Dufailly, Lemahieu, Vastel, & Guérin, 2005). 0.2–0.6 g of diet samples were weighed precisely in quartz vessels and wet-oxidised with 3 ml ultrapure water and 3 ml ultra-pure grade HNO3 (67% v/v) in the microwave digestion system. After cooling, sample solutions were quantitatively transferred into 50 ml polyethylene flasks with 100 ll of internal standard solution (1 mg/l) and the digested samples were then completed with ultrapure water to the final volume before analysis by ICP-MS. The ICP-MS methods have already been fully validated (including participation in proficiency tests) for the simultaneous analysis of cadmium, lead, mercury, arsenic (in standard mode), chromium, iron and selenium (in CCT mode) content in foodstuffs of animal origin (Dufailly, Noël, & Guérin, 2006; Noël et al., 2005, 2009). The performance criteria of the method for all other elements have also been estimated and all proficiency tests were satisfactory for fish and seafood samples (Millour et al., 2011; Noël et al., 2009). Five standards with standard linear regression and internal standardisation were prepared at levels ranging from 0 to 20 lg/l for Li, V, Co, Ni, Ga, Ge, Mo, Ag, Sb, Sr, Te, Ba and Pb, from 0 to 50 lg/l for Mn and Cu and from 0 to 100 lg/l for Cr, Fe, Se, Al and Zn. The calibration curve was plotted from six points, including the calibration blank. The isotopes 7Li, 27Al, 51V, 52Cr,55Mn, 59Co, 60 Ni, 63Cu, 65Cu, 64Zn, 66Zn, 71Ga, 74Ge, 82Se 88Sr, 92Mo, 98Mo, 107 Ag, 121Sb, 125Te, 137Ba, 138Ba, 206Pb, 207Pb and 208Pb were selected in ICP-MS standard mode and 56Fe, in ICP-CCT-MS.

Table 1 ICP-MS instrumental parameters. Operating conditions Nebulizer: concentric type pumped at 0.9 ml min1 Spray chamber: Scott-type double-pass water cooled Expansion stage: Intermediate stage: Analyser stage: Sampling cone: nickel, Skimmer cone: nickel,

2.7 mbar 2.0 104 mbar 4.6 106 mbar 1.0 mm orifice 0.75 mm orifice

Standard mode (adjusted daily) RF power: Reflected power: Plasma gas flow: Nebulizer gas flow: Auxiliary gas flow:

1350 W <5 W 15 l min1 0.75–0.9 l min1 0.90 l min1

Collision gas H2: He:

1.50 l min1 0.50 l min1

Acquisition parameters Mass range: Number of channels: Dwell time: Number of sweeps: Total acquisition time: Peak jumping mode

7–208 uma 500 160 ls 500 60 s

2.5. Quality assurance All test batches were evaluated using an internal quality approach and validated if they satisfied the defined Internal Quality Controls (IQC) discussed earlier (Millour et al., 2010). For each experiment, a run included three blanks, two CRMs, two different

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standard spiked solutions on samples randomly selected, 18 food samples analysed in duplicate to eliminate any batch-specific error, and a mid-range standard analysed after every eight samples and at the end of the sequence The certified or recommended values of the CRMs were only used when the concentrations of the elements of interest were suitable, i.e. similar to those present in real samples. When acceptance criteria were not met for a sample, results were discarded and the sample was re-analysed. For all the elements, no outlier was observed for calibration curves (r2 P 0.995; five points), blank controls and duplicates. The trueness obtained on both CRMs and randomly selected spiked test samples was well within the confidence interval (CI) (n = 1; k = 3; p = 99%) around the reference value (Table 2).

mass (mg/kg fm). For several samples, concentrations of metals were below the limits of detection (LOD) or quantification (LOQ). To calculate mean concentrations, it was assumed that the values below the LOD or the LOQ were equal to half the LOD or the LOQ (middle bound approach). 3. Results and discussion 3.1. General Table 3 gives the limits of quantification previously estimated (Millour et al., 2011) and censored data for all elements. Tables 4 and 5 give the results found in fish and in other seafood products, respectively.

2.6. Calculations and statistical methods 3.2. Essential trace elements The descriptive statistics (mean, standard deviation and range) were conducted using Excel software. Student’s t-test was employed to estimate the significance difference of values found in this study with those of literature (P < 0.05). For that, a mean moisture content of 76% (mean estimate in the Calipso study) was used to convert data express in dry mass to mg/kg of fresh mass. All concentrations are expressed in milligrams of element per kg of fresh

Table 2 Results of trueness on CRMs and spiked test samples (mg/kg; n = 9). Element

1

Cr

0.78 ± 0.06 0.73 ± 0.06 0.10 ± 0.02 a 9.45 ± 0.13 b 3.28 ± 0.08 b 146 ± 3 b 0.685 ± 0.060 a 7.69 ± 0.23 b 0.73 ± 0.06 c 5.0 c 7.5 b 0.60 ± 0.05 a 1.84 ± 0.10 b 2.83 ± 0.13 b 130 ± 5 b 1.43 ± 0.09 a 83.1 ± 1.7 b 67.1 ± 0.8 b 13.8 ± 1.4 b 0.011 ± 0.002 c 5.0 c 7.5 c 5.0 c 7.5 c 5.0 c 7.5 a 2.00 ± 0.04 b 0.12 ± 0.02 b 0.037 ± 0.004 c 5.0 c 7.5 c 5.0 c 7.5

Certified or reference value a

b

Co Cu Fe Li Mn Mo Ni Se Sr V Zn Al Sb Ba Ga Ge Pb Ag

Te 1

b

2

Confidence interval

3 Observed value

0.43–1.1 0.40–1.1 0.07–0.13 6.62–12.3 2.30–4.26 80–212 0.377–0.993 4.84–8.99 0.51–0.95 3.5–6.5 5.3–9.8 0.33–0.87 1.01–2.67 1.56–4.1 91–169 1.00–1.86 58–108 47–87 7.6–20.0 0.006–0.016 3.5–6.5 5.3–9.8 3.5–6.5 5.3–9.8 3.5–6.5 5.3–9.8 1.40–2.60 0.08–0.16 0.020–0.054 2.8–7.3 4.1–10.9 3.5–6.5 5.3–9.8

0.82 ± 0.08 0.81 ± 0.08 0.09 ± 0.01 8.27 ± 0.55 2.76 ± 0.18 104 ± 10 0.604 ± 0.060 6.92 ± 0.46 0.81 ± 0.08 5.5 ± 0.2 7.7 ± 0.6 0.74 ± 0.07 1.84 ± 0.18 2.57 ± 0.26 116 ± 8 1.39 ± 0.09 84.7 ± 5.6 63.4 ± 4.2 11.9 ± 1.2 0.009 ± 0.001 5.2 ± 0.2 7.4 ± 0.6 5.0 ± 0.2 6.9 ± 0.6 5.2 ± 0.2 7.0 ± 0.6 1.78 ± 0.12 0.11 ± 0.01
Uncertainty given as 95% confidence interval. h i R M Calculated from the theoretical value (M) of the CRMs as: CI ¼ M  k  CV100 with k = 3 (p = 99%); M the certified or reference value and CVR, the intermediate precision coefficients of variation previously established (Dufailly et al., 2006; Millour et al., 2011).  CVR Xf 3 pffiffi with k = 2 (p = 95%); Xf = the mean result and n = the  Uncertainty ¼ 2 100 n number of results. a ERMÒ CE-278; b IAEA 407; c Spiked test sample in lg/l. 2

3.2.1. Chromium Chromium was found at an average level of 0.220 mg/kg in fish. Eel and anchovy had the highest levels of Cr (0.573 and 0.450 mg/ kg, respectively) followed in decreasing order by swordfish, pout, halibut and salmon (0.314–0.393 mg/kg). In other seafood and seafood products, Cr was found at an average level of 0.228 mg/kg. Tarama contained the highest level (0.85 mg/kg) followed by spider crab, surimi, whelk, mussel, crab and periwinkle (0.269– 0.421 mg/kg). The lowest Cr levels were found in octopus and sea urchin (0.005 mg/kg). These mean levels were 2-fold higher than those found during the 1st TDS in fish (n = 62; mean 0.080 mg/ kg; max 0.307 mg/kg in salted cod) and in seafood (n = 18; mean 0.090 mg/kg; max 0.238 mg/kg in mussel) (Leblanc et al., 2005). It should be noted however that the samples selected during the two studies were sometimes very different (e.g. only mussel, oyster, shrimp and lobster for the 1st TDS) and that they were cooked (prepared as consumed) during the 1st TDS, contrary to this study. These results were significantly (P < 0.05) lower (Agah, Leermakers, Elskens, Rez Fatemi, & Baeyens, 2009; De Mora, Fowler, Wyse, & Azemard, 2004; Erkan, Özden, & Ulusoy, 2009; Mendil, Demirci, Tuzen, & Soylak, 2010; Shiraishi, 2005; Sivaperumal et al., 2007; Tuzen, 2009; Türkmen et al., 2009) or higher (De Mora et al., 2004; Ersoy & Celik, 2010; Ikem & Egiebor, 2005; Kelly, Ikonomou, Higgs, Oakes, & Dubetz, 2008; Tetsuro et al., 2005, 2007) than mean values previously found in fish and other seafood. Table 3 Limits of quantification and censored data. Element

LOQ (mg/kg fm)

Essential trace elements Chromium 0.020 Cobalt 0.002 Copper 0.017 Iron 0.086 Lithium 0.002 Manganese 0.017 Molybdenum 0.008 Nickel 0.083 Selenium 0.080 Strontium 0.017 Vanadium 0.017 Zinc 0.166 Toxic trace elements Aluminium Antimony Barium Gallium Germanium Lead Silver Tellurium

0.417 0.002 0.083 0.002 0.002 0.005 0.084 0.002

% >LOD

% >LOQ

83 99 99 100 100 97 76 92 72 100 80 100

82 72 99 100 99 93 54 37 71 100 61 100

89 63 59 38 95 87 74 31

74 22 34 29 31 70 55 21

Table 4 Mean concentrations of essential trace elements and toxic trace elements in fish (mg/kg fm). Species

Mean SD Median Min Max a

3 4 4 4 4 1 2 3 4 1 2 3 4 2 4 5 1 2 2 1 4 3 5 4 1 4 4 1 4 4 8 4

Essential trace elements

Toxic trace elements

Cr

Co

Cu

Fe

Li

Mn

Mo

Ni

Se

Sr

V

Zn

Al

Sb

Ba

Ga

Ge

Pb

Ag

Te

0.450 0.097 0.171 0.221 0.227 0.573 0.271 0.144 0.189 0.157 0.151 0.114 0.382 0.058 0.171 0.183 0.220 0.206 0.220 0.392 0.152 0.096 0.314 0.233 0.113 0.095 0.144 0.225 0.231 0.393 0.294 0.143

0.019 0.003 0.005 0.004 0.003 0.008 0.001 0.004 0.002 0.003 0.003 0.001 0.002 0.001 0.001 0.005 0.036 0.003 0.002 0.005 0.003 0.002 0.004 0.008 0.001 0.004 0.003 0.012 0.003 0.004 0.012 0.003

2.01 0.168 0.421 0.218 0.129 0.273 0.190 0.334 0.102 0.180 0.236 0.136 0.229 0.065 0.141 1.03 0.707 0.162 0.227 0.192 0.174 0.341 0.580 1.15 0.163 0.306 0.236 0.758 0.161 0.362 0.613 0.192

19.0 2.97 3.79 1.88 2.15 8.62 2.66 3.12 1.48 1.58 1.46 1.35 2.93 1.38 2.11 8.98 17.1 1.61 1.35 2.35 3.61 2.32 1.87 11.7 2.17 2.22 3.16 8.56 3.33 3.75 9.13 1.71

0.105 0.031 0.021 0.012 0.021 0.001 0.013 0.021 0.031 0.015 0.020 0.017 0.014 0.019 0.013 0.018 0.093 0.024 0.014 0.015 0.019 0.014 0.005 0.045 0.020 0.011 0.010 0.033 0.024 0.012 0.010 0.015

1.72 0.116 0.348 0.094 0.094 0.167 0.078 0.098 0.035 0.099 0.083 0.054 0.042 0.041 0.054 0.155 1.11 0.074 0.059 0.097 0.112 0.094 0.110 0.648 0.053 0.038 0.035 0.162 0.117 0.036 0.069 0.062

0.032 0.020 0.016 0.006 0.004 0.002 0.002 0.011 0.005 0.029 0.004 0.003 0.003 0.003 0.002 0.018 0.027 0.021 0.003 0.004 0.013 0.009 0.002 0.028 0.002 0.011 0.005 0.047 0.010 0.004 0.063 0.012

0.080 0.075 0.066 0.068 0.053 0.042 0.042 0.042 0.070 0.021 0.042 0.035 0.032 0.042 0.037 0.070 0.236 0.092 0.090 0.161 0.061 0.067 0.038 0.037 0.042 0.095 0.053 0.099 0.052 0.042 0.341 0.059

0.690 0.457 0.393 0.058 0.406 0.761 0.338 0.347 0.234 0.020 0.176 0.233 0.309 0.672 0.386 0.439 0.020 0.100 0.112 0.020 0.394 0.333 0.123 0.567 0.443 0.249 0.206 0.020 0.315 0.482 0.566 0.221

16.2 1.08 5.69 0.400 1.11 0.470 0.395 0.721 0.621 0.518 0.846 0.577 0.504 0.634 0.447 1.04 4.12 0.838 0.461 0.715 1.41 0.652 0.374 2.23 0.429 0.348 0.371 1.77 1.73 0.397 0.603 0.794

0.274 0.010 0.025 0.011 0.026 0.042 0.024 0.018 0.054 0.020 0.023 0.007 0.032 0.007 0.014 0.022 0.043 0.009 0.009 0.020 0.024 0.006 0.023 0.066 0.009 0.009 0.005 0.114 0.013 0.021 0.018 0.024

16.0 4.78 6.02 4.26 4.15 25.1 1.95 2.83 2.05 2.41 3.27 3.21 3.45 4.04 4.04 8.74 7.54 5.07 3.44 1.36 6.42 4.34 3.20 15.4 2.99 4.50 3.25 2.69 4.35 5.26 4.35 3.22

3.13 1.11 1.15 0.851 1.99 3.59 1.16 0.819 1.22 9.68 1.11 0.834 0.811 0.529 0.268 1.16 0.209 1.23 2.53 1.31 0.792 0.394 0.529 1.93 0.104 0.496 0.981 0.209 0.847 1.30 0.562 0.482

0.001 0.001 0.001 0.003 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.002 0.001 0.002 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.002

0.350 0.031 0.057 0.031 0.051 0.042 0.031 0.049 0.046 0.126 0.031 0.027 0.020 0.020 0.031 0.033 0.148 0.020 0.031 0.168 0.026 0.068 0.024 0.089 0.108 0.042 0.051 0.151 0.031 0.079 0.022 0.049

0.001 0.003 0.002 0.001 0.002 0.001 0.001 0.001 0.001 0.001 0.001 0.002 0.001 0.002 0.002 0.004 0.001 0.001 0.001 0.001 0.002 0.003 0.001 0.005 0.001 0.004 0.004 0.001 0.002 0.002 0.001 0.001

0.003 0.001 0.002 0.003 0.003 0.003 0.001 0.001 0.001 0.001 0.002 0.001 0.001 0.001 0.001 0.001 0.009 0.003 0.001 0.003 0.003 0.001 0.002 0.001 0.001 0.001 0.001 0.005 0.003 0.004 0.003 0.002

0.047 0.015 0.019 0.007 0.005 0.030 0.003 0.016 0.006 0.006 0.009 0.010 0.007 0.005 0.003 0.009 0.009 0.003 0.010 0.003 0.008 0.009 0.005 0.024 0.025 0.005 0.012 0.012 0.011 0.006 0.007 0.015

0.059 0.148 0.160 0.097 0.066 0.042 0.071 0.133 0.037 0.042 0.133 0.094 0.040 0.042 0.395 0.288 0.021 0.042 0.078 0.970 0.051 0.021 0.025 0.283 0.021 0.131 0.037 0.021 0.102 0.051 0.085 0.114

0.002 0.001 0.002 0.001 0.001 0.001 0.001 0.001 0.002 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.007 0.001 0.001 0.003 0.001 0.001 0.001 0.001 0.001 0.001 0.002 0.004 0.001 0.002 0.002 0.002

0.220 0.116 0.198 0.058 0.573

0.005 0.007 0.003 0.001 0.036

0.381 0.397 0.228 0.065 2.01

4.42 4.51 2.50 1.35 19.0

0.023 0.022 0.018 0.001 0.105

0.192 0.349 0.094 0.035 1.72

0.013 0.014 0.008 0.002 0.063

0.074 0.064 0.056 0.021 0.341

0.315 0.205 0.324 0.020 0.761

1.52 2.91 0.643 0.348 16.2

0.032 0.049 0.021 0.005 0.274

5.43 4.85 4.10 1.36 25.1

1.35 1.72 0.916 0.104 9.68

0.001 0.000 0.001 0.001 0.003

0.065 0.066 0.042 0.020 0.350

0.002 0.001 0.001 0.001 0.005

0.002 0.002 0.002 0.001 0.009

0.011 0.009 0.009 0.003 0.047

0.122 0.177 0.069 0.021 0.970

0.002 0.001 0.001 0.001 0.007

T. Guérin et al. / Food Chemistry 127 (2011) 934–942

Anchovy Angler fisha Catsharka Cod Dab Eela Emperora Goatfish Grenadier/Hokia Gurnard Haddock Hake Halibuta John Dory Ling Mackerel Pilchard Plaice Pollack Pout Raya Saithe/Coalfish Salmon Sardine Scorpion fish Sea Bassa Sea Breama Smoked Herring Sole Swordfisha Tunaa Whiting

n

Predatory fish as described in the Commission Regulation (EC) No. 629/2008.

937

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Table 5 Mean concentrations of essential trace elements and toxic trace elements in other seafood and products (mg/kg fm). n

Calico Scallop Cockle Crab Cuttlefish Great Scallop Mussel Octopus Oyster Periwinkle Scampi Sea Urchin Shrimp Spider Crab Squid Swimcrab Whelk Fish Soup Paella Surimi Tarama Mean SD Median Min Max

1 2 4 1 3 4 1 4 3 3 1 4 1 2 2 3 1 1 1 1

Essential trace elements

Toxic trace elements

Cr

Co

Cu

Fe

Li

Mn

Mo

Ni

Se

Sr

V

Zn

Al

Sb

Ba

Ga

Ge

Pb

Ag

Te

0.199 0.195 0.285 0.105 0.220 0.290 0.005 0.114 0.269 0.196 0.005 0.151 0.421 0.065 0.150 0.296 0.169 0.190 0.380 0.854 0.228 0.183 0.196 0.005 0.854

0.043 0.182 0.072 0.002 0.021 0.074 0.001 0.021 0.128 0.024 0.001 0.013 0.372 0.005 0.304 0.049 0.006 0.013 0.004 0.005 0.067 0.104 0.021 0.001 0.372

1.73 0.436 18.0 2.47 0.666 1.01 3.60 12.9 14.2 9.62 0.446 9.22 21.0 2.56 22.4 9.22 1.65 1.67 1.36 0.621 6.74 7.36 2.52 0.436 22.4

21.6 113 16.2 1.27 9.66 23.9 2.91 19.5 82.3 30.1 81.2 15.8 78.3 4.57 37.3 21.5 8.63 3.89 4.49 2.58 28.9 32.8 17.9 1.27 113

0.112 0.245 0.078 0.032 0.034 0.117 0.067 0.115 0.121 0.080 0.227 0.048 0.133 0.035 0.091 0.055 0.023 0.019 0.009 0.005 0.082 0.066 0.073 0.005 0.245

2.90 2.00 2.20 0.133 13.7 1.09 0.184 3.01 7.30 3.70 1.06 0.424 1.37 0.316 3.92 1.50 0.780 0.332 0.277 0.760 2.35 3.19 1.23 0.133 13.7

0.262 0.159 0.116 0.011 0.178 0.331 0.020 0.078 0.259 0.166 0.159 0.031 0.097 0.023 0.103 0.338 0.030 0.062 0.027 0.017 0.123 0.106 0.100 0.011 0.338

0.128 2.81 0.210 0.042 0.093 0.227 0.129 0.042 0.709 0.173 0.287 0.128 0.176 0.074 0.271 0.220 0.042 0.140 0.042 0.042 0.299 0.609 0.135 0.042 2.81

1.12 0.345 1.17 0.185 0.132 1.14 0.610 0.440 0.443 0.133 0.650 0.250 1.07 0.030 1.28 0.616 0.186 0.020 0.203 0.020 0.502 0.433 0.393 0.020 1.28

8.67 6.75 38.4 2.21 1.76 6.72 3.43 6.65 31.3 25.9 21.2 13.0 17.2 2.29 53.6 5.40 5.83 0.682 1.58 0.400 12.6 14.5 6.69 0.400 53.6

0.248 0.313 0.170 0.012 0.071 0.252 0.017 0.138 0.197 0.117 1.12 0.098 0.296 0.054 0.524 0.188 0.012 0.038 0.105 0.037 0.200 0.252 0.128 0.012 1.12

54.5 8.06 49.1 13.4 19.4 21.2 17.6 124 20.9 12.0 7.66 15.1 48.2 6.69 42.8 68.8 2.89 2.17 3.51 7.39 27.3 30.1 16.3 2.17 124

14.2 77.4 3.81 1.47 4.01 17.0 1.94 5.21 13.0 17.4 88.4 26.3 25.2 1.95 20.3 6.92 4.04 2.51 1.20 1.62 16.7 24.1 6.06 1.20 88.4

0.005 0.003 0.006 0.002 0.001 0.003 0.001 0.002 0.005 0.008 0.001 0.001 0.006 0.001 0.004 0.002 0.002 0.001 0.005 0.001 0.003 0.002 0.002 0.001 0.008

0.114 0.403 0.334 0.063 0.035 0.088 0.042 0.213 0.293 0.247 31.8 0.609 0.136 0.113 0.406 0.122 0.311 0.042 0.114 0.225 1.79 7.07 0.175 0.035 31.8

0.009 0.019 0.001 0.003 0.001 0.003 0.005 0.001 0.004 0.005 0.054 0.005 0.001 0.005 0.008 0.001 0.003 0.001 0.001 0.001 0.007 0.012 0.003 0.001 0.054

0.001 0.001 0.004 0.001 0.004 0.005 0.001 0.004 0.001 0.004 0.001 0.001 0.001 0.003 0.005 0.003 0.001 0.001 0.004 0.001 0.002 0.002 0.001 0.001 0.005

0.148 0.101 0.034 0.017 0.088 0.351 0.003 0.103 0.105 0.042 0.014 0.015 0.065 0.008 0.119 0.084 0.022 0.027 0.007 0.008 0.068 0.080 0.038 0.003 0.351

185 2.18 45.3 0.125 4.32 1.81 0.382 64.7 46.4 14.8 1.57 0.802 61.6 0.655 139 39.2 1.40 0.021 0.170 0.042 30.5 50.8 2.00 0.021 185

0.001 0.001 0.002 0.001 0.004 0.003 0.001 0.012 0.009 0.007 0.004 0.003 0.001 0.004 0.006 0.001 0.001 0.002 0.003 0.001 0.003 0.003 0.003 0.001 0.012

T. Guérin et al. / Food Chemistry 127 (2011) 934–942

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3.2.2. Cobalt Cobalt was found at an average level of 0.005 mg/kg in fish. Pilchard had the highest level of Co (0.036 mg/kg) followed in decreasing order by anchovy, smoked herring and tuna (0.012– 0.019 mg/kg). In other seafood and seafood products, Co was found at an average level of 0.067 mg/kg. Spider crab and swimcrab contained the highest levels (0.372 and 0.304 mg/kg, respectively) followed by cockle and periwinkle (0.182 and 0.128 mg/kg, respectively). The lowest Co levels were found in octopus and sea urchin (0.001 mg/kg). These mean levels were slightly lower than those found during the 1st TDS in fish (n = 62; mean 0.007 mg/ kg; max 0.044 mg/kg in canned sardines) and in other seafood (n = 18; mean 0.046 mg/kg; max 0.132 mg/kg in mussel) (Leblanc et al., 2005). These results were in good agreement (Agah et al., 2009), higher (De Mora et al., 2004) or lower (De Mora et al., 2004; Erkan et al., 2009; Ikem & Egiebor, 2005; Kelly et al., 2008; Mendil et al., 2010; Shiraishi, 2005; Sivaperumal et al., 2007; Tetsuro et al., 2005, 2007; Türkmen et al., 2009) than mean values previously found in fish and other seafood. 3.2.3. Copper Copper was found at an average level of 0.381 mg/kg in fish. Anchovy had the highest level of Cu (2.01 mg/kg) followed in decreasing order by sardine, mackerel, smoked herring, pilchard and tuna (0.613–1.15 mg/kg). In other seafood and seafood products, Cu was found at an average level of 6.74 mg/kg. Swimcrab and spider crab contained the highest levels (22.4 and 21.0 mg/ kg, respectively) followed in decreasing order by crab, periwinkle and oyster (12.9–18.0 mg/kg). The lowest Cu levels were found in cockle and sea urchin (about 0.44 mg/kg). These mean levels were similar to those found during the 1st TDS in fish (n = 62; mean 0.041 mg/kg; max 1.06 mg/kg in salted cod) and in other seafood (n = 18; mean 7.05 mg/kg; max 18.8 mg/kg in oyster) (Leblanc et al., 2005). These results were in good agreement (Sivaperumal et al., 2007), higher (Agah et al., 2009; De Mora et al., 2004) or lower (De Mora et al., 2004; Erkan et al., 2009; Ersoy & Celik, 2010; Ikem & Egiebor, 2005; Kelly et al., 2008; Mendil et al., 2010; Mohapatra, Rautray, Patra, Vijayan, & Mohanty, 2009; Sivaperumal et al., 2007; Tetsuro et al., 2005, 2007; Tuzen, 2009; Türkmen et al., 2009) than mean values previously found in fish and other seafood. 3.2.4. Iron Iron was found at an average level 4.42 mg/kg in fish. Anchovy and pilchard had the highest level of Fe (19.0 and 17.1 mg/kg, respectively) followed in decreasing order by sardine, tuna, mackerel, eel and smoked herring (8.56–11.7 mg/kg). In other seafood and seafood products, Fe was found at an average level of 28.9 mg/kg. Cockle, periwinkle, sea urchin and spider crab contained the highest levels (78.3–113 mg/kg) followed in decreasing order by swimcrab and scampi (30.1 and 37.3 mg/kg, respectively). The lowest Fe levels were found in cuttlefish (about 1.3 mg/kg). These results were lower (De Mora et al., 2004; Ikem & Egiebor, 2005; Mendil et al., 2010; Mohapatra et al., 2009; Shiraishi, 2005; Tuzen, 2009; Türkmen et al., 2009) or higher (Agah et al., 2009; Ersoy & Celik, 2010) than mean values previously found in fish and other seafood. 3.2.5. Lithium Lithium was found at an average level of 0.023 mg/kg in fish. Once again, anchovy and pilchard had the highest levels of Li (0.105 and 0.093 mg/kg, respectively) followed in decreasing order by sardine, smoked herring, grenadier and angler fish (0.031– 0.045 mg/kg). The lowest Li levels were observed in eel and salmon (less than 0.01 mg/kg). In other seafood and seafood products, Li was found at an average level of 0.082 mg/kg. Cockle and sea urchin contained the highest levels (0.245 and 0.227 mg/kg, respec-

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tively) followed in decreasing order by spider crab, periwinkle, mussel, oyster and calico scallop (0.11–0.133 mg/kg). The lowest Li levels were found in tarama and surimi (less than 0.01 mg/kg). These mean levels were similar for fish and slightly lower for other seafood compared to those found during the 1st TDS in fish (n = 62; mean 0.030 mg/kg; max 0.106 mg/kg in canned sardines) and in other seafood (n = 18; mean 0.123 mg/kg; max 0.485 mg/kg in mussel) (Leblanc et al., 2005). These results were lower than mean values previously found in fish and other seafood (Nabrzyski & Gajewska, 2002; Shiraishi, 2005). 3.2.6. Manganese Manganese was found at an average level of 0.192 mg/kg in fish. Anchovy and pilchard again had the highest levels of Mn (1.72 and 1.11 mg/kg, respectively) followed in decreasing order by sardine and catshark (0.648 and 0.348 mg/kg, respectively). In other seafood and seafood products, Mn was found at an average level of 2.35 mg/kg. Great scallop and periwinkle contained the highest levels (13.7 and 7.30 mg/kg, respectively) followed in decreasing order by swimcrab, scampi, oyster and calico scallop (2.90– 3.92 mg/kg). The lowest Mn levels were found in cuttlefish and octopus (less than 0.2 mg/kg). These mean levels were similar to those found during the 1st TDS in fish (n = 62; mean 0.30 mg/kg; max 1.22 mg/kg in fish nuggets) and in other seafood (n = 18; mean 2.68 mg/kg; max 5.56 mg/kg in oyster) (Leblanc et al., 2005). These results were similar (Tetsuro et al., 2005, 2007), higher (Agah et al., 2009; De Mora et al., 2004; Kelly et al., 2008; Sivaperumal et al., 2007), or lower (De Mora et al., 2004; Erkan et al., 2009; Ersoy & Celik, 2010; Ikem & Egiebor, 2005; Mendil et al., 2010; Sivaperumal et al., 2007; Tuzen, 2009; Türkmen et al., 2009) than mean values previously found in fish and other seafood. 3.2.7. Molybdenum Molybdenum was found at an average level of 0.013 mg/kg in fish. Tuna had the highest level of Mo (0.063 mg/kg) followed in decreasing order by smoked herring, anchovy, sardine, pilchard, plaice and anglerfish (0.020–0.047 mg/kg). In other seafood and seafood products, Mo was found at an average level of 0.123 mg/ kg. Whelk and mussel contained the highest levels (about 0.33 mg/kg) followed in decreasing order by calico scallop and periwinkle (0.262 and 0.259 mg/kg, respectively). The lowest Mo levels were observed in cuttlefish and tarama (less than 0.2 mg/kg). These mean levels were lower for fish and similar for other seafood compared to those found during the 1st TDS in fish (n = 62; mean 0.065 mg/kg; max 0.225 mg/kg in fish nuggets) and in other seafood (n = 18; mean 0.129 mg/kg; max 0.369 mg/kg in mussel) (Leblanc et al., 2005). These results were similar (Tetsuro et al., 2005) or slightly higher than mean values previously found in fish (Agah et al., 2009; Tetsuro et al., 2007). To our knowledge, there are no studies reporting Mo concentrations in other seafood. 3.2.8. Nickel Nickel was found at an average level of 0.074 mg/kg in fish. Tuna also had the highest level of Ni (0.341 mg/kg) followed in decreasing order by pilchard and pout (0.236 and 0.161 mg/kg, respectively). In other seafood and seafood products, Ni was found at an average level of 0.299 mg/kg. Cockle contained the highest level (about 2.8 mg/kg) followed by periwinkle (0.709 mg/kg). These mean levels were higher than those found during the 1st TDS in fish (n = 62; mean 0.050 mg/kg; max 0.209 mg/kg in salted cod) and in other seafood (n = 18; mean 0.123 mg/kg; max 0.55 mg/kg in shrimp) (Leblanc et al., 2005). These results were similar (Shiraishi, 2005; Sivaperumal et al., 2007), lower (De Mora et al., 2004; Erkan et al., 2009; Ersoy & Celik, 2010; Lavilla et al., 2008; Sivaperumal et al., 2007; Tuzen, 2009; Türkmen et al., 2009) or higher (Agah et al., 2009; De Mora et al., 2004; Ikem & Egiebor,

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2005; Kelly et al., 2008) than mean values previously found in fish and other seafood. 3.2.9. Selenium Selenium was found at an average level of 0.32 mg/kg in fish. Eel had the highest level of Se (0.761 mg/kg) followed in decreasing order by anchovy, John Dory, sardine and tuna (0.566– 0.690 mg/kg). The lowest Se levels were found in gurnard, pilchard, pout and smoked herring (0.02 mg/kg). In other seafood and seafood products, Se was found at an average level of 0.502 mg/kg. Swimcrab, crab, calico scallop, mussel and spider crab contained in decreasing order the highest levels (more than 1.0 mg/kg) with a maximum of 1.28 mg/kg. The lowest Se levels were observed in tarama, paella and squid (less than 0.03 mg/kg). These mean levels were higher than those found during the 1st TDS in fish (n = 62; mean 0.170 mg/kg; max 0.448 mg/kg in canned tuna) and in other seafood (n = 18; mean and max 0.011 mg/kg) (Leblanc et al., 2005). These results were similar (Lavilla et al., 2008), higher (Kelly et al., 2008; Mohapatra et al., 2009; Sivaperumal et al., 2007) or lower (De Mora et al., 2004; Lavilla et al., 2008; Tetsuro et al., 2005, 2007; Tuzen, 2009) than mean values previously found in fish and other seafood. 3.2.10. Strontium Strontium was found at an average level of 1.52 mg/kg in fish. Anchovy was the most contaminated species (16.2 mg/kg) followed by catshark, pilchard and sardine (2.23–5.69 mg/kg). In other seafood and seafood products, strontium was found at an average level of 12.6 mg/kg. Swimcrab was the most contaminated species (53.6 mg/kg) followed by crab, periwinkle, scampi and sea urchin (21.2–38.4 mg/kg). The lowest Sr levels were found in paella and tarama (less than 0.70 mg/kg). These results were similar (Nabrzyski & Gajewska, 2002; Tetsuro et al., 2007), lower (Shiraishi, 2005; Tetsuro et al., 2005) or higher (Kelly et al., 2008; Mohapatra et al., 2009) than mean values previously found in fish and other seafood. 3.2.11. Vanadium Vanadium was found at an average level of 0.032 mg/kg in fish. Anchovy had the highest level of V (0.274 mg/kg) followed in decreasing order by smoked herring, sardine and grenadier (0.054–0.114 mg/kg). In other seafood and seafood products, V was found at an average level of 0.200 mg/kg. Sea urchin contained the highest level (1.12 mg/kg) followed in decreasing order by swimcrab, cockle, spider crab, mussel and calico scallop (0.248– 0.524 mg/kg). The lowest V levels were found in cuttlefish and fish soup (less than 0.02 mg/kg). These results were lower (Kelly et al., 2008; Lavilla et al., 2008) or higher (Agah et al., 2009; De Mora et al., 2004; Ikem & Egiebor, 2005; Tetsuro et al., 2005, 2007) than mean values previously found in fish and other seafood. 3.2.12. Zinc Zinc was found at an average level of 5.43 mg/kg in fish. Eel had the highest level of Zn (25.1 mg/kg) followed in decreasing order by anchovy, sardine and mackerel (8.74–16.0 mg/kg). Pout and emperor had the lowest levels (less than 2 mg/kg). In other seafood and seafood products, Zn was found at an average level of 27.3 mg/ kg. Oyster contained the highest level (124 mg/kg) followed in decreasing order by whelk, calico scallop, crab, spider crab and swimcrab (42.8–68.8 mg/kg). The lowest Zn levels were found in paella and fish soup (less than 3 mg/kg). These mean levels were similar to those found during the 1st TDS in fish (n = 62; mean 5.51 mg/kg; max 18 mg/kg in canned sardines) and in other seafood (n = 18; mean 66 mg/kg; max 219 mg/kg in oyster) (Leblanc et al., 2005). These results were in good agreement (De Mora et al., 2004; Kelly et al., 2008; Sivaperumal et al., 2007), higher

(Agah et al., 2009; Ersoy & Celik, 2010) or lower (De Mora et al., 2004; Erkan et al., 2009; Ikem & Egiebor, 2005; Mendil et al., 2010; Mohapatra et al., 2009; Shiraishi, 2005; Sivaperumal et al., 2007; Tetsuro et al., 2005, 2007; Tuzen, 2009; Türkmen et al., 2009) than mean values previously found in fish and other seafood. 3.3. Toxic trace elements 3.3.1. Aluminium Aluminium was found at an average level of 1.35 mg/kg in fish. Gurnard was the most contaminated species (9.68 mg/kg) followed by eel, anchovy, and pollock (2.53–3.59 mg/kg). Fish with the lowest Al levels were scorpion fish, smoked herring and pilchard. In other seafood and seafood products, aluminium was found at an average level of 16.7 mg/kg. Sea urchin and cockle were the most contaminated species (88.4 and 77.4 mg/kg, respectively) followed to a much lesser extent by shrimp, spider crab and swimcrab (between 20.3 and 26.3 mg/kg). The lowest Al levels were found in surimi, cuttlefish, tarama, octopus and squid (less than 2 mg/ kg). These mean levels were higher for fish and similar for other seafood compared to those found during the 1st TDS in fish (n = 62; mean 0.51 mg/kg; max 2.7 mg/kg in salted cod) and in other seafood (n = 18; mean 17 mg/kg; max 33 mg/kg in mussel) (Leblanc et al., 2005). These results were similar (Kelly et al., 2008) or lower than mean values previously found in fish (Agah et al., 2009; Erkan et al., 2009). 3.3.2. Antimony The average content of antimony in fish was 0.001 mg/kg, with a maximum level of 0.003 mg/kg in cod. In other seafood and seafood products, Sb was found at an average level of 0.003 mg/kg. Scampi, crab and spider crab were the most contaminated species (0.006–0.008 mg/kg). These mean levels were similar to those found during the 1st TDS in fish (n = 62; mean and max 0.0003 mg/kg) and in other seafood (n = 18; mean 0.002 mg/kg; max 0.003 mg/kg in mussel) (Leblanc et al., 2005). These results were in good agreement (Agah et al., 2009; De Mora et al., 2004) or lower (Tetsuro et al., 2005, 2007) than mean values previously found in fish and other seafood. 3.3.3. Barium Ba was found at an average level of 0.065 mg/kg in fish. Anchovy was the most contaminated species (0.350 mg/kg) followed in decreasing order by pout, smoked herring, pilchard, gurnard and scorpion fish (0.108–0.168 mg/kg). In other seafood and seafood products, barium was found at an average level of 1.79 mg/kg. Sea urchin was the most heavily contaminated species (31.8 mg/ kg) followed to a much lesser extent by shrimp, swimcrab, cockle, crab and fish soup (0.311–0.609 mg/kg). These results were similar (Tetsuro et al., 2005) or higher (Kelly et al., 2008; Tetsuro et al., 2007) than mean values previously found in fish. A mean level of 0.331 mg/kg was also found in the category ‘‘fish and seafood’’ by Shiraishi (2005) but without any distinction between levels in fish and levels in seafood. To our knowledge, there are no studies reporting Ba concentrations in other seafood alone. 3.3.4. Gallium The average content of gallium in fish was 0.002 and 0.001 mg/ kg respectively, with a maximum level of 0.005 mg/kg in sardine. In other seafood and seafood products, Ga was found at an average level of 0.007 mg/kg. Sea urchin was the most contaminated species (0.054 mg/kg), followed by cockle (0.019 mg/kg). These results were similar (Tetsuro et al., 2005) to mean values previously found in fish. To our knowledge, there are no studies reporting Ga concentrations in other seafood.

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3.3.5. Germanium The average content of germanium in fish was 0.002 mg/kg, with a maximum level of 0.009 mg/kg in pilchard. In other seafood and seafood products, Ge was found at an average level of 0.002 mg/kg with a maximum level of 0.005 mg/kg in mussel and swimcrab. To our knowledge, there are no studies reporting Ge concentrations in fish and other seafood.

speaking, by analysing the risks and the benefits of the whole diet, seafood can be considered as a major contributor to the exposure to certain chemicals of interest (such as methylmercury, cadmium, selenium and zinc) but also as a minor contributor of other chemicals. Nevertheless it remains of high interest to provide data on other chemical concentrations to evaluate the background exposure as part of the risk evaluation process.

3.3.6. Lead Lead was found at an average level of 0.011 mg/kg in fish. In decreasing order anchovy, eel, scorpion fish and sardine were the most contaminated species (between 0.024 and 0.047 mg/kg). However, no species exceeded the maximum levels set by Commission Regulation (EC) No. 629/2008 (0.30 mg/kg for muscle meat of fish). Fish with the lowest Pb levels were emperor, ling and pout followed by dab, John Dory and salmon. In other seafood and seafood products, lead was found at an average level of 0.068 mg/ kg. Mussel was the most contaminated species (0.351 mg/kg) followed by calico scallop, swimcrab, periwinkle, oyster and cockle (between 0.101 and 0.148 mg/kg). No species exceeded the maximum levels set by Commission Regulation (EC) No. 629/2008 (0.50 for crustaceans, 1.0 for cephalopods and 1.5 mg/kg for bivalve molluscs). The lowest Pb levels were found in octopus, tarama and surimi. These mean levels were lower than those found during the 1st TDS in fish (n = 62; mean 0.023 mg/kg; max 0.138 mg/kg in salted cod) and in other seafood (n = 18; mean 0.098 mg/kg; max 0.222 mg/kg in mussel) (Leblanc et al., 2005). These results were similar (Kelly et al., 2008; Mohapatra et al., 2009; Tetsuro et al., 2005, 2007), lower (Agah et al., 2009; De Mora et al., 2004; Erkan et al., 2009; Ersoy & Celik, 2010; Mendil et al., 2010; Sivaperumal et al., 2007; Tuzen, 2009; Türkmen et al., 2009) or higher (Ikem & Egiebor, 2005) than mean values previously found in fish and other seafood.

4. Conclusion This study completes the database concerning occurrence levels of trace elements in fish and other seafood which may be used at national and international level to estimate the dietary exposure to the general population or high consumers of these products associated with the consumption of whole diet. It should be noted that the concentrations of Ag were found considerably higher in fish and other seafood than in previous studies. These results should be deepened in the future to explain these high Ag levels in fish and other seafood from the French market. Finally, for essential trace elements, there is a lack of data for Li and Mo, particularly concerning other seafood when for toxic trace elements, there is a lack of data for some elements (Al, Sb, Ba, Ga, Ge, Ag and Te) in fish and/or other seafood. Acknowledgements The authors would like to thank the General Directorate for Foods of the French Ministry of Agriculture and Fisheries for grant support. They also express their particular gratitude to P. Verger (Met@risk, INRA, Paris) and to all the participants in the CALIPSO survey. References

3.3.7. Silver Silver was found at an average level of 0.122 mg/kg in fish. Pout was the most contaminated species (0.970 mg/kg) followed by ling, mackerel and sardine (0.283–0.395 mg/kg). In other seafood and seafood products, Ag was found at an average level of 30.5 mg/kg. Calico scallop and swimcrab were the most heavily contaminated species (185 and 139 mg/kg, respectively) followed by oyster, spider crab, periwinkle, crab and whelk (39.2–64.7 mg/ kg). The lowest Ag levels were found in paella and tarama (0.02 mg/kg). These results were (Tetsuro et al., 2007) considerably higher than mean values previously found in fish and other seafood (De Mora et al., 2004; Ikem & Egiebor, 2005; Kelly et al., 2008; Tetsuro et al., 2005, 2007). 3.3.8. Tellurium The average content of tellurium in fish was 0.002 mg/kg, with a maximum level of 0.007 mg/kg in pilchard. In other seafood and seafood products, Te was found at average of 0.003 mg/kg with a maximum level of 0.012 mg/kg in oyster followed by scampi and swimcrab (0.006 mg/kg). To our knowledge, there are no studies reporting Te concentrations in fish and other seafood. 3.4. Risk–benefit analysis From a public health point of view, these data are relevant in a risk–benefit analysis perspective. Most of the studies on the risk and benefit of seafood consumption focused mainly on methylmercury and omega-3 polyunsaturated fatty acids. However, to determine seafood consumption recommendations in order to maximise the nutritional benefit and to minimise the risk due to contaminants, one should take account of all the beneficial nutrients and contaminants provided by seafood consumption. Generally

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