Science of the Total Environment 409 (2011) 2993–2996

Contents lists available at ScienceDirect

Science of the Total Environment

j ourna l homepage: www.e lsev ie r.com/ locate /sc i totenv

Short Communication

Determination of arsenic leaching from glazed and non-glazed Turkishtraditional earthenware

Emur Henden ⁎, Rengin Cataloglu, Nur AksunerDepartment of Chemistry, Faculty of Science, University of Ege, 35100 Bornova, İzmir, Turkey

⁎ Corresponding author. Tel./fax: +90 232 388 82 64E-mail address: emur.henden@ege.edu.tr (E. Henden

0048-9697/$ – see front matter © 2011 Elsevier B.V. Aldoi:10.1016/j.scitotenv.2011.04.027

a b s t r a c t

a 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 earthenware is traditionally and widely used in Turkey andmost of the Mediterraneanand the Middle East countries for cooking and conservation of foodstuff. Acid-leaching tests have been carriedout to determine whether the use of glazed and non-glazed earthenware may constitute a human healthhazard risk to the consumers. Earthenware was leached with 4% acetic acid and 1% citric acid solutions, andarsenic in the leachates was measured using hydride generation atomic absorption spectrometry. Arsenicconcentrations in the leach solution of non-glazed potteries varied from 30.9 to 800 μg L−1, while the glazedpotteries varied generally from below the limit of detection (0.5 μg L−1) to 30.6 μg L−1, but in one poorlyglazed series it reached to 110 μg L−1. Therefore, the risk of arsenic poisoning by poorly glazed and non-glazed potteries is high enough to be of concern. It appears that this is the first study reporting arsenic releasefrom earthenware into food.

.).

l rights reserved.

© 2011 Elsevier B.V. All rights reserved.

1. Introduction

Arsenic is one of the most toxic elements found in nature, and itconstitutes one of the main concerns in relation to human health.Arsenic is known for its acute toxicity at high doses, as well as chroniceffects as an established human carcinogen. Long-term exposure toarsenic can cause serious health problems such as skin ailments,cardiovascular and neurological damage, bladder and lung cancer,organ failure, as well as death (Iffland, 1994; USEPA, United StatesEnvironmental Protection Agency, 2003). Arsenic in the environmentoccurs from both natural and anthropogenic sources. Persistence ofarsenic within soil and its toxicity to plants and animals is of concern.Arsenic contamination of soil results from mining, smelting of sulfideores, 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 μg of inorganic As/kg of body weight (WHO,World Health Organization, 1989). In 1993, WHO (World HealthOrganization) (1993) lowered the guideline value for arsenic indrinking water from 50 μg L−1 down to 10 μg L−1.

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 efficient 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 significantly reduces the inter-ferences (Tsalev, 2000).

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 toregion 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 theneed for cautionwhen certain types of pottery are used in contactwithfood (Shibamoto and Bjeldanes, 1993). In many countries, authoritiesfor possible release of lead and cadmium have monitored glazedceramic and pottery (Sheets, 1999; Jakmunee and Junsomboon, 2008;Tunstall and Amarasiriwardena, 2002).

Glazed and non-glazed earthenwares are traditionally and widelyused in Turkey and most of the Mediterranean and the Middle East

2994 E. Henden et al. / Science of the Total Environment 409 (2011) 2993–2996

countries 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

2.1. Reagents

The detailed descriptions of reagents used are available in theSupplementary data.

2.2. Apparatus

GBC 904 PBTmodel atomic absorption spectrometer with GBC HG-3000 continuous flow 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 January–August 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 flow hydride generationsystem with AAS. The operating condition measurement parameterswere as reported earlier (Çiftçi et al., 2011).

Whenever interferences in the arsenic determination with thecontinuous flow 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 4.0×10−3 mol L−1 EDTA in thesemeasurements to mask the interferences.

Since As(V) does not give any signal with the batch method underthe conditions used and arsine formation efficiency from As(V) is low,

about only 30–40%, with the continuous flow 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 filled with drinking water and waited for24, 48, 72 and 144 h at room temperature. 20 mL of each solution wastaken and acidified by adding 0.25 mL concentrated HCl. The solutionswere analysed for arsenic by preparing the calibration graph usingarsenic standards in 0.1 mol L−1 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 filled with dailyprepared 4% acetic acid. The solutions were waited for 24 h at roomtemperature. After arsenic determination in the first leachate, all cupswere rinsed again with distilled H2O and air dried again. Then, for thesecond leaching test, the same cups were filled 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 figures of merit

Linear calibration graphs were obtained in the range, 5–20 μg L−1

As(III) using the continuous flow and 10–60 μg L−1 As(III) with thebatch method. For the continuous flow system, the limit of detection(LOD), defined as the concentration equivalent to three times thestandard deviation (n=10) of the reagent blank was 0.5 μg L−1.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 μg L−1,among the five 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 theunacidified solutions. Some of the arsenic leachate levels far exceededWHO permissible limits of arsenic for drinking water (10 μg L−1),posting a significant risk for arsenic contamination of drinking waterstored in such earthenware.

Table 1Concentration of arsenic (μg L−1) in leachates from non-glazed earthenware withdrinking water.

Samplinglocation

Arsenic concentration (μg L−1)

Leaching time (h)

24 48 72 144

A BLDa BLDa BLDa BLDa

B BLDa BLDa BLDa BLDa

C1 BLDa 5.59±0.13 9.45±0.18 7.51±0.15C2 4.99±0.14 13.6±0.4 38.2±0.9 30.9±0.6D 6.17±0.24 10.6±0.3 39.2±0.8 31.4±0.8

a BLD: Below the limit of detection, 0.5 μg L−1.

Table 3Concentration of arsenic (μg L−1) in leachates from non-glazed earthenware with 4%acetic acid and 1% citric acid.

Samplinglocation

Arsenic concentration (μg L−1)

4% Acetic acid leachate 1% Citric acid leachate

Leachingnumber 1

Leachingnumber 2

Leachingnumber 1

Leachingnumber 2

H1 92.0±3.6 58.9±2.9 55.9±1.7 31.4±1.1H2 141±4 87.4±3.5 76.6±2.1 40.7±1.6H3 120±5 90.2±2.7 64.0±1.6 30.9±0.9B1 136±4 95.8±3.3 136±4 467±12B2 126±3 113±4 126±3 181±7B3 149±3 102±3 148±4 267±8D1 37.5±1.1 35.3±1.2 67.4±2.1 197±6D2 44.8±1.3 54.0±2.2 98.6±2.5 94.4±2.3D3 39.1±1.1 48.9±1.5 122±4 93.8±2.8D4 63.0±1.9 46.7±1.2 97.3±3.8 142±3

2995E. Henden et al. / Science of the Total Environment 409 (2011) 2993–2996

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 μg L−1. Structure of the glaze isthought to prevent or reduce the leachingof arsenic. As shown inTable 3arsenic concentrations in the leachates of non-glazed earthenwareweremuch higher, varying in the range 35.3−149 μg L−1, 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 fifth leaching.However, there is no correlation between leachingnumber and arsenicconcentration.

Table 2Concentration of arsenic (μg L−1) in leachates from glazed earthenware with 4% aceticacid and 1% citric acid (Whenever not mentioned the glaze is colorless).

Samplinglocation

Arsenic concentration (μg L−1)

4% Acetic acid leachate 1% Citric acid leachate

Leachingnumber 1

Leachingnumber 2

Leachingnumber 1

Leachingnumber 2

C1 3.82±0.07 12.3±0.5 12.4±0.3 63.4±1.2C2 4.20±0.10 13.0±0.4 18.5±0.6 110±3C3 3.88±0.08 12.5±0.7 16.9±0.6 105±3C4 3.81±0.11 13.9±0.4 16.5±0.4 99.1±2.9C1-black BLDa BLDa 12.3±0.3 BLDa

C2-black BLDa BLDa 5.25±0.21 BLDa

C3-black BLDa BLDa 27.5±0.8 BLDa

C1-brown BLDa BLDa BLDa BLDa

E1 7.43±0.18 6.08±0.20 BLDa 30.6±0.9E2 7.68±0.21 BLDa BLDa BLDa

E3 6.14±0.18 5.28±0.15 BLDa BLDa

E4 9.24±0.27 8.86±0.27 BLDa 13.4±0.4F1 4.33±0.15 8.39±0.22 6.07±0.15 22.7±0.7F2 8.49±0.22 7.73±0.27 7.00±0.21 11.9±0.3F3 8.20±0.21 3.90±0.13 4.54±0.12 13.9±0.4F4 7.90±0.23 BLDa 5.65±0.15 14.2±0.5G1 BLDa BLDa 20.6±0.6 16.2±0.4G2 BLDa BLDa 22.7±0.5 21.0±0.6G3 BLDa BLDa 18.9±0.4 16.2±0.4A BLDa BLDa BLDa BLDa

a BLD: Below the limit of detection, 0.5 μg L−1.

3.4. Leaching of arsenic with 1% citric acid

1% citric acid is another leaching solution for pottery control usedin the literature (Sheets, 1997; Villalobos et al., 2009). Leaching testsof glazed and non-glazed potteries involve filling each pottery with 1%citric acid and allowing it to stand for 24 h. In this study, extractionwas repeated twice for each earthenware cups and arsenic analyseshave been performed. The results are shown in Tables 2 and 3. In mostcases arsenic concentrations in the citric acid leachates were higherthan that in the acetic acid leachates, similar to that reported earlierfor lead and cadmium (Sheets, 1997; Villalobos et al., 2009). Thehigher arsenic leaching into citric acid can be attributed to higheracidity of the citric acid solution, and, moreover, possibly to the moreaggressive complexing capacity of citric acid compared to acetic acid.

According to the results in Tables 2 and 3, arsenic concentrations inthe leachate of the non-glazed earthenware were found to be muchhigher than that of the glazed ones, except glazed earthenware fromsampling location C. High arsenic concentrations in the second citricacid leachates of the glazed bowls from the location C in Table 2 maybe due to the apparent deformation of the glazes. This may be a signof danger of possible arsenic release by time as the poorly glazedearthenware used. Moreover, arsenic from some non-glazed cupsleached into the acetic acid and citric acid leach solutions at muchhigher concentrations than the maximum allowable limit concentra-tion for drinking water.

In another series of experiments, following five successive leachingswith 4% acetic acid, two successive leachings were also done with 1%citric acidusing the sameearthenware. The results shown in Table 4 alsodemonstrate that arsenic leachingby citric acid ismuchhigher than thatof acetic acid even after several successive leachings with acetic acid.

4. Conclusion

Earthenware is traditionally used in Turkey and most of theMediterranean and the Middle East countries for cooking andconservation of foodstuff. No study appears to report investigation ofarsenic release frompotteries and earthenware into food. This study hasshown that arsenic is leached from well glazed earthenware into4% acetic acid and 1% citric acid at very low concentrations. Whereasarsenic leaching from non-glazed or poorly glazed earthenwareproduced in some of the studied areas were seriously high. Such non-glazed earthenware leached arsenic, at relatively high level, even intowater without acid addition. High concentrations of arsenic in theseearthenware aremost probably due to the arsenic present in the soils orwater used for themanufacture of these cups in these regions. It appearsthat there is no limit value given for arsenic leaching from potteries inthe standards. However, the results in this study show that arse-nic leaching from earthenware need to be controlled by regulations.

Table 4Arsenic leaching from non-glazed earthenware in successive leaching tests.

Samplinglocation

Arsenic concentration (μg L−1)

4% Acetic acid leachate 1% Citric acid leachate

Leaching number 1 Leaching number 2 Leaching number 3 Leaching number 4 Leaching number 5 Leaching number 1 Leaching number 2

J1 164±4 130±3 183±5 177±5 305±8 699±17 348±7J2 145±3 148±3 173±4 160±4 338±8 800±20 351±9J3 159±5 131±4 157±4 162±5 258±6 682±15 325±7C1 231±7 141±3 135±4 107±3 101±2 205±4 119±3C2 148±3 89.2±2.2 92.0±2.7 76.9±1.6 79.2±2.4 167±3 104±3D 81.2±2.1 120±3 190±5 153±4 192±6 509±10 474±8

2996 E. Henden et al. / Science of the Total Environment 409 (2011) 2993–2996

Therefore, the risk of arsenic poisoning by non-glazed and poorly glazedearthenware is high enough to be of concern.

Supplementarymaterials related to this article can be found onlineat doi:10.1016/j.scitotenv.2011.04.027.

Acknowledgements

The support of the Ege University Research Foundation is acknowl-edged with gratitude. We would like to thank Tülin Deniz Çiftçi andOnur Yayayürük for their contributions during this study.

References

American Society for Testing and Materials. Standard test method for lead andcadmium extracted from glazed ceramic surface. Method C 1973;738:483–4JADAC, 56.

ASTM test method for lead and cadmium extraction from glazed ceramic surfaces,C738-94. American Society for Testing and Materials, Philadelphia, PA, USA, 1994.

Ay Ü, Henden E. Interferences in the quartz tube atomizer during arsenic and antimonydetermination by hydride generation atomic absorption spectrometry. Spectro-chim. Acta Part B 2000;55:951–8.

Çiftçi TD, Yayayürük O, Henden E. Study of arsenic(III) and arsenic(V) removal fromwaters using ferric hydroxide supported on silica gel prepared at low pH. Environ.Technol. 2011;32:341–51.

Dedina J, Tsalev DL. Hydride generation atomic absorption spectrometry. New York:Wiley; 1995.

Erdem N, Henden H. Inter-element interferences in the determination of arsenic andantimony by hydride generation atomic absorption spectrometry with a quartztube atomizer. Anal. Chim. Acta 2004;505:59–65.

Garcia-Manyes S, Jimenez G, Padro A, Rubio R, Rauret G. Arsenic speciation incontaminated soils. Talanta 2002;58:97-109.

Iffland R. In: Seiler HG, Sigel A, Sigel H, editors. Handbook on metals in clinical andanalytical chemistry. New York: Marcel Dekker; 1994. p. 237–53.

Jakmunee J, Junsomboon J. Determination of cadmium, lead, copper and zinc in theacetic acid extract of glazed ceramic surfaces by anodic stripping voltammetricmehod. Talanta 2008;77:172–5.

Mandal BK, Suzuki KT. Arsenic round the world: a review. Talanta 2002;58:201–35.Phelps GW. Ullmann's Encyclopedia of Industrial Chemistry, Vol. A6. fifth ed.

Weinheim: VCH; 1986.Rhodes D. Clay and glazes for the potter. Radnor, PA: Chilton Book; 1973.Sheets RW. Extraction of lead, cadmium and zinc from overglaze decorations on

ceramic dinnerware by acidic and basic food substances. Sci. Total Environ.1997;197:167–75.

Sheets RW. Acid extraction of lead and cadmium from newly-purchased ceramic andmelamine dinnerware. Sci. Total Environ. 1999;234:233–7.

Shibamoto T, Bjeldanes LF. Introduction to food toxicology. New York: Academic Press;1993.

Tsalev DL. Vapor generation or electrothermal atomic absorption spectrometry?—Both!Spectrochim. Acta Part B 2000;55:917–33.

Tunstall S, Amarasiriwardena D. Characterization of lead and lead leaching properties oflead glazed ceramics from the Solis Valley, Mexico, using inductively coupledplasma-mass spectrometry (ICP-MS) and diffuse reflectance infrared Fouriertransform spectroscopy (DRIFT). Microcem. J. 2002;73:335–47.

USEPA (United States Environmental Protection Agency). Workshop on managingarsenic risks to the environment: characterization of waste, chemistry, andtreatment and disposal: EPA/625/R-03/010; 2003.

Villalobos M, Merino-Sánchez C, Hall C, Grieshop J, Gutiérrez-Ruiz ME, Handley MA.Lead (II) detection and contamination routes in environmental sources, cookwareand home-prepared foods from Zimatlán, Oaxaca Mexico. Sci. Total Environ.2009;407:2836–44.

WHO (World Health Organization). Toxicological evaluation of certain food additivesand contaminants. Food Additive Series 24. Geneva (Switzerland: WHO; 1989.

WHO (World Health Organization). Guidelines for drinking water quality. 2nd edition.Geneva (Switzerland): WHO; 1993.