title: Selenium characterization in the global rice supply chain.
abstract: 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: approximately 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 (micro-XRF) and X-ray absorption near edge structure (micro-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.
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Paul N
authors.initials: PN
authors.lastname: Williams
authors.forename: Enzo
authors.initials: E
authors.lastname: Lombi
authors.forename: Guo-Xin
authors.initials: GX
authors.lastname: Sun
authors.forename: Kirk
authors.initials: K
authors.lastname: Scheckel
authors.forename: Yong-Guan
authors.initials: YG
authors.lastname: Zhu
authors.forename: Xinbin
authors.initials: X
authors.lastname: Feng
authors.forename: Jianming
authors.initials: J
authors.lastname: Zhu
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Carey
authors.forename: Eureka
authors.initials: E
authors.lastname: Adomako
authors.forename: Youseff
authors.initials: Y
authors.lastname: Lawgali
authors.forename: Claire
authors.initials: C
authors.lastname: Deacon
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Meharg
mesh_terms: D004785:Environmental Pollutants / Q000032:analysis*; D005308:Fertilizers; D005506:Food Contamination; D005843:Geography; D005844:Geology; D007194:India; D013058:Mass Spectrometry / Q000379:methods; D008962:Models, Theoretical; D012275:Oryza / Q000187:drug effects*; D011786:Quality Control; D012643:Selenium / Q000032:analysis*; D018036:Selenium Compounds / Q000032:analysis*; D014481:United States
chemical_list: D004785:Environmental Pollutants; D005308:Fertilizers; D018036:Selenium Compounds; D012643:Selenium