1 3 A market basket survey of As, Zn and Se in rice imports in Qatar: Health 4 implications 5 6 7 Candace Rowell a Q1 , Nora Kuiper a , Khalid Al-Saad b , Jerome Nriagu c , Basem Shomar a,⇑ 8 a Qatar Environment and Energy Research Institute (QEERI), Qatar Foundation, P.O. Box 5825, Doha, Qatar 9 b Central Laboratory Unit, Department of Chemistry, Qatar University, P.O. Box 2713, Doha, Qatar 10 c Department of Environmental Health Science, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109, USA 11 12 14 article info 15 Article history: 16 Received 31 March 2014 17 Accepted 25 April 2014 18 Available online xxxx 19 Keywords: 20 Arsenic 21 Zinc 22 Selenium 23 Rice 24 Total Daily Intake (TDI) 25 Risk quotient 26 27 abstract 28 Qatar is dependent on importation of rice, its staple dish, and is therefore susceptible to compromises of 29 food quality in the global market. This market basket study assesses potential health risks of As exposure 30 from rice consumption in Qatar and examines its contribution to the recommended nutritional intakes 31 (RNI) for Zn and Se. Fifty-six rice types and 12 products sold in Qatar were analyzed by ICP/MS. Mean 32 concentrations and ranges were 96.2 ± 54.1 lg/kg (9.76–258 lg/kg) for As; 12.5 ± 5.35 mg/kg 33 (2.79–29.9 mg/kg) for Zn and 103 ± 113 lg/kg (<5.94–422 lg/kg) for Se. Calculated risk quotient shows 34 rice consumption in Qatar is not a significant route of As exposure but can contribute up to 100% and 35 50% of the RNI for Se and Zn, respectively. Results indicate that children in Qatar may be at elevated risk 36 of arsenic exposure from rice-based infant cereals but more data is needed to obtain a definitive 37 assessment. 38 Ó 2014 Published by Elsevier Ltd. 39 40 41 42 1. Introduction 43 In today’s expanding global food market, local food quality at 44 the site of production can affect the health of global consumers. 45 Rice, a dominant staple food for over half of the world’s population, 46 is primarily cultivated in Asia where four countries (China, India, 47 Indonesia and Bangladesh) account for nearly 70% of global pro- 48 duction (FAO, 2011). The Gulf Cooperation Council (GCC) nations 49 import 50–80% of all food products including rice and other cereal 50 grains which account for approximately 42.7% of total food con- 51 sumption (Alpen Capital, 2011). As diets in these countries are 52 heavily dependent on rice, the quality of rice imports in terms of 53 nutritional value and dietary exposure are critical concerns. 54 Due to elevated levels of arsenic (As), rice has drawn increased 55 attention to rice as a potential pathway of arsenic exposure 56 (Banerjee et al., 2013; Brammer and Ravenscroft, 2009; Rahman 57 and Hasegawa, 2011; Williams et al., 2005). Recently, Banerjee 58 et al. (2013) found a significant association between elevated As 59 content in rice and genotoxic effects in humans who rely on rice 60 as a staple food. Currently, concern for toxic effects have generally 61 overshadowed the potential contribution of rice to dietary intake 62 of essential elements such as zinc (Zn) and selenium (Se). In 63 countries, such as Qatar, where rice is the primary staple food, 64 rice’s contribution to nutrient intake is essential. Zinc deficiency 65 is a global concern affecting up to 72.5% of individuals in Southeast 66 Asia. In countries of the GCC, approximately 25% of the population 67 is zinc deficient; however, large populations of individuals origi- 68 nating from Southeast Asia reside in the GCC (Caulfield and 69 Black, 2004). While not as globally wide-spread, Se deficiency 70 affects up to 1 billion people worldwide (Combs, 2001; Ermakov 71 and Jovanovic, 2010; Kumar and Priyadarsini, in press). Both Zn 72 and Se deficiency have been linked to a variety of human health 73 concerns including impairment of the immune system (Beckett 74 and Arthur, 2005). 75 Like many arid nations who are dependent upon the global food 76 system, Qatar is particularly vulnerable to food quality in the glo- 77 bal market. Qatar’s arid environment limits agricultural produc- 78 tion, resulting in the need to import more than 99% of the 79 country’s food commodities and 100% of rice and rice-based prod- 80 ucts (QNFSP, 2011). This dependency leaves Qatar uniquely vulner- 81 able to changes in the world food market not only in terms of 82 quantity but quality as well. The vulnerability of the Qatar popula- 83 tion to imported food-borne toxins is further heightened by the 84 rapid population Q2 growth in recent years, from 51,000 in 1961 to 85 1,844,276 in 2012 (FAO, 2012a, 2012b; SQSA, 2010). Currently, 86 more than 80% of Qatar’s population is comprised of expatriate 87 residents with the major immigrant groups being Indian (24%), 88 Nepalese (16%), non-Qatari Arabs (13%) and Filipinos (11%) (US http://dx.doi.org/10.1016/j.fct.2014.04.041 0278-6915/Ó 2014 Published by Elsevier Ltd. ⇑ Corresponding author. Tel.: +974 4454 2872; fax: +974 4454 1528. E-mail address: [email protected](B. Shomar). Food and Chemical Toxicology xxx (2014) xxx–xxx Contents lists available at ScienceDirect Food and Chemical Toxicology journal homepage: www.elsevier.com/locate/foodchemtox FCT 7957 No. of Pages 7, Model 5G 12 May 2014 Please cite this article in press as: Rowell, C., et al. A market basket survey of As, Zn and Se in rice imports in Qatar: Health implications. Food Chem. Toxicol. (2014), http://dx.doi.org/10.1016/j.fct.2014.04.041
Please cite this article in press as: Rowell, C., et al. A market basket survey of As, Zn and Se in rice imports in Qatar: Health implications. Food Chem. T(2014), http://dx.doi.org/10.1016/j.fct.2014.04.041
Candace Rowell a, Nora Kuiper a, Khalid Al-Saad b, Jerome Nriagu c, Basem Shomar a,⇑a Qatar Environment and Energy Research Institute (QEERI), Qatar Foundation, P.O. Box 5825, Doha, Qatarb Central Laboratory Unit, Department of Chemistry, Qatar University, P.O. Box 2713, Doha, Qatarc Department of Environmental Health Science, School of Public Health, University of Michigan, 1415 Washington Heights, Ann Arbor, MI 48109, USA
a r t i c l e i n f o
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Article history:Received 31 March 2014Accepted 25 April 2014Available online xxxx
Qatar is dependent on importation of rice, its staple dish, and is therefore susceptible to compromises offood quality in the global market. This market basket study assesses potential health risks of As exposurefrom rice consumption in Qatar and examines its contribution to the recommended nutritional intakes(RNI) for Zn and Se. Fifty-six rice types and 12 products sold in Qatar were analyzed by ICP/MS. Meanconcentrations and ranges were 96.2 ± 54.1 lg/kg (9.76–258 lg/kg) for As; 12.5 ± 5.35 mg/kg(2.79–29.9 mg/kg) for Zn and 103 ± 113 lg/kg (<5.94–422 lg/kg) for Se. Calculated risk quotient showsrice consumption in Qatar is not a significant route of As exposure but can contribute up to 100% and50% of the RNI for Se and Zn, respectively. Results indicate that children in Qatar may be at elevated riskof arsenic exposure from rice-based infant cereals but more data is needed to obtain a definitiveassessment.
� 2014 Published by Elsevier Ltd.
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1. Introduction
In today’s expanding global food market, local food quality atthe site of production can affect the health of global consumers.Rice, a dominant staple food for over half of the world’s population,is primarily cultivated in Asia where four countries (China, India,Indonesia and Bangladesh) account for nearly 70% of global pro-duction (FAO, 2011). The Gulf Cooperation Council (GCC) nationsimport 50–80% of all food products including rice and other cerealgrains which account for approximately 42.7% of total food con-sumption (Alpen Capital, 2011). As diets in these countries areheavily dependent on rice, the quality of rice imports in terms ofnutritional value and dietary exposure are critical concerns.
Due to elevated levels of arsenic (As), rice has drawn increasedattention to rice as a potential pathway of arsenic exposure(Banerjee et al., 2013; Brammer and Ravenscroft, 2009; Rahmanand Hasegawa, 2011; Williams et al., 2005). Recently, Banerjeeet al. (2013) found a significant association between elevated Ascontent in rice and genotoxic effects in humans who rely on riceas a staple food. Currently, concern for toxic effects have generallyovershadowed the potential contribution of rice to dietary intakeof essential elements such as zinc (Zn) and selenium (Se). In
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countries, such as Qatar, where rice is the primary staple food,rice’s contribution to nutrient intake is essential. Zinc deficiencyis a global concern affecting up to 72.5% of individuals in SoutheastAsia. In countries of the GCC, approximately 25% of the populationis zinc deficient; however, large populations of individuals origi-nating from Southeast Asia reside in the GCC (Caulfield andBlack, 2004). While not as globally wide-spread, Se deficiencyaffects up to 1 billion people worldwide (Combs, 2001; Ermakovand Jovanovic, 2010; Kumar and Priyadarsini, in press). Both Znand Se deficiency have been linked to a variety of human healthconcerns including impairment of the immune system (Beckettand Arthur, 2005).
Like many arid nations who are dependent upon the global foodsystem, Qatar is particularly vulnerable to food quality in the glo-bal market. Qatar’s arid environment limits agricultural produc-tion, resulting in the need to import more than 99% of thecountry’s food commodities and 100% of rice and rice-based prod-ucts (QNFSP, 2011). This dependency leaves Qatar uniquely vulner-able to changes in the world food market not only in terms ofquantity but quality as well. The vulnerability of the Qatar popula-tion to imported food-borne toxins is further heightened by therapid population growth in recent years, from 51,000 in 1961 to1,844,276 in 2012 (FAO, 2012a, 2012b; SQSA, 2010). Currently,more than 80% of Qatar’s population is comprised of expatriateresidents with the major immigrant groups being Indian (24%),Nepalese (16%), non-Qatari Arabs (13%) and Filipinos (11%) (US
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Department of State-Qatar, 2012). The varied demographics of thecountry have resulted in vastly different dietary habits and sourcesof food.
Emerging research shows ingestion of arsenic containing foods,such as rice, to be an important pathway of arsenic exposure espe-cially in countries such as Qatar (O’Neill et al., 2013; Rintala et al.,2014; Williams et al., 2005). The aims of this market basket studyare to (i) quantity the concentrations of total As, Zn and Se in ricegrains available in local Qatari markets; (ii) relate the metal con-centrations to the type of rice, physical characteristics of the ricegrain, and country of origin; (iii) use Provisional Tolerable DailyIntake (PTDI) and hazard quotient to assess potential health risksof dietary As exposure from rice consumption for Qatari andnon-Qatari people; (iv) use Recommended Nutritional Intake(RNI) values to assess the dietary contribution of rice to Zn andSe intake for Qatari and non-Qatari populations.
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2. Materials and methods
2.1. Collection and classification of rice grains and products
Rice samples (n = 56) were obtained from eight local markets in Doha, Qatarbetween 30 September 2012 and 10 October 2012. The samples constituted a rep-resentation of the major rice types available to consumers in Qatar. The sampleswere classified according to nine countries of import, rice variety and length of ricegrain.
Five rice grains were randomly selected from each sample package for lengthmeasurement by micrometer caliper. The rice samples were classified by averagemeasured lengths according to International Rice Research Institute (IRRI) categori-zation into four distinct rice length categories: short (L < 5.5 mm), medium(L = 5.51–6.60 mm), long (L = 6.61–7.5 mm), and extra-long (L > 7.5 mm).
Rice products (n = 12) including rice powder (n = 4), rice pasta (n = 4) and rice-based infant cereals (n = 4) were purchased from local markets in Doha, Qatar andsubsequently analyzed.
2.2. Analysis of total arsenic, zinc and selenium
Rice grain samples were prepared and digested according to Halder et al.(2012). For determining the effect of pre-washing rice grains on As, Zn and Se con-centration, two sets of preparations were performed: (1) approximately 15 g of eachrice sample were washed with 20 mL Millipore water and subsequently oven driedfor 48 h at 45 �C and (2) approximately 15 g of each rice sample were oven dried for48 h at 45 �C without prior washing.
An aliquot of each sample (washed and unwashed, total number of samples (n)was 112) was ground with a mechanical grinder and 500 mg of each ground ricewas pre-digested overnight at room temperature with 5 mL concentrated HNO3
(Normatom for trace analysis, England). The samples were then gradually heatedto 60 �C for 2 h followed by an addition of 3 mL 30% (v/v) H2O2 (AnalaR Normapurfor trace analysis, England) and further heated to 130 �C for 3–4 h until the solutionappeared clear. With the digestion method used, samples were completely digestedand no filtering was necessary. The final dilution volume was adjusted to 10 mL byaddition of Type 1 MilliQ water. Samples were stored at 4 �C prior to analysis.
Rice products were prepared and digested by the same method as mentionedabove with omission of the washing procedure during preparation.
The acid digested samples were analyzed for total As, Zn and Se using induc-tively-coupled plasma mass spectrometry (ICP/MS) (Agilent 7500ce) in the CentralLaboratory Unit at Qatar University, Doha, Qatar.
To ensure accuracy of analysis, two reagent blanks and one standard referencematerial (SRM) (NCS ZC 73027, China National Analysis Center for Iron and Steel,Beijing) were included in each digestion batch (total number of SRM duplicateswas 10). The instrumental detection limits (DL) in this study (0.058 lg/L for As,0.34 lg/L for Zn and 0.30 lg/L for Se) were all within the acceptable ranges forthe instrumental method used. The instrumental detection limits are calculatedas mass/volume (lg/L); to relate this to the given mass/mass (lg/kg) concentrationsthroughout the results, the DLs have also been mathematically adjusted to mass/mass. Based on samples masses of 500 mg and final digestion dilution of 10 g,instrumental DL would equate to As, Zn and Se levels of 1.16 lg/kg, 6.80 lg/kgand 5.94 lg/kg, respectively, in rice grains (Table 1).
2.3. Rice consumption estimates for people in Qatar
The State of Qatar Statistic Authority’s most recent survey data indicate that theaverage household consumption of rice in Qatar for Qatari households is 64.3 kg/month and only 19.4 kg/month for non-Qatari households (average householdswere estimated to be 5.3 persons for both populations) (SQSA, 2008).
Please cite this article in press as: Rowell, C., et al. A market basket survey of As,(2014), http://dx.doi.org/10.1016/j.fct.2014.04.041
From these statistics it is estimated that a native Qatari consumes approxi-mately 404 g/day of rice, while non-Qatari diets are estimated to only include120 g/day. These differences in diets may result in vastly different exposuresbetween the two groups. Consumption was considered to be the same for malesand females as gender specific data is not currently available for Qatar.
Consumption of rice-based infant cereals was based on serving size recommen-dations on product packaging.
2.4. Estimates of dietary exposure through consumption of rice
Health risks associated with dietary intake of arsenic is assessed using the riskquotient method defined as the ratio of daily intake to the intake dose of concernrecommended by the World Health Organization (WHO). Total Daily Intake of As(TDIAs) from rice consumption was calculated for Qatari citizens and non-citizensusing the following equation:
TDIAs ðl g day�1 kg BW�1Þ ¼ ðCAs � DCÞ=BW ð1Þ
where CAs refers to the concentration of As in rice (lg/kg), DC refers to the dailyconsumption of rice and BW refers to body weight which is assumed to be 65 kgfor the average adult male, 55 kg for the average adult female and 9 kg for infantsaged 6–12 months (WHO/FAO, 2004a). There is currently no WHO recommendedTDI for As. To assess the potential dietary risk of As exposure, the previous PTDI of2.1 lg/day kg BW (withdrawn in 2010) will be used as the benchmark value (JointFAO/WHO Expert Committee on Food Additives, 2010).
The dietary contributions to recommended nutritional intakes (RNI) require-ment for both zinc and selenium we also estimated. Daily intake of zinc (DIZn)and selenium (DISe) from rice consumption were calculated for residents and citi-zens of Qatar using the following equation:
DI ðl g day�1Þ ¼ C � DC ð2Þ
where C refers to the concentration of the element of interest in rice (lg/kg) and DCrefers to the daily consumption of rice. The WHO lists a RNI for both zinc and sele-nium for adult females and males separately. The RNI for zinc (RNIZn) based on a dietproviding moderate Zn bioavailability is 14.0 mg/day for adult males and 9.8 mg/dayfor adult females (WHO/FAO, 2004a). The RNI for Se (RNISe) is 34.0 lg/day for adultmales and 26.0 lg/day for adult females (WHO/FAO, 2004b).
2.5. Data analysis
All statistical analyses were performed using IBM SPSS Statistical Package 20.Linear regressions, Analysis of Variance (ANOVA) and Student’s t-test were per-formed on the dataset. Of the samples measured for Se, 17.9% (n = 10) were belowthe instrumental detection limit (<DL). For those samples which were below thedetection limit of 0.297 lg/kg, an arbitrary value of 50% DL was used during dataanalysis. Zinc and As levels were all above the instrumental detection limits.
3. Results and discussion
The digestion and instrumental method used consistently metthe analytical criteria for each element in terms of instrumentaldetection limit and standard reference material recovery. Theresults of each batch of samples were within ±10% of the certifiedvalue for each element in the SRM (Table 1).
3.1. Arsenic, Zn and Se in rice and rice products
The mean values and ranges of total As, Zn and Se concentra-tions in rice grains collected in Qatar are shown in Table 2 accord-ing to country of origin. It is notable that Indian rice varietiesaccounted for a large proportion (37.5%) of the total sample size.
Zn and Se in rice imports in Qatar: Health implications. Food Chem. Toxicol.
Table 2Mean and range of As, Zn and Se concentrations in rice from Qatari markets compared to previously reported values in other market basket studies for As and Se.
Country oforigin
n As Se Zn
Qatar Other studies Qatar Other studies QatarTotal As Mean (min–max)(lg/kg)
a Meharg et al. (2009).b Williams et al. (2005).c <DL refers to ‘‘less than the detection limit’’.d Williams et al. (2009b).e Rahman and Hasegawa (2011).
Fig. 1. Variation of total arsenic concentrations in rice samples from differentcountries.
1 For interpretation of color in Fig. 1, the reader is referred to the web version ofthis article.
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Arsenic content in raw rice grains ranged from 41.3 to 169 lg/kg.Washing rice grains did not significantly influence the total Asconcentrations (p = 0.863); therefore washed samples were notincluded in the results and discussion. The present study did notanalyze the effect of cooking; however, previous studies havefound negligible effect on As and Zn bioavailability from cookingmethods except when using As contaminated water (Horner andBeauchemin, 2013; Rahman and Hasegawa, 2011). Zinc and Secontent in raw rice grains ranged from 2.79 to 29.9 mg/kg and<5.94 to 422 lg/kg, respectively.
There was no significant correlation between Se and Zn content(p = 0.398) or Se and As content (p = 0.485). There was a significantcorrelation between As and Zn concentrations (p = 0.031); how-ever, only 4% of Zn variance was explained by As (r2 = 0.041). Thesefindings are in contrast to Williams et al. (2009a) which found asignificant (p < 0.001) inverse relationship exists between As con-centration and both Zn and Se concentrations in Bangladeshi ricegrains. The r2 values for the cited study were low however, 0.16and 0.11 for Se and Zn, respectively, indicating limited ability toexplain variances in micronutrients. The study by Williams et al.(2009a) reported that increased uptake of As by rice grainsdecreased the bioavailable forms of essential nutrients. In the ricegrains sampled in Qatar, which have relatively low As levels com-pared to Bangladeshi rice grains, this phenomenon was notobserved.
In general, As levels found in rice grains available in Qatar mar-kets were on the low end of ranges previously reported in otherstudies (Table 2) (Meharg et al., 2009; Williams et al., 2005). Theaverage As value found in Indian rice grains in Qatari markets iswithin the range of previously reported values (Rahman andHasegawa, 2011; Meharg et al., 2009). The Se values were compara-ble to Meharg et al. (2009) data for all countries, excluding Egyptwhere the average for this study was 15 times higher than whatMeharg et al. (2009) had reported. Our results are consistent withprevious reports that rice grains originating from Italy and the Uni-ted States typically contain higher levels of arsenic, compared toother countries (Meharg et al., 2009; Williams et al., 2005). Basedon the general agreement between previously published resultsand our results, we suspect that the exposure risk in Qatar from riceconsumption would be similar for many countries that import theirrice, especially from the same countries. No packaging informationregarding fortification was available; however, observed variationswith regards to Zn and Se concentrations between rice grains is
Please cite this article in press as: Rowell, C., et al. A market basket survey of As,(2014), http://dx.doi.org/10.1016/j.fct.2014.04.041
attributable to varying soil content of these elements, varying agri-cultural management practices and cultivar characteristics(Williams et al., 2009a; Rehman et al., 2012). Rice grown in soilsnaturally high in Zn or Se may produce grains enriched in these ele-ments (Cao et al., 2001).
Variability and distribution of As in collected rice samples areshown in a Box and Whisker plot (Fig. 1). The length of the box rep-resents the 25th and 75th percentiles. The median value is repre-sented by the middle black line inside the box. The lower andupper whiskers represent the minimum and maximum value,respectively. The solid blue lines refer to the normal global range(80–200 lg As/kg) and the dotted red1 line refers to the ChineseNational Food Quality Standard for arsenic concentrations in ricegrains (150 lg As/kg). The figure shows only 3.6% of rice samplesexceeded the global normal range of 80–200 lg As/kg, calculatedby Zavala and Duxbury (2008), and only 14% of samples exceedthe Chinese National Food Quality Standard of 150 lg/kg (USDA,2006). The Chinese standard was selected as a reference point as it
Zn and Se in rice imports in Qatar: Health implications. Food Chem. Toxicol.
a Consumer Reports (2012).b Carbonell-Barrachina et al. (2012).c Meharg et al. (2008).d <DL: less than the detection limit.
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is the most conservative guideline that currently exists. For allcountries except Italy, Thailand and the USA, the 90th percentileAs concentrations fell below the national Chinese food quality stan-dard. This indicates that even the most exposed people in Qatar stillfall within an acceptable risk level. Arsenic concentrations in Indianrice grains are remarkably low compared to imports from othercountries; this is important for the Qatar population as the majorityof rice varieties sold in local markets were of Indian origin.
Of the rice-based products analyzed, the highest average Asconcentrations were observed in rice powders, while the lowestvalues were in rice pastas (Table 3). Infant cereals containedhigher levels of Zn and Se than the other products; this is dueto the intentional fortification of rice cereals with these elements.For infant cereals, total As concentrations were within levels pre-viously reported although the overall mean (92.1 lg/kg) is gener-ally less than the reported mean values (Carbonell-Barrachinaet al., 2012; Consumer Reports, 2012; Meharg et al., 2008). Differ-ences in trace metal levels in food products most likely reflectconditions in the countries of origin; the samples collected fromQatar were produced in Oman (n = 1), Iran (n = 1) and Poland(n = 2). To the best of our knowledge, samples from these coun-tries have not been included in previous studies. We are notaware of any previously reported values of Zn and Se for the typesof cereals sampled in Qatar although Ljung et al. (2011) found6.3–10 mg Zn/kg and 16–28 lg Se/kg in fortified infant rice cere-als with fruits.
Short
Medium
Long
Extra-long
Fig. 2. Distribution of rice samples by IRRI rice length categories.
Please cite this article in press as: Rowell, C., et al. A market basket survey of As,(2014), http://dx.doi.org/10.1016/j.fct.2014.04.041
3.2. Morphology and effect on the concentrations of As, Zn and Sein rice grains
Halder et al. (2012) discussed the influence of grain morphologyon the accumulation of arsenic uptake in rice grains and foundincreased As concentration with increased grain length. Fig. 2highlights the distribution of Qatar rice samples among four IRRIlength categories. The rice grain lengths were distributed with32.8% long, 31.1% short, 21.3% medium and 14.8% extra-long. Ourstudy showed no significant association (p = 0.155) between Ascontent and length of rice grains. Lack of correlation in this studymay be attributed to the varied cultivars included as well as overalllower As concentrations; the study by Halder et al. (2012) wasfocused narrowly on brown rice types with notably higher Ascontent.
A significant positive trend (p < 0.001) was observed for both Znand Se content and rice grain length (Fig. 3). Significantly higher(p < 0.05) levels of Zn were observed in long and extra-long ricegrains; and significantly higher Se levels were observed for extra-long grains. More research is necessary to understand thisphenomenon and its implications; however, these observationssuggest that consumption of longer grain rice varieties can be a sig-nificant contributor to nutritional intake of Zn and Se. In Qatar,where long-grain rice (such as basmati) is the preferred variety,rice may in fact be providing a substantial portion of the recom-mended daily requirement of Se and Zn.
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3.3. Total daily intake of As, Zn and Se from consumption of ricein Qatar
The diet of the Qatari population is heavily dependent on rice. In2010, Qatar imported 166,904 metric tons of various rice typesfrom 17 different countries (SQSA, 2010).
Varying rice consumption rates among Qatari citizens and for-eign residents were used to estimate individual TDIAs values(Table 4). Based on dietary preferences and market availability,TDIAs values were calculated for basmati rice types and for riceoriginating in India, assuming 100% rice consumption from thesetypes. A native Qatari consumes approximately 404 g/day of rice,which is 3.3 times more than the rate per day for the non-Qataridiet (120 g/day), resulting in vastly different exposures betweenthe two groups (SQSA, 2008). Based on these statistics, the TDIAs
based on total population data should not be considered to be rep-resentative of the As exposure from rice consumption for Qataricitizens. It should be noted that consumption of rice powder and/or rice pasta was not included in the TDIAs, RNIZn and RNISe calcu-lations as the market availability and consumption of these itemsis extremely limited in the country.
Zn and Se in rice imports in Qatar: Health implications. Food Chem. Toxicol.
Fig. 3. (A) Positive trend of Zn concentration with increasing length of rice grains and (B) positive trend of Se concentration with increasing length of rice grains.
Table 4TDIAs
a estimates in rice grains available in Qatar based on overall average As concentrations, average As concentrations in basmati rice and Indian rice and 90th percentile Asconcentrations in rice grains.
Total rice samplesd Total rice samples 90th percentilee Basmati ricef Indian riceg
a Total daily intake for As (lg/day kg BW).b Provisional tolerable daily intake for As based on the WHO/FAO withdrawn value of 2.1 lg/day kg BW.c Based on a weighted average assuming: (i) 50% of Qatari population is male, (ii) 68% of non-Qatari population is male and (iii) 85% of the total population is non-Qatari
(SQSA, 2008).d Based on the overall average As concentration of 96.2 lg/kg.e Based on 90th percentile As concentrations in rice grains of 170 lg/kg.f Based on average As concentrations in basmati rice of 79.8 lg/kg.g Based on average As concentration in Indian rice of 62.9 lg/kg.
Table 5DIZn
a and DISeb estimates and percent of RNIZn
c and percent of RNISed in raw Q4rice
grains available to consumers in Qatar based on overall average concentrations,average concentrations in basmati and Indian rice.
Total rice samplesf Basmati riceg Indian riceDI (%RNI) DI (%RNI) DI (%RNI)
h Based on overall average concentrations for Se and Zn of 152 lg/kg and 11.5 mg/kg, respectively.
a Daily intake for Zn (mg/day).b Daily intake for Se (lg/day).c Recommended nutrient intake for Zn.d Recommended nutrient intake for Se.e Based on a weighted average assuming: (i) 85% of the population is non-Qatari
and (ii) RNI is the average of RNI for male and females for each element(RNIZn = 11.9 mg/day, RNISe = 30 lg/day).
f Based on overall average concentrations for Se and Zn of 103 lg/kg and12.46 mg/kg, respectively.
g Based on overall average concentrations for Se and Zn of 185 lg/kg and13.9 mg/kg, respectively.
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Calculated average TDIAs values ranged from 5.80% to 33.7% ofthe WHO PTDI, with no values exceeding the PTDI. Even amongthe 90th percentile exposures for Qatari females (the highestexposed group) rice consumption only accounted for 59.6% of thePTDI. These observations indicate rice consumption in Qatar doesnot constitute a significant risk for arsenic poisoning.
DIZn and DISe values from rice consumption in Qatar are shown inTable 5. The majority of Qatar’s population falls within the moderateZn bioavailability nominal category defined by the WHO (WHO/FAO, 2004b). Weighted averages for the total population reflectthe actual intake of non-Qatari citizens and neglect to show thehigher nutrient intake from rice consumption based on the Qataridiet, therefore DI values are shown for both populations.
Zn intake from rice consumption provides less than 50% ofRNIZn, except in the case of Qatari females. Qatari females receiveup to 57.4% RNIZn from diets that favor basmati rice. For most ofthe people, however, rice from local markets is not an adequatesource of Zn and diets should be supplemented with other Zn con-taining foods.
Williams et al. (2009b) showed that rice consumption of 300 g/day could not supply the daily Se requirement of an adult. Ourstudy shows that diets with higher daily rice consumption contrib-ute significantly to the daily requirement for Se. For the Qatari diet,with an average consumption of 404 g rice/day, rice accounts formore than 100% of the RNISe for both males and females. For thenon-Qatari citizens with a much lower consumption rate of rice,
Please cite this article in press as: Rowell, C., et al. A market basket survey of As, Zn and Se in rice imports in Qatar: Health implications. Food Chem. Toxicol.(2014), http://dx.doi.org/10.1016/j.fct.2014.04.041
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the highest percentages observed were from consumption of bas-mati rice grains, and included 66% RNISe for non-Qatari malesand 86.9% RNISe for non-Qatari females.
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3.4. Exposure to As, Zn and Se through consumption of rice-basedinfant cereals in Qatar
Studies have linked prolonged consumption of As contaminatedgroundwater to childhood morbidity and mortality (Meharg et al.,2008; Wasserman et al., 2008). Children are also more vulnerableto contaminants in foods because they consume more food per unitbody weight compared to adults.
Based on serving size instructions for the infant cereals pur-chased at local markets in Qatar (40 g, 3 times per day), the esti-mated TDIAs ranged from 0.850 to 2.02 lg/day kg BW for infantsaged 6–12 months. These results in 40–96% PDI for As intake withan average of 70.1% indicating a significant route of dietary expo-sure. The WHO PTDI for As was a guideline set for adult populationsand is arguably much too high a value to accurately assess potentialrisks to infants. It is assumed that the use of the former WHO (with-drawn 2010) guideline underestimates the percent of As TDIachieved through consumption of infant rice-based cereals. Also,the risk estimate does not include exposures from other potentialrice-based sources common to children less than one year of age,such as puddings, pasta, crackers, puffed rice and biscuits.
For infants aged 6–12 months, the WHO lists a RNIZn of 4.1mg/day and a RNISe of 10 lg/day. Based on the recommendeddaily serving, average Zn intake from infant cereals in Qatarprovides 66.5% of the daily RNIZn and 63.0% of RNISe. These rice-based cereals should be considered an important likely contribu-tor to the daily requirements for Zn and Se for children aged6–12 months.
Food security has been a high priority issue on the politicalagenda of most countries especially during the last decade. Onedimension of the food security problem that is of growing con-cern has to do with the regional and global contamination ofthe agro-ecosystems which can lead to agricultural produceand associated food products that may be unsafe for human con-sumption. The unique example for this food security issue is theelevation of arsenic levels in soils resulting from long-term useof arsenic contaminated groundwater for irrigation purposes inmany countries of South and Southeast Asia. The presence ofarsenic in irrigation waters and soils at elevated levels can leadto bioaccumulation of arsenic in rice grains to levels that canpose threats to the health of consumers. Since most of theworld’s rice exports come from South and Southeast Asia, risksto the supply chain for a critical food product (rice) has beenheightened in both the producing and importing countries. SinceQatar imports all its rice, the main staple food in the country, itsfood safety and security have become intricately intertwinedwith the quality of the rice producing systems in South andSoutheast Asia. This concern has prompted this study aimed atassessing the health risks associated with consumption ofimported rice in the country.
We find that consumption of commercially available rice inQatar is not a significant threat to health, even among the high-est exposed population of Qatari women. On the other hand, theconsumption of large quantities of rice among Qataris can makea significant contribution to the total daily intake of Se and Zn –among the Qatari women, this source provides more than 50% ofthe RNI for Zn. In this regard, the traditional consumption oflong-grain basmati rice among the Qatari and non-Qatari Arab
Please cite this article in press as: Rowell, C., et al. A market basket survey of As,(2014), http://dx.doi.org/10.1016/j.fct.2014.04.041
population increases the intake of Se and Zn and should beencouraged.
Conflict of Interest
The authors declare that there are no conflicts of interest.
Transparency Document
The Transparency document associated with this article can befound in the online version.
Acknowledgements
This article was made possible by a NPRP award [6-1416-1-262]from the Qatar National Research Fund (a member of The QatarFoundation). The statements made herein are solely the responsi-bility of the authors. We would like to acknowledge the Collegeof North Atlantic – Qatar (CNA-Q) Doha, Qatar for their contribu-tion of facilities and necessary supplies.
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