Elsevier

Food and Chemical Toxicology

Volume 48, Issue 11, November 2010, Pages 3167-3170
Food and Chemical Toxicology

Occurrence of toxic metals (Hg, Cd and Pb) in fresh and canned tuna: Public health implications

https://doi.org/10.1016/j.fct.2010.08.013Get rights and content

Abstract

Hg, Pb and Cd levels in fresh and canned tuna were determined and assessed by comparing element levels in these samples with maximum permissible limits set by European legislation. The estimated weekly intakes by human consuming both fresh and canned tuna were also evaluated for possible consumer health risks. Among tested metals, Hg had the highest concentrations, followed by Pb and Cd either in fresh tuna or canned tuna. None of the tested samples surpassed the European regulatory limits fixed for Cd and Pb, whereas 8.9% of the tuna cans and 20% of fresh tuna samples exceeded standard for Hg. The size of tuna was a determining factor of Hg burden. A high intake of Hg surpassing the toxicological reference value established by WHO, was associated with consumption of larger size tuna specimens. Also canned tuna consumption with Hg concentrations higher than 1 μg kg−1, strongly increased the consumer exposure. In contrast, Cd and Pb weekly intakes through consumption either of fresh tuna or canned tuna did not exceed the toxicological reference values established by WHO, and consequently there was no human health risk. A continuous surveillance system of Hg content in these fishery products is crucial for consumer protection.

Introduction

An adequate human diet should satisfy the requirements for energy and nutritive components including essential polyunsaturated fatty acids, essential aminoacids, mineral components, vitamins and fat. Fish contains all these substances, but the most important feature of this food is an advantageous fatty acid profile, resulting from the consistent content of essential polyunsaturated fatty acids, such as eicosapentaenoic and docosahexaenoic acid, known to support good health (Usydus et al., 2009). It is estimated that the consumption of one portion of fatty fish, daily, delivers about 900 mg/day of n-3 acids, with consequent reduction of mortality in patients with coronary diseases (Kris-Etherton et al., 2002). However, the indisputable benefits deriving by fish consumption may be offset by the presence in their meat of toxic metals, such as Cd, Pb and especially Hg, which is present in many fish species often at levels exceeding the safety standards established by legislation of the various countries. In relation to this, it is important to remark that with the exception of occupational exposure, the main Hg exposure for human is the ingestion of contaminated fish, especially larger predators. Amongst those species recognised as potentially accumulating elevated metal levels, tuna is one of the most frequently consumed and commercially available groups of fish worldwide (Burger et al., 2005). These pelagic organisms are high performance fish with very high metabolism rates and, thus, high food intake rates, a property that accentuates the exposure to trace elements (Kojadinovic et al., 2007). Consequently, adverse human health effects may occur if this fish is consumed too often or in large enough quantities. In this context it is also of interest to consider canned tuna, which amongst canned fishery products is doubtless the most largely and frequently consumed. Canned tuna is, in fact, well eaten in the developed world, especially in Europe because it is convenient and affordable for most working families. Europe is the world’s largest market for canned tuna with 34% of the global consumption and Italy is, after Spain, the second country in canned tuna consumption (Food Market Exchange, 2003; Glitnir Seafood Team, 2007). Nevertheless, publications on the concentrations of toxic elements in canned tuna and dietary intakes of these elements via these fishery products in Italy are lacking. Also for fresh tuna, information on these topics is rather limited, although the few literature data confirms ability of these large pelagic predators to accumulate substantial levels of toxic metals, especially mercury (Storelli et al., 2002, Licata et al., 2005). In the light of what above reported the objectives of present investigation are the following:

  • 1)

    to determine the concentration levels of Hg, Pb, Cd either in the edible portion of tuna (thunnus Thynnus) from Mediterranean Sea (Tyrrhenian Sea), or in canned tuna (thunnus albacares) samples purchased from supermarkets located in different Italian cities

  • 2)

    to ascertain whether the metal concentrations are below the maximum levels established by the European Legislation (Official Journal of the European Union, 2006, EFSA, 2009)

  • 3)

    to estimated the weekly intake and compared it with the Provisional Tolerable Weekly Intake (PTWI) recommended by the Joint FAO/WHO Expert Committee on Food Additives (WHO, 2006, EFSA, 2009).

Section snippets

Collection of samples

In June–August 2007, 20 specimens of bluefin tuna (T. thynnus) (length: 105–218 cm, average 140.5 ± 27.1 cm; weight: 13–161 kg, average 56.4 ± 34.0 kg) from Tyrrhenian Sea were caught. Approximately 0.1–0.3 kg of muscle tissue was removed from the anterior portion of the carcass by a transverse dissection near the dorsal fin. The tissues were dissected with plastic materials that were washed with HNO3 and rinsed with distilled and deionized water, in order to avoid metal contamination. Concerning canned

Content of toxic metals in fresh tuna

Among the metals analysed, Hg (0.07–1.76, average: 0.61 μg g−1 wet wt) showed the highest concentration, followed by Pb (ND-0.33, average: 0.07 μg g−1 wet wt) and Cd (ND-0.03, average: 0.01 μg g−1 wet wt). Among these toxic metals only Hg was present in all tuna specimens, while Cd and Pb were detected in 95% and 85% of the samples analyzed, respectively. From a more detailed analysis of results it appeared that Cd and Pb levels were rather low and did not exhibit a wide between-specimen variation,

Conclusion

In all tested samples, Hg exhibited the highest concentrations followed by Pb and Cd. The amounts of Cd and Pb were well below the maximum permitted concentrations by EU legislation for the human consumption, whereas 8.9% of the tuna cans and 20% of fresh tuna samples exceeded standard for MeHg. In addition, a general picture of the results concerning the consumer exposure showed that Cd and Pb weekly intakes through either consumption of fresh tuna or canned tuna remained within safety

Conflict of Interest

The authors declare that there are no conflicts of interest.

References (37)

Cited by (97)

  • Determination of toxic metals in canned tuna sold in developed and developing countries: Health risk assessment associated with human consumption

    2023, Marine Pollution Bulletin
    Citation Excerpt :

    Following the EU and US, Latin American countries have the highest annual consumption of canned tuna (FFA, 2011). The consumption of canned tuna is increasing day by day globally (National Fisheries Institute, 2019; Storelli et al., 2010). Tuna accumulates a significant amount of mercury and other toxic metals, especially compared to some other fish species.

View all citing articles on Scopus
View full text