Radionuclides and heavy metals concentrations in Turkish market tea

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Food Control 22 (2011) 2065e2070

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Food Control

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Review

Radionuclides and heavy metals concentrations in Turkish market tea

Filiz Korkmaz Görür a,*, Recep Keser a, Nilay Akçay a, Serdar Dizman a, Nazmi Turan Okumuso�glu b

aRize University, Faculty of Sciences and Arts, Department of Physics, Rize 53100, TurkeybOndokuz Mayıs University, Faculty of Sciences and Arts, Department of Physics, Samsun, Turkey

a r t i c l e i n f o

Article history:Received 17 March 2011Received in revised form27 May 2011Accepted 7 June 2011

Keywords:TeaRadioactivityHeavy metalsICP/OES

* Corresponding author. Tel.: þ90 464 223 61 26; fE-mail address: [email protected] (F. Korkm

0956-7135/$ e see front matter � 2011 Elsevier Ltd.doi:10.1016/j.foodcont.2011.06.005

a b s t r a c t

Tea is one of the most popular beverages in the world. The Eastern Black Sea Region of Turkey is one ofthe main tea producers in Turkey and the fifth in the world. Thus, the chemical components in tea havereceived great interest because they are related to health. Since this region was contaminated by theChernobyl accident in 1986, a comprehensive study was planned and carried out to determine theradioactivity level in the tea growing region. The activity concentrations of 232Th, 238U, 40K and 137Cs weremeasured in 29 black tea and one green tea samples from local Turkish markets using gamma spec-trometry with an HpGe detector. The average activity concentration of 232Th, 226Ra, 40K and 137Cs werefound 3.2 � 0.6 Bq/kg, 6.4 � 0.7 Bq/kg, 445.6 � 17.8 Bq/kg and 42.0 � 1.4 Bq/kg in tea samples,respectively.

In addition, the concentration of five heavy metals including Fe, Mn, Zn, Cu and Pb were determined byinductively coupled plasma spectroscopy (ICP/OES) on tea samples. Among the investigated metals, Mnwas the highest levels. The levels of manganese were in the range of 1850.75e292.65 mg/g (mean:1286.35 � 0.58 mg/g). Levels of Pb in the tea samples analyzed were below the detection limits. Theconcentrations of all elements for daily intake are below safety levels for human consumptions.

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Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20652. Materials and methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2066

2.1. Sample collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20662.2. Radioactivity measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20662.3. Dose estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20662.4. Heavy metal analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20662.5. Estimated daily intake (EDI) of heavy metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2068

3. Results and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20683.1. Activity concentrations of radionuclides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20683.2. Heavy metals concentration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2068

4. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2069Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2069References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2069

1. Introduction

Tea is one of the most popular beverages all over the worldwhich is prepared from the leaves of a shrub camellia sinensis.Green and black teas are the two most popular types. Drying and

ax: þ90 464 223 53 76.az Görür).

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roasting the leaves produces green tea, black tea is obtained aftera fermentation process. Economic and social interest in tea is clearfrom the fact that about 18e20 billion tea cups are consumed dailyin the world (Marcos, Fischer, Rea, & Hill, 1998; Pedro, Martin,Pablos, & Gonzalez, 2001). China is the world’s largest teaproducer, respectively, in this country, India, Sri Lanka, Kenya,Turkey, Indonesia and Japan followed. Tea production in Turkey isabout 200,000 tons/year, %30 of which is exported for a total annual

F. Korkmaz Görür et al. / Food Control 22 (2011) 2065e20702066

revenue of 5e8 million US$. The Eastern Black Sea Region of Turkeywhich accounts for around 100% of all tea production in Turkey wasamong the areas contaminated by Chernobyle accident (TAEK,1998). 137Cs was remained in the ecosystems many years after theaccident. The level of 137Cs activity concentrations in Turkish teaplants was found to be the maximum value of 44 kBq/kg for the1986 products (Gediklio�glu & Sipahi, 1989).

Themedicinal value of tea for prevention and treatment of manyhealth problems has become more and more commonly known(Naithani & Kakkar, 2005). Tea contains flavonoids, minerals andtrace elements that are essential to human health. Current studiesshow that tea contains specific antioxidants and health promotingingredients, lowering the risk of heart diseases, stroke and certaintypes of cancer like oral, pancreatic and prostate (Pedro et al.,2001). Tea drinking could be an important source of some essen-tial minerals such as manganese, which activates numerousenzymes. The levels of manganese in other foods/beverages arerelatively small. Owing to the great importance of the mineralspresent in tea, many studies have been carried out to determinetheir levels in tea leaves and their infusions. Various analyticaltechniques that have been used for this purpose include atomicabsorption spectrometry (AAS), inductively coupled plasma atomicemission spectrometry (ICP-AES), inductively coupled plasma massspectrometry (ICP-MS) and total reflection X-ray fluorescencespectrometry (TR-XRF) (Han & Li, 2002; Matsuura, Hokura, Katsuki,& Itoh, 2001; Narin, Colak, Turkoglu, Soylak, & Dogan, 2004; Xie,von Bohlen, Klockenkamper, & Jian, 1998). Determination ofheavy metals in tea samples is important from two aspects; tojudge their nutritional value and to guard against any probable ill-effect, they may cause to human health.

The aims of in this study are to determine activity concentra-tions of 232Th, 238U, 40K and 137Cs and five heavy metals includingFe, Mn, Zn, Cu and Pb in the 30 different market tea samples forpublic health in this 24-year period after the Chernobyl accident.

2. Materials and methods

2.1. Sample collection

Twenty nine marked brands of black tea (S1eS29) and one typeof green tea (S30) which commonly consumed in Turkey, werecollected from local markets in January 2010.

2.2. Radioactivity measurements

All the collected tea samples were ashed for 24 h and 450 �C. Theashed samples then were homogenized, weighed, and transferredinto uncontaminated empty cylindrical plastic containers ofuniform size. The samples were kept four weeks before the analysisat air tight condition to allow secular equilibrium between thoriumand radium and their decay products.

The radiation levels of samples were analyzed using gammaspectrometry, which was equipped with a 55% efficiency highpurity germanium (HPGe) detector and a multi-channel analyzer.The gamma spectra were analyzed by using the ORTEC Maestro 32data acquisition and analysis system. The detector had coaxialclosed-facing geometry with the following specifications: resolu-tion full width half maximum (FWHM) at 122 keV 57Co was1.00 keV and at 1.33 MeV 60Co was 1.90 keV. The detector wasshielded by a cylindrical lead shield, which had average thickness of10 cm to reduce the background due to the cosmic rays and theradiation nearby the system. Efficiency of the detector was deter-mined with a 152Eu source of known activity. 152Eu source has beenwidely used for calibration and efficiency determination due totheir large range of energies (122, 244, 344, 411, 443, 779, 964, 1112

and 1408 keV) with emission probabilities of 3e29% (Firestone &Shirley, 1998; Grigorescu et al., 2002). An ideal measuring geom-etry of cylindrical source (homogeneously distributed activity withconstant volume and distance) was placed coaxially with thedetector for the efficiency determination and the same procedureapplied for the sample measurements.

For the measurement of 226Ra activity concentration, the g-rayenergies of 295.21 and 351.92 keV of 214Pb, 609.31 keV of 214Bi wereused. The activity concentration of 232Th was determined at the g-ray energies 911.07 keV and 969.11 keV of 228Ac, 40K and 137Cs weremeasured directly from the 1460.8 keV and 661.66 keV peakenergies, respectively (ICRP, 1990; IAEA, 1989).

Tea samples were placed symmetrically on top of the detectorand measured for a period of 100.000 s. The net area under thecorresponding peaks in the energy spectrum was computed bysubtracting counts due to Compton scattering of higher peaks andother background sources from the total area of the peaks. From thenet area of a certain peak, the activity concentrations in the sampleswere obtained using Eq. (1):

C�Bq kg�1

�¼ Cn

ePyMs(1)

where C is the activity concentration of the radionuclide in thesample given in Bq/kg, Cn is the count rate under the correspondingpeak, e is the detector efficiency at the specific g-ray energy, Pg isthe absolute transition probability of the specific g-ray, and MS isthe mass of the sample (kg).

2.3. Dose estimation

Effective dose is a useful concept that enables the radiation dosesfromdifferent radionuclides and fromdifferent types and sources ofradioactivity to be added. It is based on the risks of radiation inducedhealth effects and the use of the International Commission onRadiological Protection (ICRP) metabolic model that provides rele-vant conversion factors to calculate effective doses from the totalactivity concentrations of radionuclides measured in foods (ICRP,1990). Estimates of the radiation induced health effects associatedwith intake of radionuclides in the body are proportional to the totaldose delivered by the radionuclides. Radiation doses ingested areobtained by measuring radionuclide activities in foodstuffs (Bq/kg)andmultiplying these by themasses of food consumedover a periodof time (kg/d or kg/y). A dose conversion factor (Sv/Bq) can then beapplied to give an estimate of ingestion dose. Thus, according toICRP (ICRP, 1996), the ingested dose is given by:

HT ;r ¼X�

UiCr�gT;r (2)

where i denotes a food group, the coefficients Ui and Cr denote theconsumption rate (kg/y) and activity concentration of the radio-nuclide r of interest (Bq/kg), respectively, and gT,r is the doseconversion coefficient for the ingestion of radionuclide r (Sv/Bq) intissue T. For adult members of the public, the recommended doseconversion coefficients gT ;r for 40K, 226Ra, 232Th and 137Cs are6.2.9 � 10�9 Sv/Bq, 2.8 � 10�7 Sv/Bq, 7.2 � 10�8 Sv/Bq and1.3 � 10�8 Sv/Bq, respectively (ICRP, 1996).

2.4. Heavy metal analysis

The heavy metals of samples were analyzed using inductivelycoupled plasma spectroscopy (ICP/OES). The two methodscommonly used for preparation of tea were adopted for this studyto assess the actual amount of heavy metal reach human bodythrough drinking such beverages. The two methods are:

Table 1The ICP wavelengths used for the various measuredelements.

Element Wavelength (nm)

Fe 238.204Mn 257.610Zn 213.857Cu 324.752Pb 220.535

Table 3Heavy metal concentrations with mean values in the digestion of the tea samples.

TeaSamples

Fe (mg/g) Mn (mg/g) Zn (mg/g) Cu (mg/g) Pb(mg/g)

S1 195.29 � 0.87 1751.18 � 0.62 21.11 � 0.63 44.57 � 0.50 <BDLa

S2 269.73 � 0.17 1249.72 � 0.41 40.74 � 0.38 47.01 � 0.25 <BDLa

S3 291.75 � 0.44 1056.29 � 0.31 17.34 � 0.84 38.37 � 0.83 <BDLa

S4 314.39 � 0.91 1491.42 � 0.71 20.58 � 0.33 47.09 � 0.14 <BDLa

S5 202.35 � 0.79 1850.75 � 0.79 16.78 � 0.40 33.86 � 0.06 <BDLa

S6 177.12 � 0.45 1271.74 � 0.45 15.44 � 0.85 41.89 � 0.30 <BDLa

S7 368.85 � 0.59 1424.71 � 0.40 16.47 � 1.19 30.80 � 0.35 <BDLa

S8 181.56 � 0.88 1194.54 � 0.65 16.74 � 0.64 42.94 � 0.32 <BDLa

S9 182.57 � 0.06 1245.58 � 0.65 19.34 � 0.37 32.46 � 0.12 <BDLa

S10 174.11 � 0.41 1535.61 � 0.93 17.81 � 0.38 33.38 � 0.91 <BDLa

S11 238.67 � 0.27 1773.63 � 0.82 18.59 � 0.69 44.84 � 0.34 <BDLa

S12 200.73 � 0.54 994.08 � 0.55 15.16 � 0.69 30.50 � 0.46 <BDLa

S13 130.67 � 0.49 1063.41 � 1.13 13.64 � 0.45 25.83 � 0.62 <BDLa

S14 145.81 � 0.29 1039.42 � 0.60 13.41 � 0.08 28.04 � 0.27 <BDLa

S15 173.99 � 0.06 1285.68 � 0.35 19.00 � 0.70 41.80 � 0.18 <BDLa

S16 155.78 � 0.42 1290.26 � 0.36 20.10 � 0.38 47.71 � 0.45 <BDLa

S17 135.22 � 0.28 1382.70 � 0.09 17.16 � 0.18 28.30 � 0.12 <BDLa

S18 203.65 � 0.24 1366.02 � 0.63 21.88 � 0.56 32.67 � 0.63 <BDLa

S19 121.03 � 0.58 902.35 � 0.38 16.16 � 0.12 23.59 � 0.48 <BDLa

S20 179.23 � 0.37 1332.56 � 0.05 23.77 � 0.91 120.46 � 0.69 <BDLa

S21 170.48 � 0.56 1404.11 � 0.90 20.16 � 0.70 34.77 � 0.47 <BDLa

S22 217.90 � 0.96 1216.31 � 0.06 25.77 � 0.05 41.24 � 0.52 <BDLa

S23 128.57 � 0.55 797.76 � 0.91 29.58 � 0.32 34.35 � 0.30 <BDLa

S24 131.48 � 0.67 1603.52 � 0.30 19.51 � 2.14 45.63 � 0.38 <BDLa

S25 171.86 � 1.05 292.65 � 0.58 33.92 � 1.01 50.04 � 0.29 <BDLa

S26 247.06 � 0.20 1484.86 � 0.93 48.27 � 0.41 57.26 � 0.41 <BDLa

S27 163.89 � 0.48 1079.52 � 0.56 26.23 � 0.11 41.10 � 0.34 <BDLa

S28 204.18 � 0.65 1422.68 � 0.82 24.91 � 0.27 64.88 � 0.53 <BDLa

S29 213.52 � 0.60 1666.90 � 0.91 47.43 � 0.11 36.89 � 0.83 <BDLa

S30 119.21 � 0.40 1120.50 � 0.41 22.50 � 0.58 55.00 � 0.22 <BDLa

Mean 193.69 � 0.51 1286.35 � 0.58 22.65 � 0.55 42.07 � 0.41 <BDLa

a Below detection limit.

F. Korkmaz Görür et al. / Food Control 22 (2011) 2065e2070 2067

Brew: In this method, 2 g of black tea sample was boiled with100 ml of distilled water for 5 min. The mixture was held for 5 minat room temperature and then filtered to obtain the clear solutionfor further processing.

Infusion: Tea infusion samples were prepared in a way whichTurkish drinking habits are taken into account. In this method,100 ml of hot distilled water was added to 2 g of black tea sample.The mixture left to cool at room temperature for 5 min and thenfiltered to obtain the clear solution for further processing.

Digestion: Portions of 0.5 g of each brand were digested using10 ml of a mixture (2:1 v/v) of concentrated HNO3 and HCl. Themixture was heated on sand bath until the solution turned intowhite color and gives out white fumes. The digest sample wasfiltered and transferred into 100 ml volumetric flask and thevolume was adjusted 100 ml by adding distilled water.

Nitric and perchloric acids were of ultrapure grade. Workingstandard solutions were prepared by serial dilutions of the stocksolutions. All aqueous solutions and dilutions were prepared byultrapure water. The five standards were used in the study forcalibrations were Fe, Mn, Zn, Cu and Pb andwere prepared from thestock standards so that each metal ionwould have three calibrationpoints. After sample preparation, line selection was performed in

Table 2Activity concentrations of radionuclides in tea samples (Bq/kg) and H with meanvalues from ingestion of the food items.

Samples 226Ra Bq/kg 232Th Bq/kg 137Cs Bq/kg 40K Bq/kg H mSv/y

S1 23.41 � 2.6 2.75 � 0.48 15.52 � 1.25 479.8 � 20.68 11.01S2 1.61 � 0.28 4.63 � 0.97 83.01 � 2.09 512.36 � 18.8 10.08S3 NDa 1.97 � 0.51 19.92 � 1.19 431.97 � 17.24 8.15S4 0.14 � 0.01 3.12 � 0.76 3.49 � 0.68 355.22 � 15.27 6.70S5 11.29 � 1.2 2.17 � 0.42 27.26 � 1.34 392.65 � 16.73 8.40S6 6.18 � 0.91 3.65 � 0.46 23.96 � 1.34 498.34 � 19.29 9.96S7 13.36 � 1.33 2.69 � 0.7 48.65 � 1.89 413.37 � 18.44 9.05S8 8.07 � 1.14 3.88 � 0.49 42.78 � 1.66 458.88 � 18.86 9.46S9 9.49 � 0.97 3.58 � 0.35 22.79 � 1.36 391.1 � 18.07 8.23S10 4.96 � 0.86 2.65 � 0.4 35.12 � 1.42 408.37 � 16.95 8.20S11 0.71 � 0.07 3.27 � 0.76 5.08 � 0.83 468.52 � 20.05 8.86S12 0.55 � 0.05 0.42 � 0.07 105.96 � 2.2 381.25 � 15.71 7.55S13 12.39 � 1.53 6.36 � 1.55 89.43 � 2.26 463.6 � 17.43 10.14S14 1.19 � 0.14 0.45 � 0.07 54.62 � 2.39 457.77 � 23.85 8.83S15 4.5 � 0.85 2.72 � 0.74 69.08 � 1.87 565.4 � 18.43 11.22S16 NDa 7.38 � 1.17 30.42 � 1.51 474.72 � 19.8 9.10S17 3.13 � 0.61 3.66 � 1.08 18.98 � 1.22 439.17 � 18.01 8.58S18 6.27 � 0.62 1.17 � 0.24 52.2 � 1.73 421.03 � 18.19 8.58S19 2.13 � 0.23 3.91 � 1.04 34.87 � 1.45 388.79 � 16.99 7.63S20 9.34 � 1.4 6.01 � 1.61 43.02 � 1.81 457.35 � 18.43 9.58S21 8.51 � 1.11 1.43 � 0.15 66.8 � 2.06 483.62 � 19.25 10.00S22 9.22 � 1.29 2.07 � 0.52 112.29 � 2.37 388.97 � 16.8 8.49S23 7.66 � 1.56 4.66 � 1.11 31.82 � 1.5 372.04 � 17.49 7.78S24 5.2 � 0.81 3.86 � 1.09 44.27 � 1.71 382.27 � 17.47 7.80S25 6.37 � 0.79 4.18 � 0.87 NDa 496.39 � 14.35 9.85S26 3.04 � 0.38 2.09 � 0.36 23.89 � 1.16 397.35 � 16.97 7.78S27 5.36 � 0.47 1.68 � 0.21 17.41 � 0.88 544.94 � 16.51 10.69S28 3.57 � 0.6 3.26 � 0.52 16.21 � 0.85 570.64 � 16.21 11.04S29 6.97 � 0.61 3.52 � 0.66 37.28 � 1.36 423.36 � 16.21 8.68S30 3.85 � 0.52 2.51 � 0.54 NDa 449.68 � 16.5 8.74Mean 6.37 � 0.76 3.19 � 0.66 42.00 � 1.45 445.63 � 17.83 9.01

a Not detectable.

Table 4Heavy metal concentrations with mean values in the infusion of the tea samples.

TeaSamples

Fe (mg/g) Mn (mg/g) Zn (mg/g) Cu (mg/g) Pb(mg/g)

S1 1.20 � 0.45 181.06 � 0.57 4.97 � 0.75 5.28 � 0.44 <BDLa

S2 0.98 � 0.62 115.26 � 0.74 3.98 � 0.23 4.28 � 0.22 <BDLa

S3 1.64 � 0.76 122.56 � 0.99 4.62 � 0.30 3.74 � 0.06 <BDLa

S4 2.95 � 0.46 228.64 � 0.90 5.97 � 0.66 5.62 � 0.73 <BDLa

S5 1.48 � 1.20 194.66 � 0.97 5.18 � 0.52 5.06 � 0.60 <BDLa

S6 0.43 � 1.64 114.07 � 0.71 4.09 � 0.10 3.10 � 0.24 <BDLa

S7 2.09 � 2.07 127.60 � 1.02 3.69 � 0.69 3.53 � 0.46 <BDLa

S8 <BDLa 86.98 � 0.84 2.83 � 0.70 3.25 � 0.83 <BDLa

S9 0.53 � 0.87 140.16 � 0.37 3.94 � 0.75 3.87 � 0.79 <BDLa

S10 1.54 � 1.38 189.61 � 0.94 17.97 � 0.17 5.90 � 0.57 <BDLa

S11 1.84 � 1.60 212.75 � 0.95 6.53 � 0.52 5.07 � 0.37 <BDLa

S12 0.74 � 0.80 91.52 � 0.97 6.70 � 0.40 4.21 � 0.42 <BDLa

S13 0.48 � 0.15 85.48 � 0.75 5.86 � 0.04 3.79 � 0.38 <BDLa

S14 0.99 � 0.08 140.97 � 0.55 4.92 � 0.14 4.44 � 0.38 <BDLa

S15 0.98 � 0.36 162.85 � 0.53 11.29 � 0.19 4.75 � 0.30 <BDLa

S16 0.83 � 0.03 157.73 � 0.11 4.20 � 0.17 4.47 � 0.11 <BDLa

S17 0.87 � 0.65 196.55 � 0.29 5.10 � 0.44 5.07 � 0.54 <BDLa

S18 0.57 � 0.25 119.26 � 0.66 4.45 � 0.32 3.59 � 0.61 <BDLa

S19 0.23 � 0.20 142.53 � 1.14 4.63 � 0.41 4.09 � 0.25 <BDLa

S20 0.49 � 0.5 139.35 � 0.24 4.64 � 0.39 4.23 � 0.09 <BDLa

S21 3.15 � 1.14 247.81 � 1.56 13.15 � 0.23 5.53 � 0.44 <BDLa

S22 0.29 � 0.98 90.71 � 0.48 3.02 � 0.10 4.01 � 0.38 <BDLa

S23 0.78 � 0.91 104.151 � 1.02 4.08 � 0.71 5.50 � 0.33 <BDLa

S24 0.37 � 0.65 176.38 � 1.05 4.07 � 0.73 3.77 � 0.35 <BDLa

S25 0.64 � 0.58 79.24 � 0.25 13.69 � 0.45 6.24 � 0.17 <BDLa

S26 1.41 � 0.68 141.94 � 0.95 4.92 � 0.22 6.06 � 0.60 <BDLa

S27 0.96 � 0.15 144.43 � 0.79 6.09 � 0.79 5.03 � 0.15 <BDLa

S28 0.70 � 0.17 386.57 � 1.42 10.30 � 0.39 7.32 � 0.28 <BDLa

S29 0.80 � 0.66 127.76 � 0.27 3.56 � 0.53 8.17 � 0.11 <BDLa

S30 2.08 � 1.15 251.69 � 0.75 12.50 � 0.32 9.17 � 0.43 <BDLa

Mean 1.07 � 0.70 156.68 � 0.77 6.36 � 0.41 4.94 � 0.39 <BDLa

a Below detection limit.

Table 5Heavy metal concentrations with mean values in the brew of the tea samples.

TeaSamples

Fe (mg/g) Mn (mg/g) Zn (mg/g) Cu (mg/g) Pb(mg/g)

S1 3.60 � 0.23 410.73 � 0.12 9.81 � 0.09 4.61 � 0.42 <BDLa

S2 2.91 � 2.56 353.07 � 0.54 11.56 � 0.03 2.04 � 0.14 <BDLa

S3 11.59 � 1.41 392.80 � 0.57 19.51 � 0.42 4.091 � 0.50 <BDLa

S4 14.78 � 0.48 582.20 � 0.63 14.52 � 0.45 4.81 � 0.94 <BDLa

S5 4.99 � 1.53 541.61 � 0.51 10.30 � 0.30 5.27 � 0.86 <BDLa

S6 7.97 � 2.28 370.95 � 0.30 10.38 � 0.37 3.16 � 0.32 <BDLa

S7 8.26 � 0.81 318.87 � 0.49 7.53 � 0.23 3.52 � 0.39 <BDLa

S8 7.61 � 0.54 395.20 � 0.34 9.86 � 0.78 4.31 � 0.43 <BDLa

S9 7.64 � 1.41 448.25 � 0.35 8.88 � 1.20 2.13 � 0.47 <BDLa

S10 3.75 � 1.71 365.54 � 1.89 6.92 � 1.43 2.90 � 0.99 <BDLa

S11 13.81 � 0.72 505.84 � 0.29 9.55 � 0.06 4.98 � 0.44 <BDLa

S12 7.60 � 0.49 333.97 � 0.08 9.26 � 0.03 3.73 � 0.27 <BDLa

S13 7.49 � 0.58 300.37 � 0.05 8.23 � 0.44 4.40 � 0.15 <BDLa

S14 9.06 � 0.25 477.58 � 0.25 9.41 � 0.29 3.64 � 0.20 <BDLa

S15 10.89 � 0.46 479.68 � 0.57 10.15 � 0.15 5.48 � 0.07 <BDLa

S16 10.45 � 0.10 458.64 � 0.48 10.39 � 0.26 5.11 � 0.18 <BDLa

S17 7.44 � 1.33 445.69 � 0.36 8.91 � 0.37 4.78 � 0.52 <BDLa

S18 7.29 � 0.79 336.46 � 0.47 8.93 � 0.48 5.02 � 0.30 <BDLa

S19 6.56 � 0.99 416.60 � 0.54 9.78 � 0.42 4.90 � 0.24 <BDLa

S20 11.88 � 0.34 464.11 � 0.22 17.67 � 0.02 4.83 � 0.11 <BDLa

S21 13.47 � 0.40 476.98 � 0.12 33.39 � 0.34 5.13 � 0.15 <BDLa

S22 10.88 � 1.19 347.87 � 0.17 13.68 � 0.22 5.77 � 0.71 <BDLa

S23 8.86 � 0.49 294.66 � 0.55 9.85 � 0.18 6.92 � 0.43 <BDLa

S24 6.03 � 2.01 518.80 � 0.15 9.70 � 0.12 7.93 � 2.18 <BDLa

S25 3.04 � 0.94 131.82 � 0.25 22.87 � 0.11 4.52 � 0.42 <BDLa

S26 5.35 � 0.73 320.72 � 0.42 8.37 � 0.29 6.16 � 0.38 <BDLa

S27 3.60 � 1.74 369.09 � 1.50 13.36 � 0.47 3.36 � 0.80 <BDLa

S28 2.30 � 1.18 629.73 � 0.28 14.62 � 0.85 5.03 � 0.38 <BDLa

S29 7.00 � 0.52 327.52 � 1.23 6.74 � 0.80 7.52 � 0.38 <BDLa

S30 6.32 � 1.94 419.35 � 0.88 17.86 � 0.48 7.71 � 0.44 <BDLa

Mean 7.75 � 1.00 407.82 � 0.49 12.07 � 0.39 4.79 � 0.48 <BDLa

a Below detection limit.

F. Korkmaz Görür et al. / Food Control 22 (2011) 2065e20702068

order to select the optimal spectral lines for measurement. Multi-element standard solution was scanned by ICP-OES over 2e4offered wavelength to monitor line interferences. Finally theoptimal lines with lowest interference, highest sensitivity and bestlinear relationship were chosen for this method. The chosen linesare presented in Table 1.

Detection limit is defined as the concentration corresponding tofive times the standard deviation. Detection limit values werefound to be as 0.0024 mg/l for Fe, 0.0023 mg/l for Mn, 0.0028 mg/lfor Zn, 0.0024 mg/l for Cu and 0.0103 mg/l for Pb in digestionsamples. For brew and infusion samples, detection limit valueswere found to be as 0.0021 mg/l for Fe, 0.0033 mg/l for Mn,0.0014 mg/l for Zn, 0.0013 mg/l for Cu and 0.0119 mg/l for Pb.

2.5. Estimated daily intake (EDI) of heavy metals

The estimated daily intake (EDI) of heavy metals (Fe, Mn, Zn, Cuand Pb) depends on both the metal concentration level and theamount of consumption of tea. The EDI of metals for adults was

Table 6Overall means of heavy metals in brew and infusion extracts as well as digestion conten

Heavy metals Digestion Brew Infusion

(mg/g) (mg/g) Solubility (%) (mg/g) Sol

Fe 193.68 7.75 4.001446 1.07 0Mn 1286.35 407.82 31.70366 156.68 12Zn 22.65 12.07 53.28918 6.36 28Cu 42.06 4.79 11.38849 4.94 11Pb <BDLc <BDLc e <BDLc e

a Recommended dietary allowance (RDAs)/adequate daily dietary intake (www.nap.eb Estimated dietary intakes based on 70 kg body weight (Cassidy, 2003).c Below detection limit.

determined using the following equation (Zhuang, McBride, Xia, Li,& Li, 2009):

EDI ¼ Cmetal �Wm

(3)

where Cmetal is the concentration of heavy metals in tea; W repre-sents the daily average consumption of tea; m is the body weight.Calculations were made assuming body weight of 70 kg for adultsand a 8.21 g average daily consumption.

3. Results and discussion

3.1. Activity concentrations of radionuclides

The results of activity concentrations in the tea samples for thenatural radionuclides such as 226Ra, 232Th, 40K and the artificialradionuclide 137Cs and ingestion dose rates with mean values aregiven in Table 2.

The average activity concentration of 232Th, 226Ra, 40K and 137Cswere found 3.2 � 0.6 Bq/kg, 6.4 � 0.7 Bq/kg, 445.6� 17.8 Bq/kg and42.0 � 1.4 Bq/kg in tea samples, respectively. The activity of 40K isseen to be higher than 226Ra and 232Th in all the selected teasamples. 40K was found to contribute the highest activity in all thefood products. ICRP permits the level of 137Cs activity for foodstuffsas 1000 Bq/kg (ICRP, 2004). For this reason, we can suggest thatrange of the 137Cs activity in tea samples of the present study is ofno risk to public health. The average activity level of 137Cs and 40K intea samples from Egypt have been reported by S. Harb (Harb, 2007)as 0.9 � 0.2 Bq/kg and 623 � 25 Bq/kg, respectively. The results of40K activity concentration in the present study showed a goodagreement. However, the results of present 137Cs activity concen-tration are found to be relatively higher than that of the tea samplesthat the Eastern part of Turkey was contaminated by the Chernobylfallout.

The average activity level of 226Ra and 232Th in tea samples fromTurkey have been reported by Kılıç (Kılıç, Belivermis, Topçuo�glu, &Çotuk, 2009) as 0.9 � 0.4 Bq/kg and 2.7 � 1 Bq/kg, respectively. Theaverage 238U and 232Th radioactivity concentrations in tea sampleswere comparable to other studies in various regions determinedlower activity compared to this study.

The annual dose to individuals from the consumption of the teasamples ranged from 6.7 mSv/y to 11.2 mSv/y and 9.01 mSv/y wasdenoted as an average value. Generally, the dose from ingestion ofradionuclides can be considered to be lowwhen comparedwith thetotal exposure per person resulting from ingestion of 2400 mSv/y inthe world (UNSCEAR, 2000).

3.2. Heavy metals concentration

Heavy metals are emitted to the environment from differentsources such as transportation, industrial activities, fossil fuels,

t in tea and comparison of the average daily dietary intakes of each element.

Calculated Intake (mg/day)

Estimated Dietary Intake (mg/day)

ubility (%) Brew Infusion

.552458 0.062 0.00856 8e18a

.1802 3.26256 1.25344 1.6e2.3a

.07947 0.09656 0.05088 8e11a

.74513 0.03832 0.03952 0.700e0.900a

e e 0.0070e0.0126b

du).

Table 7Metal-to-metal correlation coefficient matrix for tea samples.

Fe Mn Zn Cu

Brew Infusion Digestion Brew Infusion Digestion Brew Infusion Digestion Brew Infusion Digestion

Fe 1 1 1 0.30 0.47 0.30 0.27 0.39 0.19 0.13 0.36 0.03Mn 1 1 1 0.05 0.43 �0.01 0.10 0.54 0.07Zn 1 1 1 0.08 0.52 0.23Cu 1 1 1

F. Korkmaz Görür et al. / Food Control 22 (2011) 2065e2070 2069

agriculture, urbanization and other human activities. The release oflarge quantities of heavy metals into the natural environment hasresulted in a number of environmental problems and due to theirnon-biodegradability and persistence they can accumulate in theenvironment elements such as the food chain, and thus may posea significant danger to human health.

Heavy metal concentrations in the digestion, the infusion andthe brew of the tea samples were given in Tables 3e5, respectively.Tables 3e5 shows that Mn has the highest concentration in thedigestion, infusion and brew samples. The results showed a goodagreement with the concentration values of some heavy metalsreported in the tea samples by Lasheen (Lasheen, Awwad, El-khalafawy, & Abdel-Rassoul, 2008).

Fe is an important metal accumulating in the liver due to thephysiological role of this organ in blood synthesis (Yamazaki,Tanizaki, & Shimokawa, 1996). In the present study, Fe concentra-tion ranged from 119.21 to 368.85 mg/g in the digestion and fromBDL to 3.15 mg/g in the infusion and from 2.30 to 14.78 mg/g in thebrew of the samples. Fe was the second highest element found intea samples. Pedro (Pedro et al., 2001) have shown Fe to be in therange of 74e1000 mg/g for black tea samples. Ashraf (Ashraf & Atiq,2008) have reported 250.5 mg/g iron in tea samples from SaudiArabia.

Mn concentration ranged from 292.65 to 1850.75 mg/g in thedigestion and from 79.24 to 386.57 mg/g in the infusion and from294.66 to 629.73 mg/g in the brew of the samples. Mn concentrationwas found to have the highest concentration among the otherelements in the present study. Yasmeen (Yasmeen, Aleem, & Anwar,2000) have reported 175 mg/g manganese in tea samples fromPakistan. The levels of Mn in black tea samples from China havebeen reported by Xie (Xie et al., 1998) as 607 � 200 mg/g. Ashraf(Ashraf & Atiq, 2008) have reported 750.9 mg/g manganese in teasamples from Saudi Arabia.

Zn and Cu are essential elements and these elements are capableof inducing the synthesis of metal binding proteins such as MT inhepatic tissue (Wagner & Boman, 2003). In the present study, Znconcentration ranged from 23.59 to 120.46 mg/g in the digestionand from 2.83 to 17.97 mg/g in the infusion and from 6.74 to33.39 mg/g in the brew of the samples. Marcos (Marcos et al., 1998)have reported average Zn concentrations in black tea samples28.2 mg/g. On the other hand, much higher levels have beenreported by Narin (Narin et al., 2004) as 147.5 mg/g for Zn. Matsuura(Matsuura et al., 2001) have reported mean Zn level in black tea as36.6 � 0.7 mg/g. Cu concentration ranged from 23.59 to 120.46 mg/gin the digestion and from 3.10 to 9.17 mg/g in the infusion and from2.04 to 7.93 mg/g in the brew of the samples. Similar results for Cuhave been reported by other workers (Narin et al., 2004; Xie et al.,1998; Ferrara, Montesanoa, & Senatore, 2001).

Pb is known to induce the reduced cognitive development andintellectual performance in children and the increased bloodpressure and the cardiovascular diseases in adults (Communities ofthe European Communuties, 2001). The main sources of Pb are thecombustion of leaded fuel, waste incineration and industry. Leadpollution is correlated with urbanization and density of population.

The concentration of Pb was relatively low ranging from BDL to0.0103 mg l�1 in the tea samples. The sampling sites of the presentstudy were among the areas mostly laid on the coastline which isdensely populated. Therefore the detection of Pb in the tea samplesis not surprising. Xie (Xie et al., 1998) have reported average Pbcontents in some Chinese black tea samples as 1.42 � 0.8 mg/g.Narin (Narin et al., 2004) has found maximum lead in Turkish teasamples at the levels of 27.3� 0.1 mg/g. The higher levels of Pb in teasamples could be attributed to dust particles during tea processingand solder being used in packaging.

The solubility and the possible daily uptake and recommendeddaily allowances are also shown in Table 6. Investigated metalswere calculated for their solubility as a ratio between brew, infu-sion and total content, varied widely between investigated metalsand ranged from 0.0 to 53.3%. The concentrations of Fe, Mn, Zn, Cuand Pb can be easily released at the higher rate in the brew. Theelement concentrations in the infusion, Turkish drinking habits, aremore significant when daily update in considered. The concentra-tions of all elements for daily intake are below safety levels forhuman consumptions.

Correlation analyses were carried out between the elementconcentrations in the brew, infusion and digestion of samples.Metal-to-metal correlation coefficient matrix is given in Table 7. Inthe brew and infusion of the samples all elements pairs havepositive correlations. In the digestion of the samples (FeeMn),(FeeZn), (FeeCu), (MneCu), (ZneCu) have positive; (MneZn)element pair has negative correlations.

4. Conclusions

Tea is one of the most popular beverages in the world. TheEastern Black Sea Region of Turkey is one of the main tea producersin Turkey and the fifth in theworld. Thus, the chemical componentsin tea have received great interest because they are related tohealth. Since this region was contaminated by the Chernobyl acci-dent in 1986, a comprehensive study was planned and carried outto determine the radioactivity level and heavy metal levels in thetea growing region. The heavy metal concentrations of Fe, Mn, Zn,Cu for daily intake are below safety levels for human consumptions.

Acknowledgment

The authors are grateful to the Rize University ScientificResearch Projects Department (BAP) for the support under theproject no. 2008.102.01.1.

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