Browsing by Author "Adomako, E.E."
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Item Arsenic limits trace mineral nutrition (Selenium, Zinc, and Nickel) in Bangladesh rice grain(2009) Williams, P.N.; Islam, S.; Islam, R.; Jahiruddin, M.; Adomako, E.E.; Solaiman, A.R.M.; Rahman, G.K.M.M.; Lu, Y.; Deacon, C.; Zhu, Y.-G.; Meharg, A.A.A reconnaissance of 23 paddy fields, from three Bangladesh districts, encompassing a total of 230 soil and rice plant samples was conducted to identify the extent to which trace element characteristics in soils and irrigation waters are reflected by the harvested rice crop. Field sites were located on two soil physiographic units with distinctly different As soil baseline and groundwater concentrations. For arsenic (As), both straw and grain trends closely fitted patterns observed for the soils and water. Grain concentration characteristics for selenium (Se), zinc (Zn), and nickel (Ni), however, were markedly different. Regressions of shoot and grain As against grain Se, Zn, and Ni were highly significant (P< 0.001), exhibiting a pronounced decline in grain trace-nutrient quality with increasing As content. To validate this further, a pot experiment cultivar screening trial, involving commonly cultivated high yielding variety (HYV) rice grown alongside two U.S. rice varieties characterized as being As tolerant and susceptible, was conducted on an As amended uniform soil. Findings from the trial confirmed that As perturbed grain metal(loid) balances, resulting in severe yield reductions in addition to constraining the levels of Se, Zn, and Ni in the grain.Item Geographical Variation in Total and Inorganic Arsenic Content of Polished (White) Rice(American Chemical Society, 2009) Meharg, A.A.; Williams, P.N.; Adomako, E.E.; Lawgali, Y.Y.; Deacon, C.; Villada, A.; Cambell, R.C.J.; Sun, G.; Zhu, Y.-G.; Feldmann, J.; Raab, A.; Zhao, F.-J.; Islam, R.; Hossain, S.; Yanai, J.An extensive data set of total arsenic analysis for 901 polished (white) grain samples, originating from 10 countries from 4 continents, was compiled. The samples represented the baseline (i.e., not specifically collected from arsenic contaminated areas), and all were for market sale in major conurbations. Median total arsenic contents of rice varied 7-fold, with Egypt (0.04 mg/kg) and India (0.07 mg/kg) having the lowest arsenic content while the U.S. (0.25 mg/kg) and France (0.28 mg/kg) had the highest content. Global distribution of total arsenic in rice was modeled by weighting each country’s arsenic distribution by that country’s contribution to global production. A subset of 63 samples from Bangladesh, China, India, Italy, and the U.S. was analyzed for arsenic species. The relationship between inorganic arsenic content versus total arsenic content significantly differed among countries, with Bangladesh and India having the steepest slope in linear regression, and the U.S. having the shallowest slope. Using country-specific rice consumption data, daily intake of inorganic arsenic was estimated and the associated internal cancer risk was calculated using the U.S. Environmental Protection Agency (EPA) cancer slope. Median excess internal cancer risks posed by inorganic arsenic ranged 30-fold for the 5 countries examined, being 0.7 per 10,000 for Italians to 22 per 10,000 for Bangladeshis, when a 60 kg person was considered.Item Inorganic arsenic and trace elements in Ghanaian grain staples(Elsevier, 2011) Adomako, E.E.; Williams, P.N.; Deacon, C.; Meharg, A.A.A total of 549 samples of rice, maize, wheat, sorghum and millet were obtained from markets in Ghana, the EU, US and Asia. Analysis of the samples, originating from 21 countries in 5 continents, helped to establish global mean trace element concentrations in grains; thus placing the Ghanaian data within a global context. Ghanaian rice was generally low in potentially toxic elements, but high in essential nutrient elements. Arsenic concentrations in rice from US (0.22 mg/kg) and Thailand (0.15 mg/kg) were higher than in Ghanaian rice (0.11 mg/kg). Percentage inorganic arsenic content of the latter (83%) was, however, higher than for US (42%) and Thai rice (67%). Total arsenic concentration in Ghanaian maize, sorghum and millet samples (0.01 mg/kg) was an order of magnitude lower than in Ghanaian rice, indicating that a shift from rice-centric to multigrain diets could help reduce health risks posed by dietary exposure to inorganic As.Item Inorganic arsenic levels in baby rice are of concern(Elsevier, 2008) Meharg, A.A.; Sun, G.; Williams, P.N.; Adomako, E.E.; Deacon, C.; Zhu, Y.-G.; Feldmann, J.; Raab, A.Inorganic arsenic is a chronic exposure carcinogen. Analysis of UK baby rice revealed a median inorganic arsenic content (n = 17) of 0.11 mg/kg. By plotting inorganic arsenic against total arsenic, it was found that inorganic As concentrations increased linearly up to 0.25 mg/ kg total arsenic, then plateaued at 0.16 mg/kg at higher total arsenic concentrations. Inorganic arsenic intake by babies (4-12 months) was considered with respect to current dietary ingestion regulations. It was found that 35% of the baby rice samples analysed would be illegal for sale in China which has regulatory limit of 0.15 mg/kg inorganic arsenic. EU and US food regulations on arsenic are non-existent. When baby inorganic arsenic intake from rice was considered, median consumption (expressed as mg/kg/d) was higher than drinking water maximum exposures predicted for adults in these regions when water intake was expressed on a bodyweight basis.Item Lead in rice: Analysis of baseline lead levels in market and field collected rice grains(Science of the Total Environment, 2014-07) Norton, G.J.; Williams, P.N.; Adomako, E.E.; Price, A.H.; Zhu, Y.; Zhao, F.-J.; McGrath, S.; Deacon, C.M.; Villada, A.; Sommella, A.; Lu, Y.; Ming, L.; De Silva, P.M.C.S.; Brammer, H.; Dasgupta, T.; Islam, M.R.; Meharg, A.A.In a large scale survey of rice grains from markets (13 countries) and fields (6 countries), a total of 1578 rice grain samples were analysed for lead. From the market collected samples, only 0.6% of the samples exceeded the Chinese and EU limit of 0.2μgg-1 lead in rice (when excluding samples collected from known contaminated/mine impacted regions). When evaluating the rice grain samples against the Food and Drug Administration's (FDA) provisional total tolerable intake (PTTI) values for children and pregnant women, it was found that only people consuming large quantities of rice were at risk of exceeding the PTTI from rice alone. Furthermore, 6 field experiments were conducted to evaluate the proportion of the variation in lead concentration in rice grains due to genetics. A total of 4 of the 6 field experiments had significant differences between genotypes, but when the genotypes common across all six field sites were assessed, only 4% of the variation was explained by genotype, with 9.5% and 11% of the variation explained by the environment and genotype by environment interaction respectively. Further work is needed to identify the sources of lead contamination in rice, with detailed information obtained on the locations and environments where the rice is sampled, so that specific risk assessments can be performed. © 2014 Elsevier B.V.Item Leaf Litter Production and Soil Fertility Improvement in a Home garden in the Akuapem District of Ghana(University of Ghana, 1999-12) Adomako, E.E.; Laing, E.; University of Ghana, College of Basic and Applied Sciences , School of Biological Sciences , Department of BotanyCeiba pentandra, Colagigantea,Lanneawelwitschii,Militia excelsa (all non-leguminous) and Milletia zechiana (leguminous) are among the various tree species retained on cropping fields in the Akuapem District of Ghana, but little is known of the actual contribution of these species to soil fertility improvement. Leaf litter samples from the above-mentioned non-leguminous species were analysed to determine their nutrient content. Leaf litter production was also quantified monthly over a fourmonth period and hence the potential contribution of the different types of leaf litter to the soil nutrient pool was calculated. Results from pot experiments, in which maize (Zea mays) was used as a test crop indicated that when the leaf litter produced by the four non-leguminous species are used as mulch, the nutrients contained in them are not readily available for plant growth. Nonetheless, studies of soil chemical properties beneath tree canopy, at canopy edge and outside tree canopy suggest that long term accumulation of leaf Utter from C. pentandra and L. wehvitschii results in higher availability of nitrogen and phosphorus. Millettia zechiana, on the other hand, was found to have nodulation ability and hence is potentially capable of contributing to soil enrichment through biological nitrogen fixation.Item Selenium characterization in the global rice supply chain(American Chemical Society, 2009) Williams, P.N.; Enzo, L.; Sun, G.; Scheckel, K.; Zhu, Y.-G.; Feng, X.; Zhu, J.; Carey, A.-M.; Adomako, E.E.; Lawgali, Y.; Deacon, C.; Meharg, A.A.For up to 1 billion people worldwide, insufficient dietary intake of selenium (Se) is a serious health constraint. Cereals are the dominant Se source for those on low protein diets, as typified by the global malnourished population. With crop Se content constrained largely by underlying geology, regional soil Se variations are often mirrored by their locally grown staples. Despite this, the Se concentrations of much of the world’s rice, the mainstay of so many, is poorly characterized, for both total Se content and Se speciation. In this study, 1092 samples of market sourced polished rice were obtained. The sampled rice encompassed dominant rice producing and exporting countries. Rice from the U.S. and India were found to be the most enriched, while mean average levels were lowest in Egyptian rice: ∼32-fold less than their North American equivalents. By weighting country averages by contribution to either global production or export, modelled baseline values for both were produced. Based on a daily rice consumption of 300 g day-1, around 75% of the grains from the production and export pools would fail to provide 70% of daily recommended Se intakes. Furthermore, Se localization and speciation characterization using X-ray fluorescence (µ-XRF) and X-ray absorption near edge structure (µ-XANES) techniques were investigated in a Se-rich sample. The results revealed that the large majority of Se in the endosperm was present in organic forms.Item Variation in rice cadmium related to human exposure(Environmental Science and Technology, 2013-05) Meharg, A.A.; Norton, G.; Deacon, C.; Williams, P.; Adomako, E.E.; Price, A.; Zhu, Y.; Li, G.; Zhao, F.J.; McGrath, S.; Villada, A.; Sommella, A.; De Silva, P.M.C.S.; Brammer, H.; Dasgupta, T.; Islam, M.R.Cereal grains are the dominant source of cadmium in the human diet, with rice being to the fore. Here we explore the effect of geographic, genetic, and processing (milling) factors on rice grain cadmium and rice consumption rates that lead to dietary variance in cadmium intake. From a survey of 12 countries on four continents, cadmium levels in rice grain were the highest in Bangladesh and Sri Lanka, with both these countries also having high per capita rice intakes. For Bangladesh and Sri Lanka, there was high weekly intake of cadmium from rice, leading to intakes deemed unsafe by international and national regulators. While genetic variance, and to a lesser extent milling, provide strategies for reducing cadmium in rice, caution has to be used, as there is environmental regulation as well as genetic regulation of cadmium accumulation within rice grains. For countries that import rice, grain cadmium can be controlled by where that rice is sourced, but for countries with subsistence rice economies that have high levels of cadmium in rice grain, agronomic and breeding strategies are required to lower grain cadmium. © 2013 American Chemical Society.