Determination of arsenic leaching from glazed and non-glazed Turkish traditional earthenware
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Science of the Total Environment 409 (2011) 29932996
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Science of the Tot
l seArsenic contamination of soil results from mining, smelting of suldeores, pesticides, wood preservation. Nevertheless, the contaminationof the soils due to irrigation with groundwater with high arseniccontent from natural origin is widely reported since it affects largeareas in the world (Mandal and Suzuki, 2002; Garcia-Manyes et al.,2002). The Food and Agriculture Organization/World Health Organi-zation (FAO/WHO) Expert Committee on Food Additives (JECFA) haverecommended a provisional tolerable weekly intake (PTWI) of notmore than 15 g of inorganic As/kg of body weight (WHO,World Health Organization, 1989). In 1993, WHO (World Health
region to produce potterywith varying characteristics (Rhodes, 1973).Furthermore, the clay itself can be mixed with different minerals tocreate different effects. Pottery used for cooking vessels is normallyglazed to produce a non-porous, water-tight surface. The glass-likeglaze of good earthenware and ceramics is produced by coating thesurface with a carefully prepared frit and heating it to a high tem-perature in a kiln. Glazes are applied to clay-based pottery products toprovide a shiny, generally smooth surface and seal the clay (Phelps,1986). Pottery containers and cooking utensils continue to causemetalcontamination of foods in spite ofwarnings by health authorities of theOrganization) (1993) lowered the guidelindrinking water from 50 g L1 down to 10
Corresponding author. Tel./fax: +90 232 388 82 64E-mail address: firstname.lastname@example.org (E. Henden
0048-9697/$ see front matter 2011 Elsevier B.V. Aldoi:10.1016/j.scitotenv.2011.04.027enic in the environmentsources. Persistence of
nd animals is of concern.
Pottery ismade fromclay,mostly formedby thehandwhile it is stillsoft and wet, and then heated in a kiln at high temperatures to changeitsmaterial quality, making it hard. The clay itself varies from region tooccurs from both natural and anthropogenicarsenic within soil and its toxicity to plants a1. Introduction
Arsenic is one of the most toxic elconstitutes one of the main concernArsenic is known for its acute toxicityeffects as an established human carciarsenic can cause serious health procardiovascular and neurological damorgan failure, as well as death (IfanEnvironmental Protection Agency, 200found in nature, and itlation to human health.doses, as well as chronicLong-term exposure tosuch as skin ailments,adder and lung cancer,4; USEPA, United States
The analysis of arsenic is important in view of serious threats andrisk evaluation of human health. Hydride generation atomic absorp-tion spectrometry (HG-AAS), which can be applied in several possibleways, has been demonstrated to be an efcient technique for thedetermination of hydride-forming elements, including arsenic, in avariety of samples (Dedina and Tsalev, 1995). The separation of theanalyte from the matrix before the measurement is one of the mainadvantages of this technique, as it signicantly reduces the inter-ferences (Tsalev, 2000).e value for arsenic ing L1.
need for cautionfood (Shibamotofor possible releceramic and pottTunstall and Am
Glazed and nused in Turkey a
l rights reserved.Short Communication
Determination of arsenic leaching from gtraditional earthenware
Emur Henden , Rengin Cataloglu, Nur AksunerDepartment of Chemistry, Faculty of Science, University of Ege, 35100 Bornova, zmir, Turk
a b s t r a c ta r t i c l e i n f o
Article history:Received 25 March 2011Received in revised form 6 April 2011Accepted 14 April 2011
Keywords:Arsenic leachingGlazed earthenwareNon-glazed earthenwareHydride generationAtomic absorption spectrometry
Glazed and non-glazed earthand the Middle East countriout to determine whetherhazard risk to the consumearsenic in the leachates waconcentrations in the leachpotteries varied generally fglazed series it reached toglazed potteries is high enoufrom earthenware into food
j ourna l homepage: www.ezed and non-glazed Turkish
ware is traditionally and widely used in Turkey andmost of the Mediterraneanr cooking and conservation of foodstuff. Acid-leaching tests have been carrieduse of glazed and non-glazed earthenware may constitute a human healtharthenware was leached with 4% acetic acid and 1% citric acid solutions, andeasured using hydride generation atomic absorption spectrometry. Arseniction of non-glazed potteries varied from 30.9 to 800 g L1, while the glazedbelow the limit of detection (0.5 g L1) to 30.6 g L1, but in one poorlyg L1. Therefore, the risk of arsenic poisoning by poorly glazed and non-to be of concern. It appears that this is the rst study reporting arsenic release
2011 Elsevier B.V. All rights reserved.
v ie r.com/ locate /sc i totenvwhen certain types of pottery are used in contactwithand Bjeldanes, 1993). In many countries, authoritiesase of lead and cadmium have monitored glazedery (Sheets, 1999; Jakmunee and Junsomboon, 2008;arasiriwardena, 2002).on-glazed earthenwares are traditionally and widelynd most of the Mediterranean and the Middle East
2994 E. Henden et al. / Science of the Total Environment 409 (2011) 29932996countries for cooking and conservation of foodstuff. In Turkey, the useof bowls for the conservation of yogurt and other traditionallyprepared meat and dried beans meals is widespread. Moreover, non-glazed earthenware pitches were commonly used in past for keepingdrinking water cool. Nowadays, such uses of earthenware pitches areseldom observed in villages. Although several studies have beenpublished in literature on lead, cadmium and zinc leaches from pot-teries, no study appears to report investigation of arsenic release frompotteries.
Earthenware potteries are widely produced in, beside the wellorganized big factories, small potteries in the Western Turkey. It isknown that arsenic level is high in the ground water and soil at someareas in these regions, so that that arsenic level in the earthenwaresproduced in such areas are expected to be high. Therefore, this studyhas intended to investigate leachable arsenic from glazed and non-glazed earthenware cups produced in various locations in theWesternTurkey. Acid-leaching tests have been carried out to determinewheth-er the use of glazed and non-glazed earthenwares may constitute ahuman health hazard risk to the consumers. The earthenware in thisinvestigation was not selected by a thoroughly random method andnot necessarily representative of earthenwares produced in the namedarea. The studies do, however, give an idea of the arsenic hazards ofusing earthenware.
2. Material and methods
The detailed descriptions of reagents used are available in theSupplementary data.
GBC 904 PBTmodel atomic absorption spectrometer with GBC HG-3000 continuous ow hydride generation systemwas used for arsenicdetermination. Whenever EDTA masking of the metal ion interfer-ences was necessary, a batch type hydride generation system with a20 mL reaction vessel, made in our laboratory (Fig. 1) (Erdem andHenden, 2004) was used for arsenic determination with the GBC 904PBT apparatus.
2.3. Sample collection
Unless otherwise stated, the earthenware cups used in this studywere bowls, four of which having 250 mL and the others 500 mLvolumes. 50 earthenware cups produced in various locations in theWestern Anatolia have been collected in JanuaryAugust 2010. Thesamples have been selected randomly. Before starting the chemicalanalysis, all the earthenware has beenwashedwith a commercial dishwashing detergent, rinsed with distilled water and air dried.
2.4. Arsenic measurement procedure
In all the measurements the total concentration of As(III) and As(V) was measured, using the continuous ow hydride generationsystem with AAS. The operating condition measurement parameterswere as reported earlier (ifti et al., 2011).
Whenever interferences in the arsenic determination with thecontinuous ow system was observed, concentrations of arsenic inthe leaching solutions were determined using the batch type HG-AASaccording to analytical procedure reported previously (Erdem andHenden, 2004; Ay and Henden, 2000). The sample and standardsolutions were made to contain 4.0103 mol L1 EDTA in thesemeasurements to mask the interferences.
Since As(V) does not give any signal with the batch method under
the conditions used and arsine formation efciency from As(V) is low,about only 3040%, with the continuous ow system employed, As(V)was reduced to As(III) before reduction with NaBH4 for thedetermination of total arsenic. For pre-reduction of As(V) to As(III),1 mL of concentrated HCl, 2 mL of 50 % KI and appropriate amount ofascorbic acid (to reduce I2 formed) were added on to 9 mL of thesample solution, and the solution was kept aside for 15 min for thereduction to complete. Final KI concentration was 8.3% and HClconcentration was 1 mol/L for pre-reduction. Then, the total arsenic inthe leach solutions was determined as As(III) using HG-AAS.
2.5. Leaching tests
All earthenware was washed with a dish washing detergent,rinsed with distilled H2O and air dried. For the leaching tests withwater, the earthenware was lled with drinking water and waited for24, 48, 72 and 144 h at room temperature. 20 mL of each solution wastaken and acidied by adding 0.25 mL concentrated HCl. The solutionswere analysed for arsenic by preparing the calibration graph usingarsenic standards in 0.1 mol L1 HCl.
For the investigation of acid leachable arsenic the standardmethodof American Society for Testing and Materials (1973) was used. Forthe leaching tests with acetic acid, all the cups were lled with dailyprepared 4% acetic acid. The solutions were waited for 24 h at roomtemperature. After arsenic determination in the rst leachate, all cupswere rinsed again with distilled H2O and air dried again. Then, for thesecond leaching test, the same cups were lled with 4% acetic acid andkept aside for another 24 h. Arsenic concentrations in the acetic acidleachates were determined using the calibration graph drawn witharsenic standards in 4% acetic acid.
For the leaching tests with 1% citric acid, the procedure used foracetic acid leaching was employed, except that the calibration graphwas drawn with arsenic standards in 1% citric acid.
3. Results and discussion
3.1. Analytical gures of merit
Linear calibration graphs were obtained in the range, 520 g L1
As(III) using the continuous ow and 1060 g L1 As(III) with thebatch method. For the continuous ow system, the limit of detection(LOD), dened as the concentration equivalent to three times thestandard deviation (n=10) of the reagent blank was 0.5 g L1.Relative standard deviation of arsenic determination in the leachsolutions varied between 2% and 8% in the calibration range used.Recoveries of added As(III) and As(V) to the leachates weremore than90%.
3.2. Leaching of arsenic with drinking water
Turkish villagers used to keep, particularly in the past, their drinkingwater in non-glazed earthenware pitchers in order to obtain cool water.We thought that these containers could cause arsenic leaching into thewater stored. In order to evaluate arsenic leaching, the standard potterytesting method established by ASTM (ASTM, 1994) was used. Fiveearthenware bowls were tested for arsenic leaching. The results areshown in Table 1, indicating that the arsenic leachate concentrationsranged widely, from below the limit of detection (BLD) to 39.2 g L1,among the ve earthenware bowls tested. According to these results,arsenic leaching increaseswith increasing leaching time. However, aftervery long leaching time (144 h) the arsenic concentrations decrease,possibly because of the arsenic back-sorption by the potteries from theunacidied solutions. Some of the arsenic leachate levels far exceededWHO permissible limits of arsenic for drinking water (10 g L1),posting a signicant risk for arsenic contamination of drinking water
stored in such earthenware.
3.3. Leaching of arsenic with 4% acetic acid
4% acetic acid, which is much closer to real situation, is used in theleach test. Under acidic conditions, leaching of heavy metal is high anddiminishes as pH increases. In this study the standard American Societyfor Testing andMaterials (1973) method was employed. Tables 2 and 3show arsenic concentrations in the leachates with 4% acetic acid fromglazed and non-glazed earthenware, respectively. Arsenic releasebehaviors of the parallel samples in most cases were incomparable,and, therefore, the result of each leaching was given separately in theTables. Arsenic concentrations in the leachates of glazed earthenwarewere low, in the range, BLD 13.9 g L1. Structure of the glaze is
of acetic acid even after several successive leachings with acetic acid.
Table 1Concentration of arsenic (g L1) in leachates from non-glazed earthenware withdrinking water.
Arsenic concentration (g L1)
Leaching time (h)
24 48 72 144
A BLDa BLDa BLDa BLDa
B BLDa BLDa BLDa BLDa
C1 BLDa 5.590.13 9.450.18 7.510.15C2 4.990.14 13.60.4 38.20.9 30.90.6D 6.170.24 10.60.3 39.20.8 31.40.8
a BLD: Below the limit of detection, 0.5 g L1.
2995E. Henden et al. / Science of the Total Environment 409 (2011) 29932996thought to prevent or reduce the leachingof arsenic. As shown inTable 3arsenic concentrations in the leachates of non-glazed earthenwareweremuch higher, varying in the range 35.3149 g L1, compared to thatof the glazed ones. This is, possibly, because the leaching solutions canpenetrate much deeper into the earthenware structure when they arenon-glazed.
Effects of successive leaching with 4% acetic acid on arsenic con-centrations in the leachates of non-glazed earthenwares were studied.Six different bowls with high arsenic leachate concentrations wereselected for this test. The results are shown in Table 4. According tothese results arsenic leaching continued even in the fth leaching.However, there is no correlation between leachingnumber and arsenicconcentration.
Table 2Concentration of arsenic (g L1) in leachates from glazed earthenware with 4% aceticacid and 1% citric acid (Whenever not mentioned the glaze is colorless).
Arsenic concentration (g L1)
4% Acetic acid leachate 1% Citric acid leachate
C1 3.820.07 12.30.5 12.40.3 63.41.2C2 4.200.10 13.00.4 18.50.6 1103C3 3.880.08 12.50.7 16.90.6 1053C4 3.810.11 13.90.4 16.50.4 99.12.9
C1-black BLDa BLDa 12.30.3 BLDa
C2-black BLDa BLDa 5.250.21 BLDa
C3-black BLDa BLDa 27.50.8 BLDa
C1-brown BLDa BLDa BLDa BLDa
E1 7.430.18 6.080.20 BLDa 30.60.9E2 7.680.21 BLDa BLDa BLDa
E3 6.140.18 5.280.15 BLDa BLDa
E4 9.240.27 8.860.27 BLDa 13.40.4F1 4.330.15 8.390.22 6.070.15 22.70.7F2 8.490.22 7.730.27 7.000.21 11.90.3F3 8.200.21 3.900.13 4.540.12 13.90.4F4 7.900.23 BLDa 5.650.15 14.20.5G1 BLDa BLDa 20.60.6...