College of Eco-Environmental Engineering, Guizhou Minzu University, Guiyang 550025, China; Key Laboratory of Environmental Pollution Monitoring and Disease Control, Ministry of Education, Guizhou Medical University, Guiyang 550025, China.
State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
J Environ Sci (China). 2022 Sep;119:119-129. doi: 10.1016/j.jes.2022.04.028. Epub 2022 May 2.
Mercury (Hg) in rice is drawing mounting concern since methylmercury (MeHg) was found capable of accumulating in rice. In-vitro bioaccessibility is a feasible and reliable method to assess the health effects of Hg in rice and has been utilized in a number of studies. This study was done to investigate the impact of cultivar, planting location, and cooking on the total mercury (THg) and MeHg bioaccessibility of rice, for which multiple statistical analysis methods were used to analyze the significance of their effects. The THg concentrations of rice samples taken from non-Hg contaminated areas of China were all below 15 ng/g and their MeHg concentrations were below 2 ng/g. Cooking could significantly reduce the MeHg bioaccessibility of rice because the MeHg was mainly combined with protein and the protein will be denatured during the cooking process, and then the denatured MeHg is difficult to be dissolved into the liquid phase. Indica- and japonica-type rice cultivars did not show significant differentiation in either the concentration of Hg or its bioaccessibility. However, the glutinous rice type differed significantly from the above rice types, and it showed greater bioaccessibility of THg and MeHg due to its distinct protein contents and starch properties. Planting location can affect the Hg concentration in rice and THg bioaccessibility but has a limited impact on MeHg bioaccessibility. Based on these results, two macro factors (rice cultivar, planting location) are presumed to impact Hg bioaccessibility by how they affect micro factors (i.e., Hg forms).
大米中的汞（Hg）引起了越来越多的关注，因为甲基汞（MeHg）被发现能够在大米中积累。体外生物可给性是评估大米中汞健康影响的一种可行且可靠的方法，已在多项研究中得到应用。本研究旨在探讨品种、种植地点和烹饪对大米中总汞（THg）和甲基汞（MeHg）生物可给性的影响，采用多种统计分析方法来分析其影响的显著性。取自中国非汞污染地区的大米样本中，THg 浓度均低于 15ng/g，MeHg 浓度低于 2ng/g。烹饪可以显著降低大米中 MeHg 的生物可给性，因为 MeHg 主要与蛋白质结合，而在烹饪过程中蛋白质会变性，然后变性的 MeHg 难以溶解到液相中。籼稻和粳稻品种在汞浓度及其生物可给性方面均无显著差异。然而，糯米型与上述两种类型的大米有明显的区别，由于其独特的蛋白质含量和淀粉特性，其 THg 和 MeHg 的生物可给性更高。种植地点会影响大米中的汞浓度和 THg 生物可给性，但对 MeHg 生物可给性的影响有限。基于这些结果，可以认为两个宏观因素（品种、种植地点）通过影响微观因素（即汞形态）来影响汞的生物可给性。
