Assessment of Cadmium, Mercury and Lead contents of frozen Eurorean sea bass (<i>Dicentrarchus labrax</i> L., 1758) and Gilthead sea bream (<i>Sparus aurata</i> L., 1758) fillet from Turkey

doi:10.4236/as.2012.35081

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Vol.3, No.5, 669-673 (2012) Agricultural Sciences

http://dx.doi.org/10.4236/as.2012.35081

Assessment of cadmium, mercury and lead contents

of frozen Eurorean sea bass (Dicentrarchus labrax L.,

1758) and gilthead sea bream (Sparus aurata L.,

1758) fillets from Turkey

Murat Yabanli*, Yunus Alparslan, Tacnur Baygar

Muğla Sıtkı Koçman University, Faculty of Fisheries, Mugla, Turkey; *Corresponding Author: [email protected]

Received 16 June 2012; revised 17 July 2012; accepted 30 July 2012

ABSTRACT

In this study, trace metals [cadmium (Cd), mer-

cury (Hg) and lead (Pb)] consentration of 76

pieces of frozen European sea bass (Dicen-

trarchus labrax Linnaeus-1758) and gilthead sea

bream (Sparus aurata Linnaeus-1758) fillets,

produced and marketed in Turkey, were deter-

mined using Inductively Coupled Plasma Mass

Spectrometry (ICP-MS) after microwave damp

burning process, and results obtained were as-

sessed in terms of public health. This study was

conducted from June 2010 to July 2011. At the

end of study, maximum heavy metal levels for

sea bass and sea bream fillets were determined

as 256.50, 216.22 µg/kg for Cd; 414.79, 338.46

µg/kg for Hg ve 1047.61, 147.14 µg/kg for Pb,

respectively. At the end of the study, the levels

of cadmium (for 3 samples) and lead (for 1 sam-

ples) were higher than the recommended legal

limits of the European Union for human con-

sumption. It was detected that the fillets which

were analyzed was good quality from the point

of cadmium, mercury and lead contents.

Keywords: Europ ean Sea Bass Fillet; Gilthead Sea

Bream Fillet; Cadmium; Mercury; Lead; Turkey

1. INTRODUCTION

The effects of heavy metals on human health and the

environment is of great interest today, especially for

aquatic products [1]. Toxic elements can be very harmful

even at low concentration when ingested over a long

time period. The essential metals can also produce toxic

effects when their intake is excessive [2]. Levels of trace

elements including cadmium, mercury and lead in fish

and fishery products from many areas in Turkey have

been reported [2,3]. In many countries, significant al-

terations in industrial development lead to an increased

discharge of chemical effluents into the ecosystem, lead-

ing to damage of marine habitats. Heavy metal dis-

charged into the marine environment can damage both

marine species diversity and ecosystems, due to their

toxicity and accumulative behaviour [4]. Heavy metals

are present in the aquatic environment where they bio

accumulate along the food chain. Accumulation occurs in

the tissues of aquatic animals and may become toxic for

fish and also for people when it reaches a substantially

high level [5].

Fish has been the main supply of cheap and healthy

protein to a large percentage of the world’s population

[6]. The proper human diet should satisfy the require-

ments for energy and nutritive components including:

essential polyunsaturated fatty acids, exogenous amino

acids being the component of standart proteins, mineral

components, fat and water-soluble vitamins [7]. In addi-

tion to the key nutrients mentioned, fish can accumulate

substantial concentrations of heavy metals in their tissues.

Fish is therefore a product for which suitable measures

should be taken to provide chemical monitoring of the

risks derived from its consumption [8]. High metal con-

centrations in food can provoke serious health hazards in

humans (Table 1).

Turkey is surrounded by four different seas with 8333

km long coastal line and fishing is one of the biggest

income sources for the country. The four seas around

Turkey each reflect a different ecological characters, for

instance salinity is 18 per thousand in the Black Sea, 23

per thousand in the Marmara Sea, 32 per thousand in the

Aegean Sea and 38 per thousand in the Mediterranean

Sea. The aim of this study was to determine ranges of

toxic trace metals (Cd, Hg and Pb) in the fisheries pro-

ducts (frozen European sea bass and gilthead sea bream

illets) produced and marketed in Turkey. f

M. Yabanli et al. / Agricultural Sciences 3 (2012) 669-673

670

Table 1. Potantial health hazards of cadmium, mercury and lead.

Element Potential health hazards References

Cd Kidney damage, testicular tumors, renal dysfunction, hypertension, arteriosclerosis, growth inhibition,

chronic diseases of old age, and cancer [9,10]

Minamata disease, cardiovascular disease, sensorimotor symptoms, memory loss in adult, late talking and late

walking in children/infants, decreases rate of fertility in both males and females, birth of abnormal offsprings,

decreases overall immunity of the body, cancer

[11-13]

Pb Delays in physical or mental development in infants, slight deficits in attention span and learning abilities in

children, kidney problems, high blood pressure, anemia, muscle paralysis [9,14]

2. MATERIALS AND METHODS

2.1. Samples Collection

Total seventy six composed European sea bass and

gilthead sea bream fillet samples were collected ram-

domly from İzmir which is a port city in Turkey to assess

the levels of cadmium, mercury and lead. This study was

conducted from June 2010 to July 2011.

2.2. Reagents

Double deionized water (ELGA water purification

system, 18.0 MΩ cm resistivity) was used for all dilu-

ons. All reagents used were of analytical grade (nitric

acid, 65% Suprapur Merck; hydrochloric acid, 30% Su-

apur Merck). Multi-element calibration solutions of all

investigated elements were prepared daily by dilution of

10 mg/L mix element standard stock solution (AccuTrace

MES-21-1) and 10 mg/L mercury standard stock solution

(AccuTrace MES-21-HG-1).

2.3. Sample Preparation (Microwave

Digestion)

European sea bass and gilthead sea bream fillets were

homogenized throughly in a laboratory blender (Waring

trade marker) with stainless steel cutters. For each ho-

mogenized samples, 0.5 g homogenate (wet weight) was

weighed and placed in polytetrafluorethylene (PTFE)

vessel with 5 mL of 65% nitric acid. Material was then

subjected to a microwave program (Ta ble 2 ). The tem-

perature of each vessel was rised to 190˚C in approxi-

mately 10 minutes and remained at 190˚C for 15 minutes.

Digest was finally made up with 2% nitric acid, 0.5%

hydrochloric acid solution to 50 mL in acid washed

standard flasks and then placed in 50 mL polypropylene

centrifuge tubes.

2.4. App aratus

Bergh of speed wave MWS-3 microwave digestion sys-

tem with DAP 60+ vessels was used to digest European

sea bass and gilthead sea bream fillet samples prior to

toxic element analysis. Inductively coupled plasma-mass

spectroscopy (Agilent 7700×) with auto sampler (Agilent

ASX-500) was used to analyze digested samples for total

metals. The operating conditions for ICP-MS are shown

in Table 3.

2.5. Determination of Recovery

Ten homogenized fish muscle tissues were spiked with

1000 µg/kg each metal (cadmium, mercury and lead) for

the recovery repeatability test. Ten spiked samples and

ten blanks were taken through the microwave digestion

procedure. And then, digested spiked samples were ana-

lyzed using ICP-MS. Obtained values were given in Ta-

ble 4. The mean recoveries for cadmium, mercury and

lead 100.22, 107.11 and 92.82 respectively. Acceptable

recovery of >90% - <110% were obtained for studied

metals, an indication of good analytical protocol.

2.6. Statistical Analysis

To determine the correlations between the metal con-

centrations in fish and fish products was performed with

Mann-Whitney U Test by using Statistica software pro-

gram. Any statistical significant difference was not de-

tected for cadmium, mercury and lead between European

sea bass and Gilthead sea bream samples (p = 0.599; p >

Table 2. Microwave burning process.

Process 1 2 3

T (˚C) 160 190 100

Ta (transition time, minute) 5 1 1

Waiting time (minute) 5 15 10

Table 3. ICP-MS operating conditions.

Radio frequency power 1550 W

RF matching 2.1 V

Sample depth 8 mm

Carrier gas 1.05 L/min

S/C temperature 2˚C

Nebulizer type MicroMist

M. Yabanli et al. / Agricultural Sciences 3 (2012) 669-673 671

Table 4. Recoveries of cadmium, mercury and lead from fish muscle tissue.

µg/kg Sample concentration Concentration of lead added Concentration of recovered % Recovery

Cd 1.08 1000 1003.28 100.22

Hg 7.60 1000 1079.25 107.11

Pb 65.41 1000 988.95 92.82

0.05 for cadmium, p = 0.277; p >0.05 for mercury and p

= 0.590; p > 0.05 for lead).

3. RESULT AND DISSCUSSION

In this study, seventy six samples of fillet were ana-

lysed for cadmium, mercury and lead. Good recovery

was obtained for studied elements (Ta ble 4). The mean

levels obtained in our study are listed in Table 5. Box

Whisker plot of measured toxic metal concentrations in

fillets are given Figure 1. The evaluation of the levels of

the cadmium, mercury and lead in the European sea bass

and gilthead sea bream fillets was performed based on

the maximum levels set forth in Commission Regulation

EC 1881/2006 [15]. Public health concerns have focused

on the fish fillets the levels of cadmium in only three

samples analyzed (one sample European sea bass fillet,

two samples gilthead sea bream fillet) was found that

might have exceeded the regulatory limits. The concen-

tration of lead in one European sea bass fillet investi-

gated was higher than the recommended legal limits (Ta-

ble 6). In European sea bass and gilthead sea bream fil-

lets analyzed, the mean concentrations of toxic elements

decreased as mercury > lead > cadmium.

3.1. Cadmium (Cd)

Cadmium is a non-essential metal, but competes with

other essential metallic ions when accumulated in orga-

nisms and produces unpredictable changes [16]. Mean

cadmium concentrations of the studied fillets were 7.92

µg/kg for European sea bass, 9.88 µg/kg for gilthead sea

bream. The highest cadmium content was found in the

European sea bass fillet (256.50 µg/kg). 2.63% of sam-

ples of gilthead sea bream fillet, 5.26% of samples of

European sea bass fillet exceeded the limits of EC

1881/2006 [15]. Mean cadmium concentrations of Euro-

pean sea bass and gilthead sea bream muscle tissues was

found as 92 µg/kg and 120 µg/kg, respectively, by Dural

et al. [17]. In another study, mean cadmium concentra-

tions in the flesh of cultured European sea bass were

found 270 µg/kg [18]. Our obtained values were found as

lower than these values.

3.2. Mercury (Hg)

Mercury is a known toxicant which is present in the

environment as a result of natural processes and anthro-

pogenic activities [19]. Fish accumulate substantial con-

centrations of mercury in their tissues and thus, can rep-

resent a major dietary source of this element to humans

[20]. The highest mercury value was detected in the

European sea bass fillet (353.36 µg/kg). All examined

samples had a mercury content below the permissible

level of 500 µg/kg (wet weight of fish) for human con-

sumption recommended by EC 1881/2006 [15]. The

highest mercury concentrations measured in our study is

lower then that reported by Abreu et al. [21], 1700 µg/kg,

in European sea bass muscle tissues in Portugal. In a

similar way, mean mercury levels (120 µg/kg) were

found higher than current study (74.90 µg/kg) in gilthead

sea bream muscle tissues in Ligurian Sea, Italy [22].

3.3. Lead (Pb)

Lead is a widely distributed environmental poison and,

solder used in the manufacture of cans is a source of

contamination of food by Pb. Therefore, the monitoring

of lead concentration became essential [23]. Lead is a

ubiquitous environmental and industrial pollutant that

has been detected in almost all phases of environmental

and biological systems [24]. The general population is

exposed to lead from air and food in roughly equal pro-

portions [25]. Mean cadmium concentrations of the

European sea bass and gilthead sea bream fillets were

57.69 and 27.89 µg/kg, respectively. Generally, lead lev-

els of analyzed European sea bass fillet samples (97.37%)

were found to be lower than legal limits of EC 1881/

2006. Any sea bream fillet samples analyzed did not ex-

ceeded EC 1881/2006 limits [15]. The mean lead levels

of analyzed European sea bass and gilthead sea bream

fillet samples are lower than those reported in the litera-

ture (1030 µg/kg for European sea bass, Alasalvar et al.

[18]; 480 µg/kg for European sea bass, Türkmen et al.

[26]; 620 µg/kg for gilthead sea bream, Uluozlu et al. [1];

7330 µg/kg for gilthead sea bream, Yılmaz [27].

4. CONCLUSION

The concentration of trace metals in samples is de-

pended on fish species. Some species is accumulated

trace metals at high ratio [28]. The consequence of heavy

metal pollution can be hazardous to man and it often

becomes mandatory to check chemical contaminants in

M. Yabanli et al. / Agricultural Sciences 3 (2012) 669-673

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Table 5. Cadmium, mercury and lead concentrations (µg/kg on a wet weight basis) in frozen European sea bass and gilthead sea

bream fillet, number of products investigated (n), arithmetic mean (Mean), standard error (SD).

Mean ± SE

Product n

Cd Hg Pb

European sea bass fillet 38 7.92 ± 6.73 97.65 ± 17.26 57.69 ± 28.46

Gilthead sea bream fillet 38 9.88 ± 6.68 74.90 ± 13.43 27.89 ± 7.08

Table 6. The percentage of samples exceeding limits of EC and EC limits.

Sample rate (%) that exceeded of EC 1881/2006 limits

Element

European sea bass fillet Gilthead sea bream fillet

Maximum residue limits (µg/kg)

according to EC 1881/2006

Cd 2.63 5.26 50

Hg * * 500

Pb 2.63 * 300

*Any samples analyzed did not exceed limits.

(a) (b)

Figure 1. Box whisker plot of concentrations of measured toxic elements in European sea bass filets (a) and gilthead sea bream filets

(b) (▫: median, □: 25% - 75%, −: min-max).

foods from the aquatic environment to understand their

hazard levels [4]. According to current study results

amount of toxic elements in studied muscle tissues (fil-

lets) may vary depending on species. The cadmium,

mercury and lead concentrations in the majority of the

European sea bass and gilthead sea bream fillets ana-

lyzed were convenient within the recommended legal

limits for human consumption, except in a few cases.

Monitoring of fisheries products in terms of heavy met-

als is of great importance for public health.

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