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Fs): Occurrence in fishery products and dietary intake
Food Chemistry 127 (2011) 1648–1652
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Polychlorinated biphenyls (PCBs), dioxins and furans (PCDD/Fs): Occurrence in fishery products and dietary intake Maria Maddalena Storelli a,⇑, Grazia Barone a, Veronica Giuliana Perrone a, Roberto Giacominelli-Stuffler b a
Pharmacological–Biological Department, Chemistry and Biochemistry Section, Veterinary Medicine Faculty, University of Bari, Strada Prov. le per Casamassima Km 3, 70010 Valenzano (Ba), Italy b Comparative Biomedical Sciences Department, Biochemistry and Molecular Biology Section, Veterinary Medicine Faculty, University of Teramo, Piazza A. Moro 45, 64100 Teramo, Italy
a r t i c l e
i n f o
Article history: Received 24 November 2010 Received in revised form 21 December 2010 Accepted 7 February 2011
Keywords: PCBs PCDD/Fs Fish consumption Estimated weekly intake
a b s t r a c t Concentrations and congener specific profiles of PCBs, PCDDs and PCDFs were determined in various edible fish from the Adriatic Sea. PCBs were the dominant chemicals (116–1980 ng g1 lipid wt), followed by PCDFs (ND-58.3 pg g1 lipid wt) and PCDDs (ND-20 pg g1 lipid wt). The levels of these contaminants varied among species. Benthic organisms possessed the highest concentrations, followed by demersal and pelagic fish species. PCB and PCDD/F accumulation pattern in the samples analysed showed a distribution typically reported for marine samples. The mean weekly intake of toxic equivalency (TEQ) was estimated to be 0.84 pg TEQs/kg bw/week. The dioxin-like PCBs accounted for more than 77% of this intake, followed by PCDDs (15.5%) and PCDFs (13.1%). In general, the samples analysed in this survey can be considered safe with regard to the levels obtained and the in-force legislation, nevertheless the consumption of some species may be of significance importance for consumer health. Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzo-furans (PCDFs), commonly known with the term ‘‘dioxins’’, and polychlorinated biphenyls (PCBs) are groups of contaminants that are very persistent and widely distributed in the environment, exhibiting potential risk for human health. Their toxic properties include carcinogenic potency, immunotoxicity and a range of endocrine effects related to reproduction (Nakatani, Yamamoto, & Ogaki, 2010). Ingestion via food consumption is the principal way of human exposure to these toxic chemicals, accounting for >90%, if compared to the other ways such as inhalation and dermal contact (Bordajandi, Martín, Abad, Rivera, & Gonzáles, 2006). There is well-established evidence that fishery products are one of the main contributors to the total dietary intake of these compounds (Bocio, Domingo, Falcó, & Llobet, 2007). Despite this, consumption of fish is considered healthy due to its high protein and vitamin content, as well as other essential nutrients. However, the most important feature of this food is an advantageous fatty acid profile, resulting from the high content of essential polyunsaturated fatty acids, such as eicosapentaenoic and docosohexaenoic, known to support good health (Kris-Etherton, Harris, & Appel, 2002). It has been estimated that the
⇑ Corresponding author. Tel.: +39 805443865; fax: +39 805443863. E-mail address: [email protected] (M.M. Storelli). 0308-8146/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2011.02.032
consumption of one fatty fish meal per day could result in an omega-3 fatty acid intake of approximately 900 mg/day, an amount shown to beneficially affect coronary heart disease mortality rate (Kris-Etherton et al., 2002). In addition, especially the eicosapentaenoic acid has also positive effects in reducing arrhythmias and thrombosis, lowering plasma triglyceride levels, reducing blood clotting tendency, and even decreasing the risks of certain cancers (Kris-Etherton et al., 2002). Consequently over recent decades there has been a notable promotion of fish consumption in many European countries (Cahu, Salen, & de Lorgeril, 2004). Meanwhile wide-ranging efforts have been made to protect the consumer health. These have resulted in new regulations establishing maximum allowed levels of these toxic chemicals in foods and re-evaluations of tolerable human exposure levels. As part of the exposure reduction strategy the European Council (EC) has, in fact, introduced maximum levels for PCDDs, PCDFs and dioxin-like-PCBs in fishery products, via Council Regulation No. 1881/2006 (Official Journal of the European Union, 2006). More, the Scientific Committee on Food (SCF) (2001) of the European Commission has conducted a re-evaluation of the tolerable weekly intake (TWI) for dioxins and dioxin-like PCBs as toxic equivalents (WHO–TEQs), according to the World Health Organization (WHO) toxic equivalency factor (TEF) scheme (Official Journal of the European Union, 2001; Van den Berg et al., 1998, 2006). The WHO has also recommended to assess human exposure to these contaminants on a regular basis in order to evaluate either the health risks associated with the population exposure or the time trends of
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exposure and the effectiveness of specific management measures. In this picture, the present study shows the results of congenerspecific analysis of PCBs and PCDD/Fs performed on a variety of fish largely consumed in Italy, where fishery products occupy a relevant part of the diet, and estimates and compares the dietary intakes of these pollutants with those from the most recent international reports on this issue.
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phase film (RTX-5, Restek, US, Bellefonte, PA, USA) for PCBs, while for PCDD/Fs a capillary column with length of 30 m 0.25 mm and 0.25 lm thickness stationary phase film (RTX-200 Restek, US, Bellefonte, PA, USA) was employed. The MS was used in the SIM mode with the two most intensive ions of the molecular ion cluster monitored in specific windows. 2.3. Quality assurance (QA) and Quality control (QC)
2. Materials and methods 2.1. Sample collection Different fish species, including benthic [conger (Conger conger), angler fish (Lophius budegassa), rosefish (Helicolenus dactylopterus), red mullet, (Mullus barbatus), fourspotted megrim (Lepidorhombus boscii), scaldfish (Arnoglossus laterna), yellow gurnard (Trigla lucerna), red gurnard (Aspitrigla cuculus)], demersal [hake (Merluccius merluccius), Atlantic stargazer (Uranoscopus scaber), brown comber (Serranus hepatus), wreckfish (Polyprion americanus), bogue (Boops boops), sea bream (Pagellus erythrinus), forkbeard greater (Phycis blennoides)] and pelagic organisms [horse mackerel (Trachurus trachurus), mediterranean horse mackerel (Trachurus mediterraneus)] were analysed. For the collection of samples, 12 specimens of wreckfish and 35–45 specimens of the remaining species were pooled according to the size. From fish of each pool, muscle tissue was taken, homogenised and kept in a deep freeze at 20 °C until chemical analysis. 2.2. Chemical and instrumental analysis The concentrations of 17 individual PCB congeners (PCBs: 8, 20, 28, 35, 52, 60, 77, 101, 105, 118, 126, 138, 153, 156, 169, 180 and 209), including the ‘‘dioxin-like’’ PCBs (non-ortho DL-PCBs: 77, 126, 169, mono-ortho DL-PCBs: 105, 118, 156), together with the seventeen 2,3,7,8-substituted PCDD/F congeners were determined. A complete description of the experimental procedures relative to PCBs and PCDD/Fs has been recently described and validated (Storelli, Barone, Storelli, & Marcotrigiano, 2011). Briefly, fish fillets were ground in a porcelain mortar and pestle with Na2SO4 and spiked with PCB 143 used as internal standard. The mixture was extracted with hexane and the extracts were concentrated and subsamples were taken in order to determine the tissue fat content by gravimetry. An aliquot (about 100 mg) of the remaining extract was dissolved in hexane and cleaned by passing through 8 g of acid silica (H2SO4, 44% w/w), using 50 ml of a mixture of hexane/dichloromethane (1/1, v/v) for elution of the analytes. The eluate was evaporated to dryness and redissolved in 100 ll of iso-octane. For the determination of PCDD/Fs (US EPA method 1613) the samples, extracted as reported above, were subjected to a multi-step clean-up to remove the matrix and the potential interfering components. The first stage was a fat destruction step consisting of a treatment of the sample solution with sulphuric acid and base back-extraction. The obtained extracts were then subjected to a pre-conditioned florisil clean-up column, that was eluted with different solutions in order to remove interfering components. The first eluted solvent was discarded, while the second eluate, which contained PCDD/Fs, was collected. The extracts were evaporated to dryness and redissolved in iso-octane. Appropriate C13-labelled extraction standards were added to the samples in order to control the whole sample preparation process. The final obtained PCBs and PCDD/Fs extracts were injected and analysed separately on a Thermo Trace GC connected with a Thermo PolarisQ MS operated in electron impact ionisation (EI) mode. The chromatographic separation was achieved by splitless injection on a capillary column with length of 30 m, i.d. 0.25 mm and 0.25 lm thickness stationary
QA/QC was performed through the analysis of procedural blanks, a duplicate sample and a standard reference material [CRM 349 for PCBs (cod liver oils) (BCR, Brussels) and CARP-2 for PCDD/Fs (NRCC)] for each set of samples. For the replicate and standard reference materials, the relative standard deviations (RSD) were <10% for all the detected compounds. Additionally, the PCB method performance was assessed through participation to interlaboratory studies organised by QUASIMEME (Laboratory Performance Studies). Obtained values deviated by less than 20% from the consensus values. Concentrations of PCBs and PCDD/Fs are presented as ng g1 on a lipid weight basis and pg g1 on a lipid weight basis, respectively, while TEQ concentrations are expressed in pg-TEQ g1 wet weight. 2.4. Estimated dietary intake of dioxin-like PCBs and PCDD/Fs The estimated dietary intakes were calculated by multiplying the fish consumption data (315 g/week) (INRAN, 2008) by mean TEQ concentrations of dioxin-like PCBs and PCDD/Fs in each fish species followed by dividing by the body weight (60 kg). The concentrations of the non-detected isomers of the chemicals are expressed as zero. The concentrations of toxic equivalents (TEQs) for PCDD/Fs and dioxin-like PCBs have been given using World Health Organization (WHO)-Toxic equivalency factors (TEF) established in 2005 (Van den Berg et al., 2006). 3. Results and discussion 3.1. Concentrations and congener profiles of PCBs and PCDD/Fs Chemical analysis results of PCBs and PCDD/Fs are illustrated in Table 1. As revealed by statistical analysis (Mann–Whitney’s U test), PCBs were the dominant chemicals (range: 116–1980 ng g1 lipid wt), followed by PCDFs (range: ND-58.3 pg g1 lipid wt) and PCDDs (range: ND-20 pg g1 lipid wt) (p < 0.05). Moreover, in agreement to what could be expected, levels of these contaminants varied greatly among species. Generally, the benthic organisms contained the highest concentrations (Mann–Whitney’s U test), followed by demersal and pelagic species (p < 0.05). The preferential accumulation of these compounds in benthic species with respect to the others is not an unexpected finding, but is part of a general picture (Storelli, Barone, & Marcotrigiano, 2007a; Storelli, Giacominelli-Stuffler, Storelli, & Marcotrigiano, 2003; Voorspoels, Covaci, Maervoet, De Meester, & Schepens, 2004) highlighting the importance of habitat in bioaccumulation of these contaminants. However, a more detailed examination of results showed that of the 17 PCB congener peaks for which analyses were conducted in this study, PCBs 138, 153, 180 were detected in all fish, PCBs 52, 60, 77, 101, 105, 118 and 156 were present in most of the examined samples, whereas the remaining congeners PCBs: 8, 20, 28, 35, 126; 169 and 209 were below the limit of detection in all fishery products tested. With regard to PCDD/Fs, congener-specific analysis revealed that certain compounds occurred frequently (2,3,7,8-TCDD and 2,3,7,8-TCDF), others were present only in some fish species (1,2,3,7,8-PeCDD, 1,2,3,4,7,8-HxCDD, 1,2,3,4,6,7,8HpCDD, 1,2,3,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF and
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Table 1 Concentrations of individual congeners of PCBs (ng g1 lipid weight) and of RPCDD/Fs (pg g1 lipid weight) in the different fish species. Lipid %
PCB 52
PCB 60
PCB 77
PCB 101
PCB 105
PCB 118
PCB 138
PCB 153
PCB 156
PCB 180
RPCBs
Benthic fish Conger Angler fish Rosefish Red mullet Fourspotted megrim Scaldfish Yellow gurnard Red gurnard
1.4 0.1 0.3 1.6 0.3 0.4 0.5 0.7
ND ND ND ND ND ND ND ND
30 ND 23 26 ND ND 21 ND
3 8 5 7 ND ND ND ND
33 ND 47 35 ND 32 ND ND
95 ND 15 44 ND ND ND ND
69 12 98 92 ND 23 37 ND
526 95 221 139 67 150 67 52
793 120 305 201 97 232 102 74
131 ND 70 ND ND ND ND ND
300 10 95 70 55 96 26 26
1980 245 879 614 219 533 253 152
ND 0.6 9.1 20.0 ND ND ND 3.0
18.5 5.0 58.3 49.0 ND ND ND 28.2
18.5 5.6 67.4 69.0 ND ND ND 31.2
Demersal fish Hake Atlantic stargazer Brown comber Wreckfish Bogue Sea bream Greater forkbeard
0.9 0.1 0.8 1.1 2.7 0.1 0.2
ND ND ND 10 ND ND ND
ND 8 ND 9 ND ND 65
13 ND ND 2 ND 3 9
54 22 9 41 ND 15 71
ND 39 ND 3 5 40 ND
41 144 12 50 15 90 47
120 194 45 144 29 183 100
105 289 65 189 39 195 176
ND ND ND ND ND ND ND
46 67 17 78 28 40 68
379 763 148 526 116 566 536
ND 2.0 5.0 2.0 3.0 ND 0.5
8.7 3.6 31.6 3.8 5.8 ND 4.3
8.7 5.6 36.6 5.8 8.8 ND 4.8
1.4 1.3
ND ND
ND ND
5 4
55 50
17 19
39 30
102 95
150 135
11 15
60 52
439 400
ND ND
ND 0.2
ND 0.2
Pelagic fish Horse mackerel Mediterranean horse mackerel
RPCDDs
RPCDFs
RPCDD/ Fs
ND = not detected.
OCDF), while the remaining such as 1,2,3,6,7,8-HxCDD, 1,2,3,7,8,9HxCDD, OCDD, 2,3,4,7,8-PeCDF, 1,2,3,7,8,9-HxCDF, 2,3,4,6,7,8HxCDF, 1,2,3,4,6,7,8-HpCDF and 1,2,3,4,7,8,9-HpCDF were not detected in any fish samples. However, independently by the frequency of detection, the congener profiles were rather similar among the different species. PCB congener distribution showed that hexachlorobiphenyls PCB 153 (27.7–49.0%) and PCB 138 (18.7–38.8%), were the most abundant, followed by PCB 180 (4.1–25.1%). Other chlorobiphenyls found in major amounts included PCB 101 (1.7–14.2%) and PCB 118 (3.5–18.9%). The predominance of these congeners is consistent with what is reported in literature for other marine inhabitants, including not only fish (Kannan, Corsolini, Imagawa, Focardi, & Giesy, 2002; Storelli et al., 2007a), but also reptiles (Lazar et al., in press) and mammals (Fair et al., 2010; Storelli, Barone, Piscitelli, Storelli, & Marcotrigiano 2007b). Their abundance in so different taxa is due both to their high lipophilicity, stability and persistence, that facilitate the accumulation in the aquatic ecosystem, and their molecular structure, which makes them refractory to metabolic attack by mono-oxygenases. With regard to non-ortho congeners, PCB 77 was the only compound found, while among mono-ortho congeners, PCB 118 was the most predominant, followed by 105 and 156, which gave an almost equal contribution. In 2,3,7,8-PCDD/Fs profiles, 2,3,7,8-TCDF appeared to be the most abundant congener in all the samples analysed. Also, 2,3,7,8-TCDD and 1,2,3,6,7,8HxCDF accounted for a relatively high percentage of dioxins. This congener pattern is in accordance to what was reported in the literature for different marine organisms, where the higher chlorinated congeners OCDD, OCDF and, to some extent also, heptachlorinated PCDD/F congeners are not detected or else only present at low concentrations (Bocio et al., 2007; Moon & Choi, 2009). This can be attributed to a reduced absorbance of these congeners in the digestive tract of fish and/or to a lower biomagnification potential of congeners with the highest degree of chlorination in the marine food webs (Ruus, Berge, Bergstad, Knutsen, & Hylland, 2006). 3.2. Toxic potential of dioxin-like PCBs and PCDD/Fs The European Union (EU) has established maximum limits for these undesirable substances in food, aiming to ensure that it is
safe for consumer. As specified in EC Regulation 1881/2006 (Official Journal of the European Union, 2006) the maximum permissible levels for human consumption are of 4 and 8 pg g1 wet weight of toxic equivalents (WHO–TEQ), for PCDD/Fs and PCDD/ Fs plus dioxin-like PCB compounds, respectively in the muscle meat of fish and fishery products. The data here showed that the concentrations (0.0004–0.38 pg TEQ/g wet weight) of these contaminants in all samples tested were below the legal limits, when expressed on a wet weight basis. Also the estimated dietary intakes (0.02–6.17 pg TEQs/kg bw/week, average: 0.84 pg TEQs/kg bw/ week (Table 2) were below the tolerable weekly intake (TWI) proposed by European Commission of 14 pg TEQs/kg bw/week. However, dietary exposure values was subjected to variations
Table 2 Estimated weekly intakes (pg TEQs/kg bw/week) of dioxin-like PCBs and PCDD/Fs from fish consumption. pg TEQs/kg bw/week WHO–TEF 2006 (1998)
% Contribution to WHO–TEQPCDD/Fs+dlPCBs
Benthic fish Conger Angler fish Rosefish Red mullet Fourspotted megrim Scaldfish Yellow gurnard Red gurnard
0.81 0.01 0.32 2.49 – 0.01 0.03 0.21
(6.17) (0.08) (0.97) (3.29) (0.05) (0.09) (0.21)
15.5 0.2 6.1 47.6 – 0.2 0.6 4.0
(0.3) (0.6) (1.5)
Demersal fish Hake Atlantic stargazer Brown comber Wreckfish Bogue Sea bream Greater forkbeard
0.16 0.04 0.24 0.17 0.34 0.02 0.03
(0.30) (0.11) (0.28) (0.38) (0.54) (0.07) (0.07)
3.1 0.8 4.6 3.3 6.5 0.4 0.6
(2.1) (0.8) (2.0) (2.7) (3.8) (0.5) (0.5)
Pelagic fish Horse mackerel Mediterranean horse mackerel Sum Average
(43.1) (0.1) (6.8) (23.0)
0.19 (0.85) 0.16 (0.89)
3.6 (5.9) 3.1 (6.2)
5.23 (14.30) 0.31 (0.84)
– –
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M.M. Storelli et al. / Food Chemistry 127 (2011) 1648–1652 Table 3 Literature data concerning human dietary intake of dioxin-like PCBs and PCDD/Fs from seafood consumption. Location
a b c
Dietary intake (pg TEQ/day)
Human dietary intake (pg TEQs/kg bw/week)
References
European countries Italy Italy Netherlands Netherlands Belgium Spain Finland Sweden
7.55 (0.14–52.88) 2.65 (0.11–21.35) – – – 38.00 95.00 31.00
0.84 (0.02–6.17)a 0.31 (0.01–2.49)b 0.86 1.34 0.85 0.002–1.38 9.87 2.94
This study This study Freijer et al., 2001 Baars et al., 2004 Windal et al., 2010 Bocio et al., 2007 Kiviranta et al., 2004 Darnerud et al., 2006
Extra-European countries Japan Japan Japan Korea Korea China (Guangzhou) China (Zhoushan) Taiwan
86.57 63.09 59.98–80.35 40.80 66.80 63.00 51.00 –
12.12 4.69–11.80 1.20–1.61 3.06 8.61 7.35 5.95 3.00–4.30c
Tsutsumi et al., 2001 Sasamoto et al., 2006 Nakatani et al., 2010 Moon & Ok, 2006 Moon & Choi, 2009 Jiang et al., 2007 Jiang et al., 2007 Wang et al., 2009
TEFs recommended by WHO (Van den Berg et al., 1998). TEFs recommended by WHO (Van den Berg et al., 2006). PCDD/Fs.
depending on the consumed fish species. Conger and red mullet contributed to the highest intake of 6.17 pg TEQs/kg bw/week and 3.29 pg TEQs/kg bw/week, accounting for 43.1% and 23.0% of the total dietary TEQ intake, respectively. Rosefish (6.8%), Mediterranean horse mackerel (6.2%) and horse mackerel (5.9%) showed moderate contributions, while the other species collectively accounted for less than 15% of the total dietary TEQ intake. Emphasis should be placed on the fact that more than 77% of the intake was due to dioxin-like PCBs and the rest was PCDDs (15.5%) and PCDFs (13.1%). In all cases the largest contribution to the TEQ value due to dioxin-like PCBs, corresponded to PCB 118 (58.7%), followed by PCB 105 (20.3%), PCB 156 (16.7%) and PCB 77 (4.3%). The noticeable contribution of dioxin-like PCBs to the TEQ value, consistent with what was reported in other studies (Shaw et al., 2006; Moon & Choi, 2009), underlines the importance of the determination of this family of contaminants in food matrices, above all fishery products being them generally the major contributors to the total intake.
3.3. Comparison with levels in other countries A comparison of the present results with dietary intake values described in the literature should be done carefully because of differences among various studies, including the way of expressing concentrations (upper, medium and lower bound), the use of international TEF (I-TEF) or WHO–TEFs values, the inclusion of dioxinlike PCBs in the calculation and many other factors influencing the final result. Nevertheless, data from other countries are summarised in Table 3 to give an overview. In addition, only results calculated with 1998 TEF are discussed in this section, since most of the publications to date have used this scheme. Compared to European studies, our values were in the same range of those described for Belgium (Windal et al., 2010), Spain (Bocio et al., 2007) and Netherlands (Freijer et al., 2001; Baars et al., 2004), but lower than those reported for Finland (Kiviranta, Ovaskainen, & Vartiainen, 2004) and Sweden (Darnerud et al., 2006). The differences in dietary intake among different countries are probably due, at least in part, to the specific dietary habits. For instance, in the Nordic countries (e.g. Finland and Sweden) a major consumption of fatty fishes, as salmon and herring, (Becker, Darnerud, & PeterssonGrawé, 2007) might be responsible of higher exposures. With
regard to data reported for extra-European countries the intake in this study was clearly lower than that described for heavily industrialised countries such as Japan (Nakatani et al., 2010; Sasamoto et al., 2006; Tsutsumi et al., 2001), Korea (Moon & Choi, 2009; Moon & Ok, 2006), China (Jiang et al., 2007) and Taiwan (Wang, Wu, Lin, & Chang-Chien, 2009). This could be a consequence of a greater amount of pollution in Asian regions and/or the result of the rigorous measures taken in Europe in the last 25 years to reduce the emissions of these pollutants. 4. Conclusion PCBs were the dominant chemicals, followed by PCDFs and PCDDs, in all samples examined. The concentrations of these substances changed according to species and, in particular, benthic organisms were the most contaminated, respectively compared to those of demersal and pelagic nature. In consequence of this, the dietary exposure values were subjected to wide variations. The consumption of some species (e.g. conger and red mullet), resulting in a significant increase in the human exposure level, was of concern. However, the dietary estimated mean intake was below the value of 14 pg TEQs/kg bw/week set by the Scientific Committee on Food of the European Commission. The largest contribution to the TEQ value due to dioxin-like PCBs reinforced the importance of the determination of this chemical family in all food matrices. As a final conclusion, the dietary consumption of these species does not represent a risk for human health, although the ingestion of some species may be of significance importance for consumer health. That fact implies that continuous monitoring of these contaminants is still strongly recommended. References Baars, A. J., Bakker, M. I., Baumann, R. A., Boon, P. E., Freijer, J. I., Hoogenboom, L. A. P., et al. (2004). Dioxins, dioxin-like PCBs and non-dioxin-like PCBs in foodstuffs: Occurrence and dietary intake in The Netherlands. Toxicology Letters, 151, 51–61. Becker, W., Darnerud, P. O., Petersson-Grawé, K. (2007). Risks and benefits of fish consumption. A risk-benefit analysis based on the occurrence od dioxin/PCB, methyl mercury, n-3 fatty acids and vitamin D in fish. National Food Administrtion Report Series No. 12/2007. Bocio, A., Domingo, J. L., Falcó, G., & Llobet, J. M. (2007). Concentrations of PCDD/ PCDFs and PCBs in fish and seafood from the Catalan (Spain) market: Estimated human intake. Environment International, 33, 170–175.
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Official Journal of the European Union, 2006. Commission regulation (EC) No. 1881/ 2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs. L 364/5. Ruus, A., Berge, J. A., Bergstad, O. A., Knutsen, J. A., & Hylland, K. (2006). Disposition of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in two Norwegian epibenthic marine food webs. Chemosphere, 62, 1856–1868. Sasamoto, T., Ushio, F., Kikutani, N., Saitoh, Y., Yamaki, Y., Hashimoto, T., et al. (2006). Estimation of 1999–2004 dietary daily intake of PCDDs, PCDFs and dioxin-like PCBs by a total diet study in metropolitan Tokyo, Japan. Chemosphere, 64, 634–641. SCF (Scientific Committee on Food). (2001). Opinion of the Scientific Committee on Food on the risk assessment of dioxins and dioxin-like PCBs in food-update based on new scientific information available since the adoption of the SCF opinion of 22nd November 2000. Shaw, S. D., Brenner, D., Berger, M. L., Carpenter, D. O., Hong, C. S., & Kannan, K. (2006). PCBs, PCDD/Fs and organochlorine pesticides in farmed Atlantic salmon from Maine, eastern Canada and Norway, and wild salmon from Alaska. Environmental Science and Technology, 40, 5347–5354. Storelli, M. M., Giacominelli-Stuffler, R., Storelli, A., & Marcotrigiano, G. O. (2003). Polychlorinated biphenyls in seafood: Contamination levels and human dietary exposure. Food Chemistry, 82, 491–496. Storelli, M. M., Barone, G., & Marcotrigiano, G. O. (2007a). Residues of polychlorinated biphenyls in edible fish of the Adriatic Sea: Assessment of human exposure. Journal of Food Science, 72, C183–C187. Storelli, M. M., Barone, G., Piscitelli, G., Storelli, A., & Marcotrigiano, G. O. (2007b). Tissue-related polychlorinated biphenyls accumulation in Mediterranean cetaceans: Assessment of toxicological status. Bulletin of Environmental Contamination and Toxicology, 78, 206–210. Storelli, M. M., Barone, G., Storelli, A., & Marcotrigiano, G. O. (2011). Levels and congener profiles of PCBs and PCDD/Fs in blue shark (Prionace glauca) liver from the South Eastern Mediterranean Sea (Italy). Chemosphere, 82, 37–42. Tsutsumi, T., Yanagi, T., Nakamura, M., Kono, Y., Uchibe, H., Iida, T., et al. (2001). Update of daily intake of PCDDs, PCDFs, and dioxin-like PCBs from food in Japan. Chemosphere, 45, 1129–1137. Van den Berg, M., Birnbaum, L., Bosveld, A. T. C., Brunström, B., Feeley, M., Cook, P., et al. (1998). Toxic equivalency factors (TEFs) for PCBs, PCDDs, PCDFs for humans and wildlife. Environmental Health Perspectives, 106, 775–792. Van den Berg, M., Birnbaum, L., Denison, M., De Vito, M., Farland, W., Feeley, M., et al. (2006). The 2005 World Health Organization reevaluation of human and mammalian toxic equivalency factors for dioxins and dioxin-like compounds. Toxicological Sciences, 93, 223–241. Voorspoels, S., Covaci, A., Maervoet, J., De Meester, I., & Schepens, P. (2004). Levels and profiles of PCBs and OCPs in marine benthic species from the Belgian North Sea and the Western Scheldt Estuary. Marine Pollution Bulletin, 49, 393–404. Wang, I. C., Wu, Y. L., Lin, L. F., & Chang-Chien, G. P. (2009). Human dietary exposure to polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in Taiwan. Journal of Hazardous Materials, 164, 621–626. Windal, I., Vandevijvere, S., Maleki, M., Goscinny, S., Vinks, C., Focant, J. F., et al. (2010). Dietary intake of PCDD/Fs and dioxin-like PCBs of the Belgian population. Chemosphere, 79, 334–340.
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Polychlorinated biphenyls (PCBs), dioxins and furans (PCDD/Fs): Occurrence in fishery products and dietary intake Maria Maddalena Storelli a,⇑, Grazia Barone a, Veronica Giuliana Perrone a, Roberto Giacominelli-Stuffler b a
Pharmacological–Biological Department, Chemistry and Biochemistry Section, Veterinary Medicine Faculty, University of Bari, Strada Prov. le per Casamassima Km 3, 70010 Valenzano (Ba), Italy b Comparative Biomedical Sciences Department, Biochemistry and Molecular Biology Section, Veterinary Medicine Faculty, University of Teramo, Piazza A. Moro 45, 64100 Teramo, Italy
a r t i c l e
i n f o
Article history: Received 24 November 2010 Received in revised form 21 December 2010 Accepted 7 February 2011
Keywords: PCBs PCDD/Fs Fish consumption Estimated weekly intake
a b s t r a c t Concentrations and congener specific profiles of PCBs, PCDDs and PCDFs were determined in various edible fish from the Adriatic Sea. PCBs were the dominant chemicals (116–1980 ng g1 lipid wt), followed by PCDFs (ND-58.3 pg g1 lipid wt) and PCDDs (ND-20 pg g1 lipid wt). The levels of these contaminants varied among species. Benthic organisms possessed the highest concentrations, followed by demersal and pelagic fish species. PCB and PCDD/F accumulation pattern in the samples analysed showed a distribution typically reported for marine samples. The mean weekly intake of toxic equivalency (TEQ) was estimated to be 0.84 pg TEQs/kg bw/week. The dioxin-like PCBs accounted for more than 77% of this intake, followed by PCDDs (15.5%) and PCDFs (13.1%). In general, the samples analysed in this survey can be considered safe with regard to the levels obtained and the in-force legislation, nevertheless the consumption of some species may be of significance importance for consumer health. Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzo-furans (PCDFs), commonly known with the term ‘‘dioxins’’, and polychlorinated biphenyls (PCBs) are groups of contaminants that are very persistent and widely distributed in the environment, exhibiting potential risk for human health. Their toxic properties include carcinogenic potency, immunotoxicity and a range of endocrine effects related to reproduction (Nakatani, Yamamoto, & Ogaki, 2010). Ingestion via food consumption is the principal way of human exposure to these toxic chemicals, accounting for >90%, if compared to the other ways such as inhalation and dermal contact (Bordajandi, Martín, Abad, Rivera, & Gonzáles, 2006). There is well-established evidence that fishery products are one of the main contributors to the total dietary intake of these compounds (Bocio, Domingo, Falcó, & Llobet, 2007). Despite this, consumption of fish is considered healthy due to its high protein and vitamin content, as well as other essential nutrients. However, the most important feature of this food is an advantageous fatty acid profile, resulting from the high content of essential polyunsaturated fatty acids, such as eicosapentaenoic and docosohexaenoic, known to support good health (Kris-Etherton, Harris, & Appel, 2002). It has been estimated that the
⇑ Corresponding author. Tel.: +39 805443865; fax: +39 805443863. E-mail address: [email protected] (M.M. Storelli). 0308-8146/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2011.02.032
consumption of one fatty fish meal per day could result in an omega-3 fatty acid intake of approximately 900 mg/day, an amount shown to beneficially affect coronary heart disease mortality rate (Kris-Etherton et al., 2002). In addition, especially the eicosapentaenoic acid has also positive effects in reducing arrhythmias and thrombosis, lowering plasma triglyceride levels, reducing blood clotting tendency, and even decreasing the risks of certain cancers (Kris-Etherton et al., 2002). Consequently over recent decades there has been a notable promotion of fish consumption in many European countries (Cahu, Salen, & de Lorgeril, 2004). Meanwhile wide-ranging efforts have been made to protect the consumer health. These have resulted in new regulations establishing maximum allowed levels of these toxic chemicals in foods and re-evaluations of tolerable human exposure levels. As part of the exposure reduction strategy the European Council (EC) has, in fact, introduced maximum levels for PCDDs, PCDFs and dioxin-like-PCBs in fishery products, via Council Regulation No. 1881/2006 (Official Journal of the European Union, 2006). More, the Scientific Committee on Food (SCF) (2001) of the European Commission has conducted a re-evaluation of the tolerable weekly intake (TWI) for dioxins and dioxin-like PCBs as toxic equivalents (WHO–TEQs), according to the World Health Organization (WHO) toxic equivalency factor (TEF) scheme (Official Journal of the European Union, 2001; Van den Berg et al., 1998, 2006). The WHO has also recommended to assess human exposure to these contaminants on a regular basis in order to evaluate either the health risks associated with the population exposure or the time trends of
M.M. Storelli et al. / Food Chemistry 127 (2011) 1648–1652
exposure and the effectiveness of specific management measures. In this picture, the present study shows the results of congenerspecific analysis of PCBs and PCDD/Fs performed on a variety of fish largely consumed in Italy, where fishery products occupy a relevant part of the diet, and estimates and compares the dietary intakes of these pollutants with those from the most recent international reports on this issue.
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phase film (RTX-5, Restek, US, Bellefonte, PA, USA) for PCBs, while for PCDD/Fs a capillary column with length of 30 m 0.25 mm and 0.25 lm thickness stationary phase film (RTX-200 Restek, US, Bellefonte, PA, USA) was employed. The MS was used in the SIM mode with the two most intensive ions of the molecular ion cluster monitored in specific windows. 2.3. Quality assurance (QA) and Quality control (QC)
2. Materials and methods 2.1. Sample collection Different fish species, including benthic [conger (Conger conger), angler fish (Lophius budegassa), rosefish (Helicolenus dactylopterus), red mullet, (Mullus barbatus), fourspotted megrim (Lepidorhombus boscii), scaldfish (Arnoglossus laterna), yellow gurnard (Trigla lucerna), red gurnard (Aspitrigla cuculus)], demersal [hake (Merluccius merluccius), Atlantic stargazer (Uranoscopus scaber), brown comber (Serranus hepatus), wreckfish (Polyprion americanus), bogue (Boops boops), sea bream (Pagellus erythrinus), forkbeard greater (Phycis blennoides)] and pelagic organisms [horse mackerel (Trachurus trachurus), mediterranean horse mackerel (Trachurus mediterraneus)] were analysed. For the collection of samples, 12 specimens of wreckfish and 35–45 specimens of the remaining species were pooled according to the size. From fish of each pool, muscle tissue was taken, homogenised and kept in a deep freeze at 20 °C until chemical analysis. 2.2. Chemical and instrumental analysis The concentrations of 17 individual PCB congeners (PCBs: 8, 20, 28, 35, 52, 60, 77, 101, 105, 118, 126, 138, 153, 156, 169, 180 and 209), including the ‘‘dioxin-like’’ PCBs (non-ortho DL-PCBs: 77, 126, 169, mono-ortho DL-PCBs: 105, 118, 156), together with the seventeen 2,3,7,8-substituted PCDD/F congeners were determined. A complete description of the experimental procedures relative to PCBs and PCDD/Fs has been recently described and validated (Storelli, Barone, Storelli, & Marcotrigiano, 2011). Briefly, fish fillets were ground in a porcelain mortar and pestle with Na2SO4 and spiked with PCB 143 used as internal standard. The mixture was extracted with hexane and the extracts were concentrated and subsamples were taken in order to determine the tissue fat content by gravimetry. An aliquot (about 100 mg) of the remaining extract was dissolved in hexane and cleaned by passing through 8 g of acid silica (H2SO4, 44% w/w), using 50 ml of a mixture of hexane/dichloromethane (1/1, v/v) for elution of the analytes. The eluate was evaporated to dryness and redissolved in 100 ll of iso-octane. For the determination of PCDD/Fs (US EPA method 1613) the samples, extracted as reported above, were subjected to a multi-step clean-up to remove the matrix and the potential interfering components. The first stage was a fat destruction step consisting of a treatment of the sample solution with sulphuric acid and base back-extraction. The obtained extracts were then subjected to a pre-conditioned florisil clean-up column, that was eluted with different solutions in order to remove interfering components. The first eluted solvent was discarded, while the second eluate, which contained PCDD/Fs, was collected. The extracts were evaporated to dryness and redissolved in iso-octane. Appropriate C13-labelled extraction standards were added to the samples in order to control the whole sample preparation process. The final obtained PCBs and PCDD/Fs extracts were injected and analysed separately on a Thermo Trace GC connected with a Thermo PolarisQ MS operated in electron impact ionisation (EI) mode. The chromatographic separation was achieved by splitless injection on a capillary column with length of 30 m, i.d. 0.25 mm and 0.25 lm thickness stationary
QA/QC was performed through the analysis of procedural blanks, a duplicate sample and a standard reference material [CRM 349 for PCBs (cod liver oils) (BCR, Brussels) and CARP-2 for PCDD/Fs (NRCC)] for each set of samples. For the replicate and standard reference materials, the relative standard deviations (RSD) were <10% for all the detected compounds. Additionally, the PCB method performance was assessed through participation to interlaboratory studies organised by QUASIMEME (Laboratory Performance Studies). Obtained values deviated by less than 20% from the consensus values. Concentrations of PCBs and PCDD/Fs are presented as ng g1 on a lipid weight basis and pg g1 on a lipid weight basis, respectively, while TEQ concentrations are expressed in pg-TEQ g1 wet weight. 2.4. Estimated dietary intake of dioxin-like PCBs and PCDD/Fs The estimated dietary intakes were calculated by multiplying the fish consumption data (315 g/week) (INRAN, 2008) by mean TEQ concentrations of dioxin-like PCBs and PCDD/Fs in each fish species followed by dividing by the body weight (60 kg). The concentrations of the non-detected isomers of the chemicals are expressed as zero. The concentrations of toxic equivalents (TEQs) for PCDD/Fs and dioxin-like PCBs have been given using World Health Organization (WHO)-Toxic equivalency factors (TEF) established in 2005 (Van den Berg et al., 2006). 3. Results and discussion 3.1. Concentrations and congener profiles of PCBs and PCDD/Fs Chemical analysis results of PCBs and PCDD/Fs are illustrated in Table 1. As revealed by statistical analysis (Mann–Whitney’s U test), PCBs were the dominant chemicals (range: 116–1980 ng g1 lipid wt), followed by PCDFs (range: ND-58.3 pg g1 lipid wt) and PCDDs (range: ND-20 pg g1 lipid wt) (p < 0.05). Moreover, in agreement to what could be expected, levels of these contaminants varied greatly among species. Generally, the benthic organisms contained the highest concentrations (Mann–Whitney’s U test), followed by demersal and pelagic species (p < 0.05). The preferential accumulation of these compounds in benthic species with respect to the others is not an unexpected finding, but is part of a general picture (Storelli, Barone, & Marcotrigiano, 2007a; Storelli, Giacominelli-Stuffler, Storelli, & Marcotrigiano, 2003; Voorspoels, Covaci, Maervoet, De Meester, & Schepens, 2004) highlighting the importance of habitat in bioaccumulation of these contaminants. However, a more detailed examination of results showed that of the 17 PCB congener peaks for which analyses were conducted in this study, PCBs 138, 153, 180 were detected in all fish, PCBs 52, 60, 77, 101, 105, 118 and 156 were present in most of the examined samples, whereas the remaining congeners PCBs: 8, 20, 28, 35, 126; 169 and 209 were below the limit of detection in all fishery products tested. With regard to PCDD/Fs, congener-specific analysis revealed that certain compounds occurred frequently (2,3,7,8-TCDD and 2,3,7,8-TCDF), others were present only in some fish species (1,2,3,7,8-PeCDD, 1,2,3,4,7,8-HxCDD, 1,2,3,4,6,7,8HpCDD, 1,2,3,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF and
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Table 1 Concentrations of individual congeners of PCBs (ng g1 lipid weight) and of RPCDD/Fs (pg g1 lipid weight) in the different fish species. Lipid %
PCB 52
PCB 60
PCB 77
PCB 101
PCB 105
PCB 118
PCB 138
PCB 153
PCB 156
PCB 180
RPCBs
Benthic fish Conger Angler fish Rosefish Red mullet Fourspotted megrim Scaldfish Yellow gurnard Red gurnard
1.4 0.1 0.3 1.6 0.3 0.4 0.5 0.7
ND ND ND ND ND ND ND ND
30 ND 23 26 ND ND 21 ND
3 8 5 7 ND ND ND ND
33 ND 47 35 ND 32 ND ND
95 ND 15 44 ND ND ND ND
69 12 98 92 ND 23 37 ND
526 95 221 139 67 150 67 52
793 120 305 201 97 232 102 74
131 ND 70 ND ND ND ND ND
300 10 95 70 55 96 26 26
1980 245 879 614 219 533 253 152
ND 0.6 9.1 20.0 ND ND ND 3.0
18.5 5.0 58.3 49.0 ND ND ND 28.2
18.5 5.6 67.4 69.0 ND ND ND 31.2
Demersal fish Hake Atlantic stargazer Brown comber Wreckfish Bogue Sea bream Greater forkbeard
0.9 0.1 0.8 1.1 2.7 0.1 0.2
ND ND ND 10 ND ND ND
ND 8 ND 9 ND ND 65
13 ND ND 2 ND 3 9
54 22 9 41 ND 15 71
ND 39 ND 3 5 40 ND
41 144 12 50 15 90 47
120 194 45 144 29 183 100
105 289 65 189 39 195 176
ND ND ND ND ND ND ND
46 67 17 78 28 40 68
379 763 148 526 116 566 536
ND 2.0 5.0 2.0 3.0 ND 0.5
8.7 3.6 31.6 3.8 5.8 ND 4.3
8.7 5.6 36.6 5.8 8.8 ND 4.8
1.4 1.3
ND ND
ND ND
5 4
55 50
17 19
39 30
102 95
150 135
11 15
60 52
439 400
ND ND
ND 0.2
ND 0.2
Pelagic fish Horse mackerel Mediterranean horse mackerel
RPCDDs
RPCDFs
RPCDD/ Fs
ND = not detected.
OCDF), while the remaining such as 1,2,3,6,7,8-HxCDD, 1,2,3,7,8,9HxCDD, OCDD, 2,3,4,7,8-PeCDF, 1,2,3,7,8,9-HxCDF, 2,3,4,6,7,8HxCDF, 1,2,3,4,6,7,8-HpCDF and 1,2,3,4,7,8,9-HpCDF were not detected in any fish samples. However, independently by the frequency of detection, the congener profiles were rather similar among the different species. PCB congener distribution showed that hexachlorobiphenyls PCB 153 (27.7–49.0%) and PCB 138 (18.7–38.8%), were the most abundant, followed by PCB 180 (4.1–25.1%). Other chlorobiphenyls found in major amounts included PCB 101 (1.7–14.2%) and PCB 118 (3.5–18.9%). The predominance of these congeners is consistent with what is reported in literature for other marine inhabitants, including not only fish (Kannan, Corsolini, Imagawa, Focardi, & Giesy, 2002; Storelli et al., 2007a), but also reptiles (Lazar et al., in press) and mammals (Fair et al., 2010; Storelli, Barone, Piscitelli, Storelli, & Marcotrigiano 2007b). Their abundance in so different taxa is due both to their high lipophilicity, stability and persistence, that facilitate the accumulation in the aquatic ecosystem, and their molecular structure, which makes them refractory to metabolic attack by mono-oxygenases. With regard to non-ortho congeners, PCB 77 was the only compound found, while among mono-ortho congeners, PCB 118 was the most predominant, followed by 105 and 156, which gave an almost equal contribution. In 2,3,7,8-PCDD/Fs profiles, 2,3,7,8-TCDF appeared to be the most abundant congener in all the samples analysed. Also, 2,3,7,8-TCDD and 1,2,3,6,7,8HxCDF accounted for a relatively high percentage of dioxins. This congener pattern is in accordance to what was reported in the literature for different marine organisms, where the higher chlorinated congeners OCDD, OCDF and, to some extent also, heptachlorinated PCDD/F congeners are not detected or else only present at low concentrations (Bocio et al., 2007; Moon & Choi, 2009). This can be attributed to a reduced absorbance of these congeners in the digestive tract of fish and/or to a lower biomagnification potential of congeners with the highest degree of chlorination in the marine food webs (Ruus, Berge, Bergstad, Knutsen, & Hylland, 2006). 3.2. Toxic potential of dioxin-like PCBs and PCDD/Fs The European Union (EU) has established maximum limits for these undesirable substances in food, aiming to ensure that it is
safe for consumer. As specified in EC Regulation 1881/2006 (Official Journal of the European Union, 2006) the maximum permissible levels for human consumption are of 4 and 8 pg g1 wet weight of toxic equivalents (WHO–TEQ), for PCDD/Fs and PCDD/ Fs plus dioxin-like PCB compounds, respectively in the muscle meat of fish and fishery products. The data here showed that the concentrations (0.0004–0.38 pg TEQ/g wet weight) of these contaminants in all samples tested were below the legal limits, when expressed on a wet weight basis. Also the estimated dietary intakes (0.02–6.17 pg TEQs/kg bw/week, average: 0.84 pg TEQs/kg bw/ week (Table 2) were below the tolerable weekly intake (TWI) proposed by European Commission of 14 pg TEQs/kg bw/week. However, dietary exposure values was subjected to variations
Table 2 Estimated weekly intakes (pg TEQs/kg bw/week) of dioxin-like PCBs and PCDD/Fs from fish consumption. pg TEQs/kg bw/week WHO–TEF 2006 (1998)
% Contribution to WHO–TEQPCDD/Fs+dlPCBs
Benthic fish Conger Angler fish Rosefish Red mullet Fourspotted megrim Scaldfish Yellow gurnard Red gurnard
0.81 0.01 0.32 2.49 – 0.01 0.03 0.21
(6.17) (0.08) (0.97) (3.29) (0.05) (0.09) (0.21)
15.5 0.2 6.1 47.6 – 0.2 0.6 4.0
(0.3) (0.6) (1.5)
Demersal fish Hake Atlantic stargazer Brown comber Wreckfish Bogue Sea bream Greater forkbeard
0.16 0.04 0.24 0.17 0.34 0.02 0.03
(0.30) (0.11) (0.28) (0.38) (0.54) (0.07) (0.07)
3.1 0.8 4.6 3.3 6.5 0.4 0.6
(2.1) (0.8) (2.0) (2.7) (3.8) (0.5) (0.5)
Pelagic fish Horse mackerel Mediterranean horse mackerel Sum Average
(43.1) (0.1) (6.8) (23.0)
0.19 (0.85) 0.16 (0.89)
3.6 (5.9) 3.1 (6.2)
5.23 (14.30) 0.31 (0.84)
– –
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M.M. Storelli et al. / Food Chemistry 127 (2011) 1648–1652 Table 3 Literature data concerning human dietary intake of dioxin-like PCBs and PCDD/Fs from seafood consumption. Location
a b c
Dietary intake (pg TEQ/day)
Human dietary intake (pg TEQs/kg bw/week)
References
European countries Italy Italy Netherlands Netherlands Belgium Spain Finland Sweden
7.55 (0.14–52.88) 2.65 (0.11–21.35) – – – 38.00 95.00 31.00
0.84 (0.02–6.17)a 0.31 (0.01–2.49)b 0.86 1.34 0.85 0.002–1.38 9.87 2.94
This study This study Freijer et al., 2001 Baars et al., 2004 Windal et al., 2010 Bocio et al., 2007 Kiviranta et al., 2004 Darnerud et al., 2006
Extra-European countries Japan Japan Japan Korea Korea China (Guangzhou) China (Zhoushan) Taiwan
86.57 63.09 59.98–80.35 40.80 66.80 63.00 51.00 –
12.12 4.69–11.80 1.20–1.61 3.06 8.61 7.35 5.95 3.00–4.30c
Tsutsumi et al., 2001 Sasamoto et al., 2006 Nakatani et al., 2010 Moon & Ok, 2006 Moon & Choi, 2009 Jiang et al., 2007 Jiang et al., 2007 Wang et al., 2009
TEFs recommended by WHO (Van den Berg et al., 1998). TEFs recommended by WHO (Van den Berg et al., 2006). PCDD/Fs.
depending on the consumed fish species. Conger and red mullet contributed to the highest intake of 6.17 pg TEQs/kg bw/week and 3.29 pg TEQs/kg bw/week, accounting for 43.1% and 23.0% of the total dietary TEQ intake, respectively. Rosefish (6.8%), Mediterranean horse mackerel (6.2%) and horse mackerel (5.9%) showed moderate contributions, while the other species collectively accounted for less than 15% of the total dietary TEQ intake. Emphasis should be placed on the fact that more than 77% of the intake was due to dioxin-like PCBs and the rest was PCDDs (15.5%) and PCDFs (13.1%). In all cases the largest contribution to the TEQ value due to dioxin-like PCBs, corresponded to PCB 118 (58.7%), followed by PCB 105 (20.3%), PCB 156 (16.7%) and PCB 77 (4.3%). The noticeable contribution of dioxin-like PCBs to the TEQ value, consistent with what was reported in other studies (Shaw et al., 2006; Moon & Choi, 2009), underlines the importance of the determination of this family of contaminants in food matrices, above all fishery products being them generally the major contributors to the total intake.
3.3. Comparison with levels in other countries A comparison of the present results with dietary intake values described in the literature should be done carefully because of differences among various studies, including the way of expressing concentrations (upper, medium and lower bound), the use of international TEF (I-TEF) or WHO–TEFs values, the inclusion of dioxinlike PCBs in the calculation and many other factors influencing the final result. Nevertheless, data from other countries are summarised in Table 3 to give an overview. In addition, only results calculated with 1998 TEF are discussed in this section, since most of the publications to date have used this scheme. Compared to European studies, our values were in the same range of those described for Belgium (Windal et al., 2010), Spain (Bocio et al., 2007) and Netherlands (Freijer et al., 2001; Baars et al., 2004), but lower than those reported for Finland (Kiviranta, Ovaskainen, & Vartiainen, 2004) and Sweden (Darnerud et al., 2006). The differences in dietary intake among different countries are probably due, at least in part, to the specific dietary habits. For instance, in the Nordic countries (e.g. Finland and Sweden) a major consumption of fatty fishes, as salmon and herring, (Becker, Darnerud, & PeterssonGrawé, 2007) might be responsible of higher exposures. With
regard to data reported for extra-European countries the intake in this study was clearly lower than that described for heavily industrialised countries such as Japan (Nakatani et al., 2010; Sasamoto et al., 2006; Tsutsumi et al., 2001), Korea (Moon & Choi, 2009; Moon & Ok, 2006), China (Jiang et al., 2007) and Taiwan (Wang, Wu, Lin, & Chang-Chien, 2009). This could be a consequence of a greater amount of pollution in Asian regions and/or the result of the rigorous measures taken in Europe in the last 25 years to reduce the emissions of these pollutants. 4. Conclusion PCBs were the dominant chemicals, followed by PCDFs and PCDDs, in all samples examined. The concentrations of these substances changed according to species and, in particular, benthic organisms were the most contaminated, respectively compared to those of demersal and pelagic nature. In consequence of this, the dietary exposure values were subjected to wide variations. The consumption of some species (e.g. conger and red mullet), resulting in a significant increase in the human exposure level, was of concern. However, the dietary estimated mean intake was below the value of 14 pg TEQs/kg bw/week set by the Scientific Committee on Food of the European Commission. The largest contribution to the TEQ value due to dioxin-like PCBs reinforced the importance of the determination of this chemical family in all food matrices. As a final conclusion, the dietary consumption of these species does not represent a risk for human health, although the ingestion of some species may be of significance importance for consumer health. That fact implies that continuous monitoring of these contaminants is still strongly recommended. References Baars, A. J., Bakker, M. I., Baumann, R. A., Boon, P. E., Freijer, J. I., Hoogenboom, L. A. P., et al. (2004). Dioxins, dioxin-like PCBs and non-dioxin-like PCBs in foodstuffs: Occurrence and dietary intake in The Netherlands. Toxicology Letters, 151, 51–61. Becker, W., Darnerud, P. O., Petersson-Grawé, K. (2007). Risks and benefits of fish consumption. A risk-benefit analysis based on the occurrence od dioxin/PCB, methyl mercury, n-3 fatty acids and vitamin D in fish. National Food Administrtion Report Series No. 12/2007. Bocio, A., Domingo, J. L., Falcó, G., & Llobet, J. M. (2007). Concentrations of PCDD/ PCDFs and PCBs in fish and seafood from the Catalan (Spain) market: Estimated human intake. Environment International, 33, 170–175.
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