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Total reflection X-ray fluorescence analysis of trace-elements in candies marketed in Mexico
Spectrochimica Acta Part B 65 (2010) 499–503
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Spectrochimica Acta Part B j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / s a b
Analytical note
Total reflection X-ray fluorescence analysis of trace-elements in candies marketed in Mexico☆ T. Martinez a,⁎, J. Lartigue a, G. Zarazua b, P. Avila-Perez b, M. Navarrete a, S. Tejeda b a b
Facultad de Química, Departamento de Química Inorgánica y Nuclear. Universidad Nacional Autónoma de Mexico, Mexico, DF.04510, Mexico National Institute of Nuclear Research. Ocoyoacac, Edo. de Mexico, 05045, Mexico
a r t i c l e
i n f o
Article history: Received 13 August 2009 Accepted 9 April 2010 Available online 18 April 2010 Keywords: Candies Trace elements Total reflection X-ray fluorescence
a b s t r a c t Trace metals concentrations in food are significant for nutrition, due either to their nature or toxicity. Sweets, including chewing gum and candies, are not exactly a food, but they usually are unwearied consumed by children, the most vulnerable age-group to any kind of metal contamination in the food chain. The presence of relatively high concentrations of heavy metals such as Lead elicits concern since children are highly susceptible to heavy metals poisoning. Trace-metals concentrations were determined for six different flavors of a Mexican candy by means of Total X-ray Fluorescence Spectrometry. Triplicate samples of the various candy's flavours (strawberry, pineapple, lemon, blackberry, orange and chilli) were digested in 8 mL of a mix of supra-pure HNO3 and H2O2 (6 mL: 2 mL) in a microwave oven MARS-X. Results show the presence of essential and toxic elements such as Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, and Pb. All metal concentrations were higher and significantly different (α = 0.05) in chilli candy, compared to other candy flavours. Lead concentration fluctuated in the range of 0.102 to 0.342 μg g− 1. A discussion about risk consumption and concentration allowed by Mexican and International Norms is made. As a part of the Quality Control Program, a NIST standard of “Citrus Leaves” and a blank were treated in the same way. © 2010 Elsevier B.V. All rights reserved.
1. Introduction Trace elements are those of the periodic table occurring in animals and humans, amounting to micrograms (or less) per body-weight gram [1]. Humans require all of the trace elements in quantities amounting miligrams per day [2]. Some of these are considered as indispensable for growth and health, while the remaining are not [3] or they are toxic [4]. Some of the non-essential trace elements can also be beneficial for health through pharmacological action [5] and all of the trace elements are toxic if consumed in excess. Trace elements, such as Cd, Cr (VI), Ni, As, Hg and Pb, are major toxics [4], the first four being known as carcinogens, while Pb has been classified as 2B carcinogen by the International Agency for Research on Cancer (IARC) [4]. The last two are well-known antagonists of the central nervous system. Lead is a major toxic element and one of the most comprehensively studied [6,7]; its effects on young people's brain and behaviour are well known [8]. Trace-metal composition of food is interesting because of its essential or toxic nature. Trace-metal content of food is directly taken
☆ This paper was presented at the 13th Conference on Total reflection X-ray Fluorescence Analysis and Related Methods (TXRF 2009), held in Gothenborg, Sweden, 15–19 June 2009, and is published in the Special Issue of Spectrochimica Acta Part B, dedicated to that conference. ⁎ Corresponding author. Tel./fax: +52 55 56225232. E-mail address: [email protected] (T. Martinez). 0584-8547/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.sab.2010.04.002
into the body [5]. Sweets, including chewing gums and candies, are not food; they, however, are assiduously consumed by children and pregnant women, the most sensitive and vulnerable age-group to any kind of metal contamination [1]. The relatively high metal concentrations in children-consumed products that are heavily marketed elicits special concern because children are particularly sensitive to them [9]. The environmental program of the Faculty of Chemistry of the National University of Mexico has been approaching the determination of trace metals, especially lead, in several types of biological and environmental samples [10–15]. The present work is aimed to identify lead and other trace-elements concentrations in six distinctly flavored samples of a highly-consumed candy in Mexico, and to analyze the actual risks they pose. Total X-ray fluorescence spectrometry was adopted because it is a well-established technique for multi-element determination of trace elements in various types of matrices [16]. 2. Experimental 2.1. Sampling Six samples of one of the most consumed candy in the Mexican market (“M”) were randomly purchased in local grocery stores, each one distinctly flavored as follows: pineapple (sample MS1), orange (MS2), lemon (MS3), blackberry (MS4), strawberry (MS5) and Chili (MS6). Ingredients of these six candies are as follows: iodized salt, sugar, citric acid, soybean, flour, flavors and artificial colors plus “chile
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piquín” in sample MS6. The net weight for the first five samples was 3 g and 5 g for the latter, all of them legally registered in the Mexican Department of Health (SS). 2.2. Sample preparation Wrapping paper was carefully separated from candies. Three 0.5 g replicates for each of the samples were prepared to evaluate measurement reproducibility. Simultaneously and according to the Quality Control Program, two blanks and two sub-samples of the standard reference material – (SRM) NIST 1572 “Citrus Leaves” – were equally treated. All samples were subjected to acidic digestion with 7 mL as total volume (5 mL of HNO3, 1 mL of HCl and 1 mL of H2O2 of supra-pure grade-quality) in a closed-digestion vessel in a microwave oven “CEM-Mars-X”, according to 5AG-1 method for “Citrus Leaves” as modified by G. Zarazua [17]. The digested sample was transferred into a volumetric flask; the reaction vessels were washed out with deionized water; the flask made up to 10 mL final volume. As internal standard, 100 µL of Ga standard solution (10 µg mL− 1) were added to each of the digested samples and then mixed; 10 µL of the resulting mixture were deposited into a silicon quartz reflector and dried under infrared light. 2.3. Sample analysis Trace element analysis was performed by Total Reflection X-ray Fluorescence Spectrometry (TXRF) in an Ital-Structures Total Refection X-ray Fluorescence Spectrometer Model TX-2000. The tube was operated at 40 kV and 30 mA. The emanated fluorescent X-ray was detected by means of a 20-mm2-front-area solid-state lithiumdrifted silicon detector, cooled by liquid nitrogen. The Si (Li)-detector energy resolution (FWHM) was 140 eV for Mn Kα, while its beryllium window was 8 µm thick; counting time was 1000 s. Samples and standard-reference material were counted by triplicate. Analysis of the spectra and quantification of trace element were made by “EDXRF32-Ital Structures” Software (Version 2.051), according to “Sensitivities with internal standard” theoretical method [18,19]. 3. Results and discussion Validation of accuracy and reproducibility was made by measuring trace-elements concentration in the standard reference material NIST 1572 “Citrus leaves”; comparison between certified and obtained values is shown in Table 1. As can be seen, the measured concentration is consistent with certified values. The Relative Error Percentage (RE %) varied from 2% to 13%. Accuracy measured as the percentage of recoveries after acid digestion (difference between RE
Table 1 Comparison between measured and certified elements concentration (μg g− 1) for the NIST 1572 “citrus leaves”. Element
Certified values concentration ± SD 1
Obtained values concentration ± SD 1
DL2 μg g−1
3RE %
Ca* Ti Cr Mn Fe Ni Cu Zn Br Rb Sr Pb
3.15 ± 0.10 NR 0.80 ± 0.2 20 ± 2 90 ± 10 0.6 ± 0.3 16.5 ± 1 29 ± 2 8.2 ± ** 4.84 ± 0.06 100 ± 2 13.3 ± 2.4
3.20 ± 0.06 bDL 0.75 ± 0.3 20 ± 1 92 ± 1 b0.7 16.1 ± 0.5 30 ± 1 8.7 ± 0.18 4.72 ± 0.33 95 ± 1 12.9 ± 0.3
0.1 0.05 0.06 0.04 0.04 0.06 0.03 0.03 0.02 0.02 0.02 0.03
+ 1.6
*%. 1. Standard deviation. 2. Detection limit. 3. % relative error. **Not reported (concentration value is not certified). NR. not reported.
− 6.25 − 13 +2 − 2.4 −3.3 + 6.1 − 2.5 −5 −3
percentage to 100%) was higher than 94%, excepting Mn, 87%. The Relative Standard Deviation or Coefficient of Variation for all of the elements was lower than 7%, in the range of those of the Standard Reference Material; the exception was Cr, 40%, although slightly higher than those of the SRM (25%). Detection limits (DL) for the experimental conditions are also shown. Fig. 1 shows comparison between the spectra of samples MS2 (orange) and MS6 (chilli). Sample MS6 shows the highest concentration for all of the elements. The cumulative order of trace metals in samples generally was Ca N Fe N Mn N Ti N Zn N Ni N Cu N Sr N Rb ≥ Br N Cr ≥ Pb. As mentioned before and as it can be seen in Fig. 2, sample MS6 (chili) shows the highest concentration of Pb, followed by sample MS5 (strawberry). A previous study has found that strawberry and other fruits show high Pb concentration. Pb concentration in oranges in the same study, 0.15 ± 0.08 µg g− 1 [20], is similar to that found in sample MS2 (orange). In general, concentrations for all elements, especially Pb, in samples MS1 to MS5 were between 30 to 50% of those of sample MS6. Data generated during the study was processed by means of various statistical tests with Statgraphics V.5 Plus (Manugistic 2000) software, such as standard deviation and the One-Way Analysis of Variance. The chosen significance level was 0.05 (equivalent to 5%). Results show that the mean concentration for all of the elements was higher and significantly different (α = 0.05) for sample MS6 (chilli) when compared to the rest. Fe, Ni, Cu, Zn, Pb, Br and Sr mean concentrations in MS5 (strawberry) were significantly different to others flavours. For sample MS4 (blackberry), Cu, Zn, Cr, Pb, and Br mean concentrations were significantly different from those of other flavours. Zn, Cu and Br mean concentrations were significantly different among all of the flavours. Table 2 shows trace-element concentration of the six samples. Relative Standard deviation or Variation Coefficient ranged from 1 to 7%, the range obtained for the standard-reference material. It also shows trace-elements concentration and Maximum Permissible Levels (MPL) found in the literature for similar products: chewing gum, chocolate, cocoa-sugar mixtures, sweet candy, etc. Ca, Cr (III), Mn, Fe, Cu and Zn, are considered as essential trace nutrients [21]; they make up less than 0.01% of the dry weight of a given organism and are required for normal health function and development [22]. As a trace nutrient, Chromium (III) serves as a component of the glucose-tolerance factor [4]. It works as co-factor for insulin action and has a role in its peripheral activity by forming a ternary complex with insulin receptor, so facilitating the insulin fixing and influencing carbohydrate, lipid and protein metabolism. Cr (VI), however, it is mentioned as carcinogenic. The Cr concentrations obtained in this study, as it can be seen in Table 2, were lower than the range of those of the chewing gum, candies marketed in Turkey [1] and other commercial sweets [23], while Cu concentrations were in the range of those obtained for chewing gum and candies marketed in Turkey [1] and commercial sweets [2]. Cu is an essential element of several enzymes; it functions as a biocatalyst and it is necessary for body pigmentation (in addition to Fe) in maintaining a healthy central system, preventing anemia, and it is interrelated to the function of Fe and Zn in the body [24]. The permissible level of Cu in both chewing gums and candy is 10 µg g− 1, according to Turkish Standards [25,26], 5 µg g− 1 for chocolate and cocoa-sugar mixtures in Spain's legislation [27] and for the same products 15 and 50 µg g− 1 respectively [28]. Results of Fe concentration for all of the analyzed samples were in the range of 8.9–25.42 µg g− 1. Like the rest of results, iron level in sample MS6 (chili) was higher than fruit-flavored candies. The iron concentration was much the same that the highest concentration reported in selected sweets from Karachi City [2], fluctuating into the range of those for potato chips and biscuit from Nagpur City, India [5] and other types of foods [28]. Mn is a co-factor for a number of enzymatic reactions, particularly those involved in phosphorilation,
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Fig. 1. Total X-ray fluorescence spectra of samples MS6, chili (upper line) and MS2, orange (lower line).
cholesterol, and fatty-acids synthesis; Mn concentration for samples in this study were in the reported ranges [1,2,5]. From a preliminary survey of children's preferences, it was found that chili-based candies are the first choice. Taking into account the highest concentration of studied trace elements in sample MS6 (chili) and in an extreme consume-case of 10 candies per day (50 g day− 1), the calculated intake (µg day− 1) of each one element in this study is shown in Table 3. As it can be seen, calculated intakes were lower than the Reference Daily Intake or Reference Dietary Intake (RDI) [21, 29)] by far, as expected and varying between 1.5 to 65%. RDI is defined as “the level of intake of essential nutrients, on the basis of scientific knowledge, that are judged by the Food and Nutrition Board to be adequate to meet the known nutrients needs of practically all healthy persons” [21,29]. The accepted RDIs showed for comparison in Table 3 are stipulated for children aged 1–10 years old [29]. Ni has been identified as a respiratory-tract carcinogen in the nickel industry's workforce [4]. Nickel probably is an essential trace metal for mammals and plants, according to growing evidence in several studies. In trace amounts, nickel may be beneficial as an activator for some enzyme systems [30]. At higher levels, its
accumulation in lungs may cause bronchial hemorrhage. Ni is poorly absorbed from diet (less than 5%) and it is evacuated by feces. Nickel concentration for all samples varied from 0.1 to1.83 µg g− 1, in the range of selected sweets in Karachi City [2] and in chewing gums and candies in Turkey [1], and in the lower range of chocolates and candies from Munbai, India [31]. Ni concentrations in samples do not affect the daily intake because oscillated between 13 and 31% of RDI [29], taking into account the maximum and minimum values of this standard. Br is at this time under discussion as an essential element, provided its effects on growth have been tested in experimental animals, although none essential function has conclusively been shown [29]. Br content in candies oscillates from 0.19 to 1.27 µg kg− 1. Calculated daily intake is 63.5 µg day− 1, lower than the maximum acceptable amount of Br intake (1 mg kg− 1) in respect to bodyweight per-day, according to the World Health Organization (WHO) [32]. Estimated daily intake of bromine worldwide from food and water is 1 mg–3 mg per day [29]. As it can be seen in Table 2, Pb concentration varies from 0.102 ± 0.007 to 0.342 ± 0.009 µg g− 1, higher than the maximum level of 0.1 µg g− 1, as recommended by the U.S Food and Drug Administration
Fig. 2. Distribution of some important elements (μg g− 1) in candies samples.
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Table 2 Elemental concentration in candies samples and Maximum permissible levels, MPL in (µg g−1). Element
MS1
MS2
MS4
MS5
MS6
Ca Ti Cr Mn Fe
236 ± 10 2.53 ± 0.11 0.14 ± 0.01 2.15 ± 0.06 10.42 ± 0.18
230 ± 14 2.31 ± 0.18 0.16 ± 0.01 2.21 ± 0.06 16.76 ± 0.28
MS3 322 ± 9 4.28 ± 0.19 0.12 ± 0.01 1.79 ± 0.12 9.22 ± 0.43
233 ± 3 3.83 ± 0.24 0.088 ± 0.01 2.02 ± 0.06 8.91 ± 0.80
237 ± 7 3.89 ± 0.29 0.15 ± 0.01 2.43 ± 0.08 21.30 ± 0.46
377 ± 10 5.41 ± 0.41 0.39 ± 0.02 7.65 ± 0.27 25.42 ± 0.29
Ni Cu Zn Br Rb Sr Pb
0.94 ± 0.03 2.41 ± 0.06 1.95 ± 0.10 0.33 ± 0.02 0.34 ± 0.01 1.57 ± 0.02 0.167 ± 0.002
0.14 ± 0.01 1.21 ± 0.01 2.35 ± 0.07 0.41 ± 0.01 0.34 ± 0.004 1.45 ± 0.05 0.140 ± 0.004
0.12 ± 0.01 2.74 ± 0.08 2.22 ± 0.01 0.56 ± 0.02 0.36 ± 0.01 2.22 ± 0.15 0.146 ± 0.009
0.10 ± 0.05 1.44 ± 0.04 1.58 ± 0.06 0.26 ± 0.002 0.34 ± 0.01 1.44 ± 0.03 0.102 ± 0.007
1.25 ± 0.11 1.07 ± 0.02 1.32 ± 0.03 0.19 ± 0.02 0.34 ± 0.01 1.26 ± 0.03 0.173 ± 0.006
1.83 ± 0.02 1.66 ± 0.03 3.07 ± 0.12 1.27 ± 0.02 1.23 ± 0.07 2.56 ± 0.03 0.342 ± 0.009
Literature reference [#]
MPL
0.74–6.27 [1] 30.4–72 [23];0.5–1.6 [5] 4.5–11.5 [2]; 0.5–8.25 [5]; 1.9–5 [1] 3.96–9.86 [1]; 0.2–25 [28]; 0.4–19 [ 2] 8.7–36.25 [5] 0.12–2.59[1]; 0.1–3.8 [2]; 0.04–8.2 [31 ] 0.22–2.5 [1]; 0.07–4.0 [2];1.05–4.7 [5] 0.8–15.8 [5]; NF NF NF 0.049–8.4[31]; 0.3–3.5 [2];0.03–2.46 [1] 9.98–0.13 [5]
10 [1]; 5 [23]: 15, 50 [24]
1, 2 [25,26]; 1 [28] 0.1[33]; 0.2μg [34]
MPL = Maximum permissible level. NF = Not found.
(FDA) and the California Department of Public Health (CDPH). Yet, it falls into the range of 0.5 µg g− 1 previously accepted level [33]. This is equivalent to the Food Chemical Codex (FCC) specification for Pb in sucrose (sugar), the main ingredient for many candy products [34]. Pb concentrations obtained in this study were similar to those reported by the California Department of Public Health [35] in August 2007, for salt/sugar mix flavored candies, samples F07C00951 to F07C00954. Exception made of sample MS6, the rest rank below the Mexican Norm, 0.2 µg g− 1 [36]. The higher concentration found in sample MS6 could be explained by chili-powder action which, as previously reported [33], contains a broad range of Pb levels, perhaps due to bad handling prior to chili grinding. Several dietary factors, such as nutritional status and Pb chemical form, stimulate the human absorption of this metal. In general, food-intake patterns could also influence Pb absorption. Pre-school children's intake of both foods and non-food items (e.g. toys soil/dust) is a matter of concern [37]. Ziegler, et al. [38] reported that young children, aged two weeks to two years, absorbed 42% of ingested Pb at intake levels greater than 5 µg kg− 1 body weight. Drill, et al. [39] estimated an absorption rate of 17% for Pb in paint chips in children aged 2–3 years, and 30% gastrointestinal absorption for Pb from soil and dirt. The amount of Pb ingested by children from non-food items such as soil, dust and paint chips through normal mouthing activity is a major concern in calculating Pb exposure. Such a risk has been reduced in Mexico and others countries by enforcing norms [9]. Pb-exposure for children consumers and related health risks are here expressed as the Provisional Tolerable Weekly Intake (PTWI) and Provisional Tolerable Daily Intake (PTDI). As it can be seen in Table 3, the calculated Pb daily-intake of 17.1 µg and the calculated weeklyintake of 119.7 µg were lower, (32%) than the PTWI of 25 µg kg− 1 per
body weight [40], which is equal to 375 µg week− 1 and 53.6 µg d− 1 for a 15 kg body-weight child. For the purpose of establishing a quantitative and significant relationship between the intake of Pb (through food) by children and blood lead levels (BLLs), the Joint FAO/ WHO Expert Committee on Food Additives (JECFA) accepted the conversion factor of 0.16 µg dL− 1 per 1 µg of lead intake per day. This latter was adopted by the International Programme on Chemical Safety (IPCS) Task Group [40]. For the calculated daily intake, this means a BLL of 2.74 µg Pb dL− 1. This relationship is equivalent to the 27.4% rate of the indicative levels of WHO and the Mexican norm for pregnant women and children, of 10 µg dL− 1 [41]. In Mexico City [11] it has been reported a geometric mean of 2.79 µg dL− 1 for the 0– 10 age-group, similar to those of National Nutrition Examination Surveys, NHANES III, phase 2 (2.7 µg dL− 1). Beside of this and considering an absorption rate of 42% through the gastrointestinal tract for young children at high rates of intakes [36] it gives a calculated total daily intake of 7.18 µg d− 1of Pb. This latter slightly higher than the FDA's Provisional Total Tolerable Intake Level (PTTIL) by small children of 6 µg d− 1 [33,42] and translating it into a BLL of 1.15 µg Pb dL− 1, being equivalent to the 11.5% rate of the indicative levels of WHO and the Mexican Norm [41]. FDA' PTTIL corresponds [42] to a Pb intake capable of elevating the BLL's of a small child by 1 µg dL− 1. Varying input values (intake and Pb levels) and using the Monte Carlo simulation [33], the FDA calculated PTTIL 6 µg d− 1 and its current recommended maximum Pb level of 0.1 µg g− 1 for candies. Furthermore, a recently published law in California [43] requires the Office of Environmental Health Hazard Assessment (OEHA) to develop acceptable standards for the naturally Pb occurring-level in candies, and assumes that the Pb “naturally occurring level” in candies is only “natural” [44] to the extent that it is not avoidable by good
Table 3 RDIs, calculated intake, %RDIs and PTDI, PTWI for Pb (daily intake; 50 g, sample MS6). Element
RDI (mg d−1) except as indicated and 1–10 years old
Calculated intake (μg d− 1)
% RDI for 1– 10 years old
Ca Ti Cr Mn Fe Ni Cu Zn Br Rb Sr Pb
600–800
18.9 270.5 19.5 382.5 1271 91.5 83 153.5 63.5 61.5 128 17.1
2.4–3.2
30–50& 1–3 10–15 300–700& 1–2.5 10 None. 15 * None
& = (μg d− 1); * = Maximum acceptable level [32].
PTDI (μg d− 1) children 15 kg B.W.
PTWI (μg w− 1) children 15 kg B.W.
Calculated DI (μg d− 1) children 15 kg B. W.
CalculatedWI (μg w− 1) children 15 Kg B. W.
Calculated % PTDI and PTWI
53.6
375
17.1
119.7
32
39–65 13–38 8.5–13 13–30.5 .3–8 1.5 0.4*
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agriculture, manufacturing, and procurement practices currently feasible. Pb background levels in soil [45] are in the range of 10– 70 µg g− 1. For Mexican agricultural soils, Pb concentration are in the lower value (6 µg g− 1); it has also been shown [46] that 3.2% of lead concentration is incorporated in chili, which means an average concentration of 0.2 to 0.3 µg g− 1 from natural origin, similar to those found in chili-flavored candies. In a first attempt to establish sources especially for Pb, the Pearson Correlation coefficients of metallic elements were obtained. High Pearson correlation coefficients (r N 0.8) were found between Pb with most of the elements, including Rb (r N 0.95), which possibly indicates a natural origin. The exceptions were Cu and Ti for which Pb was negatively correlated (r =−0.1). 4. Conclusions 1. The experimental results for the Reference Standard Material NIST1572, Citrus Leaves and samples show that the digestion procedure and the TXRF technique provide precise (reproducible) and accurate (trueness) data for specific elements in candy samples. 2. The mean concentration for all of the analyzed elements was highest in sample MS6 (chili), significantly different (α = 0.05) if compared to others candy flavours, mainly due to higher Pb-content in dry chili. 3. Pb concentrations in Mexican candies are lower than those specified by the Mexican norm, excepting chili-flavored candies, which are slightly higher than the current FDA and CDPH recommended maximum Pb level. In order to probe that Pb in candies (mainly in sample MS6-chili) comes either from natural sources or bad agricultural and manufacturing practices, it would be needed to perform a lead-isotopic ratio-study. [As well, it could be useful to accomplish a research on the Pb content in different chili species] 4. It could be concluded that our estimated daily intake for the studied elements are below RDIs, PTDIs, PTWIs and PTTIL standards. Thus, consume average amounts of these candies seem not to pose a health-risk for the consumer. Besides, and considering that Pb comes to small children not only through candies but primarily from exposure to associated lead-contaminated dust and soil, it would be needed to analyze all of these factors by modelling the daily intake and proposing indicative BLL's for this risk group. References [1] A. Duran, M. Tuzen, M. Soylak, Trace Metal contents in chewing gums and candies marketed in Turkey, Environ. Monit. Assess. 149 (2009) 283–289. [2] I.I. Navqui, Q. Saced, M.A. Farruki, Determination of trace metals (Co, Cu, Cd, Pb, Fe, Ni and Mn) in selected sweets of different shops of Karachi City by atomic absoprtion spectroscopy, Pak. J. Biol. Sci. 7 (2004) 1355–1359. [3] M.G. Yalcin, O. Aydin, H. Elhatip, Heavy metal content and the water quality of Karasu Creek in Nigde.Turkey, Environ. Monit. Assess. 137 (2007) 169–178. [4] M.O. Amdur, J. Doull, C.D. Klaassen, Casaret and Doull's Toxicology, The Basic Science of Poisons, Fourth Edit, Pergamon Press. Inc, New York, 1991, pp. 623–680. [5] M. Gopalani, M. Shahare, D.S. Ramteke, S.R. Wate, Heavy Metal, Content of Potato Chips and Bicuits from Nagpur City, India, Bull. Environ. Contam. Toxicol. 79 (2007) 384–387. [6] J.O. Nriagu, Lead in the Environment and Lead Poisoning in the Antiquity, Elsevier North Holland Biomedical Press, Amsterdam, 1983. [7] A.R. Flegal, D.R. Smith, Measurement of environmental lead contamination and human exposure, Rev. Environ. Contam. Toxicol. 143 (1995) 1–45. [8] H.L. Needleman, A. Schell, D. Beellinger, A. Leviton, E.N. Allred, Long-term effects of childhood exposure to lead at low dose; an eleven-year-follow-up report, New Engl. J. Med. 322 (1990) 83–88. [9] E.K. Silbergeld, Preventing lead poisoning in children, Annu. Rev. Public Health 18 (1997) 187–210. [10] T. Martinez, J. Lartigue, P. Avila-Perez, G. Zarazua, M. Navarrete, S. Tejeda, A. Ramìrez, Determination of trace elements in blood samples by TXRF analysis, J. Radioanal. Nucl. Chem. 259 (2004) 511–514. [11] T. Martinez, J. Lartigue, P. Avila-Perez, G. Zarazua, L. Cabrera, S. Tejeda, A. Ramírez, Determination of lead in blood by TXRF ands its correlation to environmental lead, Nucl. Instrum. Methods Phys. Res., B 213 (2004) 584–589. [12] T. Martinez, J. Lartigue, F. Juárez, P. Avila-Perez, C. Marquez, G. Zarazua, S. Tejeda, 40 K activities and potassium concentration in tobacco samples of Mexican cigarettes, J. Radioanal. Nucl. Chem. 273 (2007) 569–572.
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Niazi, Flow injection-faas determination of chromiun, iron, potasium and sodium in commercial sweets with on-line pre-concentration using ion-exchange resin, J. Res. (Science) 11 (2000) 6–10. [24] I.O. Akinyele, O. Osibanjo, Levels of some trace elements in hospital diets, Food Chem. 8 (1982) 247–251. [25] Turkish Standard, TS 8000 (1996). Chewing gum. [26] Turkish Standard, TS 10929 (1993). Jelly Candy. [27] A.A. Carbonell-Barrachina, E. García, J. Sánchez Soriano, P. Aracil, F. Burlo, Effects of raw materials, ingredients and production lines on Arsenic and Copper concentration in confectionary products, J. Agric. Food. Chem 50 (2002) 3738–3742. [28] Anonymous, Regulations of setting maximum levels for certain contaminants in foodstuffs, Oficial Gazette, 16 October, 2002 (24908). [29] Acu-Cell Nutrition, http://www.accu-cell.com/znk.html. 30 October, 2009. [30] National Academy of Sciences Nickel Committee on medical and biological effects of environmental pollutants, Nickel Academy of Sciences, Washington, D. C, 1975. [31] S. Dahiya, R. Karpe, A.G. Hedge, R.M. Sharma, Lead, cadmium and nickel in chocolates and candies from suburban areas of Mumbai, India, J. Food Compos. Anal. 18 (2005) 517–522. [32] World Health Organization, Tec. Rep. Ser. 502 (1972). [33] U.S. Food Drug Administration, Supporting Document for Recommended Maximun Level for Lead in Candy Likely To Be Consumed Frequently by Smalll Children (Docket NO. 2005D-0481, U. S. Department of Health and Drug. Administration, Center for Food Safety and Applied Nutrition (CFSAN, December 2005. [34] Fed. Regist. Vol. 58 (June 21 1993) 33860. [35] California Department of Public Health, A.B. 121 lead in candy analysis data 2007 and 2008, Contam. Toxicol. 117 (1991) 1. [36] Norma Oficial Mexicana NOM-131.SSA1-1995, Bienes y Servicios. Alimentos para lactantes y niños de corta edad. Disposiciones sanitarias y nutrimentales. 17/ Dic/1997 [37] Inorganic lead, Environmental Health Criteria 165, International Program on Chemical Safety, World Health Organization, Geneva, 1995. [38] E.E. Ziegler, B.B. Edwads, R.L. Jensen, K.R. Mahaffey, S.J. Fomon, Pediatr. Res. 12 (1978) 29. [39] S. Drill, J. Konz, H. Mahar, M. Morse, The environmental lead problem: An assessment of lead in drinking water from a multi-media perspective, U.S Environmental Protection Agency, Washington, D.C, 1979 (EPA-570/9-79-003, NTIS-PB-296556). [40] FAO/WHO, Evaluation of certain foods additives and contaminants; forty-first report of the Joint FAO/WHO Expert Committee on Food Additives, WHO Technical Report Series, 837, 1993, (Geneva). [41] Norma Oficial Mexicana, NOM-EM-004-SSA1-1999. Salud Ambiental. Criterios para la determinación de plomo en la sangre. [42] CDC, Preventing lead poisoning in young children: a statement by the Center for Diseases Control, October 1991, U: D: Department of Health and Human Services, Public Health Service, CDC, Atlanta Georgia, 1991. [43] Assembly Bill No. 121. Chapter 707. An Act to Add Section 110552 to the Health and Safety Code, relating to lead contamination of candy. Approved by Governor. October 7, 2005. [44] C.H.W. Rankin, J.O. Nriagu, J.K. Aggarwal, T.A. Arowolo, K. Adebayo, A.R. Flegal, Lead contamination in cocoa and cocoa products: isotopic evidence of global contamination, Environ. Health Perspect. 113 (2005) 1344–1348. [45] GEMS, Global Environmental Monitoring System: Assessment of human exposure to lead, Comparison between Belgium, Malta, Mexico and Sweden, Stockholm, Karolinska Institute, 1985. [46] E. Manzanares-Acuña, H.R. Vega-Carrillo, M.A. Salas-Luevano, V.M. HernandezDavila, C. Letechipia-Leon, R. Bañuelos-Valenzuela, Salud Pública Mex. Vol, 48 (Cuernavaca May/June 2006).
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Spectrochimica Acta Part B j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / s a b
Analytical note
Total reflection X-ray fluorescence analysis of trace-elements in candies marketed in Mexico☆ T. Martinez a,⁎, J. Lartigue a, G. Zarazua b, P. Avila-Perez b, M. Navarrete a, S. Tejeda b a b
Facultad de Química, Departamento de Química Inorgánica y Nuclear. Universidad Nacional Autónoma de Mexico, Mexico, DF.04510, Mexico National Institute of Nuclear Research. Ocoyoacac, Edo. de Mexico, 05045, Mexico
a r t i c l e
i n f o
Article history: Received 13 August 2009 Accepted 9 April 2010 Available online 18 April 2010 Keywords: Candies Trace elements Total reflection X-ray fluorescence
a b s t r a c t Trace metals concentrations in food are significant for nutrition, due either to their nature or toxicity. Sweets, including chewing gum and candies, are not exactly a food, but they usually are unwearied consumed by children, the most vulnerable age-group to any kind of metal contamination in the food chain. The presence of relatively high concentrations of heavy metals such as Lead elicits concern since children are highly susceptible to heavy metals poisoning. Trace-metals concentrations were determined for six different flavors of a Mexican candy by means of Total X-ray Fluorescence Spectrometry. Triplicate samples of the various candy's flavours (strawberry, pineapple, lemon, blackberry, orange and chilli) were digested in 8 mL of a mix of supra-pure HNO3 and H2O2 (6 mL: 2 mL) in a microwave oven MARS-X. Results show the presence of essential and toxic elements such as Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, and Pb. All metal concentrations were higher and significantly different (α = 0.05) in chilli candy, compared to other candy flavours. Lead concentration fluctuated in the range of 0.102 to 0.342 μg g− 1. A discussion about risk consumption and concentration allowed by Mexican and International Norms is made. As a part of the Quality Control Program, a NIST standard of “Citrus Leaves” and a blank were treated in the same way. © 2010 Elsevier B.V. All rights reserved.
1. Introduction Trace elements are those of the periodic table occurring in animals and humans, amounting to micrograms (or less) per body-weight gram [1]. Humans require all of the trace elements in quantities amounting miligrams per day [2]. Some of these are considered as indispensable for growth and health, while the remaining are not [3] or they are toxic [4]. Some of the non-essential trace elements can also be beneficial for health through pharmacological action [5] and all of the trace elements are toxic if consumed in excess. Trace elements, such as Cd, Cr (VI), Ni, As, Hg and Pb, are major toxics [4], the first four being known as carcinogens, while Pb has been classified as 2B carcinogen by the International Agency for Research on Cancer (IARC) [4]. The last two are well-known antagonists of the central nervous system. Lead is a major toxic element and one of the most comprehensively studied [6,7]; its effects on young people's brain and behaviour are well known [8]. Trace-metal composition of food is interesting because of its essential or toxic nature. Trace-metal content of food is directly taken
☆ This paper was presented at the 13th Conference on Total reflection X-ray Fluorescence Analysis and Related Methods (TXRF 2009), held in Gothenborg, Sweden, 15–19 June 2009, and is published in the Special Issue of Spectrochimica Acta Part B, dedicated to that conference. ⁎ Corresponding author. Tel./fax: +52 55 56225232. E-mail address: [email protected] (T. Martinez). 0584-8547/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.sab.2010.04.002
into the body [5]. Sweets, including chewing gums and candies, are not food; they, however, are assiduously consumed by children and pregnant women, the most sensitive and vulnerable age-group to any kind of metal contamination [1]. The relatively high metal concentrations in children-consumed products that are heavily marketed elicits special concern because children are particularly sensitive to them [9]. The environmental program of the Faculty of Chemistry of the National University of Mexico has been approaching the determination of trace metals, especially lead, in several types of biological and environmental samples [10–15]. The present work is aimed to identify lead and other trace-elements concentrations in six distinctly flavored samples of a highly-consumed candy in Mexico, and to analyze the actual risks they pose. Total X-ray fluorescence spectrometry was adopted because it is a well-established technique for multi-element determination of trace elements in various types of matrices [16]. 2. Experimental 2.1. Sampling Six samples of one of the most consumed candy in the Mexican market (“M”) were randomly purchased in local grocery stores, each one distinctly flavored as follows: pineapple (sample MS1), orange (MS2), lemon (MS3), blackberry (MS4), strawberry (MS5) and Chili (MS6). Ingredients of these six candies are as follows: iodized salt, sugar, citric acid, soybean, flour, flavors and artificial colors plus “chile
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piquín” in sample MS6. The net weight for the first five samples was 3 g and 5 g for the latter, all of them legally registered in the Mexican Department of Health (SS). 2.2. Sample preparation Wrapping paper was carefully separated from candies. Three 0.5 g replicates for each of the samples were prepared to evaluate measurement reproducibility. Simultaneously and according to the Quality Control Program, two blanks and two sub-samples of the standard reference material – (SRM) NIST 1572 “Citrus Leaves” – were equally treated. All samples were subjected to acidic digestion with 7 mL as total volume (5 mL of HNO3, 1 mL of HCl and 1 mL of H2O2 of supra-pure grade-quality) in a closed-digestion vessel in a microwave oven “CEM-Mars-X”, according to 5AG-1 method for “Citrus Leaves” as modified by G. Zarazua [17]. The digested sample was transferred into a volumetric flask; the reaction vessels were washed out with deionized water; the flask made up to 10 mL final volume. As internal standard, 100 µL of Ga standard solution (10 µg mL− 1) were added to each of the digested samples and then mixed; 10 µL of the resulting mixture were deposited into a silicon quartz reflector and dried under infrared light. 2.3. Sample analysis Trace element analysis was performed by Total Reflection X-ray Fluorescence Spectrometry (TXRF) in an Ital-Structures Total Refection X-ray Fluorescence Spectrometer Model TX-2000. The tube was operated at 40 kV and 30 mA. The emanated fluorescent X-ray was detected by means of a 20-mm2-front-area solid-state lithiumdrifted silicon detector, cooled by liquid nitrogen. The Si (Li)-detector energy resolution (FWHM) was 140 eV for Mn Kα, while its beryllium window was 8 µm thick; counting time was 1000 s. Samples and standard-reference material were counted by triplicate. Analysis of the spectra and quantification of trace element were made by “EDXRF32-Ital Structures” Software (Version 2.051), according to “Sensitivities with internal standard” theoretical method [18,19]. 3. Results and discussion Validation of accuracy and reproducibility was made by measuring trace-elements concentration in the standard reference material NIST 1572 “Citrus leaves”; comparison between certified and obtained values is shown in Table 1. As can be seen, the measured concentration is consistent with certified values. The Relative Error Percentage (RE %) varied from 2% to 13%. Accuracy measured as the percentage of recoveries after acid digestion (difference between RE
Table 1 Comparison between measured and certified elements concentration (μg g− 1) for the NIST 1572 “citrus leaves”. Element
Certified values concentration ± SD 1
Obtained values concentration ± SD 1
DL2 μg g−1
3RE %
Ca* Ti Cr Mn Fe Ni Cu Zn Br Rb Sr Pb
3.15 ± 0.10 NR 0.80 ± 0.2 20 ± 2 90 ± 10 0.6 ± 0.3 16.5 ± 1 29 ± 2 8.2 ± ** 4.84 ± 0.06 100 ± 2 13.3 ± 2.4
3.20 ± 0.06 bDL 0.75 ± 0.3 20 ± 1 92 ± 1 b0.7 16.1 ± 0.5 30 ± 1 8.7 ± 0.18 4.72 ± 0.33 95 ± 1 12.9 ± 0.3
0.1 0.05 0.06 0.04 0.04 0.06 0.03 0.03 0.02 0.02 0.02 0.03
+ 1.6
*%. 1. Standard deviation. 2. Detection limit. 3. % relative error. **Not reported (concentration value is not certified). NR. not reported.
− 6.25 − 13 +2 − 2.4 −3.3 + 6.1 − 2.5 −5 −3
percentage to 100%) was higher than 94%, excepting Mn, 87%. The Relative Standard Deviation or Coefficient of Variation for all of the elements was lower than 7%, in the range of those of the Standard Reference Material; the exception was Cr, 40%, although slightly higher than those of the SRM (25%). Detection limits (DL) for the experimental conditions are also shown. Fig. 1 shows comparison between the spectra of samples MS2 (orange) and MS6 (chilli). Sample MS6 shows the highest concentration for all of the elements. The cumulative order of trace metals in samples generally was Ca N Fe N Mn N Ti N Zn N Ni N Cu N Sr N Rb ≥ Br N Cr ≥ Pb. As mentioned before and as it can be seen in Fig. 2, sample MS6 (chili) shows the highest concentration of Pb, followed by sample MS5 (strawberry). A previous study has found that strawberry and other fruits show high Pb concentration. Pb concentration in oranges in the same study, 0.15 ± 0.08 µg g− 1 [20], is similar to that found in sample MS2 (orange). In general, concentrations for all elements, especially Pb, in samples MS1 to MS5 were between 30 to 50% of those of sample MS6. Data generated during the study was processed by means of various statistical tests with Statgraphics V.5 Plus (Manugistic 2000) software, such as standard deviation and the One-Way Analysis of Variance. The chosen significance level was 0.05 (equivalent to 5%). Results show that the mean concentration for all of the elements was higher and significantly different (α = 0.05) for sample MS6 (chilli) when compared to the rest. Fe, Ni, Cu, Zn, Pb, Br and Sr mean concentrations in MS5 (strawberry) were significantly different to others flavours. For sample MS4 (blackberry), Cu, Zn, Cr, Pb, and Br mean concentrations were significantly different from those of other flavours. Zn, Cu and Br mean concentrations were significantly different among all of the flavours. Table 2 shows trace-element concentration of the six samples. Relative Standard deviation or Variation Coefficient ranged from 1 to 7%, the range obtained for the standard-reference material. It also shows trace-elements concentration and Maximum Permissible Levels (MPL) found in the literature for similar products: chewing gum, chocolate, cocoa-sugar mixtures, sweet candy, etc. Ca, Cr (III), Mn, Fe, Cu and Zn, are considered as essential trace nutrients [21]; they make up less than 0.01% of the dry weight of a given organism and are required for normal health function and development [22]. As a trace nutrient, Chromium (III) serves as a component of the glucose-tolerance factor [4]. It works as co-factor for insulin action and has a role in its peripheral activity by forming a ternary complex with insulin receptor, so facilitating the insulin fixing and influencing carbohydrate, lipid and protein metabolism. Cr (VI), however, it is mentioned as carcinogenic. The Cr concentrations obtained in this study, as it can be seen in Table 2, were lower than the range of those of the chewing gum, candies marketed in Turkey [1] and other commercial sweets [23], while Cu concentrations were in the range of those obtained for chewing gum and candies marketed in Turkey [1] and commercial sweets [2]. Cu is an essential element of several enzymes; it functions as a biocatalyst and it is necessary for body pigmentation (in addition to Fe) in maintaining a healthy central system, preventing anemia, and it is interrelated to the function of Fe and Zn in the body [24]. The permissible level of Cu in both chewing gums and candy is 10 µg g− 1, according to Turkish Standards [25,26], 5 µg g− 1 for chocolate and cocoa-sugar mixtures in Spain's legislation [27] and for the same products 15 and 50 µg g− 1 respectively [28]. Results of Fe concentration for all of the analyzed samples were in the range of 8.9–25.42 µg g− 1. Like the rest of results, iron level in sample MS6 (chili) was higher than fruit-flavored candies. The iron concentration was much the same that the highest concentration reported in selected sweets from Karachi City [2], fluctuating into the range of those for potato chips and biscuit from Nagpur City, India [5] and other types of foods [28]. Mn is a co-factor for a number of enzymatic reactions, particularly those involved in phosphorilation,
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Fig. 1. Total X-ray fluorescence spectra of samples MS6, chili (upper line) and MS2, orange (lower line).
cholesterol, and fatty-acids synthesis; Mn concentration for samples in this study were in the reported ranges [1,2,5]. From a preliminary survey of children's preferences, it was found that chili-based candies are the first choice. Taking into account the highest concentration of studied trace elements in sample MS6 (chili) and in an extreme consume-case of 10 candies per day (50 g day− 1), the calculated intake (µg day− 1) of each one element in this study is shown in Table 3. As it can be seen, calculated intakes were lower than the Reference Daily Intake or Reference Dietary Intake (RDI) [21, 29)] by far, as expected and varying between 1.5 to 65%. RDI is defined as “the level of intake of essential nutrients, on the basis of scientific knowledge, that are judged by the Food and Nutrition Board to be adequate to meet the known nutrients needs of practically all healthy persons” [21,29]. The accepted RDIs showed for comparison in Table 3 are stipulated for children aged 1–10 years old [29]. Ni has been identified as a respiratory-tract carcinogen in the nickel industry's workforce [4]. Nickel probably is an essential trace metal for mammals and plants, according to growing evidence in several studies. In trace amounts, nickel may be beneficial as an activator for some enzyme systems [30]. At higher levels, its
accumulation in lungs may cause bronchial hemorrhage. Ni is poorly absorbed from diet (less than 5%) and it is evacuated by feces. Nickel concentration for all samples varied from 0.1 to1.83 µg g− 1, in the range of selected sweets in Karachi City [2] and in chewing gums and candies in Turkey [1], and in the lower range of chocolates and candies from Munbai, India [31]. Ni concentrations in samples do not affect the daily intake because oscillated between 13 and 31% of RDI [29], taking into account the maximum and minimum values of this standard. Br is at this time under discussion as an essential element, provided its effects on growth have been tested in experimental animals, although none essential function has conclusively been shown [29]. Br content in candies oscillates from 0.19 to 1.27 µg kg− 1. Calculated daily intake is 63.5 µg day− 1, lower than the maximum acceptable amount of Br intake (1 mg kg− 1) in respect to bodyweight per-day, according to the World Health Organization (WHO) [32]. Estimated daily intake of bromine worldwide from food and water is 1 mg–3 mg per day [29]. As it can be seen in Table 2, Pb concentration varies from 0.102 ± 0.007 to 0.342 ± 0.009 µg g− 1, higher than the maximum level of 0.1 µg g− 1, as recommended by the U.S Food and Drug Administration
Fig. 2. Distribution of some important elements (μg g− 1) in candies samples.
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Table 2 Elemental concentration in candies samples and Maximum permissible levels, MPL in (µg g−1). Element
MS1
MS2
MS4
MS5
MS6
Ca Ti Cr Mn Fe
236 ± 10 2.53 ± 0.11 0.14 ± 0.01 2.15 ± 0.06 10.42 ± 0.18
230 ± 14 2.31 ± 0.18 0.16 ± 0.01 2.21 ± 0.06 16.76 ± 0.28
MS3 322 ± 9 4.28 ± 0.19 0.12 ± 0.01 1.79 ± 0.12 9.22 ± 0.43
233 ± 3 3.83 ± 0.24 0.088 ± 0.01 2.02 ± 0.06 8.91 ± 0.80
237 ± 7 3.89 ± 0.29 0.15 ± 0.01 2.43 ± 0.08 21.30 ± 0.46
377 ± 10 5.41 ± 0.41 0.39 ± 0.02 7.65 ± 0.27 25.42 ± 0.29
Ni Cu Zn Br Rb Sr Pb
0.94 ± 0.03 2.41 ± 0.06 1.95 ± 0.10 0.33 ± 0.02 0.34 ± 0.01 1.57 ± 0.02 0.167 ± 0.002
0.14 ± 0.01 1.21 ± 0.01 2.35 ± 0.07 0.41 ± 0.01 0.34 ± 0.004 1.45 ± 0.05 0.140 ± 0.004
0.12 ± 0.01 2.74 ± 0.08 2.22 ± 0.01 0.56 ± 0.02 0.36 ± 0.01 2.22 ± 0.15 0.146 ± 0.009
0.10 ± 0.05 1.44 ± 0.04 1.58 ± 0.06 0.26 ± 0.002 0.34 ± 0.01 1.44 ± 0.03 0.102 ± 0.007
1.25 ± 0.11 1.07 ± 0.02 1.32 ± 0.03 0.19 ± 0.02 0.34 ± 0.01 1.26 ± 0.03 0.173 ± 0.006
1.83 ± 0.02 1.66 ± 0.03 3.07 ± 0.12 1.27 ± 0.02 1.23 ± 0.07 2.56 ± 0.03 0.342 ± 0.009
Literature reference [#]
MPL
0.74–6.27 [1] 30.4–72 [23];0.5–1.6 [5] 4.5–11.5 [2]; 0.5–8.25 [5]; 1.9–5 [1] 3.96–9.86 [1]; 0.2–25 [28]; 0.4–19 [ 2] 8.7–36.25 [5] 0.12–2.59[1]; 0.1–3.8 [2]; 0.04–8.2 [31 ] 0.22–2.5 [1]; 0.07–4.0 [2];1.05–4.7 [5] 0.8–15.8 [5]; NF NF NF 0.049–8.4[31]; 0.3–3.5 [2];0.03–2.46 [1] 9.98–0.13 [5]
10 [1]; 5 [23]: 15, 50 [24]
1, 2 [25,26]; 1 [28] 0.1[33]; 0.2μg [34]
MPL = Maximum permissible level. NF = Not found.
(FDA) and the California Department of Public Health (CDPH). Yet, it falls into the range of 0.5 µg g− 1 previously accepted level [33]. This is equivalent to the Food Chemical Codex (FCC) specification for Pb in sucrose (sugar), the main ingredient for many candy products [34]. Pb concentrations obtained in this study were similar to those reported by the California Department of Public Health [35] in August 2007, for salt/sugar mix flavored candies, samples F07C00951 to F07C00954. Exception made of sample MS6, the rest rank below the Mexican Norm, 0.2 µg g− 1 [36]. The higher concentration found in sample MS6 could be explained by chili-powder action which, as previously reported [33], contains a broad range of Pb levels, perhaps due to bad handling prior to chili grinding. Several dietary factors, such as nutritional status and Pb chemical form, stimulate the human absorption of this metal. In general, food-intake patterns could also influence Pb absorption. Pre-school children's intake of both foods and non-food items (e.g. toys soil/dust) is a matter of concern [37]. Ziegler, et al. [38] reported that young children, aged two weeks to two years, absorbed 42% of ingested Pb at intake levels greater than 5 µg kg− 1 body weight. Drill, et al. [39] estimated an absorption rate of 17% for Pb in paint chips in children aged 2–3 years, and 30% gastrointestinal absorption for Pb from soil and dirt. The amount of Pb ingested by children from non-food items such as soil, dust and paint chips through normal mouthing activity is a major concern in calculating Pb exposure. Such a risk has been reduced in Mexico and others countries by enforcing norms [9]. Pb-exposure for children consumers and related health risks are here expressed as the Provisional Tolerable Weekly Intake (PTWI) and Provisional Tolerable Daily Intake (PTDI). As it can be seen in Table 3, the calculated Pb daily-intake of 17.1 µg and the calculated weeklyintake of 119.7 µg were lower, (32%) than the PTWI of 25 µg kg− 1 per
body weight [40], which is equal to 375 µg week− 1 and 53.6 µg d− 1 for a 15 kg body-weight child. For the purpose of establishing a quantitative and significant relationship between the intake of Pb (through food) by children and blood lead levels (BLLs), the Joint FAO/ WHO Expert Committee on Food Additives (JECFA) accepted the conversion factor of 0.16 µg dL− 1 per 1 µg of lead intake per day. This latter was adopted by the International Programme on Chemical Safety (IPCS) Task Group [40]. For the calculated daily intake, this means a BLL of 2.74 µg Pb dL− 1. This relationship is equivalent to the 27.4% rate of the indicative levels of WHO and the Mexican norm for pregnant women and children, of 10 µg dL− 1 [41]. In Mexico City [11] it has been reported a geometric mean of 2.79 µg dL− 1 for the 0– 10 age-group, similar to those of National Nutrition Examination Surveys, NHANES III, phase 2 (2.7 µg dL− 1). Beside of this and considering an absorption rate of 42% through the gastrointestinal tract for young children at high rates of intakes [36] it gives a calculated total daily intake of 7.18 µg d− 1of Pb. This latter slightly higher than the FDA's Provisional Total Tolerable Intake Level (PTTIL) by small children of 6 µg d− 1 [33,42] and translating it into a BLL of 1.15 µg Pb dL− 1, being equivalent to the 11.5% rate of the indicative levels of WHO and the Mexican Norm [41]. FDA' PTTIL corresponds [42] to a Pb intake capable of elevating the BLL's of a small child by 1 µg dL− 1. Varying input values (intake and Pb levels) and using the Monte Carlo simulation [33], the FDA calculated PTTIL 6 µg d− 1 and its current recommended maximum Pb level of 0.1 µg g− 1 for candies. Furthermore, a recently published law in California [43] requires the Office of Environmental Health Hazard Assessment (OEHA) to develop acceptable standards for the naturally Pb occurring-level in candies, and assumes that the Pb “naturally occurring level” in candies is only “natural” [44] to the extent that it is not avoidable by good
Table 3 RDIs, calculated intake, %RDIs and PTDI, PTWI for Pb (daily intake; 50 g, sample MS6). Element
RDI (mg d−1) except as indicated and 1–10 years old
Calculated intake (μg d− 1)
% RDI for 1– 10 years old
Ca Ti Cr Mn Fe Ni Cu Zn Br Rb Sr Pb
600–800
18.9 270.5 19.5 382.5 1271 91.5 83 153.5 63.5 61.5 128 17.1
2.4–3.2
30–50& 1–3 10–15 300–700& 1–2.5 10 None. 15 * None
& = (μg d− 1); * = Maximum acceptable level [32].
PTDI (μg d− 1) children 15 kg B.W.
PTWI (μg w− 1) children 15 kg B.W.
Calculated DI (μg d− 1) children 15 kg B. W.
CalculatedWI (μg w− 1) children 15 Kg B. W.
Calculated % PTDI and PTWI
53.6
375
17.1
119.7
32
39–65 13–38 8.5–13 13–30.5 .3–8 1.5 0.4*
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agriculture, manufacturing, and procurement practices currently feasible. Pb background levels in soil [45] are in the range of 10– 70 µg g− 1. For Mexican agricultural soils, Pb concentration are in the lower value (6 µg g− 1); it has also been shown [46] that 3.2% of lead concentration is incorporated in chili, which means an average concentration of 0.2 to 0.3 µg g− 1 from natural origin, similar to those found in chili-flavored candies. In a first attempt to establish sources especially for Pb, the Pearson Correlation coefficients of metallic elements were obtained. High Pearson correlation coefficients (r N 0.8) were found between Pb with most of the elements, including Rb (r N 0.95), which possibly indicates a natural origin. The exceptions were Cu and Ti for which Pb was negatively correlated (r =−0.1). 4. Conclusions 1. The experimental results for the Reference Standard Material NIST1572, Citrus Leaves and samples show that the digestion procedure and the TXRF technique provide precise (reproducible) and accurate (trueness) data for specific elements in candy samples. 2. The mean concentration for all of the analyzed elements was highest in sample MS6 (chili), significantly different (α = 0.05) if compared to others candy flavours, mainly due to higher Pb-content in dry chili. 3. Pb concentrations in Mexican candies are lower than those specified by the Mexican norm, excepting chili-flavored candies, which are slightly higher than the current FDA and CDPH recommended maximum Pb level. In order to probe that Pb in candies (mainly in sample MS6-chili) comes either from natural sources or bad agricultural and manufacturing practices, it would be needed to perform a lead-isotopic ratio-study. [As well, it could be useful to accomplish a research on the Pb content in different chili species] 4. It could be concluded that our estimated daily intake for the studied elements are below RDIs, PTDIs, PTWIs and PTTIL standards. Thus, consume average amounts of these candies seem not to pose a health-risk for the consumer. Besides, and considering that Pb comes to small children not only through candies but primarily from exposure to associated lead-contaminated dust and soil, it would be needed to analyze all of these factors by modelling the daily intake and proposing indicative BLL's for this risk group. References [1] A. Duran, M. Tuzen, M. Soylak, Trace Metal contents in chewing gums and candies marketed in Turkey, Environ. Monit. Assess. 149 (2009) 283–289. [2] I.I. Navqui, Q. Saced, M.A. Farruki, Determination of trace metals (Co, Cu, Cd, Pb, Fe, Ni and Mn) in selected sweets of different shops of Karachi City by atomic absoprtion spectroscopy, Pak. J. Biol. Sci. 7 (2004) 1355–1359. [3] M.G. Yalcin, O. Aydin, H. Elhatip, Heavy metal content and the water quality of Karasu Creek in Nigde.Turkey, Environ. Monit. Assess. 137 (2007) 169–178. [4] M.O. Amdur, J. Doull, C.D. Klaassen, Casaret and Doull's Toxicology, The Basic Science of Poisons, Fourth Edit, Pergamon Press. Inc, New York, 1991, pp. 623–680. [5] M. Gopalani, M. Shahare, D.S. Ramteke, S.R. Wate, Heavy Metal, Content of Potato Chips and Bicuits from Nagpur City, India, Bull. Environ. Contam. Toxicol. 79 (2007) 384–387. [6] J.O. Nriagu, Lead in the Environment and Lead Poisoning in the Antiquity, Elsevier North Holland Biomedical Press, Amsterdam, 1983. [7] A.R. Flegal, D.R. Smith, Measurement of environmental lead contamination and human exposure, Rev. Environ. Contam. Toxicol. 143 (1995) 1–45. [8] H.L. Needleman, A. Schell, D. Beellinger, A. Leviton, E.N. Allred, Long-term effects of childhood exposure to lead at low dose; an eleven-year-follow-up report, New Engl. J. Med. 322 (1990) 83–88. [9] E.K. Silbergeld, Preventing lead poisoning in children, Annu. Rev. Public Health 18 (1997) 187–210. [10] T. Martinez, J. Lartigue, P. Avila-Perez, G. Zarazua, M. Navarrete, S. Tejeda, A. Ramìrez, Determination of trace elements in blood samples by TXRF analysis, J. Radioanal. Nucl. Chem. 259 (2004) 511–514. [11] T. Martinez, J. Lartigue, P. Avila-Perez, G. Zarazua, L. Cabrera, S. Tejeda, A. Ramírez, Determination of lead in blood by TXRF ands its correlation to environmental lead, Nucl. Instrum. Methods Phys. Res., B 213 (2004) 584–589. [12] T. Martinez, J. Lartigue, F. Juárez, P. Avila-Perez, C. Marquez, G. Zarazua, S. Tejeda, 40 K activities and potassium concentration in tobacco samples of Mexican cigarettes, J. Radioanal. Nucl. Chem. 273 (2007) 569–572.
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