Browsing by Author "Adomako, E."
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Item Enhanced transfer of arsenic to grain for Bangladesh grown rice compared to US and EU(Elsevier, 2010) Adomako, E.; Solaiman, A.R.M.; Williams, P.N.; Deacon, C.; Rahman, G.K.M.M.; Meharg, A.A.A field survey was conducted in arsenic impacted and non-impacted paddies of Bangladesh to assess how arsenic levels in rice (Oryza sativa L.) grain are related to soil and shoot concentrations. Ten field sites from an arsenic contaminated tubewell irrigation region (Faridpur) were compared to 10 field sites from a nonaffected region (Gazipur). Analysis of the overall data set found that both grain and shoot total arsenic concentrations were highly correlated (P<0.001) with soil arsenic. Median arsenic concentrations varied by 14, 10 and 3 fold for soil, shoot and grain respectively comparing the two regions. The reason for the sharp decline in the magnitude of difference between Gazipur and Faridpur for grain arsenic was due to an exponential decline in the grain/shoot arsenic concentration ratio with increasing shoot arsenic concentration. When the Bangladesh data were compared to EU and US soil–shoot–grain transfers, the same generic pattern could be found with the exception that arsenic was more efficiently transferred to grain from soil/shoot in the Bangladesh grown plants. This may reflect climatic or cultivar differences.Item Global Sourcing of Low‑Inorganic Arsenic Rice Grain(Exposure and Health, 2019-11-12) Adomako, E.; Carey, M.; Meharg, C.; Williams, P.; Marwa, E.; Jiujin, X.; Farias, J.G.; De Silva, P.M.C.S.; Signes‑Pastor, A.; Lu, Y.; Nicoloso, F.T.; Savage, L.; Campbell, K.; Elliott, C.; Green, A.J.; Moreno‑Jiménez, E.; Carbonell‑Barrachina, A.A.; Triwardhani, E.A.; Pandiangan, F.I.; Haris, P.I.; Lawgali, Y.F.; Sommella, A.; Pigna, M.; Brabet, C.; Montet, D.; Njira, K.; Watts, M.J.; Meharg, A.A.Arsenic in rice grain is dominated by two species: the carcinogen inorganic arsenic (the sum of arsenate and arsenite) and dimethylarsinic acid (DMA). Rice is the dominant source of inorganic arsenic into the human diet. As such, there is a need to identify sources of low-inorganic arsenic rice globally. Here we surveyed polished (white) rice across representative regions of rice production globally for arsenic speciation. In total 1180 samples were analysed from 29 distinct sampling zones, across 6 continents. For inorganic arsenic the global ̃x was 66 μg/kg, and for DMA this figure was 21 μg/kg. DMA was more variable, ranging from < 2 to 690 μg/kg, while inorganic arsenic ranged from < 2 to 399 μg/kg. It was found that inorganic arsenic dominated when grain sum of species was < 100 μg/kg, with DMA dominating at higher concentrations. There was considerable regional variance in grain arsenic speciation, particularly in DMA where temperate production regions had higher concentrations. Inorganic arsenic concentrations were relatively consistent across temperate, subtropical and northern hemisphere tropical regions. It was only in southern hemisphere tropical regions, in the eastern hemisphere that low-grain inorganic arsenic is found, namely East Africa ( ̃x < 10 μg/kg) and the Southern Indonesian islands ( ̃x < 20 μg/kg). Southern hemisphere South American rice was universally high in inorganic arsenic, the reason for which needs further exploration.Item Rice Grain Cadmium Concentrations in the Global Supply‑Chain(Exposure and Health, 2020-02-19) Adomako, E.; Shi, Z.; Carey, M.; Meharg, C.; Williams, P.N.; Signes‑Pastor, A.J.; Triwardhani, E.A.; Pandiangan, F.I.; Campbell, K.; Elliott, C.; Marwa, E.M.; Jiujin, X.; Farias, J.G.; Nicoloso, F.T.; De Silva, P.M.C.S.; Lu, Y.; Norton, G.; Green, A.J.; Moreno‑Jiménez, E.; Zhu, Y.; Carbonell‑Barrachina, A.A.; Haris, P.I.; Lawgali, Y.F.; Sommella, S.; Pigna, M.; Brabet, C.; Montet, D.; Njira, K.; Watts, M.J.; Hossain, M.; Islam, M.R.; Tapia, Y; Oporto, C.; Meharg, A.A.One of cadmium’s major exposure routes to humans is through rice consumption. The concentrations of cadmium in the global polished (white), market rice supply-chain were assessed in 2270 samples, purchased from retailers across 32 countries, encompassing 6 continents. It was found on a global basis that East Africa had the lowest cadmium with a median for both Malawi and Tanzania at 4.9 μg/kg, an order of magnitude lower than the highest country, China with a median at 69.3 μg/ kg. The Americas were typically low in cadmium, but the Indian sub-continent was universally elevated. In particular certain regions of Bangladesh had high cadmium, that when combined with the high daily consumption rate of rice of that country, leads to high cadmium exposures. Concentrations of cadmium were compared to the European Standard for polished rice of 200 μg/kg and 5% of the global supply-chain exceeded this threshold. For the stricter standard of 40 μg/kg for processed infant foods, for which rice can comprise up to 100% by composition (such as rice porridges, puffed rice cereal and cakes), 25% of rice would not be suitable for making pure rice baby foods. Given that rice is also elevated in inorganic arsenic, the only region of the world where both inorganic arsenic and cadmium were low in grain was East Africa.Item Variations in concentrations of arsenic and other potentially toxic elements in mine and paddy soils and irrigation waters from southern Ghana(Springer, 2010) Adomako, E.; Deacon, C.; Meharg, A.A.This study was undertaken to ascertain the impact of gold mining on soil and water chemistry as well as on rice grain quality. Samples collected from both gold mining and non-gold mining regions of southern Ghana were analysed by inductively coupled plasma mass spectrometry (ICP-MS) to determine the concentrations of arsenic and other potentially toxic elements (PTEs). Significant differences were observed between sites with respect to soil As, Co, Cu, Pb and Zn concentrations. Paddy soils from the Anum Valley Irrigation Project site, located close to the old Konongo Gold Mine in the Ashanti region, contained up to 103 mg arsenic/kg. Although higher arsenic concentrations were recorded in mine soils from Bogosu in the western region, paddy soil samples from this region contained relatively low concentrations of arsenic, suggesting that the contribution of gold mining to soil contamination is a function of distance from the point source of contaminants. Transfer of soil arsenic to rice grain was significantly higher in gold mining regions compared to non-gold mining regions. At the Anum Valley Irrigation Project site, where surface waters containing 144 μg arsenic/l were used for paddy irrigation, rice grain arsenic concentration reached 0.59 mg/kg, indicating a potential risk of arsenic transfer to the food chain.