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Selenium Characterization In The Global Rice Supply Chain
Citation:
Williams, P. N., E. Lombi, G. Sun, K. G. SCHECKEL, Y. Zhu, X. Feng, J. Zhu, A. Carey, E. Adomako, Y. Lawgali, C. Deacon, AND A. A. Meharg. Selenium Characterization In The Global Rice Supply Chain. J. Schnoor (ed.), ENVIRONMENTAL SCIENCE AND TECHNOLOGY. American Chemical Society, Washington, DC, 43(15):6024-6030, (2009).
Impact/Purpose:
Conducted a worldwide market-based survey of Se concentrations in white polished rice to determine variation in national rice grain Se concentrations. From this, we were able to model Se concentration distributions for both the global rice production and rice export pools. To compliment global Se baseline estimates, detailed evidence is presented in the form of in situ speciation characterization and spatial distribution of naturally occurring Se in an enriched rice grain sample.
Description:
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, modeled 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-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.
