A human health risk assessment of rare earth elements through daily diet consumption from Bayan Obo Mining Area, China

Development of a direct dilution method for the simultaneous determination of 40 metal and non-metallic elements in urine and blood samples within 6 min using ICP-MS: Application of comprehensive biomonitoring of elementomic phenotypes of individuals in paired biological samples

The deficiency and overnutrition of both metal and non-metallic elements in human body can pose harmful effects to human health. Therefore, it is necessary to determination of elements in human body for assessing health risk of elementome. In this study, a simple and accurate biomonitoring approach was developed for quantifying 40 elements in biological samples within 6 min using a direct dilution method combined with inductively coupled plasma mass spectrometry (ICP-MS). It had good linearity (R2 ≥ 0.999) and high sensitivity (limit of detection (LOD) as low as 2 ng/L) with spiked recovery rates ranged between 82.53 % and 110.03 % for serum samples and between 81.92 % and 108.66 % for urine samples. The intra-day and inter-day precision are less than 15 %. In addition, uncertainty indicators and green analytical chemistry (GAC) approaches are used to evaluate the sources of uncertainty and greenness of developed analytical procedures. This method was finally used to detect the paired biofluids samples collected from 202 Chinese children. The distribution of element in this population through detection rate and level of body burden was analyzed. Furthermore, the function of paired serum and urine samples for detection of 40 elements is first explored by analyzing pairing samples. These results demonstrated that the proposed method for analysis of paired biological samples provides an alternative quantitative elementomics method to enable the comprehensive assessment of health risk associated with 40 elemental phenotypes of individuals.

Contamination status and health risk assessment of potentially toxic trace elements in soils surrounding rare earth tailings in China: A retrospective review

The contamination of soils surrounding rare earth tailings (SRET) with potentially toxic trace elements (PTEs), including Ni, Cd, Cr, As, Pb, Mn, Cu, Zn, and Hg, has garnered increasing scientific concern. However, existing studies predominantly focused on localized regions, limiting insights into nationwide pollution patterns associated with SRET. To address this gap, we systematically compiled and analyzed PTE concentration data from SRET across China using peer-reviewed studies published between 2012 and 2023. The index of geo-accumulation (Igeo) was applied to quantify contamination levels, while Monte Carlo simulation (MCS) was employed to assess uncertainty and sensitivity in health risks posed by ingestion, inhalation, and dermal exposure pathways. Results revealed that average concentrations of Cd, As, Pb, Mn, Zn, and Hg exceeded Chinese soil background values by up to 11.16-fold. Igeo revealed significant Cd contamination in SRET in Inner Mongolia (Igeo = 1.77), Fujian (Igeo = 5.64), and Sichuan (Igeo = 3.89). Moderate Mn contamination was identified in Guangdong (Igeo = 1.80) and Inner Mongolia (Igeo = 1.63). Adults exhibited elevated health risks via oral ingestion of PTEs-contaminated SRET. MCS demonstrated that the median hazard index (HI) and carcinogenic risk (CR) values in five provinces surpassed safety thresholds (CR > 1.00 ×10-6, HI > 1.00). Sensitivity analyses identified daily soil intake and exposure duration were positively linked to health risks, with As, Ni, Cd, Cr, and Mn concentrations contributing substantially to cumulative risks. This study provides actionable insights for optimizing cost-effective PTE remediation strategies in SRET-affected regions.

Adverse effects and underlying mechanism of rare earth elements

BACKGROUND

Rare earth elements (REEs) have found broad application in a range of industries, including electronics, automotive, agriculture, and healthcare. However, their widespread utilization and release into the environment pose potential risks of human exposure. Despite extensive research on REEs toxicity, the relationship between exposure and subsequent health concerns remains ambiguous. Given that the biological effects of REEs can vary based on their design and application, assessing their toxicity can be highly challenging.

OBJECTIVE

This review is to offer a thorough comprehension of REEs' application and toxicity, guiding future research and policy-making to safeguard public health and environmental integrity.

METHODS

A systematic search across PubMed, Web of Science, Cochrane Library, and Embase was conducted using the terms: ("rare earth" OR "lanthanoid") AND ("health hazard" OR "toxic" OR "adverse health effect"). From 5,924 initial records, 89 studies were selected through deduplication and two-stage screening to assess systemic toxicity of REEs. An additional 100 articles on REEs mechanisms and applications were incorporated via citation tracking. All selections followed PRISMA guidelines with dual-author verification to ensure rigor.

CONCLUSION

The review emphasizes REEs' applications in various domains and documents potential environmental pathways. Furthermore, it elaborates on current processes to assess REEs-related toxicity across different model organisms and cell lines, estimating health threats posed by REEs exposure. Finally, based on the findings of both in vivo and in vitro experiments, the potential toxic mechanisms of REEs are detailed. To guide future research and policy development to safeguard public health and environmental integrity.

Rare earth elements and health risk assessment of road dust from the vicinity of coal fired thermal power plants

As emerging pollutants, rare earth elements (REEs) have been explored in different environmental samples. This is the first study to use road dust samples to monitor REEs form the vicinity of thermal power plant (TPPs). Road dust samples were collected from 17 locations (main and side roads) in a 15 km radius surrounding two coal-fired TPP (TPP Kostolac A & B, Serbia). Concentrations of nine REEs (Sc, La, Ce, Nd, Sm, Eu, Tb, Dy, Yb) were measured in the road dust samples (f < 63 μm, easily resuspended fraction size) using instrumental neutron activation analysis (INAA). We have found that the concentrations of REEs do not depend on the distance of the sampling location from TPP. There were no statistically significant differences between the main road and side road samples suggest that traffic is not the main source of REE in the studied area. Principal component analysis, hierarchical cluster analysis as well as geo-accumulation index (Igeo) and enrichment factors (EF) point to an enrichment with Dy of road dust samples collected in September. The road dust samples do not pose any harm to human health in the tested area, as shown by a hazard index of less than 0.1. Despite the low REE risk, it is important to consider the possibility of negative health consequences, mainly because these samples may contain numerous other organic and inorganic pollutants.

Rare Earth Elements in Human Calcified Aortic Valves and Epicardial Adipose Tissue

Background/Objectives: Rare earth elements (REEs) are emerging environmental pollutants, with human exposure increasing due to recent industrial and technological activities. While most studies have focused on detecting REEs in human fluids, their presence in tissues remains understudied. Aortic valve degeneration is known to facilitate the adsorption of various chemical elements; however, the occurrence of REEs in human valves has not yet been investigated. This exploratory study aimed to determine the presence of REEs in the aortic valves of patients with aortic stenosis undergoing surgical valve replacement. It also analyzed potential correlations between REE levels in the valves, epicardial adipose tissue, serum, and selected disease markers. Methods: Samples of aortic valve, epicardial adipose tissue, and serum were collected from 20 adult patients undergoing elective aortic valve replacement. The concentrations of 14 REEs in these samples were measured using inductively coupled plasma mass spectrometry. Biochemical and clinical parameters of the patients were also considered to explore potential associations with the determined REE levels. Results: Total REEs, heavy REEs, and light REEs in aortic valves, epicardial fat, and serum were not intercorrelated. Moreover, for any sample type, they were not significantly related to the patient's demographics (age and sex), clinical characteristics (body mass index, heart failure severity, and systolic pressure gradients), kidney function (estimated glomerular filtration rate), and biochemical markers (creatinine, lipoprotein(a), total cholesterol, HDL, LDL, and fibrinogen). Smoking was the only factor influencing REE burden in studied patients, with active smokers revealing 61% higher serum REE concentrations and past smokers exhibiting 133% higher REE valvular deposition. Conclusions: The findings suggest that REE accumulation in aortic valve tissues occurs independently of systemic and clinical parameters but may be promoted by smoking, highlighting the need to investigate the underlying mechanisms of REE deposition. Given the small sample size and the cross-sectional, hypothesis-generating design, these observations should be interpreted with caution and treated as preliminary. Larger, longitudinal studies are needed to validate these results and explore potential causal relationships. Further research should also include the tissue originating from individuals without aortic stenosis for comparison. A deeper understanding of the pathways and health risks associated with REEs in cardiovascular tissues may offer valuable insights into their broader implications for human health.

Levels of Rare Earth Elements in Food and Human Dietary Exposure: A Review

Rare earth elements (REEs) are a group consisting of the following 17 metals: Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Pm, Sc, Sm, Tb, Tm, Y and Yb. In the current century, the number of applications of REEs has significantly increased. They are being used as components in high technology devices of great importance industrial/economic. However, information on the risk of human exposure to REEs, as well as the potential toxic effects of these elements is still limited. In general terms, dietary intake is the main route of exposure to metals for non-occupationally exposed individuals, which should be also expected for REEs. The current paper aimed at reviewing the studies -conducted over the world- that focused on determining the levels of REEs in foods, as well as the dietary intake of these elements. Most studies do not suggest potential health risk for consumers of freshwater and marine species of higher consumption, or derived from the intake of a number of vegetables, fruits, mushrooms, as well as other various foodstuffs (honey, tea, rice, etc.). The current estimated daily intake (EDI) of REEs does not seem to be of concern. However, considering the expected wide use of these elements in the next years, it seems to be clearly recommendable to assess periodically the potential health risk of the dietary exposure to REEs. This is already being done with well-known toxic elements such as As, Cd, Pb and Hg, among other potentially toxic metals.

The Rare Earth Element Lanthanum (La) Accumulates in Brassica rapa L. and Affects the Plant Metabolism and Mineral Nutrition

Lanthanum (La) is often used in industry and agriculture, leading to its accumulation in natural environments and potential ecological risks. The objective of this study was to examine the effects on the growth, metabolism, and nutrient composition of Brassica rapa exposed to at low (1 µM), medium (1 mM), and high (10 mM) La concentrations. We used chemical analytical, molecular, and metabolomic methods and found that high La exposure induced a hormetic effect, triggering both stimulatory and inhibitory responses. La reduced aluminum (Al), cobalt (Co), nickel (Ni), and chromium (Cr) levels at all concentrations, while medium and high doses also decreased phosphorus (P) and iron (Fe). La accumulation in B. rapa increased with La levels, affecting metabolic processes by modulating reactive oxygen species (ROS), increasing proline, and reducing total polyphenol content. Flavonoid levels were altered, chlorophyll and carotenoids declined, and non-photochemical quenching increased. Gene expressions related to flavonoid, carotenoid, and chlorophyll metabolism, as well as ion transport, exhibited a dose-dependent modulation. On the contrary, fatty acid composition remained unaffected. Our results indicate that La accumulates in in B. rapa and disrupts the plant metabolism. Despite an evident effect on plant productivity, our results also raise concerns about the potential health risks of consuming La-enriched B. rapa plants.

Evaluating the bioavailability of rare earth elements in paddy soils and their uptake in rice grains for human health risk

Rare earth elements (REEs) are a critical global focus due to their increasing use, raising concerns about their environmental distribution and human exposure, both vital to food safety and human health. Surface soil (0-30 cm) and corresponding rice grain samples (n = 85) were collected from paddy fields in Taiwan. This study investigated the total REE contents in soil through aqua regia digestion, as well as their labile forms extracted using 0.05 M ethylenediaminetetraacetic acid (EDTA), 0.10 M hydrogen chloride (HCl), and 0.01 M calcium chloride (CaCl2). The REE concentrations in the rice grains (Oryza sativa L.) were also analyzed. The estimated daily intake (EDI) of REEs through rice consumption for males was 1.3 times higher than that for females. Children under 12 years of age, regardless of gender, had the highest EDI of REEs compared to other age groups. High rice consumption and a high proportion of children are potentially at higher risk for elevated REE exposure. The transport of REEs from soil to rice demonstrated their shift of fractionation by the lower ratio of light REEs and heavy REEs in rice grain compared to soil and their upper continental crust (UCC)-normalized patterns. Empirical equations were developed to estimate the concentrations of REEs in rice grains based on soil pH, clay content, organic carbon, cation exchange capacity, dithionite-citrate-bicarbonate extractable iron, and labile REEs. This study provides critical insights into the health risks of REEs, clarifying their human exposure and the bioavailability from paddy soil to rice.

Subchronic Exposure to Low-Level Lanthanum, Cerium, and Yttrium Mixtures Altered Cell Cycle and Increased Oxidative Stress Pathways in Human LO-2 Hepatocytes but Did Not Cause Malignant Transformation

Human exposures to rare earth elements are increasing with expanded use in aerospace, precision instruments, and new energy batteries, materials, and fertilizers. Individually these elements have low toxicity, although few investigations have examined the health effects of longer-term mixture exposures. We used the LO-2 cell line to examine the effects of graded exposures to lanthanum, cerium, and yttrium (LCY) mixtures at 1-, 100-, and 1000-fold their human background levels (0.31 μg/L La, 0.25 μg/L Ce, and 0.12 μg/L Y) on cell cycle, oxidative stress, and nuclear factor erythroid-2-related factor (NRF2) pathway biomarkers, assessing responses every 10 passages up to 100 passages. Cell migration, concanavalin A, malignant transformation, and tumorigenesis in nude mice were also examined. Mixed LCY exposures activated oxidative stress and the NRF2 pathway by the 30th passage and increased the proportion of cells in the S phase and cell cycle-specific biomarkers by the 40th passage. LCY exposures did not cause malignant transformation of hepatocytes or induced tumorigenesis in nude mice but enhanced cell proliferation, migration, and agglutination. Importantly, LCY mixtures with longer-term exposure activated the NRF2 pathway and altered the hepatocyte cell cycle at doses far below those used in previous toxicological studies. The consequences of LCY mixtures for public health merit further study.

Rare earth elements reveal the human health and environmental concerns in the largest tributary of the Mekong river, Northeastern Thailand

The widespread application of rare earth elements (REEs) in contemporary industries and agriculture, has caused emerging contaminant accumulation in aquatic environments. However, there is a limited scope of risk assessments, particularly in relation to human health associated with REEs. This study investigated the provenance, and contamination levels of REEs, further evaluating their environmental and human health risks in river sediments from an agricultural basin. The concentrations of REEs ranged from 30.5 to 347.7 mg/kg, with showing an upward trend from headwater to downstream. The positive matrix factorization (PMF) model identified natural and anthropogenic input, especially from agricultural activities, as the primary source of REEs in Mun River sediments. The contamination assessment by the geoaccumulation index (I-geo) and pollution load index (PLI) confirmed that almost individual REEs in the samples were slightly to moderately polluted. The potential ecological risk index (PERI) showed mild to moderate risks in Mun River sediment. Regular fertilization poses pollution and ecological risks to agricultural areas, manifesting as an enrichment of light REEs in river sediments. Nevertheless, Monte Carlo simulations estimated the average daily doses of total REEs from sediments to be 0.24 μg/kg/day for adults and 0.95 μg/kg/day for children, comfortably below established human health thresholds. However, the risk of REE exposure appears to be higher in children, and sensitivity analyses suggested that REE concentration contributed more to health risks, whether the adults or children. Thus, concerns regarding REE contamination and risks should be raised considering the wide distribution of agricultural regions, and further attention is warranted to assess the health risks associated with other routes of REE exposure.