Ngole-Jeme Veronica M, Ekosse Georges-Ivo E
Department of Crop Science, Faculty of Agriculture, Science and Technology, North West University, Private Bag X2046, Mmabatho 2735, South Africa.
Directorate of Research and Innovation, University of Venda, Private Bag X5050, Thohoyandou, Limpopo Province 0950, South Africa.
Int J Environ Res Public Health. 2015 Jul 31;12(8):8933-55. doi: 10.3390/ijerph120808933.
This study compared the granulometric properties, mineralogical composition and concentrations of major and trace element oxides of commonly ingested soils (geophagic soil) collected from different countries with a view of understanding how varied they may be in these properties and to understand the possible health implications of ingesting them. Soil samples were collected from three different countries (South Africa, Swaziland and Democratic Republic of Congo (DRC)) and their granulometric properties, concentrations of major and trace element oxides as well as mineralogical composition determined. Differences were observed in the granulometric properties of geophagic soil from the three different countries with most of them having <20% clay content. The soils also showed varied degrees of weathering with values of Chemical Index of Alteration (CIA) and Chemical Index of Weathering (CIW) being between 60% and 99.9% respectively. The mineral assemblages of the soils from South Africa and Swaziland were dominated by the primary minerals quartz and feldspar whereas soils from DRC had more of kaolinite, a secondary mineral than primary minerals. Soils from DRC were associated with silt, clay, Al2O3, and CIA unlike most samples from South Africa which were associated with SiO2, sand, K2O, CaO, and MgO. The soils from Swaziland were closely associated with silt, H2O and Fe2O3(t). These associations reflect the mineralogy of the samples. These soils are not likely to serve as nutrient supplements because of the low concentrations of the nutrient elements contained. The coarse texture of the samples may also result in dental destruction during mastication. Sieving of the soils before ingestion to remove coarse particles is recommended to reduce the potential health threat associated with the ingestion of coarse-textured soils.
本研究比较了从不同国家采集的常见食用土壤（食土）的粒度特性、矿物成分以及主要和微量元素氧化物的浓度，旨在了解这些特性的差异程度，并了解摄入这些土壤可能对健康产生的影响。从三个不同国家（南非、斯威士兰和刚果民主共和国）采集了土壤样本，并测定了它们的粒度特性、主要和微量元素氧化物浓度以及矿物成分。观察到来自三个不同国家的食土在粒度特性上存在差异，其中大多数土壤的粘土含量<20%。这些土壤还表现出不同程度的风化，蚀变化学指数（CIA）和风化化学指数（CIW）的值分别在60%至99.9%之间。南非和斯威士兰土壤的矿物组合以原生矿物石英和长石为主，而刚果民主共和国的土壤中次生矿物高岭石比原生矿物更多。与南非的大多数样本与SiO2、沙子、K2O、CaO和MgO相关不同，刚果民主共和国的土壤与粉砂、粘土、Al2O3和CIA相关。斯威士兰的土壤与粉砂、H2O和Fe2O3(t)密切相关。这些关联反映了样本的矿物学特征。由于所含营养元素浓度较低，这些土壤不太可能作为营养补充剂。样本的粗糙质地也可能导致咀嚼时牙齿受损。建议在摄入前对土壤进行筛分以去除粗颗粒，以减少因摄入质地粗糙的土壤而带来的潜在健康威胁。
