Uranium in foodstuffs, in particular mineral water

A Metallomic Approach to Assess Associations of Plasma Metal Levels with Amnestic Mild Cognitive Impairment and Alzheimer's Disease: An Exploratory Study

Alzheimer’s disease (AD) involves the abnormal activity of transition metals and metal ion dyshomeostasis; however, the potential of trace metal biomarkers in predicting cognitive decline has not been evaluated. This study aimed to assess the potential of 36 trace elements in predicting cognitive decline in patients with amnestic mild cognitive impairment (aMCI) or AD. Participants (9 controls, 23 aMCI due to AD, and 8 AD dementia) underwent comprehensive cognitive tests, including the Mini-Mental State Examination (MMSE) and trace metal analysis. The correlations between the plasma trace element levels and annual MMSE changes during follow-up were analyzed. We found that an increase in disease severity was linked to lower plasma levels of boron (B), bismuth (Bi), thorium (Th), and uranium (U) (adjusted p < 0.05). Higher baseline calcium levels (r = 0.50, p = 0.026) were associated with less annual cognitive decline; those of B (r = −0.70, p = 0.001), zirconium (r = −0.58, p = 0.007), and Th (r = −0.52, p = 0.020) with rapid annual cognitive decline in the aMCI group; and those of manganese (r = −0.91, p = 0.035) with rapid annual cognitive decline in the AD group. Overall, our exploratory study suggests that plasma metal levels have great potential as in vivo biomarkers for aMCI and AD. Larger sample studies are necessary to confirm these results.

Paddy soil geochemistry, uptake of trace elements by rice grains (Oryza sativa) and resulting health risks in the Mekong River Delta, Vietnam

Soil geochemistry and phytoavailable trace elements were investigated in 80 paddy soil samples and corresponding rice grains from the Mekong River Delta in Vietnam. Soil parameters like Fe-, Al-, and Mn-phases, organic matter, and pH-value determine element concentrations in soil and affect their transfer into rice grains. Arsenic exceeded the allowed limit for Vietnamese agricultural soils in 11% of the samples, presumably caused by natural processes. Lead surpassed the limit in one soil sample. Other toxic elements were close to their natural concentrations and far below allowable limits for agricultural soil. There was no clear correlation of trace element concentrations in soils with those in corresponding grains, even if the different soil parameters and the large pH-range between 3.7 and 6.8 were considered. To assess health risks of critical elements in rice, the thresholds of tolerable upper intake level for total food and drinking water (UL) and of permissible maximum concentration (MC) for rice grains were evaluated. Surprisingly, rice grains grown on non- or low-polluted soils can surpass the upper limits. According to the UL concept, 12% of the grains exceeded the UL of As, 29% that of Cd, and 27% that of Pb for each gender. According to the MC concept, 5% of the rice grains exceeded the MC of inorganic As for adults and 38% that for young children. 24% of the grains surpassed the MC of Pb, while Cd in all grains was below the MC. The differing results of the UL and MC approaches show an urgent need for revision and harmonization concerning As, Cd, and Pb limits, especially regarding countries with high rice consumption.

Harmful and nutrient elements in paddy soils and their transfer into rice grains (Oryza sativa) along two river systems in northern and central Vietnam

Thirty soil samples and 24 corresponding unpolished rice samples along the Red and Huong Rivers in northern and central Vietnam respectively, were analyzed in order to evaluate (a) soil geochemistry, (b) factors that determine the transfer of harmful and nutrient elements from soils into rice grains, (c) health risk to the local population through rice consumption. The concentrations of As, Bi, and U in the soils of this area are higher relative to those of average shale probably due to natural redox-related processes. Also, Zn, Ce, Th, La, Sn, Pb, and Cd are accumulated in some soils because of mining activities or industrial wastewater application. Arsenic concentrations exceed the Vietnamese allowable limit of 15 mg kg^-1 in 80% of the tested soils. Twelve percent of the unpolished rice grains surpass the permissible maximum concentration of 0.2 mg Cd kg^-1 grain dry matter by FAO/WHO and European Union, and all samples are below the Pb limit. The daily intake of As is within the range of the tolerable intake levels proposed by the European Food Safety Authority. Influences of soil parameters such as pH value, contents of soil organic matter, oxides/hydroxides of Al, Fe, and Mn cause a broad spread of transfer factors from soil to grains. Positive trends exist between the transfer factors within the groups (a) As, Sb, and U, (b) Co, Cu, Ni, and Zn, (c) Cd and Mn which indicate similar influences of soil parameters on their uptake. We propose that the allowable Cd maximum concentration for rice should be set to less than 0.2 mg kg^-1. The analysis of As and Cd concentrations in soils and corresponding rice grains as well as the soil pH value should be made obligatory in order to prevent intoxication. In addition, critical elements from nonferrous metal mining and industrial areas should also be evaluated.