Levels of mercury, cadmium, lead and other selected

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Levels of mercury, cadmium, lead and other selected elements in canned tuna fish commercialised in Jordan a

Fuad A. Ababneh & Idrees F. Al-Momani

b

a

Department of Chemistry, Al-Hussein Bin Talal University, P.O. Box 20, Ma’an, Jordan b

Department of Chemistry, Yarmouk University, Irbid-Jordan

Version of record first published: 25 Jun 2012.

To cite this article: Fuad A. Ababneh & Idrees F. Al-Momani (2012): Levels of mercury, cadmium, lead and other selected elements in canned tuna fish commercialised in Jordan, International Journal of Environmental Analytical Chemistry, DOI:10.1080/03067319.2012.672981 To link to this article: http://dx.doi.org/10.1080/03067319.2012.672981

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Intern. J. Environ. Anal. Chem. 2012, 1–12, iFirst

Levels of mercury, cadmium, lead and other selected elements in canned tuna fish commercialised in Jordan Fuad A. Ababneha* and Idrees F. Al-Momanib a

Department of Chemistry, Al-Hussein Bin Talal University, P.O. Box 20, Ma’an, Jordan; b Department of Chemistry, Yarmouk University, Irbid-Jordan

Downloaded by [Yarmouk University] at 11:03 15 October 2012

(Received 15 September 2011; final version received 17 February 2012) During 2010, the concentrations of mercury and eight other trace elements in 90 canned tuna samples commercialised in Jordan were determined using mercury analyser (Hydra C ) and the inductively coupled plasma-optical emission spectrometer (ICP-OES). The mean concentrations and ranges for elements analysed in mg kg 1 (wet base) were as follows: total Hg (0.21; 0.06–0.57), Cd (0.06; 5 0.01–0.63), Pb (0.09; 50.04–0.24), total As (0.74; 0.11–1.56), Ni (0.51; 0.03–2.85), V (0.04; 50.03–0.1), Al (0.26; 0.08–1.63), Ba (0.13; 0.05–0.42) and Ag was not detected in any of the analysed samples (50.02 mg kg 1). The data obtained in the present study compared well with data obtained from similar studies carried out in different parts of the world. Few samples had the mercury and cadmium levels slightly exceeding the Codex Committee on Food Additives and Contaminants draft guidelines. However, the estimated weekly intakes of these metals showed that there was no health risk associated with the consumption of the analysed canned tuna samples. Keywords: canned tuna; trace elements; ICP OES; mercury analyser; seafood; Jordan

1. Introduction Heavy metals are considered as one of the most important forms of aquatic pollutants due to their toxicity and accumulative behaviour. Industrial effluents, agricultural activities, municipal wastes, smelting processes and mining can create a probable source of heavy metal pollution in the aquatic environment and thus can damage both marine species diversity and ecosystems [1]. Metals are taken up mainly from water, food and sediment by various aquatic organisms such as fish. Some heavy metals can be transferred to human beings through fish consumption [2]. Fish and seafood in general are widely consumed in many parts of the world because they provide a healthy, good source of protein, various nutrients and unsaturated fatty acids that have protective effects in preventing cardiovascular disease [3]. Besides the good health benefits of fish consumption, levels of contaminants in fish are of substantial interest because of their potential effects on humans. Fish are often the final chain of aquatic food web and may accumulate high levels of some metals [4].Consequently, fish species of elevated trophic levels such as shark, swordfish and tuna may accumulate considerable amounts of toxic elements. A wide range of fish species has been cultivated in aquaculture ponds; the artificial feed is known to *Corresponding author. Email: [email protected] ISSN 0306–7319 print/ISSN 1029–0397 online 2012 Taylor & Francis http://dx.doi.org/10.1080/03067319.2012.672981 http://www.tandfonline.com


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F.A. Ababneh and I.F. Al-Momani

contain various chemical contaminants [5]. Therefore, not only wild fish, but also farmed fish can contain various amounts of metals which pose serious health risks to humans. Toxic elements such as Mercury (Hg), Cadmium (Cd), Lead (Pb) and Arsenic (As) perform no beneficial biological roles and can be very dangerous even at low concentrations when ingested over a long period of time [6]. Silver (Ag) is a non essential element, and nickel (Ni) and vanadium (V) are probably essential elements but they may cause health problems at high concentrations. Barium (Ba) and aluminium (Al) are highly tolerable but Al is linked to Alzheimer’s disease [7]. The major source of human exposure to heavy metals is through food ingestion. Among food, fish and shellfish were reported to contain the highest amount of the toxic elements As, Cd, Hg, and Pb [8]. Several studies have reported trace elements concentrations in various fish species [2,6,9,10] and in canned tuna fish from Kingdom of Saudi Arabia [11], USA [12–14], Turkey [15–17], Iran [18–20], Spain [21], Poland [22], Italy [23], Libya [24], France [25,26] and Portugal[27]. However, there are limited data on the heavy metals content in canned tuna marketed in Jordan, and the publications on the concentrations of toxic elements are lacking. Therefore, the aim of this study was to determine the concentration levels of toxic elements found in canned tuna to ensure that this food is safe for human consumption.

2. Experimental 2.1 Sampling During the years 2009 and 2010, ninety samples of 18 brands of canned tuna samples were purchased from popular supermarkets from three cities of different zones of Jordan. They were Irbid (north), Amman (Center) and Ma’an (south). Samples were transported to the laboratory, coded for easy identification. Brand codes, contents and other information are presented in Table 1. After opening, the fish sauce and oil contents (liquids) were drained off, the meat content was homogenised in food blender, a portion of the homogenised meat was sub-sampled and weighed for elemental analysis.

2.2 Reagents and materials Deionised water with specific resistivity of 18.0 M cm 1 was generated by treating distilled water with reverse osmosis followed by deioniser system (EASY pure Thermo scientific). All glassware used in the present study were previously soaked in 10% (v/v) HNO3 solution for 12 hours and rinsed with deionised water. Nitric acid (HNO3, 69%) and (H2O2, 30%) were of ultrapure quality (Trace SELECT , Fluka). Multielement standard stock solutions of Cd, Pb, As, Ag, Al, Ni and V at concentration of 1000 mg L 1 were used. A multi-element working standard solution appropriately diluted was prepared and used to calibrate the ICP-OES before metal determination. Working standards of 1.0 and 0.1 mg L 1 of mercury were prepared by diluting concentrated stock solutions of 1000 mg L 1 (TraceCERT , Fluka) in aqueous solution of 10% HNO3. These standards were used for the calibration of Mercury analyser (Hydra C , Teledyne Leeman Labs, USA) before the analysis of mercury in canned tuna samples. Two certified reference materials (DORM-2, Dogfish muscle obtained from National Research Council (NRC) Canada.) and (BCR-463, obtained from Fluka) were used for methods validation.

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International Journal of Environmental Analytical Chemistry Table 1. Characteristics of canned tuna used in this study.


Net Drained Brand weight weight (g) (g) code A1 A2 A3 A4 A5 A6 A7 B1 B2 B3 C1 C2 C3 D1 D2 E1 E2 F G H I J K L M N O P Q R

195 195 185 120 120 120 120 170 170 95 170 170 170 160 95 185 95 170 160 170 170 160 95 95 95 95 160 170 170 160

140 140 133 84 84 84 84 119 119 67 119 120 120 112 67 130 75 120 112 119 119 112 67 67 67 70 112 120 120 112

Contents and additives

Production date

Light meat tuna(chunks), vegetable oil, salt White meat tuna(chunks), water, salt Light meat tuna(chunks), vegetable oil, salt Light meat tuna(grilled-fingers), sunflower oil, salt, starch Light meat tuna(grilled- steak), smoked, sunflower oil, salt Light meat tuna(slices), olive oil, salt White tuna slices, sunflower oil, pepper, salt, lemon flavor Light meat tuna(chunks), water, salt Light meat tuna(chunks), vegetable oil, salt White meat tuna(chunks), water, salt White meat tuna(chunks), water White meat tuna(chunks), vegetable oil White meat tuna, water Light meat tuna(chunks), vegetable oil, salt Light meat tuna(chunks), vegetable oil, salt Light meat tuna(chunks), vegetable oil, salt, chili White meat tuna(chunks), vegetable oil, salt Light tuna (chunks),oil, salt Light meat tuna(flakes), vegetable oil, salt Light meat tuna(flakes), vegetable oil, salt Light meat tuna(chunks), vegetable oil, salt Light meat tuna(chunks), vegetable oil, salt Light meat tuna(chunks), vegetable oil, salt Light meat tuna(chunks), vegetable oil, salt Light meat tuna(chunks), vegetable oil, salt Light meat tuna(chunks), vegetable oil, salt Light meat tuna(chunks), vegetable oil, salt Light meat tuna(flakes), vegetable oil Light meat tuna(chunks), vegetable oil, salt Light meat tuna(shredded), vegetable oil, salt

05/2008 04/2008 04/2008 04/2008 04/2008 04/2008 04/2008 11/2009 05/2009 09/2008 05/2009 05/2009 05/2009 04/2009 04/2009 01/2009 07/2008 04/2009 04/2009 02/2009 11/2008 03/2009 01/2008 05/2008 01/2009 01/2007 06/2008 02/2009 05/2008 03/2009

2.3 Sample preparation and analysis Aliquots (about 1.0–3.0 g) of the homogenised samples were digested in 200 ml glass beakers with 20 ml of a mixture of freshly (1:1) (v/v) HNO3 (69%)–H2O2 (30%) solution. Each beaker was covered with a watch glass and stored at room temperature for 24 hours. The samples were then heated on hot plate at 150–165 C, aliquots of nitric acid were added until the solutions were clear. Solutions were contentiously boiled until the volume for each sample reduced to about 5 ml. The solutions were then allowed to cool, filtered (glass wool), and diluted up to 50 ml with acidified (HNO3) deionised water, and then placed in acid washed 60 ml polyethylene bottles. All digested samples were analysed, in triplicate, for Cd, Pb, As, Ni, V, Al, Ba and Ag contents using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES)(VISTA–MPX instrument ). The simultaneous ICP-OES was equipped with axial vision, a radio frequency (RF) source of 30 MHz, a CCD (Charge Coupled Device), a peristaltic pump, and a Glass concentric nebuliser. Experimental conditions of ICP-OES and wavelengths used are outlined in Table 2.

4

F.A. Ababneh and I.F. Al-Momani Table 2. The operating conditions for VISTA–MPX instrument (ICP-OES). Parameter


RF power (W) Plasma gas flow Auxiliary gas flow Nebuliser gas flow Sample flow rate Wash time Read delay Replicate readings Torch configuration Wavelengths (nm)

Instrument operating conditions 1400 15 l/min 1.5 l/min 0–1.3 L/min increments 1 ml/min 40 s 110 s 3 Axial Cd(214.43), Pb(220.35), As(188, 89), Ag(328.06), Ni(231.6), V(292.40), Al(396.15), Ba(455.40)

For mercury determinations, the US EPA Method 7473 was adopted and used; aliquots of homogenised samples were weighed (0.1–0.3 g) in pre-cleaned nickel boats before placement on the Hydra C auto sampler. Samples were analysed based on the principle of thermal decomposition, amalgamation and atomic absorption spectrophotometric detection. The analysis for all samples, blanks, and CRMs were carried out in triplicate, and the results obtained were analysed by means of ANOVA, statistical package SPSS 11.0 was used at significance level of 5%.

2.4 Quality control/quality assurance In order to validate the instrumental methods and analytical procedures for accuracy, all the samples were taken in triplicates and all measurements were run in triplicates for standards and samples. The average relative difference between triplicates of individual samples was less than 7.0%. Analytical blank involving all reagents was run (in triplicate) to check for interferences and cross-contamination every batch of 10 samples. Certified reference materials (DORM-2 and BCR-463) were also analysed every batch. Accuracy was determined by comparing the measured concentrations with the certified values and was expressed as a percentage recovery (% recov.). The achieved results were in good agreement with certified values. The results are given in Table 3. Because of the high levels of As, Ni and Al and the absence of V and Ba in the certified reference material (DORM-2), recovery experiments were carried out by spiking of standard solutions of these elements in selected homogenised samples at a concentration of 0.1 mg kg 1 and then reanalysing the samples. The average percentage recoveries were as follows: 93, 101, 83, 110, 96, 104, 96 and 91% for Ag, Al, As, Ba, Cd, Ni, Pb and V, respectively.

3. Results and discussion Ninety samples of canned tuna fish (belonging to 30 various brands or contents) were analysed for mercury (Hg), cadmium (Cd), lead (Pb), arsenic (As), nickel (Ni), vanadium

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International Journal of Environmental Analytical Chemistry Table 3. Trace elements concentrations in two certified reference materials. Element Aga Ala Asa Cda Nia Pba Hgb

Certified values (mg g 1)

Measured values (mg g 1)

Recovery (%)

0.041 0.013 10.9 1.7 18 1.1 0.043 0.008 19.4 3.1 0.065 0.007 2.85 0.16

0.038 0.01 11.1 1.3 16.2 2.0 0.040 0.009 18.8 1.4 0.061 0.01 2.75 0.20

93 102 90 93 97 94 96


Note: CRM; aDORM-2 Dogfish, bBCR-463 Tuna fish.

(V), aluminium (Al) barium (Ba), and silver (Ag).The concentrations of these elements in canned tuna are presented in Table 4. Among these elements, Hg, As, Ni, Ba and Al were detected in all analysed samples. However, Cd, Pb, V and Ag were detected in 37%, 77%, 70% and 0% of the analysed samples, respectively. A one-way (ANOVA) statistical procedure was employed in the assessment of variation in metal concentrations across canned tuna samples. There were no significant variations (P 4 0.05) in the concentrations of Pb, As, Ba, V and Al across the canned tuna samples. However, there were significant variations (P 5 0.05) in the concentrations of Hg, Cd and Ni across the canned tuna samples. Mercury has been recognised as a severe environmental pollutant. It is released into the environment from both natural and anthropogenic sources. Once introduced to the surface waters, inorganic mercury may be reduced to mercury vapour and returned to the atmosphere [28], or it can be methylated through biochemical or abiotic processes [29,30] into methylmercury (MeHg); one of the most toxic forms of mercury species. Methylmercury has the tendency to accumulate in the aquatic food chain, and most mercury in fish is methylmercury [31]. Other than occupational exposure, fish consumption is the major source of organic mercury (methylmercury) in humans [32]. It has been reported that human exposure to mercury and methyl mercury may increase the risk of heart diseases [33] and damage developing foetuses [34]. Irrespective of the canned tuna brand, source or contents, mercury concentrations in all samples analysed ranged from 0.06 to 0.57 mg kg 1 (wet weight), with an average of 0.21 mg kg 1 (wet weight). The mean mercury concentrations in canned tuna samples found in this study were in excellent agreement with those reported by other studies shown in Table 5. For instance, Burger and Gochfeld [12], Ikem and Egiebor [13], Martorell et al. [21], and Mol [17] reported the mean Hg concentrations in canned tuna as 0.31 mg kg 1, 0.28 mg kg 1, 0.222 mg kg 1 and 0.14 mg kg 1, respectively. The average Hg value was also comparable to those reported in canned tuna from United Kingdom (0.19 mg kg 1; [35]), Canada (0.157 mg kg 1; [36]) and Spain (0.30 mg kg 1; [37]. The range of mercury concentration in this study (0.06–0.57 mg kg 1) resembles with that for most studies presented in Table 5 (0.01–1.1 mg kg 1). An evaluation of the mercury content in these canned tuna based on the permissible limit set by various authorities, showed that Only three samples (3.3%) had the mercury concentrations above CODEX [38] limit of 0.50 mg kg 1 for fish, and none of the tested samples exceeded the European legislations [39] of 1 mg kg 1 for predatory fish.

231 16 123 9 261 12 148 13 101 11 139 10 94 7 470 18 244 21 383 13 230 10 110 6 151 5 206 9 147 11 252 12 565 19 292 20 224 16 117 12 247 14 111 7 201 15 102 11 399 21 237 14 137 8 73 5 98 8 61 7

Hga

0.54 0.05 50.01 50.01 50.01 0.08 0.02 0.04 0.01 0.05 0.01 0.04 0.01 0.63 0.04 50.01 0.09 0.02 50.01 50.01 0.04 0.01 0.04 0.02 50.01 50.01 0.08 0.02 50.01 50.01 50.01 50.01 50.01 50.01 50.01 50.01 50.01 0.13 0.03 50.01 50.01

Cd 0.07 0.01 50.04 50.04 50.04 0.11 0.02 0.08 0.01 0.08 0.02 0.07 0.02 50.04 0.09 0.02 0.09 0.02 0.08 0.02 0.06 0.01 0.10 0.03 0.09 0.03 0.14 0.04 0.24 0.03 50.04 0.20 0.01 0.05 0.01 0.20 0.01 0.11 0.03 50.04 50.04 0.10 0.04 0.22 0.02 0.09 0.02 0.07 0.02 0.05 0.01 0.07 0.02

Pb 0.12 0.03 0.06 0.01 0.09 0.02 0.12 0.02 0.15 0.04 0.10 0.03 0.15 0.05 0.06 0.02 0.06 0.02 0.11 0.03 0.05 0.02 0.11 0.05 0.14 0.03 0.07 0.04 0.12 0.02 0.06 0.02 0.23 0.07 0.18 0.10 0.21 0.09 0.08 0.02 0.06 0.02 0.05 0.02 0.09 0.04 0.08 0.03 0.21 0.04 0.07 0.02 0.17 0.03 0.42 0.04 0.26 0.07 0.16 0.08

Ba

Note: aMercury measured in ng g 1, Silver(Ag) concentrations were below 0.02 mg kg

A1 A2 A3 A4 A5 A6 A7 B1 B2 B3 C1 C2 C3 D1 D2 E E F G H I J K L M N O P Q R

Sample code

1

V 50.03 50.03 0.04 0.01 50.03 50.03 0.05 0.01 50.03 0.09 0.04 0.06 0.02 0.04 0.01 0.06 0.02 0.05 0.01 50.03 0.05 0.03 0.05 0.02 0.07 0.03 0.10 0.02 0.09 0.04 0.10 0.03 0.07 0.02 0.09 0.03 0.08 0.02 50.03 0.05 0.02 0.07 0.01 0.06 0.01 50.03 0.06 0.02 0.05 0.02 50.03

for all samples.

0.99 0.07 0.08 0.04 0.1 0.05 0.08 0.03 0.09 0.02 0.1 0.03 0.09 0.03 0.26 0.14 0.09 0.03 0.1 0.03 0.99 0.12 0.11 0.05 0.13 0.04 0.15 0.05 0.54 0.09 0.08 0.02 0.08 0.02 0.11 0.04 0.13 0.04 0.45 0.10 1.63 0.13 0.47 0.08 0.09 0.04 0.08 0.04 0.09 0.03 0.08 0.03 0.11 0.05 0.13 0.04 0.12 0.04 0.36 0.08

Al

Table 4. Concentrations of trace elements (average value standard deviation) in canned tuna (mg kg 1, wet weight).


1.56 0.10 0.11 0.06 1.07 0.08 0.77 0.03 0.32 0.03 0.68 0.08 0.62 0.07 1.03 0.13 0.84 0.12 0.37 0.04 1.10 0.08 0.75 0.08 1.20 0.06 0.54 0.11 0.81 0.07 0.39 0.05 1.30 0.03 1.18 0.12 0.41 0.05 0.29 0.10 0.43 0.05 0.46 0.06 0.98 0.05 0.58 0.04 0.68 0.07 1.03 0.08 0.35 0.05 0.83 0.03 0.40 0.02 0.92 0.05

As

1.92 0.03 0.11 0.02 0.36 0.04 0.36 0.04 0.39 0.03 0.28 0.02 0.29 0.03 0.03 0.01 0.52 0.03 0.29 0.04 0.04 0.01 0.13 0.03 0.70 0.05 0.03 0.01 0.27 0.04 0.11 0.02 0.50 0.05 0.21 0.04 0.06 0.02 0.03 0.01 0.04 0.01 0.04 0.01 0.14 0.04 0.26 0.04 0.52 0.06 2.85 0.06 0.08 0.03 2.10 0.05 2.45 0.04 0.21 0.02

Ni

6 F.A. Ababneh and I.F. Al-Momani

0.28 (0.08–1.0)

0.21 (0.06–0.57)

Portugal

Jordan

0.06 (0– 0.63)

0.04 (0.01–0.16)

– –

0.18 (0.09–0.32)

0.04 (0.01–0.14)

0.036

0.014

0.05 (0.008–0.15) (0.016–0.029) 0.0223 (0.005–0.072)

0.09 (0– 0.24)

– (up to 0.1)

– 0.007 f

0.28 (0.18–0.4)

0.061 (0.02–0.16)

0.01

0.017

0.096 (0.021–0.301) (0.072–0.154) 0.0366 (0.016–0.0726)

(0.076–0.117) 0.10 0.28 (0.0001–4.13)

0.0011 (0.0–0.031) 0.04 f

0.0019 (0.0–0.0539) 0.03 f (0.182–0.246) 0.08 0.01 (0.0001–0.09)

–

0.23 (0.03–0.51)

0.185 f (0.028–0.426)

Pb

–

0.22 (0.07–0.64)

0.014 f (50.003–0.047)

Cd

Note: f fresh/frozen tuna, w white tuna, L light tuna, –: not available.

– –

France

0.067

Poland

0.29 (0.2–0.66)

0.222

Spain

Libya

0.125 (0.01–0.401) – 0.0117 (0.043–0.253)

Iran

0.41 (0.04–1.79)

– – 0.14 (0.0002–1.14)

Turkey

Italy

0.31 (0.01–0.51)w 0.10(0.02–0.31)L 0.284 (0.053–0.739) 0.65 f

–

0.350 f (0.025–0.968)

Hg

U.S.A

Saudi Arabia

Brazil

Country

0.74 (0.11–1.56)

–

0.81 –

–

–

1.05

0.776

– – 0.1289 (0.0369–0.26)

– – –

0.31 (0.0–1.72) 1.0 f

–

–

1.81 f (0.18–3.67)

As

0.51 (0.03–2.85)

–

– 0.34 f

–

–

–

–

– – –

– 0.85 –

0.004 (0.0–0.124) –

–

0.41 (0.13–0.81)

–

Ni

This study

27

25 26

24

23

22

21

18 19 20

15 16 17

13 14

12

11

10

Reference

Table 5. Means and ranges (in brackets) of trace elements concentrations (mg kg 1, wet weight) in canned tuna reported in various studies.


International Journal of Environmental Analytical Chemistry 7


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There is no dietary study in Jordan about the weekly consumption of food (seafood). However, by assuming a consumption of 250 g of canned tuna/week, and by using the mean Hg concentration (0.21 mg kg 1), human body weight of 60 kg, the estimated weekly intake (EWI) of Hg calculated (0.875 mg kg 1 body weight) was below the established Provisional Tolerable Weekly Intake (PTWI) for Hg (4.0 mg kg 1 body weight/week) and the PTWI for methylmercury (1.6 mg kg 1 body weight/week) set by the World health organisation (WHO) [40]. Therefore, the consumption of canned tuna will pose no hazardous health effects with respect to mercury contents. However, for pregnant and nursing women and children moderate consumption of canned tuna is recommended. Human exposure to cadmium is associated with some adverse health effects; cadmium accumulation may cause damages to bones and reproductive system, kidney dysfunction, severe respiratory irritation and lung disease [41]. The average concentration of cadmium in canned tuna obtained in this study was 0.06 mg kg 1 (wet weight) and data ranged from 50.01 to 0.63 mg kg 1. These results were in good agreements with other results of previous studies (Table 5).For instance, the mean cadmium level in canned tuna was reported as 0.08 mg kg 1 [16], 0.05 mg kg 1 [18], 0.036 mg kg 1 [22], 0.0223 mg kg 1 [20] and 0.04 mg kg 1 [23]. However, cadmium concentration was reported slightly higher than our values, being 0.22 mg kg 1 [11], 0.182–0.246 mg kg 1 [15] and 0.18 mg kg 1 [24] or approximately 10 times lower; 0.0019 mg kg 1 [13].The mean cadmium level in this study was below the Codex Committee on Food additives and Contaminants (CCFAC) [38] guideline of 0.5 mg kg 1 for this element in fish. However 6.6% of the analysed samples exceeded this value and 10% of the analysed samples exceeded the European dietary limit of 0.1 mg kg 1 for cadmium [39]. By using the mean cadmium concentration (0.06 mg kg 1) found in canned tuna, human body weight of 60 kg and a consumption of 250 g canned tuna/week, the estimated weekly intake (EWI) calculated (0.25 mg kg 1 body weight/week) was below the established Provisional Tolerable Weekly Intake (PTWI) for Cd (2.5 mg kg 1 body weight/week) set by the World health organisation (WHO, 2006). Therefore, these levels of cadmium are unlikely to constitute any significant cadmium exposure to the general population because of consumption of canned tuna. The use of lead organic compounds as fuel additives is the dominant source for the wide-spread of lead in the environment. However, in canned food, soldering process is another possible source of lead contamination. Lead exposure is linked to liver damage, low birth weights, premature births and renal failure in humans. It is also associated with the reduced cognitive development in children [42]. In this study, the mean lead concentration in canned tuna was 0.09 mg kg 1 (wet weight) with data ranged from 50.04 to 0.24 mg kg 1 (wet weight). Similarly, Tu¨zen and Soylak [16], Storelli et al. [23] and Rahimi et al. [18] reported average values of 0.10, 0.06 and 0.096 mg kg 1, respectively. On the other hand, Ikem and Egiebor [13] and Martorell et al. [21] reported lower lead concentrations in canned tuna, being 0.0011 and 0.017 mg kg 1, respectively. Several studies reported higher lead concentrations, for example, the average amount of lead in canned tuna from Turkey [17], Kingdom of Saudi Arabia [11] and Libya [24] and in tuna fish from Brazil [10] were reported as 0.28, 0.23, 0.28, and 0.185 mg kg 1, respectively, with the highest recorded value as 4.13 mg kg 1 [17]. Lead concentrations in all analysed samples in this work were below the CODEX [38] guideline of 0.3 mg kg 1. Only 6.6 % of the analysed samples approached (40.2 mg kg 1) this limit. The samples analysed in our study did not present a health risk considering lead contents.


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Arsenic exposure has been related to the appearance of internal cancers such as lung, liver, bladder and possibly the kidney and colon cancers [43]. The major long-term storage site for arsenic is keratin-rich tissues, such as skin, hair, and nails. In the present study, arsenic levels obtained for canned tuna ranged from 0.11 to1.56 mg kg 1, with an average value of 0.74 mg kg 1. In the literature, arsenic contents have been reported in the range of 0.0 to 1.72 mg kg 1 in canned tuna samples (Table 5). Khansari et al. [20] reported low mean arsenic concentration in canned tuna (0.129 mg kg 1). However, several studies reported the mean arsenic concentration in canned tuna as 0.81 mg kg 1 [25], 1.05 mg kg 1 [22] and 0.776 mg kg 1 [21]. Fresh and or frozen tuna had arsenic concentration of 1.81 mg kg 1 [10], 1.0 mg kg 1 [14] and 2.45 mg kg 1 [25]. These previous results were compared well with our results. In this study, all of the analysed samples had arsenic level below the 2 mg kg 1 maximum permissible limit stipulated by the European Union. However, 26.6% of the analysed samples had arsenic levels above the 1 mg kg 1 limit recommended by Malaysia and Australia for fish. The toxicity of arsenic depends on its speciation; inorganic and trivalent arsenic compounds are more toxic than organic and zero-valent or pentavalent compounds. Arsenobetaine (organic form of arsenic) is considered as a relatively harmless form of arsenic, it constitutes more than 90% of total arsenic present in food of marine origin [44]. Based on what has been stated above, all of the samples analysed in our study were safe for human consumption and they did not pose health risks considering arsenic contents. Nickel and vanadium are probably essential elements. However, nickel has no clear identified biological role in humans, and it may cause respiratory problems and other adverse health effects [45]. In this study, nickel concentrations in all the analysed samples ranged from 0.03 to 2.85 mg kg 1 (wet weight) with average value of 0.51 mg kg 1 (wet weight). Previous studies reported similar results for nickel concentrations in canned tuna (Table 5). For instance, Tu¨zen and Soylak [16] and Ashraf et al. [11] reported the mean Ni concentrations in canned tuna as 0.85 mg kg 1 (wet wt) and 0.41 mg kg 1 (wet wt), respectively. In fresh tuna, nickel concentration has been reported as 0.341 mg kg 1 (wet wt) [26] and 0.112 mg kg 1 (wet wt) [46]. In various fish species Ni concentrations were ranged from 0.9 to 5.4 mg kg 1 (wet wt) [47]. These results compared well with ours. Literature data concerning vanadium levels in canned tuna are limited. In present work, the mean vanadium levels in the analysed canned tuna samples was 0.046 mg kg 1 (wet wt) and data ranged from 50.03 to 0.1 mg kg 1. In recent study, vanadium concentration in canned tuna has been reported as 0.0054 mg kg 1 (wet wt) with range of data of (0.0–0.029 mg kg 1, wet weight) [13]. In another study, vanadium concentration was reported as 0.018 mg kg 1 (ww) in tuna fish and mean value of 0.032 mg kg 1 (ww) in various fish species [26]. Likewise, vanadium concentration was found to be 0.02 mg kg 1 (wet wt) in bluegill muscles from aquaculture source [5]. Aluminium is an important human toxin; it is believed that aluminium affects enzymes relevant to Alzheimer’s disease [7]. Nevertheless, experimental evidences for significant link between aluminium exposure and Alzheimer’s disease are weak. In this work, aluminium concentrations in canned tuna samples were varied from 0.08 to 1.63 mg kg 1(wet wt) with mean value of 0.26 mg kg 1 (wet wt). In previous studies, aluminium concentrations were reported in the range 0.31–0.89 mg kg 1 in marine and canned fish samples [48], and had an average value of 0.56 mg kg 1(wet wt) in tuna fish [26]. In various fish species, levels of aluminium were reported in the range of


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0.02–5.4 mg kg 1(dry weight) [2] and 0.3–8.0 mg kg 1 (wet wt) [47]. Our values were in good agreements with such previously reported values. Barium occurs in variety of foods at generally low concentrations. In the Canadian total diet study, mean barium concentrations were reported in the range (0.027–0.394) mg kg 1 (wet weight) in marine fish and shellfish and 0.083 mg kg 1 in canned fish [48]. In this study, barium was found at an average level of 0.128 mg kg 1 (wet wt) with a range of 0.05–0.42 mg kg 1 (wet wt) in canned tuna. Similarly, mean barium concentrations were reported as 0.022 mg kg 1 (wet wt) in tuna fish and 0.65 mg kg 1 (wet wt) in various fish species [26]. Another survey showed that the mean barium concentrations in several marine fish species from Southeast Asia were ranged between 0.002 and 0.70 mg kg 1 (wet wt) [49]. Because of the high reference dose set for barium (70 mg kg 1 body wt day 1) [50] compared to the low levels found in canned tuna, the consumption of these tuna samples has no health risk with respect to barium contents. Silver is a non-essential elements, it was not detected in any of the analysed canned tuna samples (50.02 mg kg 1, wet wt), similarly, mean silver concentrations were reported as 0.0 mg kg 1 (wet wt) in canned fish (tuna, red salmon and sardines) and 0.024 mg kg 1 (wet wt) in canned herring [13]. Likewise, mean silver concentration was reported in the range of 50.001 to 0.003 mg kg 1 (dry wt) in muscles of two fish species from the gulf of Oman [51]. A higher mean value than ours has been reported for mean silver level in tuna fish, being 0.085 mg kg 1 (wet wt) [26]. According to our results, there was no health risk associated with the consumption of canned tuna with respect to silver contents.

4. Conclusions The levels of trace elements in canned tuna samples marketed in Jordan were determined and assessed for their quality by comparing elemental concentrations in samples with maximum permitted levels stipulated by EU and other organisations. The averages and ranges of Pb, As, Ba, and Ag concentrations in all the analysed canned tuna samples were well below the maximum permitted concentrations. The mean concentration values for Hg and Cd were also below the permitted values. However, in limited cases legal limits were exceeded with respect to Hg and Cd concentrations, the estimated intakes of mercury and cadmium from weekly consumption of 250 g of canned tuna pose no health risk since they were lower than the Provisional Tolerable Weekly Intake for both elements. According to our results, the examined canned tuna samples were safe for human consumption.

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