Increase in rice grain arsenic for regions of Bangladesh irrigating paddies with elevated arsenic in groundwaters

Concern has been raised by Bangladeshi and international scientists about elevated levels of arsenic in Bengali food, particularly in rice grain. This is the first inclusive food market-basket survey from Bangladesh, which addresses the speciation and concentration of arsenic in rice, vegetables, pulses, and spices. Three hundred thirty aman and boro rice, 94 vegetables, and 50 pulse and spice samples were analyzed for total arsenic, using inductivity coupled plasma mass spectrometry (ICP-MS). The districts with the highest mean arsenic rice grain levels were all from southwestern Bangladesh: Faridpur (boro) 0.51 > Satkhira (boro) 0.38 > Satkhira (aman) 0.36 > Chuadanga (boro) 0.32 > Meherpur (boro) 0.29 microg As g(-1). The vast majority of food ingested arsenic in Bangladesh diets was found to be inorganic; with the predominant species detected in Bangladesh rice being arsenite (AsIII) or arsenate (AsV) with dimethyl arsinic acid (DMAV) being a minor component. Vegetables, pulses, and spices are less important to total arsenic intake than water and rice. Predicted inorganic arsenic intake from rice is modeled with the equivalent intake from drinking water for a typical Bangladesh diet. Daily consumption of rice with a total arsenic level of 0.08 microg As g(-1) would be equivalent to a drinking water arsenic level of 10 microg L(-1).     

Arsenic in rice: I. Estimating normal levels of total arsenic in rice grain

High levels of arsenic (As) in rice grain are a potential concern for human health. Variability in total As in rice was evaluated using 204 commercial rice samples purchased mostly in retail stores in upstate New York and supplemented with samples from Canada, France, Venezuela, and other countries. Total As concentration in rice varied from 0.005 to 0.710 mg kg(-1). We combined our data set with literature values to derive a global "normal" range of 0.08-0.20 mg kg(-1) for As concentration in rice. The mean As concentrations for rice from the U.S. and Europe (both 0.198 mg kg(-1)) were statistically similar and significantly higher than rice from Asia (0.07 mg kg(-1)). Using two large data sets from Bangladesh, we showed that As contaminated irrigation water, but not soil, led to increased grain As concentration. Wide variability found in U.S. rice grain was primarily influenced by region of growth rather than commercial type, with rice grown in Texas and Arkansas having significantly higher mean As concentrations than that from California (0.258 and 0.190 versus 0.133 mg kg(-1)). Rice from one Texas distributor was especially high, with 75% of the samples above the global "normal" range, suggesting production in an As contaminated environment.     

Total and speciated arsenic levels in rice from China

Although the need for policy development on arsenic (As) in rice has been recognized and a legally enforceable maximum contaminant level (MCL) for inorganic arsenic (As_i) in rice has been established in China, evidence reported in this article indicates that the risk of exposure to As for the Chinese population through rice is still underestimated. Polished rice from various production regions of China was analyzed for total As and arsenic species using HPLC–ICPMS. Total As concentration ranged 65.3–274.2 ng g^?1, with an average value of 114.4 ng g^?1. Four arsenic species, including arsenite (As(III)), arsenate (As(V)), dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA), were detected in most rice samples. The As_i (As(III) + As(V)) species was predominant, accounting for approximately 72% of the total As in rice, with a mean concentration of 82.0 ng g^?1. In assessing the risk from As in rice, we found that As intake for the Chinese population through rice is higher than from drinking water, with a 37.6% contribution to the maximum tolerable daily intake (MTDI) of As recommended by World Health Organization (WHO), compared with 1.5% from drinking water. Compared to other countries, the risk for the Chinese from exposure to As through rice is more severe due to the large rice consumption in China. Therefore, not only the scientific community but also local authorities should take this risk seriously. Furthermore, more stringent legislation of the MCL for rice should be enacted to protect the Chinese consumer from a high intake of As.     

Cooking rice in excess water reduces both arsenic and enriched vitamins in the cooked grain

This paper reports the effects of rinsing rice and cooking it in variable amounts of water on total arsenic, inorganic arsenic, iron, cadmium, manganese, folate, thiamin and niacin in the cooked grain. We prepared multiple rice varietals both rinsed and unrinsed and with varying amounts of cooking water. Rinsing rice before cooking has a minimal effect on the arsenic (As) content of the cooked grain, but washes enriched iron, folate, thiamin and niacin from polished and parboiled rice. Cooking rice in excess water efficiently reduces the amount of As in the cooked grain. Excess water cooking reduces average inorganic As by 40% from long grain polished, 60% from parboiled and 50% from brown rice. Iron, folate, niacin and thiamin are reduced by 50–70% for enriched polished and parboiled rice, but significantly less so for brown rice, which is not enriched.     

Immunocrossreactivity of antisera against grain prolamines of wheat, rye, barley and oats

Summary Prolamines extracted from wheat (gliadin), rye (secalin), barley (hordein) and oats (avenin) were used to raise antibodies in rabbits. The four prolamines were separated by SDS-PAGE and blotted onto nitrocellulose. The immunocrossreactivity of the separated prolamines with the four antisera was studied. The close botanical relationship between wheat and rye, and to a lesser extent barley, is clearly established. The crossreactivity of gliadin, secalin and hordein with anti-avenin serum was found to be weak. In contrast, avenin shows a strong crossreactivity with anti-gliadin serum.

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Immunkreuzreaktionen von Antisera gegen die Prolamine von Weizen, Roggen, Gerste und Hafer

Zusammenfassung Zur Gewinnung von Antiprolamin-Sera wurden Kaninchen mit den Prolaminen von Weizen (Gliadin), Roggen (Secalin), Gerste (Hordein) und Hafer (Avenin) immunisiert. Die vier Prolamine wurden durch SDS-PAG-Elektrophorese aufgetrennt, auf Nitrocellulose übertragen und auf Immunkreuzreaktionen mit den vier Antisera untersucht. Die nahe botanische Verwandtschaft von Weizen und Roggen, in geringerem Masse auch von Gerste, spiegelt sich deutlich wider. Die Kreuzreaktionen von Gliadin, Secalin und Hordein mit Antiavenin-Serum sind dagegen schwach ausgeprägt. Im Gegensatz dazu zeigt Avenin eine starke Kreuzreaktion mit Antigliadin-Serum.

     

Immunocrossreactivity of antisera against grain prolamines of wheat, rye, barley and oats

Prolamines extracted from wheat (gliadin), rye (secalin), barley (hordein) and oats (avenin) were used to raise antibodies in rabbits. The four prolamines were separated by SDS-PAGE and blotted onto nitrocellulose. The immunocrossreactivity of the separated prolamines with the four antisera was studied. The close botanical relationship between wheat and rye, and to a lesser extent barley, is clearly established. The crossreactivity of gliadin, secalin and hordein with anti-avenin serum was found to be weak. In contrast, avenin shows a strong crossreactivity with anti-gliadin serum.     

Fatty acid composition of grain from winter and spring sown oats, barley and wheat.

The fatty acid composition of grain has been studied in six varieties of oats, two of wheat and two of barley, sown in pots in an unheated glasshouse in winter and in spring. Differences were found between the species in composition and in their response to sowing date. Oats showed the greatest varietal variation in both total fatty acid (TFA) content and in the proportion of its component fatty acids. The content and degree of unsaturation of the oat TFA was higher in the winter sown than in the spring sown crop. Increases in the TFA content of oats, whether arising from differences in variety or sowing date, were generally followed by an increase in the proportion of oleic acid and a decrease in the proportions of palmitic and linoleic acid in the TFA. Winter sowing, as compared with spring, led to a small, but significant, decrease in the TFA content of barley and an increase in its degree of unsaturation. There were no significant changes in the content or composition of wheat TFA as a result of differences in sowing date. Factors influencing the differences in TFA content and composition between species, varieties and sowing dates are discussed.     

Market basket survey shows elevated levels of As in South Central U.S. processed rice compared to California: consequences for human dietary exposure

We report the largest market basket survey of arsenic (As) in U.S. rice to date. Our findings show differences in transitional-metal levels between polished and unpolished rice and geographical variation in As and selenium (Se) between rice processed in California and the South Central U.S. The mean and median As grain levels for the South Central U.S. were 0.30 and 0.27 mimcrog As g(-1), respectively, for 107 samples. Levels for California were 41% lower than the South Central U.S., with a mean of 0.17 microg As g(-1) and a median of 0.16 microg As g(-1) for 27 samples. The mean and median Se grain levels for the South Central U.S. were 0.19 microg Se g(-1). Californian rice levels were lower, averaging only 0.08 and 0.06 microg Se g(-1) for mean and median values, respectively. The difference between the two regions was found to be significant for As and Se (General Linear Model (GLM): As p < 0.001; Se p < 0.001). No statistically significant differences were observed in As or Se levels between polished and unpolished rice (GLM: As p= 0.213; Se p= 0.113). No significant differences in grain levels of manganese (Mn), cobalt (Co), copper (Cu), or zinc (Zn) were observed between California and the South Central U.S. Modeling arsenic intake for the U.S. population based on this survey shows that for certain groups (namely Hispanics, Asians, sufferers of Celiac disease, and infants) dietary exposure to inorganic As from elevated levels in rice potentially exceeds the maximum intake of As from drinking water (based on consumption of 1 L of 0.01 mg L(-1) In. As) and Californian state exposure limits. Further studies on the transformation of As in soil, grain As bioavailability in the human gastrointestinal tract, and grain elemental speciation trends are critical.     

Mycotoxins in cereal grain. Part X. Invasion of fungi mycelium into wheat and barley kernels

Histochemical examination of wheat kernels invaded by Aspergilli and Penicillia proved penetration of fungal mycelium into subaleurone and endosperm cells through aleurone layer cells. Walls of aleurone layer cells in invaded kernels were found to be thicker and split. Formation of spores in cleistothecia's in endosperm cells was found. The observation of kernels under a stereoscopic microscope was found to be a sensitive way to detect fungi invasion in cereal kernels.     

Inorganic arsenic in rice bran and its products are an order of magnitude higher than in bulk grain

Rice is more elevated in arsenic than all other grain crops tested to date, with whole grain (brown) rice having higher arsenic levels than polished (white). It is reported here that rice bran, both commercially purchased and specifically milled for this study, have levels of inorganic arsenic, a nonthreshold, class 1 carcinogen, reaching concentrations of approximately 1 mg/kg dry weight, around 10-20 fold higher than concentrations found in bulk grain. Although pure rice bran is used as a health food supplement, perhaps of more concern is rice bran solubles, which are marketed as a superfood and as a supplement to malnourished children in international aid programs. Five rice bran solubles products were tested, sourced from the United States and Japan, and were found to have 0.61-1.9 mg/kg inorganic arsenic. Manufactures recommend approximately 20 g servings of the rice bran solubles per day, which equates to a 0.012-0.038 mg intake of inorganic arsenic. There are no maximum concentration levels (MCLs) set for arsenic or its species in food stuffs. EU and U.S. water regulations, set at 0.01 mg/L total or inorganic arsenic, respectively, are based on the assumption that 1 L of water per day is consumed, i.e., 0.01 mg of arsenic/ day. At the manufacturers recommended rice bran solubles consumption rate, inorganic arsenic intake exceeds 0.01 mg/ day, remembering that rice bran solubles are targeted at malnourished children and that actual risk is based on mg kg(-1) day(-1) intake.     

Effect of gaseous chlorine dioxide treatment on the quality of rice and wheat grain

Gaseous chlorine dioxide (ClO₂), which is a strong disinfecting agent with strong oxidation properties and penetration ability, is used to control insect pests and fungal contamination in stored grains. However, the effect of gaseous ClO₂ on stored grain has yet to be reported. In the present study, we exposed rice and wheat seeds to several concentrations of ClO₂ gas for various durations and found that the viability of rice was affected less than that of wheat. After 100 ppm of gaseous ClO₂ for 12 h, the normal rice seedling rate was not significantly different than that of the control. However, that of wheat was significantly decreased. We also measured the ClO₂ residueon stored rice and wheat after 200 ppm of gas treatment for 24 h. After 10 days of storage following the treatment, ClO₂ and chlorine were not detected on either rice or wheat. Chlorite was detected on rice at 0.22 mg/kg of grain; however, it was not detected on wheat. These results suggest that gaseous ClO₂ treatment affects the viability of rice and wheat seed but leaves minimal chemical residue.     

Mycotoxins in cereal grain. Part IX. Zearalenone and Fusaria in wheat,barley, rye and corn kernels

Toxigenic Fusaria, producing zearalenon, appeared in 31% of cereal grain samples. However zearalenone was present only in 0.5% of 584 cereal samples assayed during 1979-1981 at level 0.2-1.2 mg/kg. Fungi able to form zearalenone were present mainly in grain collected from breeding stations. Fusarium culmorum was dominant among toxigenic isolates from domestic cereals and yield of zearalenone was up to 700 mg/kg.     

Genotypic variation in oil and protein in barley grain

Oil content and composition, protein content and grain weight have been estimated in 86 barley genotypes from diverse sources grown in a replicated field experiment. Overall range between genotypes in composition was: oil content, 1.9-4.1 %; palmitic, 21.4-28.7%; stearic, 0.6-1.8%; oleic, 10.4-16.9%; linoleic, 52.4-58.3%; linolenic, 4.5-7.3%. Modern European varieties varied from 2.2-2.8% oil, and oil content was higher in two-rowed than six-rowed types and higher in naked than husked types. Protein content was higher in naked than husked types, but there was no significant difference between the protein content of two- and six-rowed types. Mean grain weight was higher in both two-rowed and in husked types. Oil was positively correlated with grain protein and the proportion of oleic acid, and negatively correlated with the proportions of palmitic and stearic acid. The highest oil contents were found in Rise 1508 and Hiproly which are high-lysine genotypes.     

粳稻谷中总砷和无机砷含量的测定及分布情况

本文采用ICP-MS法和LC-AFS法分别测定粳稻谷中的总砷和无机砷含量.结果表明:总砷在0?10 ng/mL的浓度范围内呈良好的线性关系,检出限为0.020 7 ng/mL;As3+和As5+在0?50 ng/mL的浓度范围内呈良好的线性关系,As3+检出限为0.24 ng/mL,As5+检出限为0.44 ng/mL...     

Total and inorganic arsenic in rice and rice bran purchased in Thailand

Concentrations of total and inorganic arsenic were determined in 180 samples of polished and brown rice of three rice types, namely white, jasmine, and sticky, and 44 samples of rice bran from these three rice types purchased in Thailand. Concentrations (expressed in nanograms per gram) of inorganic arsenic in polished white, jasmine, and sticky rice were 68.3 ± 17.6 (with a range of 45.0 to 106), 68.4 ± 15.6 (41.7 to 101), and 75.9 ± 24.8 (43.5 to 156), respectively, while those in the three brown rice samples were 124 ± 34.4 (74.5 to 193), 120 ± 31.6 (73.1 to 174), and 131 ± 35.6 (78.0 to 188), respectively. Inorganic arsenic concentrations (expressed in nanograms per gram) in rice bran produced from the three rice types were 633 ± 182 (375 to 919), 599 ± 112 (447 to 824), and 673 ± 195 (436 to 1,071), respectively. Rice bran contained concentrations of total and inorganic arsenic approximately seven and nine times higher, respectively, than those found in the corresponding polished rice. The levels of inorganic arsenic in the three rice types of both polished and brown rice were within the only published regulatory limit of 200 ng/g.     

Rye bread reduces plasma cholesterol levels in hypercholesterolaemic pigs when compared to wheat at similar dietary fibre level

BACKGROUND: Rye is a whole‐grain cereal with the potential of contributing to a healthy diet, but research on rye in relation to chronic diseases is scarce compared to wheat and oats. In this study, a total of 17 hypercholesterolaemic pigs were fed high‐fat high‐cholesterol rye (n = 9) or wheat‐based buns (n = 8) with similar dietary fibre (DF) content for 9–10 weeks to study the effect on cardiovascular risk factors. RESULTS: Ingestion of rye bread resulted in a 40% lower plasma total and LDL cholesterol compared to the wheat group, whereas HDL cholesterol, insulin and glucose concentrations were not affected by dietary treatments. Intestinal viscosity was 7.2 times higher, and organic matter and fat digestibility significantly reduced in the pigs fed rye buns. The hepatic expression of the cholesterol 7α‐hydroxylase gene (CYP7A1) was lower in rye‐fed pigs, whereas four other key genes involved in cholesterol metabolism were not affected. Plasma cholesterol correlated inversely with intestinal viscosity and organic matter digestibility. CONCLUSION: The ability of DF from rye to interfere with digestion and absorption is more important for whole‐body cholesterol homeostasis than regulation in the liver at gene level. Copyright © 2008 Society of Chemical Industry     

Effects of heating procedures on deoxynivalenol, nivalenol and zearalenone levels in naturally contaminated barley and wheat.

The influence of heating temperature and time on deoxynivalenol (DON), nivalenol (NIV) and zearalenone (ZEA) contents in naturally co-contaminated barley and wheat was investigated intending to establish the basis for a decontamination model of Fusarium mycotoxins in cereals. The standard toxins and whole barley powder samples were heated in a convection oven at 140, 160, 180, 200, or 220 degrees C, and kernel subsamples (200 g each) were roasted in an experimental rotary gas-fired roaster at 150, 180 or 220 degrees C. All treatments resulted in a time-temperature-dependent decomposition of the toxins; the logarithm of the toxin remaining % presented a linear relationship with heating time. The lines equations were used to estimate the half (H) and decimal (D) decomposition times (time required to destroy 50 or 90% of the toxin, respectively). DON and NIV H and D decomposition times were similar and 50% shorter for heated standards than for whole barley powder. ZEA standard values were considerably longer, while whole barley powder values were comparable with those of DON and NIV. At 220 degrees C, D decomposition times of DON, NIV and ZEA heated standards were 11, 10 and 85 min, respectively, while the values obtained in whole barley powder were the same for the three toxins (25 min). The determination of H and D decomposition values constitutes a basis to understand the heating stability nature of each toxin.     

Mycotoxins in cereal grain. Part III. Production of ochratoxin A in different varieties of wheat,rye and barley

Kernels of several varieties of wheat, rye and barley were found to have different resistance to fungi attack and ochratoxin A production, particularly in first step of fungus development on kernels. Zinc was stated to be a limiting factor of ochratoxin production. Viable sound kernels were very resistant against fungi. Dead (e.g. autoclaved) kernels were attacked by fungus very quickly. Varieties with stronger resistance to fungi invasion during storage were selected.     

Nitrate modifies urea root uptake and assimilation in wheat seedlings

BACKGROUND: Some authors suggest that nitrate improves the effects of ammonium and urea nutrition on plant growth via an increase in both the root uptake of ammonium and urea, and the further activation of its assimilation. In order to verify these hypotheses, wheat (Triticum aestivum L.) seedlings were grown with various nitrogen supplies containing the main nitrogen forms (ammonium, nitrate and urea). Root nitrogen uptake and the concentration of each of the nitrogen forms in roots and shoots were studied. RESULTS: Results indicated that nitrate increases root uptake of ammonium and urea, with this effect being highly significant when the three nitrogen forms are supplied simultaneously. Nitrate significantly increased both urea and ammonium assimilation in the shoot of plants fed urea‐and‐nitrate. However, nitrate did not significantly affect ammonium assimilation in either shoots or roots in plants fed ammonium‐and‐nitrate. CONCLUSION: The beneficial effect of nitrate seems to be related to an enhancement of root uptake of ammonium and urea, although their assimilation was significantly increased in urea‐fed plants, but not in ammonium‐fed plants. Copyright © 2008 Society of Chemical Industry     

Arsenic bioavailability to rice is elevated in Bangladeshi paddy soils

Some paddy soils in the Bengal delta are contaminated with arsenic (As) due to irrigation of As-laden groundwater, which may lead to yield losses and elevated As transfer to the food chain. Whether these soils have a higher As bioavailability than other soils containing either geogenic As or contaminated by mining activities was investigated in a pot experiment. Fourteen soils varying in the source and the degree (4-138 mg As kg 1?1) of As contamination were collected, 10 from Bangladeshi paddy fields (contaminated by irrigation water) and two each from China and the UK (geogenic or mining impacted), for comparison. Bangladeshi soils had higher percentages of the total As extractable by ammonium phosphate (specifically sorbed As) than other soils and also released more As into the porewater upon flooding. Porewater As concentrations increased with increasing soil As concentrations more steeply in Bangladeshi soils, with arsenite being the dominant As species. Rice growth and grain yield decreased markedly in Bangladeshi soils containing > 13 mg As kg 1?1, but not in the other soils. Phosphate-extractable or porewater As was a better indicator of As bioavailability than total soil As. Rice straw As concentrations increased with increasing soil As concentrations; however, As phytotoxicity appeared to result in lower grain As concentrations. The relative proportions of inorganic As and dimethylarsinic acid (DMA) in grain varied among soils, and the percentage DMA was larger in greenhouse-grown plants than grain samples collected from the paddy fields of the same soil and the same rice cultivar, indicating a strong environmental influence on As species found in rice grain. This study shows that Bangladeshi paddy soils contaminated by irrigation had a higher As bioavailability than other soils, resulting in As phytotoxicity in rice and substantial yield losses.