Addressing lanthanum toxicity in plants: Sources, uptake, accumulation, and mitigation strategies

Lanthanum (La), the second most abundant rare earth element (REE) is emerging as an environmental issue, with the potential to impact ecosystems and human health. Major sources of soil contamination by La include agricultural, and industrial activities. Lanthanum is non-essential for plant growth but accumulates in various plant parts. The uptake of La by plants is intricately influenced by various factors such as soil pH, redox potential, cation exchange capacity, presence of organic acids and rhizosphere composition. These factors significantly impact the availability and absorption of La ions. Lanthanum impact on plants depends on soil characteristics, cultivated species, developmental stage, La concentration, treatment period, and growth conditions. Excessive La concentrations affect cell division, DNA structure, nutrient uptake, and photosynthesis and induce toxicity symptoms. Plants employ detoxification mechanisms like vacuolar sequestration, osmolyte synthesis, and antioxidant defense system. However, higher concentrations of La can overwhelm these defense mechanisms, leading to adverse effects on plant growth and development. Further, accumulation of La in plants increases the risk for human exposure. Strategies to mitigate La toxicity are, therefore, vital for ecosystem protection. The application of phytoremediation, supplementation, chelation, amendments, and biosorption techniques contributes to the mitigation of La toxicity. This review provides insights into La sources, uptake, toxicity, and alleviation strategies in plants. Identifying research gaps and discussing advancements aims to foster a holistic understanding and develop effective strategies for protecting plant health and ecosystem resilience against La contamination.

Biochemical and biophysical interaction of rare earth elements with biomacromolecules: A comprehensive review

The growing utilization of rare earth elements (REEs) in industrial and technological applications has captured global interest, leading to the development of high-performance technologies in medical diagnosis, agriculture, and other electronic industries. This accelerated utilization has also raised human exposure levels, resulting in both favourable and unfavourable impacts. However, the effects of REEs are dependent on their concentration and molecular species. Therefore, scientific interest has increased in investigating the molecular interactions of REEs with biomolecules. In this current review, particular attention was paid to the molecular mechanism of interactions of Lanthanum (La), Cerium (Ce), and Gadolinium (Gd) with biomolecules, and the biological consequences were broadly interpreted. The review involved gathering and evaluating a vast scientific collection which primarily focused on the impact associated with REEs, ranging from earlier reports to recent discoveries, including studies in human and animal models. Thus, understanding the molecular interactions of each element with biomolecules will be highly beneficial in elucidating the consequences of REEs accumulation in the living organisms.

The impact of global climate changes on trace and rare earth elements mobilization in emerging periglacial terrains: Insights from western shore of Admiralty Bay (King George Island, Antarctic)

In the rapidly changing climate, the biogeochemical behaviours of trace elements and Rare Earth Elements (REEs) in emerging periglacial environments assumes profound importance. This study provides pivotal insights into this dynamic by investigating the Antarctic's response to global climate change. The bedrock of King George Island is rich in REEs, with the presence of trace metals (TEs), with the highest concentrations of metals found in ornithogenic soil (∑REE 84.01-85.53 mg∙kg-1 dry weight). REEs in the studied soil, found mainly in igneous rocks, as is indicated by the positive correlation of these elements with sodium and calcium. The TEs released as a result of weathering are leached by water flowing down local watercourses to Admiralty Bay, as indicated by the decreasing results of ∑REE = 11.59 μg∙dm-3 in watercourse water, ∑REE = 1.62 μg∙dm-3 in watercourse pools and ∑REE = 0.66 μg∙dm-3 in the water of Admiralty Bay at the outlet of the watercourse. Water originating from the melting of snow on the glacier also carried REEs (∑REE = 0.14 μg∙dm-3), a fact which suggest the further influx of these elements from atmospheric deposition. The Prasiola crispa turned out to be the most susceptible to the accumulation of REEs (∑ 80.73 ± 5.05 μg g-1) and TEs, with the exception of chromium and zinc, whose concentrations were found to be at their highest in Deschampsia antarctica. In Usnea antarctica, Xanthoria candelaria, and Ceratodon purpureus and Politrichastrum alpinum, a dominant role in the accumulation of REEs was played by HREEs. The determined enrichment factor (EF) indicates that the soil cover is a source of REEs (EFAlgae for ∑REE = 5.07; EFLichen for ∑REE = 6.65; EFBryophyta for ∑REE = 5.04; EFVascular for ∑REE = 4.38), while Ni, As and Pb accumulated in plants may originate from other sources than the soil.

Capturing cerium ions via hydrogel microspheres promotes vascularization for bone regeneration

The rational design of multifunctional biomaterials with hierarchical porous structure and on-demand biological activity is of great consequence for bone tissue engineering (BTE) in the contemporary world. The advanced combination of trace element cerium ions (Ce3+) with bone repair materials makes the composite material capable of promoting angiogenesis and enhancing osteoblast activity. Herein, a living and phosphorylated injectable porous hydrogel microsphere (P-GelMA-Ce@BMSCs) is constructed by microfluidic technology and coordination reaction with metal ion ligands while loaded with exogenous BMSCs. Exogenous stem cells can adhere to and proliferate on hydrogel microspheres, thus promoting cell-extracellular matrix (ECM) and cell-cell interactions. The active ingredient Ce3+ promotes the proliferation, osteogenic differentiation of rat BMSCs, and angiogenesis of endotheliocytes by promoting mineral deposition, osteogenic gene expression, and VEGF secretion. The enhancement of osteogenesis and improvement of angiogenesis of the P-GelMA-Ce scaffold is mainly associated with the activation of the Wnt/β-catenin pathway. This study could provide novel and meaningful insights for treating bone defects with biofunctional materials on the basis of metal ions.

Contrast Media-driven Anthropogenic Gadolinium: Knowns and Unknowns

Gadolinium-based contrast agents (GBCAs) have augmented the capabilities of MRI, which has led to their widespread and increasing use in radiology practice. GBCAs are introduced into the environment through disposal of unused product and elimination after intravenous injection, both primarily via liquid dispersion into the environment. This human introduction of gadolinium into the environment, referred to as anthropogenic gadolinium, is associated with the detection of gadolinium in water systems, raising concerns for potential adverse impact and prompting certain mitigation actions. This article summarizes the existing knowledge and problem scope, conveys the relevant underlying chemical principles of chelate dissociation, and offers an inferred perspective that the magnitude of the problem is most unlikely to cause human harm. The merits and limitations regarding possible mitigation tactics, such as collecting urine after GBCA administration, use of lower-dose high-relaxivity macrocyclic GBCAs, and the option for virtual contrast-enhanced examinations, will be discussed. Finally, the potential for monitoring gadolinium uptake in bone will be presented, and recommendations for future research will be offered. © RSNA, 2024 See also the article by Ibrahim et al in this issue. See also the article by McKee et al in this issue.

Investigation of background, novelty and recent advance of iron (II,III) oxide- loaded on 3D polymer based scaffolds as regenerative implant for bone tissue engineering: A review

Bone tissue engineering had crucial role in the bone defects regeneration, particularly when allograft and autograft procedures have limitations. In this regard, different types of scaffolds are used in tissue regeneration as fundamental tools. In recent years, magnetic scaffolds show promising applications in different biomedical applications (in vitro and in vivo). As superparamagnetic materials are widely considered to be among the most attractive biomaterials in tissue engineering, due to long-range stability and superior bioactivity, therefore, magnetic implants shows angiogenesis, osteoconduction, and osteoinduction features when they are combined with biomaterials. Furthermore, these scaffolds can be coupled with a magnetic field to enhance their regenerative potential. In addition, magnetic scaffolds can be composed of various combinations of magnetic biomaterials and polymers using different methods to improve the magnetic, biocompatibility, thermal, and mechanical properties of the scaffolds. This review article aims to explain the use of magnetic biomaterials such as iron (II,III) oxide (Fe2O3 and Fe3O4) in detail. So it will cover the research background of magnetic scaffolds, the novelty of using these magnetic implants in tissue engineering, and provides a future perspective on regenerative implants.

Erbium-ytterbium containing upconversion mesoporous bioactive glass microspheres for tissue engineering: luminescence monitoring of biomineralization and drug release

The development of functional biomaterials with real-time monitoring of mineralization processes, drug release and biodistribution has potential applications but remains an unsolved challenge. Herein, erbium- and ytterbium- containing mesoporous bioactive glass microspheres (MBGs:Er/Yb) with blue and red emission at an excitation wavelength of 980 nm were synthesized by a sol-gel combined with organic template method. As the concentration of Yb3+ ions gradually increases, the emission intensity of the MBGs:Er/Yb exhibits a clear concentration quenching effect. Combined with in vitro bioactivity tests, the optimal molar ratio of Er3+/Yb3+ was determined to be 4:3. Therefore, MBGs:4Er/3Yb was selected for in vitro biomineralization and drug release monitoring. The results of biomineralization monitoring show that the upconversion luminescence intensity is closely related to the degree of biomineralization. The upconversion luminescence intensity of MBGs:4Er/3Yb is quenched with the increase of the degree of biomineralization. The degree of luminescence quenching during biomineralization can be semiquantized. Drug release monitoring experiments showed that the anticancer drug doxorubicin hydrochloride (DOX) was successfully loaded into MBGs:4Er/3Yb and selectively quenched the green emission. When DOX was released, the green emission recovered stably, and It/I0 increased gradually. Moreover, there was a linear relationship between It/I0 and cumulative drug release, indicating that DOX-MBGs:4Er/3Yb is highly sensitive to DOX release, and monitoring the It/I0 values of DOX-MBGs:4Er/3Yb can achieve real-time tracking of the DOX release process to a certain extent. In conclusion, MBGs:4Er/3Yb has potential application as an upconversion luminescence biomonitoring material in the field of bone tissue engineering. STATEMENT OF SIGNIFICANCE: Mesoporous bioactive glasses have great potential for applications in bone tissue repair due to their excellent biological properties, but the effective information of the repair process cannot be grasped in a timely manner. Therefore, real-time monitoring of mineralization and drug release processes will be beneficial to obtain the degree of healing and optimize the amount and distribution of drugs to improve targeted therapeutic effects. For biomaterials, in vitro biological properties determine their biological properties in vivo, where the environment is more complex and diverse, and thus in vitro biomonitoring is particularly crucial. The organic combination of physical properties and biological properties will also provide a feasible idea for the development of biomaterials.

Hair-biomonitoring assessment of rare-earth-element exposure in residents of the largest rare-earth mining and smelting area of China

The long-term and large-scale mining of rare earth minerals may lead to an accumulation of rare earth elements (REEs) in the environment, posing potential health risks to residents. We collected scalp hair (n = 254) from residents of a smelting area, a mining area, and a reference area to clarify human exposure to REEs. The contents of 15 REEs investigated in human hair samples were notably higher in the mining and smelting areas than in the reference area. Significant differences between some REEs were observed between the mining and smelting areas, for instance, cerium (Ce), dysprosium, and praseodymium. In the study areas, exposure to different sources of REEs may be one of the factors that contributed to the variations of REE correlations and clusters in human hair. Furthermore, in the smelting area, Ce contents in hair decreased with increasing age of children. However, Ce contents in the hair of adults increased with age. In contrast, Ce accumulation continuously increased in the reference area residents' hair with age. Regression results indicated that age and location were more important than sex when considering the influence on REE accumulation in residents' hair. The results of this study may help policymakers to implement guidelines to alleviate residents' exposure to REE in mining and smelting areas.

Nacre-mimetic cerium-doped nano-hydroxyapatite/chitosan layered composite scaffolds regulate bone regeneration via OPG/RANKL signaling pathway

Autogenous bone grafting has long been considered the gold standard for treating critical bone defects. However, its use is plagued by numerous drawbacks, such as limited supply, donor site morbidity, and restricted use for giant-sized defects. For this reason, there is an increasing need for effective bone substitutes to treat these defects. Mollusk nacre is a natural structure with outstanding mechanical property due to its notable "brick-and-mortar" architecture. Inspired by the nacre architecture, our team designed and fabricated a nacre-mimetic cerium-doped layered nano-hydroxyapatite/chitosan layered composite scaffold (CeHA/CS). Hydroxyapatite can provide a certain strength to the material like a brick. And as a polymer material, chitosan can slow down the force when the material is impacted, like an adhesive. As seen in natural nacre, the combination of these inorganic and organic components results in remarkable tensile strength and fracture toughness. Cerium ions have been demonstrated exceptional anti-osteoclastogenesis capabilities. Our scaffold featured a distinct layered HA/CS composite structure with intervals ranging from 50 to 200 μm, which provided a conducive environment for human bone marrow mesenchymal stem cell (hBMSC) adhesion and proliferation, allowing for in situ growth of newly formed bone tissue. In vitro, Western-blot and qPCR analyses showed that the CeHA/CS layered composite scaffolds significantly promoted the osteogenic process by upregulating the expressions of osteogenic-related genes such as RUNX2, OCN, and COL1, while inhibiting osteoclast differentiation, as indicated by reduced TRAP-positive osteoclasts and decreased bone resorption. In vivo, calvarial defects in rats demonstrated that the layered CeHA/CS scaffolds significantly accelerated bone regeneration at the defect site, and immunofluorescence indicated a lowered RANKL/OPG ratio. Overall, our results demonstrate that CeHA/CS scaffolds offer a promising platform for bone regeneration in critical defect management, as they promote osteogenesis and inhibit osteoclast activation.

Rare earth element bioaccumulation and cerium anomalies in biota from the Eastern Canadian subarctic (Nunavik)

Recent increases in the demand for rare earth elements (REE) have contributed to various countries' interest in exploration of their REE deposits, including within Canada. Current limited knowledge of REE distribution in undisturbed subarctic environments and their bioaccumulation within northern species is addressed through a collaborative community-based environmental monitoring program in Nunavik (Quebec, Canada). This study provides background REE values (lanthanides + yttrium) and investigates REE anomalies (i.e., deviations from standard pattern) across terrestrial, freshwater, and marine ecosystems in an area where a REE mining project is in development. Results are characteristic of a biodilution of REE, with the highest mean total REE concentrations (ΣREE) reported in sediments (10² nmol/g) and low trophic level organisms (i.e., biofilm, macroalgae, macroinvertebrates, common mussels, and reindeer lichens; 10¹-10² nmol/g), and the lowest mean concentrations in higher-level consumers (i.e., goose, ptarmigan, char, whitefish, cod, sculpin and seal; 10^-2 - 10¹ nmol/g). The animal tissues are of importance to northern villages and analyses demonstrate a species-specific bioaccumulation of REE, with mean concentrations up to 40 times greater in liver compared to muscle, with bones and kidneys presenting intermediate concentrations and the lowest in blubber. Further, a tissue-specific fractionation was presented, with significant light REE (LREE) enrichment compared to heavy REE (HREE) in consumer livers (LREE/HREE ≅ 10¹) and the most pronounced negative cerium (Ce) anomalies (<0.80) in liver and bones of fish species. These fractionation patterns, along with novel negative relationships presented between fish size (length, mass) and Ce anomalies suggest metabolic, ecological, and/or environmental influences on REE bioaccumulation and distribution within biota. Background concentration data will be useful in the establishment of REE guidelines; and the trends discussed support the use of Ce anomalies as biomarkers for REE processing in animal species, which requires further investigation to better understand their controlling factors.

Cytotoxicity and hemolysis of rare earth ions and nanoscale/bulk oxides (La, Gd, and Yb): Interaction with lipid membranes and protein corona formation

The widespread application of rare earth elements (REEs) has raised concerns about their potential release into the environment and subsequent ingestion by humans. Therefore, it is essential to evaluate the cytotoxicity of REEs. Here, we investigated the interactions between three typical REEs (La, Gd, and Yb) ions as well as their nanometer/μm-sized oxides and red blood cells (RBCs), a plausible contact target for nanoparticles when they enter the bloodstream. Hemolysis of REEs at 50-2000 μmol L^-1 was examined to simulate their cytotoxicity under medical or occupational exposure. We found that the hemolysis due to the exposure of REEs was highly dependent on their concentration, and the cytotoxicity followed the order of La³⁺ > Gd³⁺ > Yb³⁺. The cytotoxicity of REE ions (REIs) is higher than REE oxides (REOs), while nanometer-sized REO caused more hemolysis than that μm-sized REO. The production of reactive oxygen species (ROS), ROS quenching experiment, as well as the detection of lipid peroxidation, confirmed that REEs causes cell membrane rupture by ROS-related chemical oxidation. In addition, we found that the formation of a protein corona on REEs increased the steric repulsion between REEs and cell membranes, hence mitigating the cytotoxicity of REEs. The theoretical simulation indicated the favorable interaction of REEs with phospholipids and proteins. Therefore, our findings provide a mechanistic explanation for the cytotoxicity of REEs to RBCs once they have entered the blood circulation system of organisms.

Lithological distribution of rare earth elements in soils in the As-Sb-Tl Allchar mining area, North Macedonia

Despite the growing interest, the information available on rare earth elements (REEs) in the last two decades is relatively premature and sparse. The importance of these elements as indicators of soil and physiological processes and responses have contributed to the increased interest in these previously less considered elements in the environmental sciences. This study provides an overview of the content and distribution of rare earth elements in the soil in the vicinity of the hydrothermal volcanogenic As-Sb-Tl deposit of Allchar, North Macedonia. Elemental contents were determined by inductively coupled plasma mass spectrometry (ICP-MS). The light rare earth elements (LREEs) content in the study area ranges from 8.92 to 188 mg/kg, while the heavy rare earth elements (HREEs) content ranges from 1.95 to 42.7 mg/kg. It can be concluded that there is some enrichment of light REEs in the volcanic intrusive rocks of the Allchar mine area, including latite, quartz-latite, trachyte and occasionally andesite and dacite. The spatial distribution of HREEs is closely related to the lithology of the region, especially the sandstone and claystone, followed by layered and massive carbonate rocks (limestone, dolomite, marble) that occurred in the Middle and Upper Triassic.

Gadolinium-doped whitlockite/chitosan composite scaffolds with osteogenic activity for bone defect treatment: In vitro and in vivo evaluations

Reducing the incidence of bone defects caused by trauma and other primary diseases is an urgent task in modern society. In the present study, we developed a gadolinium-doped whitlockite/chitosan (Gd-WH/CS) scaffold and assessed its biocompatibility, osteoinductivity, and bone regeneration capacity for the treatment of calvarial defect in a Sprague-Dawley (SD) rat model. The Gd-WH/CS scaffolds possessed a macroporous structure, with a pore size ranging 200-300 μm, which facilitated the growth of bone precursor cells and tissues into scaffold. Results of cytological and histological biosafety experiments showed that both WH/CS and Gd-WH/CS scaffolds were non-cytotoxic to human adipose-derived stromal cells (hADSCs) and bone tissue, which demonstrated the excellent biocompatibility of Gd-WH/CS scaffolds. Results of western blotting and real-time PCR analysis provided a possible mechanism that Gd³⁺ ions in the Gd-WH/CS scaffolds promoted the osteogenic differentiation of hADSCs through the GSK3β/β-catenin signaling pathway and significantly upregulated the expression of osteogenic related genes (OCN, OSX and COL1A1). Finally, in animal experiments, SD rat cranial defects were effectively treated and repaired with Gd-WH/CS scaffolds due to its appropriate degradation rate and excellent osteogenic activity. This study suggests the potential utility of the Gd-WH/CS composite scaffolds in treating bone defect disease.

Rare earth elements in the upland soils of northern China: Spatial variation, relationships, and risk assessment

While global demand for rare earth elements (REEs) is rapidly growing, recent studies have suggested that REEs are pollutants of emerging concern. In this study, the spatial distribution and risk assessments of REEs in the upland soils of northern China were comprehensively investigated. The total REE concentrations ranged from 81 to 180 mg/kg, with average concentrations of 123, 128, and 98.3 mg/kg in the northwestern, northern, and northeastern zones, respectively. The decreasing trend of REE contents from northwest to northeast might be influenced by variation in the REE metallogenic belt distribution, mining activities, and precipitation intensity in these regions. The ratio of light rare elements (LREEs) to heavy rare elements (HREEs) ranged from 5.04 to 9.06, revealing obvious fractionation between them in upland soils and indicating that LREEs enrichment was common in northern China. The significantly positive correlations between the REEs indicated that REEs might frequently coexist and share similar sources in the upland soils of northern China. Based on a modified ecological risk index (eRI), REEs were estimated to pose relatively low ecological risks to current environmental residues, with eRI values ranging from 0.564 to 0.984. Fortunately, the estimated daily intakes of REEs from soils for children (1.08-2.41 μg/kg/day) and adults (0.119-0.312 μg/kg/day) were well below the safety thresholds. However, the health risks posed by REEs in upland soils were estimated to be higher for children. Thus, the continuous monitoring of REE abundance in soils is essential to avoid potential health risks.

Residual levels and health risk assessment of rare earth elements in Chinese resident diet: A market-based investigation

The widespread use of rare earth elements (REEs) in agriculture and high-tech industry resulted in significant release of REEs into the environment. However, there is a scarcity of studies focusing on the presence of REEs in the food worldwide. The present study investigated the residual levels of REEs in 14 representative food categories collected from 33 major cities of China. The measured total REEs (ΣREE) levels in the foods of aquatic origin were 174.97 μg kg^-1 wet weight (ww), which was 6.35 times higher than those of terrestrial origin. It is interesting to observe a trophic dilution effect for REEs in both terrestrial and aquatic food samples. REEs in food samples at low trophic levels exhibited relatively high REEs levels; while for high trophic level food, relatively low REEs levels were observed. The distribution patterns of REEs varied across the different food categories and regions, with Ce being the most abundant REEs in all food samples, followed by La, Nd and Sm. High levels of ΣREE in food samples were observed in Midland, while low levels were found in the Northeast. Cereals was the dominant contributor to the estimated daily intake of REEs. The health risk of REEs by daily food consumption in China was acceptable.

Risk assessment of rare earth elements in fruits and vegetables from mining areas in China

Assessment of contaminated food through the dietary intake is essential for human health. To investigate the health risk of rare earth element (REE) exposure to fruits and vegetables in mining areas in China, we collected 288 fruit samples and 942 vegetable samples from four representative mining points (Bayan Obo in Inner Mongolia, Weishan in Shandong, Maoming in Guangdong, Longnan in Jiangxi) and their control areas. The content of REEs was determined by inductively coupled plasma-mass spectrometry (ICP-MS). The total REEs in fruits from mining and control areas were 12.90 μg kg^-1 and 11.89 μg kg^-1, and in vegetables were 92.90 μg kg^-1 and 62.38 μg kg^-1, and the difference was statistically significant in vegetables (P = 0.048). The drupes had more REE concentration in fruits (68.41 μg kg^-1, 16.90 μg kg^-1 in mining and control areas, respectively) (P < 0.01), and the leafy vegetables had more REE concentration in vegetables (245.81 μg kg^-1, 123.51 μg kg^-1 in mining and control areas, respectively) (P < 0.01). With the enrichment of light rare earth elements (LREE), the REE distribution patterns coincided in mining and control areas and different types of fruits and vegetables. The health risk assessment indicated that the estimated daily intakes (0.02-0.06 μg kg^-1 day^-1, 0.53-1.22 μg kg^-1 day^-1 for fruits and vegetables, respectively) were lower than the allowable daily intake value (60.4 μg kg^-1 day^-1). In mining areas, REEs obtained from fruits and vegetables were insufficient to cause health damage to human beings. However, sustained exposure to low REEs, especially for children, still needs attention.

The Abundance of Trace Elements in Human Bone Relative to Bone Type and Bone Pathology

As the global population ages and the proportion of individuals afflicted with musculoskeletal disease spirals upward, there is an increasing interest in understanding and preventing bone-related diseases. Bone diseases, such as osteoporosis and osteoarthritis, are known to be influenced by a variety of factors including age, gender, nutrition, and genetics, but are also inherently linked to the human body's ability to produce biominerals of suitable quality. Because the crystal lattice structure and mineralogy of bone hydroxyapatite is surprisingly analogous to geological hydroxyapatite, trace element levels and exposure have long been proposed to influence the structure of biominerals as they do geological minerals (e.g., strontium substitution changes the crystal lattice of bone minerals, while toxic lead disrupt bone cellular processes leading to bone disease). Here, we explore the distribution of trace elements in human bones to evaluate the distribution of these elements with respect to bone type (cortical vs. trabecular) and bone disease (osteoarthritis vs. osteoporosis). We find higher concentrations of many metabolically active transition metals, as well as lead, in cortical bone compared to trabecular bone. When compared to patients who have osteoarthritis, and thus presumably normal bone minerals, osteoporosis patients have higher concentrations of scandium and chromium (Cr) in trabecular bone, and Cr and lead in cortical bone. Lower concentrations of barium and titanium are associated with osteoporotic trabecular bone. This survey is an exploratory cross-sectional geochemical examination of several trace element concentrations previously understudied in human bone minerals.

Environmental risk assessment of the potential "Chemical Time Bomb" of ion-adsorption type rare earth elements in urban areas

Ion-adsorption type rare earth elements (REEs) located in tropical and subtropical zones have abundant movable and bioavailable ion-exchangeable REEs and could be an environmental hazard. However, our understanding of their environmental risk in urban areas is limited. We aimed to determine whether ion-adsorption type REEs in Guangzhou represent a kind of potential "Chemical Time Bomb" (CTB) and assess the environmental risk. We conducted a comprehensive survey of REEs in 181 samples including regolith (n = 70), surface water (n = 55), sediment (n = 25), vegetables (n = 22) and rhizosphere soil (n = 9), collected from five regions around Guangzhou, as a representative city of ion-adsorption type REEs in tropical and subtropical zones. The existing environmental risk was assessed by calculating the estimated daily intake (EDI) of REEs through vegetable consumption, and leaching simulation experiments were used to discuss the factors affecting the long-term stability of REEs. The average REEs concentrations (ΣREEs) in the regolith and sediment were 458.5 and 218.6 μg·g^-1, respectively, which were higher than the background values of regolith (197.3 μg·g^-1) and sediment (173.3 μg·g^-1), and large proportions of ion-exchangeable REEs were observed in regolith and sediment, indicating that ion-adsorption type REEs in Guangzhou are a kind of potential CTB. The average ΣREEs in surface water (3.9 μg·L^-1), rhizosphere soil (466.9 μg·g^-1) and vegetables (25.0 μg·g^-1·dw) suggest that REEs have migrated to the supergene environment even organisms. The average EDI (55.4 μg·kg^-1·d^-1) close to the safety limitation (70 μg·kg^-1·d^-1) suggests that the existing health risk is very worrisome. Human factors, including acid rain, mining and farming, probably ignite the CTB, causing the release of REEs to the urban environment on a large scale. This prospective study demonstrated that REEs exposure problems in urban areas of ion-adsorption type REEs should not be ignored.

A Two-Generation Reproductive Toxicity Study of Lanthanum Nitrate in SD Rats

In order to evaluate the effects of lanthanum nitrate on the development of the parent, offspring, and the third generation of Sprague-Dawley (SD) rats, a two-generation reproductive toxicity experiment, was conducted. Two hundred and forty specific pathogen-free (SPF) healthy SD rats were randomly divided into the control group, low-, medium-, and high-dose group, with 30 male and 30 female rats in each group. The rats in each group were given 0 mg/kg, 10.0 mg/kg, 30.0 mg/kg, and 90.0 mg/kg lanthanum nitrate by gavage, respectively. There was no statistically significant difference between the weight gain and food intake of rats in each group. High-dose lanthanum nitrate had no effect on rat implantation and no embryo toxicity. The absolute and relative liver weights of F1a and F1b male rats in the high-dose group were significantly decreased. The absolute liver and spleen weight of F1b female rats in the high-dose group decreased significantly, but the relative weight did not change significantly. Histopathological examination results showed that there were no significant differences in the effects of different doses of lanthanum nitrate on the uterus, ovaries, oviduct, testes and epididymis, and liver of SD rats. Under the experimental conditions, 90.0 mg/kg lanthanum nitrate had an effect on the liver weight of the SD rats, but there was no liver toxicity. The no visible harmful effect level (NOAEL) of lanthanum nitrate on SD rats' reproduction toxicity is 90 mg/kg.

Overview of Traditional and Environmental Factors Related to Bone Health

Bone mass in adulthood depends on growth and mineralization acquired during childhood and adolescence. It is well known that these stages of life are crucial for bone development, where genetic, nutritional, hormonal, and lifestyle factors play a significant role. Bone loss is normally a natural and slow process that begins years later after the peak bone mass is achieved and continues throughout the lifespan. Lifestyle choices in childhood and adolescence such as minimal physical activity, excessive caffeine or carbonated beverages intake, malnutrition, cigarette use, or high alcohol consumption and other factors like environmental pollutants can also negatively affect bone health and accelerate the bone loss process. The aim of this work is an overview of risk factors associated with inadequate bone health in early life.

Risk assessment of rare earth elements, antimony, barium, boron, lithium, tellurium, thallium and vanadium in teas

In recent years, a great intensification in the use of various elements especially in modern technology can be observed. However, the anthropogenic activities, including industrialisation, urbanisation or intensive agriculture, have led to the release of many of the elements into the environment. The consequence of the accumulation of the elements both in soil and water systems is their presence in the food chain. Inhalation and consumption of the contaminated food and beverages have been indicated as the main pathways of the exposure to many elements. Due to the fact, that tea is considered the second most popular beverage worldwide and its consumption is constantly increasing, it is crucial to evaluate the safety of the product, especially for toxic elements contamination. Thus, the aim of the project was to evaluate the contamination levels of rare earth elements (REEs) including lanthanides, scandium (Sc) and yttrium (Y) and also antimony (Sb), barium (Ba), boron (B), lithium (Li), tellurium (Te), thallium (Tl) and vanadium (V) in teas. Subsequently, the risk assessment was carried out. Additionally, the Fellowship provided hands-on training on the evaluation of applications of new biocides and participation in the science-based advises given to the Danish Food and Veterinary Administration, Danish Environment Protection Agency and Danish Medical Agency.

Distribution of rare earth elements (REEs) and their roles in plant growth: A review

The increasing use of rare earth elements (REEs) in various industries has led to a rise in discharge points, thus increasing discharge rates, circulation, and human exposure. Therefore, REEs have received widespread attention as important emerging pollutants. This article thus summarizes and discusses the distribution and occurrence of REEs in the world's soil and water, and briefly introduces current REEs content analysis technology for the examination of different types of samples. Specifically, this review focuses on the impact of REEs on plants, including the distribution and fractionation of REEs in plants and their bioavailability, the effect of REEs on seed germination and growth, the role of REEs in plant resistance, the physiological and biochemical responses of plants in the presence of REEs, including mineral absorption and photosynthesis, as well as a description of the substitution mechanism of REEs competing for Ca in plant cells. Additionally, this article summarizes the potential mechanisms of REEs to activate endocytosis in plants and provides some insights into the mechanisms by which REEs affect endocytosis from a cell and molecular biology perspective. Finally, this article discusses future research prospects and summarizes current scientific findings that could serve as a basis for the development of more sustainable rare earth resource utilization strategies and the assessment of REEs in the environment.

Cerium oxide nanoparticles loaded nanofibrous membranes promote bone regeneration for periodontal tissue engineering

Bone regeneration is a crucial part in the treatment of periodontal tissue regeneration, in which new attempts come out along with the development of nanomaterials. Herein, the effect of cerium oxide nanoparticles (CeO2 NPs) on the cell behavior and function of human periodontal ligament stem cells (hPDLSCs) was investigated. Results of CCK-8 and cell cycle tests demonstrated that CeO2 NPs not only had good biocompatibility, but also promoted cell proliferation. Furthermore, the levels of alkaline phosphatase activity, mineralized nodule formation and expressions of osteogenic genes and proteins demonstrated CeO2 NPs could promote osteogenesis differentiation of hPDLSCs. Then we chose electrospinning to fabricate fibrous membranes containing CeO2 NPs. We showed that the composite membranes improved mechanical properties as well as realized release of CeO2 NPs. We then applied the composite membranes to in vivo study in rat cranial defect models. Micro-CT and histopathological evaluations revealed that nanofibrous membranes with CeO2 NPs further accelerated new bone formation. Those exciting results demonstrated that CeO2 NPs and porous membrane contributed to osteogenic ability, and CeO2 NPs contained electrospun membrane may be a promising candidate material for periodontal bone regeneration.

Bioactive glasses incorporating less-common ions to improve biological and physical properties

Bioactive glasses (BGs) have been a focus of research for over five decades for several biomedical applications. Although their use in bone substitution and bone tissue regeneration has gained important attention, recent developments have also seen the expansion of BG applications to the field of soft tissue engineering. Hard and soft tissue repair therapies can benefit from the biological activity of metallic ions released from BGs. These metallic ions are incorporated in the BG network not only for their biological therapeutic effects but also in many cases for influencing the structure and processability of the glass and to impart extra functional properties. The "classical" elements in silicate BG compositions are silicon (Si), phosphorous (P), calcium (Ca), sodium (Na), and potassium (K). In addition, other well-recognized biologically active ions have been incorporated in BGs to provide osteogenic, angiogenic, anti-inflammatory, and antibacterial effects such as zinc (Zn), magnesium (Mg), silver (Ag), strontium (Sr), gallium (Ga), fluorine (F), iron (Fe), cobalt (Co), boron (B), lithium (Li), titanium (Ti), and copper (Cu). More recently, rare earth and other elements considered less common or, some of them, even "exotic" for biomedical applications, have found room as doping elements in BGs to enhance their biological and physical properties. For example, barium (Ba), bismuth (Bi), chlorine (Cl), chromium (Cr), dysprosium (Dy), europium (Eu), gadolinium (Gd), ytterbium (Yb), thulium (Tm), germanium (Ge), gold (Au), holmium (Ho), iodine (I), lanthanum (La), manganese (Mn), molybdenum (Mo), nickel (Ni), niobium (Nb), nitrogen (N), palladium (Pd), rubidium (Rb), samarium (Sm), selenium (Se), tantalum (Ta), tellurium (Te), terbium (Tb), erbium (Er), tin (Sn), tungsten (W), vanadium (V), yttrium (Y) as well as zirconium (Zr) have been included in BGs. These ions have been found to be particularly interesting for enhancing the biological performance of doped BGs in novel compositions for tissue repair (both hard and soft tissue) and for providing, in some cases, extra functionalities to the BG, for example fluorescence, luminescence, radiation shielding, anti-inflammatory, and antibacterial properties. This review summarizes the influence of incorporating such less-common elements in BGs with focus on tissue engineering applications, usually exploiting the bioactivity of the BG in combination with other functional properties imparted by the presence of the added elements.

Trace elements in the muscle, ova and seminal fluid of key clupeid representatives from the Gdansk Bay (South Baltic Sea) and Iberian Peninsula (North-East Atlantic)

BACKGROUND

Baltic herring and European sardine are pelagic, fish of particular ecological importance, on the one hand control numbers of planktonic organisms, and on the other hand exist as food for predators on higher trophic levels. Moreover, these fish are among the main species caught for human consumption. Rare earth elements (REEs) come mainly from geogenic sources but, due to their use in technology, agriculture and medicine, the importance of anthropogenic sources is growing steadily.

METHODS

Samples used for the study were available on the market. Fresh materials of fish muscle, ova and seminal fluid were mineralized and elements were determined by means of inductively coupled plasma - mass spectrometry (ICP-MS).

RESULTS

The conducted research indicated the presence of REEs in the muscles of the Baltic herring (∑REE = 0.076 ± 0.047 mg/kg) and European sardine (∑REE = 0.191 ± 0.163 mg/kg), with a clear dominance of heavy REEs in both fish species. Trace elements (TE) in the muscles of the tested fish demonstrated a similar system of concentration (Baltic herring: Zn > As > Se > Cu > Cr > Ni > Pb > Cd; European sardine: Zn > As > Se > Cu > Ni > Cr > Pb > Cd). REEs and TEs in these fish were presence in ova and seminal fluid indicates intergenerational transfer.

CONCLUSION

Changes in the concentrations of some trace elements (As, Cu, Cd) in the muscles of herring indicate increases compared to the historical data. The availability of metals in the aquatic environment may be determined by ongoing climate changes, effected water salinity and warming increased availability of labile forms of trace metals. Decline trends in the condition of pelagic fish need to extend the research in the context of contemporary environmental threats.

Rare earth elements characterization associated to the phosphate fertilizer plants of Gabes (Tunisia, Central Mediterranean Sea): Geochemical properties and behavior, related economic losses, and potential hazards

This is the first study on the behavior and industrial fluxes of rare earth elements (REE) in the coastal fertilizer plants of Gabes (south-eastern Tunisia), the economic losses related to their wastes, and their environmental and human health hazards. The concentrations of 16 REE were assessed in phosphate rock (PR), phosphogypsum (PG) and phosphogypsum foam (PGF) samples, collected from Gabes plants. REE concentrations ranged from 0.23 (for Sc in PG) to 309.33 mg kg^-1 (for Ce in PGF). Ce was the most abundant in the three matrices, with concentrations ranging between 80.40 (in PG) and 309.33 mg kg^-1 (in PGF). PGF was the most enriched with REE (1075.32 mg kg^-1). The annual flow of REE from the fertilizer factories to the marine environment may reach 1523.67 t. The economic losses related to the discharge of phosphogypsum REE in the Gulf of Gabes (GG) was estimated at ~58 million US$ y^-1. The potential hazards of discharged REE on the local environment and human health were also evaluated and discussed. These findings show the need for the development of a new industry exploiting REE from phosphogypsum wastes (short term) and phosphate ores (long term) which should lead to reduce its high environmental and human health footprint and to potential economic gains.

Can the recycling of europium from contaminated waters be achieved through living macroalgae? Study on accumulation and toxicological impacts under realistic concentrations

Europium (Eu) strategic importance for the manufacturing industry, high economic value and high supply risk, categorizes it as critical raw material. Due to anthropogenic contamination, Eu levels in ecosystems have been growing, which opens opportunities for innovation: its recovery and recycling from contaminated water as element source - circular economy. In this pioneering study, six widely available living marine macroalgae (Ulva intestinalis, Ulva lactuca, Gracilaria sp., Osmundea pinnatifida, Fucus vesiculosus and Fucus spiralis) were characterized (water content and specific surface area) and evaluated in the pre-concentration and recovery of Eu from contaminated seawater, under different relevant contamination scenarios (10, 152 and 500 μg L^-1). U. lactuca and Gracilaria sp. (3 g L^-1, fresh weight) proved to be the most effective in removing Eu, reaching up to 85% in 72 h, while the highest Eu enrichment was observed in U. intestinalis biomass, up to 827 μg g^-1 (bioconcentration factor of 1800), which is higher than Eu levels in common apatite ores. The effect of Eu exposure on macroalgae growth rate and organism biochemical performance (LPO, SOD, GPx and GSTs) was also evaluated for the first time, to the best of our knowledge. Although no cellular damage was recorded, findings revealed toxicity and defence mechanisms activation, emphasizing the need of further studies on the potential risks associated with the presence of this emerging contaminant in aquatic ecosystems.

Cell and molecular toxicity of lanthanum nanoparticles: are there possible risks to humans?

Lanthanum nanoparticles are widely used in industry, agriculture, and biomedicine. Over 900 kg of lanthanum is annually released into the environment only in Europe, 50 times higher than the metals, mercury, and cadmium's environmental spread. Human health risk associated with long-term exposure to the abundant lanthanum nanoparticles is a concerning environmental issue. Due to lanthanum's ability to disrupt the main biological barriers and interrupt various cells' hemostasis, they seem to cause severe disruptions to various tissues. This review opens a new perspective regarding the cellular and molecular interaction of nanosized and ionic lanthanum with the possible toxicity on the nervous system and other tissues that would show lanthanum nanoparticles' potential danger to follow in toxicological science.

Light rare earth elements hinder bone development via inhibiting type H vessels formation in mice

Light rare earth elements (LREEs) are widely used in medical, industrial, and agricultural fields. Wide application of light rare earth and exposure to these elements in human society leads to increasing accumulation of LREE in human skeletal system. However, the effects of LREEs on human bone health is not clear. In this study, we found that LREE reduced CD31highEmcnhigh endothelial cell mediated type H vessels formation at the metaphyseal sites, resulting in reduced bone mass and low bone quality in mouse bone development. To explore the underlying mechanism, we induced bone marrow macrophages (BMMs) to preosteoclasts (pOCs) with exposure of LREE (Pr3+, Nd3+, Sm3+). The cytotoxicity of LREE was evaluated by CCK-8. Platelet-derived growth factor (PDGF-BB) is the cytokine secreted by pOCs that most responsible for inducing Type H vessel formation. We used ELISA kit to determine the PDGF-BB level in pOC supernatant, and mouse serum finding that the PDGF-BB level was reduced by LREEs treatment. Then we tested the ability of migration and tube formation of HUVECs using condition medium from pOCs. The migration and tube formation ability of HUVECs were both suppressed with LREEs pretreatment. We concluded that LREEs hinder mouse bone development by suppressing type H vessels associated bone formation. DATA AND MATERIALS AVAILABILITY: All data generated or analyzed during this study are included in this article. Please contact the corresponding author for unique material requests. Some material used in the reported research may require requests to collaborators and agreements with both commercial and non-profit institutions, as specified in the paper. Requests are reviewed by Third Military Medical University to verify whether the request is subject to any intellectual property or confidentiality obligations. Any material that can be shared will be released via a Material Transfer Agreement.

Bi-directional regulation functions of lanthanum-substituted layered double hydroxide nanohybrid scaffolds via activating osteogenesis and inhibiting osteoclastogenesis for osteoporotic bone regeneration

Rationale: Osteoporotic patients suffer symptoms of excessive osteoclastogenesis and impaired osteogenesis, resulting in a great challenge to treat osteoporosis-related bone defects. Based on the positive effect of rare earth elements on bone metabolism and bone regeneration, we try to prove the hypothesis that the La³⁺ dopants in lanthanum-substituted MgAl layered double hydroxide (La-LDH) nanohybrid scaffolds simultaneously activate osteogenesis and inhibit osteoclastogenesis.

Methods: A freeze-drying technology was employed to construct La-LDH nanohybrid scaffolds. The in vitro osteogenic and anti-osteoclastogenic activities of La-LDH nanohybrid scaffolds were evaluated by using ovariectomized rat bone marrow stromal cells (rBMSCs-OVX) and bone marrow-derived macrophages (BMMs) as cell models. The in vivo bone regeneration ability of the scaffolds was investigated by using critical-size calvarial bone defect model of OVX rats.

Results: La-LDH nanohybrid scaffolds exhibited three-dimensional macroporous structure, and La-LDH nanoplates arranged perpendicularly on chitosan organic matrix. The La³⁺ dopants in the scaffolds promote proliferation and osteogenic differentiation of rBMSCs-OVX by activating Wnt/β-catenin pathway, leading to high expression of ALP, Runx-2, COL-1 and OCN genes. Moreover, La-LDH scaffolds significantly suppressed RANKL-induced osteoclastogenesis by inhibiting NF-κB signaling pathway. As compared with the scaffolds without La³⁺ dopants, La-LDH scaffolds provided more favourable microenvironment to induce new bone in-growth along macroporous channels.

Conclusion: La-LDH nanohybrid scaffolds possessed the bi-directional regulation functions on osteogenesis and osteoclastogenesis for osteoporotic bone regeneration. The modification of La³⁺ dopants in bone scaffolds provides a novel strategy for osteoporosis-related bone defect healing.

Association between exposure of light rare earth elements and outcomes of in vitro fertilization-embryo transfer in North China

The adverse health effects of rare earth elements (REEs) on reproductive health remain a subject of debate, and few clinical observations are available. This study investigated the association between light REEs (LREEs) exposure and the outcome of in vitro fertilization-embryo transfer (IVF-ET). We recruited a total of 305 women undergoing IVF-ET in Beijing City and Shandong Province of northern China. Their demographic information and lifestyle characteristics were collected using questionnaires at enrollment. Fasting blood samples were collected on the day before the IVF-ET treatment cycle began. Serum concentrations of the LREEs of concern were analyzed using inductively coupled plasma-mass spectrometry, and four LREEs were measured with a high detection rate, including lanthanum (La), cerium (Ce), praseodymium (Pr), and neodymium (Nd). We found that a higher serum La concentration was associated with a 30% increased likelihood of clinical pregnancy failure [relative risk (RR) = 1.30, 95% confidence interval (CI): 1.00-1.67] and a 230% increased likelihood of preclinical spontaneous abortion (RR = 3.30, 95% CI: 1.57-6.94). There was a negative correlation between serum La concentration and the number of good-quality oocytes. For the other LREEs, no statistically significant associations were observed. We concluded that a high serum La concentration may have an adverse effect on IVF-ET outcomes.

Alimentary exposure and elimination routes of rare earth elements (REE) in marine mammals from the Baltic Sea and Antarctic coast

Marine mammals found at the top of the trophic pyramid are excellent bioindicators of pollutants in the marine environment, the concentrations of which increase along with the trophic level of the organism. As these animals are usually protected species, their contamination has to be assessed non-invasively by analysing excrement and epidermal structures such as fur or claws. The present study involved testing the excrement and fur of the grey seal (Halichoerus grypus) from the Southern Baltic coast and the Southern elephant seal (Mirounga leonine) from Admiralty Bay, along with fish muscle (food) and the lithological background of both areas, for the presence of rare earth elements (REE). The soil on the Baltic coast is characterized by the predomination of light rare earth elements (LREE): yttrium, lanthanum and cerium (∑REE = 7.86 mg·kg^-1 dw). In the soil and bedrock of Admiralty Bay all REEs were found except for terbium, thulium and lutetium (∑REE = 96.1 mg·kg^-1 dw). The REE levels found in the muscles of Baltic herring (∑REE = 0.057 mg·kg^-1 ww) were lower than those in the muscles of marbled rockcod (∑REE = 0.540 mg·kg^-1 ww). The situation was analogous in the mammals, with the REE concentrations in grey seal fur (∑REE = 0.489 mg·kg^-1 dw) and excrement (∑REE = 0.676 mg·kg^-1 dw) being lower than those found in the fur (∑REE = 10.1 mg·kg^-1 dw) and excrement (∑REE = 83.6 mg·kg^-1 dw) of the elephant seal. The LREE/HREE partition coefficients in the grey seal excrement (3.37) and its fur (4.00), but also in the faeces of the elephant seal (2.63) and its fur (2.65), indicate that in each species the process of elimination from the body occurs in similar proportions.

Graphene-modified CePO4 nanorods effectively treat breast cancer-induced bone metastases and regulate macrophage polarization to improve osteo-inductive ability

BACKGROUND

Breast cancer bone metastasis has become one of the most common complications; however, it may cause cancer recurrence and bone nonunion, as well as local bone defects.

METHODS

Herein, In vitro, we verified the effect of bioscaffold materials on cell proliferation and apoptosis through a CCK8 trial, staining of live/dead cells, and flow cytometry. We used immunofluorescence technology and flow cytometry to verify whether bioscaffold materials regulate macrophage polarization, and we used ALP staining, alizarin red staining and PCR to verify whether bioscaffold material promotes bone regeneration. In vivo, we once again studied the effect of bioscaffold materials on tumors by measuring tumor volume in mice, Tunel staining, and caspase-3 immunofluorescence. We also constructed a mouse skull ultimate defect model to verify the effect on bone regeneration.

RESULTS

Graphene oxide (GO) nanoparticles, hydrated CePO₄ nanorods and bioactive chitosan (CS) are combined to form a bioactive multifunctional CePO₄/CS/GO scaffold, with characteristics such as photothermal therapy to kill tumors, macrophage polarization to promote blood vessel formation, and induction of bone formation. CePO₄/CS/GO scaffold activates the caspase-3 proteasein local tumor cells, thereby lysing the DNA between nucleosomes and causing apoptosis. On the one hand, the as-released Ce³⁺ ions promote M2 polarization of macrophages, which secretes vascular endothelial growth factor (VEGF) and Arginase-1 (Arg-1), which promotes angiogenesis. On the other hand, the as-released Ce³⁺ ions also activated the BMP-2/Smad signaling pathway which facilitated bone tissue regeneration.

CONCLUSION

The multifunctional CePO₄/CS/GO scaffolds may become a promising platform for therapy of breast cancer bone metastases.

A study of kudurs used by wild animals located on the water sources high in REE content in the Caucasus Nature Reserve

One of the theories explaining the reasons for geophagy, which was proposed earlier by the authors of the article, consists in the assumption that animals need rare-earth elements (REE). In order to test this hypothesis, we studied the chemical composition of spring waters in the territory of the Caucasus Nature Reserve at three kudurs along the Achipsta River, as well as at the Mamaevsky kudur (southwestern slope of the Pshekish mountain). At the Mamaevsky kudur, we also studied the chemical composition of earth consumed by animals, and the species, age and gender composition, seasonal and daily activity of ungulate animals-visitors of the kudur. It was determined that the most active visitors of the Mamaevsky kudur were European bison (Bison bonasus) with one activity peak during the rut, in July. The frequency of visits to the kudur by red deer (Cervus elaphus) was 4 times lower with the highest peak activity in April and a lower peak in August. Only in one of four water sources at the Mamaevsky kudur there was an elevated concentration of Na (by 7 times). In the other three the concentration was comparable to the local river water. The waters of two "sodium-free" springs had increased concentrations of REE (by 5-8 times). Geophagic earths near the Mamaevsky springs are decomposition products of siltstone and sandstone shale rocks of the Jurassic age consisting of clay minerals (illite mixed with smectite, and chlorites)-from 42 to 45%, and quartz and feldspar (in total up to 50%) mixed with Fe and Ca carbonates. The chemical composition of acid extracts (0.1 N HCl, pH = 1.0) from consumed earth showed the highest extractability of Ca and Fe. In trace elements, Sr, Ba, Zn, Cu, Ni, Co, V, light lanthanides, and Y are most actively extracted. Na is extracted at 0.03-0.1 g/kg. The sodium bicarbonate spring water consumed by animals at kudurs on the Achipsta River had Na contents 70-300 times, and REE contents 25-40 times higher than that in the river water. The revealed facts do not contradict the hypothesis that the desire for geophagy in animals in the Caucasus (in addition to the long-known "urge" for Na) can be also related to the properties of lanthanides group elements exchange in the body.

Distribution Characteristics of Rare Earth Elements and Selenium in Hair of Centenarians Living in China Longevity Region

In order to explore the characteristics of the rare earth elements (REEs) and selenium (Se) among the Chinese centenarians, the concentrations of REE and Se were detected in the hair of healthy centenarians living in typical Chinese longevity region, and the influences of physiological conditions and behavior on the concentrations of REE and Se were assessed. The average values of light RE (LRE) and heavy RE (HRE) are 31.87 and 11.12 ng/g. Female centenarians had higher concentrations of lanthanum (La), praseodymium (Pr), gadolinium (Gd), terbium (Tb), erbium (Er), thulium (Tm), yttrium (Y), and Se but lower levels of cerium (Ce), neodymium (Nd), samarium (Sm), europium (Eu), dysprosium (Dy), holmium (Ho), ytterbium (Yb), and lutetium (Lu). Except for Ce, the higher the age, the lower the REE and Se content were. Smoking was positively associated with Dy, Er, and Yb levels, whereas drinking habits showed no significant effect on all the elements. Elderly individuals who ate smoked and pickled food and who consumed high amounts of salt had higher levels of REE and Se in their hair, and centenarians who consumed egg and milk had higher Se and REE in the hair than did the non-eaters. This comprehensive study on the REE and Se concentrations among the healthy centenarians can provide scientific support for shaping a healthy aging society.

Geobiochemistry characteristics of rare earth elements in soil and ground water: a case study in Baotou, China

The distribution of rare earth elements and the microbial community in nearby ground water and soil were influenced by tailings ponds. Accordingly, the behaviors of rare earth elements in ground water and soil around the tailings pond, and the changes of microbial communities were both investigated in this study. The results showed that rare earth elements accumulated in ground water and soil around the tailings pond appeared as light rare earth elements enrichment. Through the normalization of rare earth elements, different extents of anomaly (from negative to positive) were observed for Ce and Eu in the distribution patterns of REEs in groundwater, however, Ce and Eu were negatively anomaly in soil. According to the correlation analysis, Mn²⁺, SO₄^2-, Cl^-, ammonia nitrogen and Ca²⁺ are significantly correlated with the distribution of rare earth elements. Meanwhile, there were the same dominant bacteria in ground water and soil including Actinobateria, Proteobacteria and Acidobacteria at the phylum level. This microbial community composition is similar to that reported in arid lands around the world. On the other hand, Bacillus and Blastococcus showed significant correlation with rare earth elements at the genus level. This study might provide an important basis for the risk assessment of REEs in the environment.

Concentrations of rare earth elements in maternal serum during pregnancy and risk for fetal neural tube defects

Rare earth elements (REEs) are ubiquitous in the environment. Animal experiments have shown that many REEs have adverse impacts on the health of fetuses. However, data from humans are scarce. In this study, we examined the associations between concentrations of 10 REEs in maternal serum and the risk for fetal neural tube defects (NTDs). The study included 200 pregnant women with pregnancies affected by NTDs and 400 pregnant women with healthy fetuses/infants. Fifteen REEs in maternal serum were assessed; 10 of them were detectable in over 60% of samples and were included in statistical analyses, including lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), terbium (Tb), dysprosium (Dy), lutetium (Lu), and yttrium (Y). When the elements were considered individually with the use of Logistic regression model, the risk for NTDs increased by 2.78-fold (1.25-6.17) and 4.31-fold (1.93-9.62) for La, and 1.52-fold (0.70-3.31) and 4.73-fold (2.08-10.76) for Ce, in the second and third tertiles, respectively, compared to the lowest concentration tertile. When Bayesian kernel machine regression was used to examine the joint effect of exposure to all 10 REEs, the risk for NTDs increased with overall levels of these REEs and the association between La and NTD risk remained when other nine elements were taken into consideration simultaneously. Taken together, this study shows that the risk for NTDs increases with La concentrations when single REEs are considered and with concentrations of all 10 REEs when these REEs are considered as a co-exposure mixture.

Effects of exogenous lanthanum(III) exposure on the positive interaction between mutually beneficial populations

Rare earth elements (REEs) are widely used in various fields, and their accumulation has been reported to pose environmental risks. Most studies confirmed the damage of excessive REE exposure to individual plants; however, little attention has been given to their effects on plant populations. A positive interaction indicates a mutually beneficial relationship between two populations, which is beneficial to the survival and growth of the populations. However, it remains unknown whether exogenous REEs affect the positive interactions between populations. This study investigated the effects of exogenous lanthanum(III) [La(III)] exposure on the positive interaction between soybean (Glycine max L.) and wheat (Triticum aestivum L.) populations by their modules. At normal nutrient level (½-strength Hoagland), the inhibition of excessive La(III) on population modules decreased with increasing population density. Decreases of 39.26 to 1.05% for soybean and 41.45 to 2.41% for wheat indicated the inhibition of La(III) on the positive interaction of both populations weakened with increasing population density. At low nutrient level (¼-strength Hoagland), the inhibition of excessive La(III) on population modules increased with increasing population density. Decreases of 5.82-57.14% for soybean and 4.22-59.04% for wheat indicated the inhibition of La(III) on the positive interaction of both population was strengthened with increasing population density. In summary, the inhibitory effects of exogenous La(III) exposure on the positive interaction between populations vary with both nutrient level and population density. This is a new factor that needs to be considered when evaluating the safety risks of REEs in the environment.

Magnetic lanthanum-doped hydroxyapatite/chitosan scaffolds with endogenous stem cell-recruiting and immunomodulatory properties for bone regeneration

Magnetic lanthanum hydroxyapatite/chitosan scaffolds can better repair bone defects through stem cell recruitment and immunomodulation.

Evaluation of several phosphate amendments on rare earth element concentrations in rice plant and soil solution by X-ray diffraction

The exploitation and smelting of rare earth resources lead to serious pollution of rare earth elements (REEs) in farmland around mining area. The influence of four kinds of phosphate amendments-phosphate rock (PR), superphosphate (SSP), bone char (BC), and calcium magnesium phosphate (CMP)-on the bioavailability of REEs and the uptake and accumulation of 15 types of REE in rice were conducted in this study. Soil solutions were collected at tillering stage, heading stage and maturing stage, and rice was harvested at maturing stage. The mechanism of phosphate amendments reducing the bioavailability of REEs was studied by X-Ray diffraction and ICP-MS. PR treatment inhibited rice growth, but SSP, BC and CMP treatments all promoted rice growth, improved biomass of roots, shoots and grains, and promoted the uptake of phosphorous in rice. When compared with the CK, SSP, BC and CMP reduced the total REE concentrations in rice roots by 82.2%, 67.9% and 89.6%, shoots by 75.4%, 40.1% and 65.5%, grains by 23.8%, 29.0% and 29.3%, respectively. PR, SSP, BC and CMP significantly reduced the concentrations of REEs in the soil solution at three stages of rice growth. Analytic results of X-ray diffraction shows that adding PR, SSP, BC and CMP can lead to the formation of rare earth phosphate in the soil, thus reduce the activity of the REEs in the soil. Because SSP releases H+ during its dissolution, which has the risk of activating REEs in soil, CMP and BC are potential materials for remediation of REE-contaminated soil.

Synthesis, Structure and Luminescence Characterization of Erbium Doped Hydroxyapatite Nanoparticles by Precipitation Method

Introduction:

Hydroxyapatite, Ca10 (PO4)6(OH)2, a ceramic material is the major inorganic component in bones and teeth of animals and humans. Although erbium is one of the prominent representative elements among the lanthanides, erbium doped hydroxyapatite has not been studied to a greater extent. This study reports the synthesis of erbium doped hydroxyapatite using the simple precipitation method and its structural and optical properties.

Objective:

The primary objective of this study was to synthesize erbium doped hydroxyapatite and to study the structural and optical properties.

Materials and Methods:

Nanocrystalline erbium doped hydroxyapatite was successfully prepared using simple precipitation method. Average particle size of the synthesized particle was around 8-10 nm.

Results:

The typical absorption spectra of the erbium doped hydroxyapatite sample shows almost well defined peaks of the erbium ions. The absorption bands were observed at 360 nm, 373 nm, 448 nm, 490 nm, 524 nm and at 653 nm. The photoluminescence spectrum showed the presence of a green band at 550 nm and a red band which peaked at 750 nm.

Conclusion:

Spherical shaped nanocrystalline hydroxyapatite, Ca10 (PO4)6(OH)2 substituted with Erbium(III) were obtained using precipitation method. The synthesized Er3+ doped hydroxyapatite can be used for biophotonic applications, which exploits their exquisite optical properties and infrared imaging and several other therapeutic applications.

Gadolinium-doped mesoporous calcium silicate/chitosan scaffolds enhanced bone regeneration ability

Chitosan (CTS) and mesoporous calcium silicate (MCS) have been developed for bone defect healing; however, their bone regeneration capacity still does not satisfy the patients with bone diseases. Gadolinium (Gd) is accumulated in human bones, and plays a beneficial role in regulating cell performance and bone regeneration. We firstly constructed Gd-doped MCS/CTS (Gd-MCS/CTS) scaffolds by a lyophilization technology. The interconnected arrangement of CTS films lead to forming macropores by using ice crystals as templates during the lyophilization procedure, and the Gd-MCS nanoparticles dispersed uniformly on the macropore walls. The biocompatible chemical components and hierarchical pores facilitated the attachment and spreading of rat bone marrow-derived mesenchymal stem cells (rBMSCs). Interestingly, the Gd dopants in the scaffolds effectively activated the Wnt/β-catenin signaling pathway, resulting in excellent cell proliferation and osteogenic differentiation capacities. The osteogenic-related genes such as alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2) and collagen type1 (COL-1) were remarkably up-regulated by Gd-MCS scaffolds as compared with MCS scaffolds, and their expression levels increased in a positive correlation with Gd doping amounts. Moreover, in vivo rat cranial defect tests further confirmed that Gd-MCS/CTS scaffolds significantly stimulated collagen deposition and new bone formation. The exciting finding suggested the beneficial effects of Gd³⁺ ions on osteogenic differentiation and new bone regeneration, and Gd-MCS/CTS scaffolds can be employed as a novel platform for bone defect healing.

Cryptic footprints of rare earth elements on natural resources and living organisms

BACKGROUND

Rare earth elements (REEs) are gaining attention due to rapid rise of modern industries and technological developments in their usage and residual fingerprinting. Cryptic entry of REEs in the natural resources and environment is significant; therefore, life on earth is prone to their nasty effects. Scientific sectors have expressed concerns over the entry of REEs into food chains, which ultimately influences their intake and metabolism in the living organisms.

OBJECTIVES

Extensive scientific collections and intensive look in to the latest explorations agglomerated in this document aim to depict the distribution of REEs in soil, sediments, surface waters and groundwater possibly around the globe. Furthermore, it draws attention towards potential risks of intensive industrialization and modern agriculture to the exposure of REEs, and their effects on living organisms. It also draws links of REEs usage and their footprints in natural resources with the major food chains involving plants, animals and humans.

METHODS

Scientific literature preferably spanning over the last five years was obtained online from the MEDLINE and other sources publishing the latest studies on REEs distribution, properties, usage, cycling and intrusion in the environment and food-chains. Distribution of REEs in agricultural soils, sediments, surface and ground water was drawn on the global map, together with transport pathways of REEs and their cycling in the natural resources.

RESULTS

Fourteen REEs (Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sm, Tb, Th and Yb) were plighted in this study. Wide range of their concentrations has been detected in agricultural soils (<15.9-249.1 μg g^-1) and in groundwater (<3.1-146.2 μg L^-1) at various sites worldwide. They have strong tendency to accumulate in the human body, and thus associated with kidney stones. The REEs could also perturb the animal physiology, especially affecting the reproductive development in both terrestrial and aquatic animals. In plants, REEs might affect the germination, root and shoot development and flowering at concentration ranging from 0.4 to 150 mg kg^-1.

CONCLUSIONS

This review article precisely narrates the current status, sources, and potential effects of REEs on plants, animals, humans health. There are also a few examples where REEs have been used to benefit human health. However, still there is scarce information about threshold levels of REEs in the soil, aquatic, and terrestrial resources as well as living entities. Therefore, an aggressive effort is required for global action to generate more data on REEs. This implies we prescribe an urgent need for inter-disciplinary studies about REEs in order to identify their toxic effects on both ecosystems and organisms.

Incorporation of cerium oxide in hollow mesoporous bioglass scaffolds for enhanced bone regeneration by activating the ERK signaling pathway

Hierarchically porous structures and bioactive compositions of artificial biomaterials play a positive role in bone defect healing and new bone regeneration. Herein, cerium oxide nanoparticles-modified bioglass (Ce-BG) scaffolds were firstly constructed by the incorporation of hollow mesoporous Ce-BG microspheres in CTS via a freeze-drying technology. The interconnected macropores in Ce-BG scaffolds facilitated the in-growth of bone cells/tissues from material surfaces into the interiors, while the hollow cores and mesopore shells in Ce-BG microspheres provides more active sites for bone mineralization. The cerium oxide nanoparticles in the scaffolds rapidly promoted the proliferation and osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs), as confirmed by the up-regulation of osteogenesis-related markers such as OCN, ALP and COL-1. The enhanced osteoinductivity of Ce-BG scaffolds was mainly related to the activated ERK pathway, and it was blocked by adding a selective ERK1/2 inhibitor (SCH772984). In vivo rat cranial defect models revealed that Ce-BG scaffolds accelerated collagen deposition, osteoblast formation and bone regeneration as compared to BG scaffolds. The exciting results demonstrated that the synergistic effects between hierarchically porous structures and cerium oxide nanoparticles contributed to osteogenic ability, and hollow mesoporous Ce-BG scaffolds would be a novel platform for bone regeneration.

La-Doped biomimetic scaffolds facilitate bone remodelling by synchronizing osteointegration and phagocytic activity of macrophages

The capacity of osteoconduction held by HA/CS, osteoinduction by La³⁺, and biodegradability by a La-HA/CS composite, contributes to an ideal scaffold for osteointegration and remodelling.

Lanthanum phosphate/chitosan scaffolds enhance cytocompatibility and osteogenic efficiency via the Wnt/β-catenin pathway

BACKGROUND

Fabrication of porous scaffolds with great biocompatibility and osteoinductivity to promote bone defect healing has attracted extensive attention.

METHODS

In a previous study, novel lanthanum phosphate (LaPO4)/chitosan (CS) scaffolds were prepared by distributing 40- to 60-nm LaPO4 nanoparticles throughout plate-like CS films.

RESULTS

Interconnected three dimensional (3D) macropores within the scaffolds increased the scaffold osteoconductivity, thereby promoting cell adhesion and bone tissue in-growth. The LaPO4/CS scaffolds showed no obvious toxicity and accelerated bone generation in a rat cranial defect model. Notably, the element La in the scaffolds was found to promote osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) through the Wnt/β-catenin signalling pathway and induced high expression of the osteogenesis-related genes alkaline phosphatase, osteocalcin and Collagen I (Col-I). Moreover, the LaPO4/CS scaffolds enhanced bone regeneration and collagen fibre deposition in rat critical-sized calvarial defect sites.

CONCLUSION

The novel LaPO4/CS scaffolds provide an admirable and promising platform for the repair of bone defects.

Associations between age and 50 trace element contents and relationships in intact thyroid of males

BACKGROUND

It is unclear why a prevalence of thyroid dysfunction is higher in the elderly as compared to the younger population. An excess or deficiency of trace element contents in thyroid may play important role in goitre- and carcinogenesis of gland.

AIM

To examine the variation with age of the mass fraction of 50 trace elements in intact (normal) male thyroid.

METHOD

Samples of thyroid parenchyma obtained from 72 healthy males (mean age 37.8 years, range 2-80 years) was investigated. Measurements were performed using a combination of non-destructive and destructive methods: instrumental neutron activation analysis and inductively coupled plasma mass spectrometry, respectively. Tissue samples were divided into two portions. One was used for morphological study while the other was intended for trace element analysis.

RESULTS

There is a statistically significant increase in Cd and Se mass fraction, as well as a decrease in Al, Be, Dy, Ga, Gd, Li, Mn, U, and Y mass fraction in the normal thyroid of male during a lifespan. Moreover, a disturbance of intra-thyroidal chemical element relationships (correlations) with increasing age was found.

DISCUSSION

Our findings suggest that, at least, a goitrogenic and carcinogenic effect of Cd overload and Mn deficiency in the thyroid of old males may be assumed. Many trace elements in human thyroid behave themselves as antagonists or synergists. Therefore, an age-related disturbance in correlations between Mn and other trace element mass fractions in thyroid parenchyma may also contribute to harmful effects on the gland.

CONCLUSION

Age-related changes in intra-thyroidal trace element contents and disturbances in trace element relationships are involved in goitre- and carcinogenesis.

Rare earth elements in German soils - A review

Rare earth elements (REEs) are increasingly used in high-tech industry, agriculture, and healthcare technologies what leads to their release into soils and waters, and to the transfer into plants what may have negative impacts on human health and the environment. The toxicity and potential mobilization of REEs in soils can be assessed by their content and geochemical behavior along with soil properties. However, those interactions are so far not reviewed in German soils although such a review is important for a better understanding and prediction of the potential mobilization and toxicity. Therefore, this review summarizes the recent knowledge about REE contents and potential mobilization in different soil profiles in Germany. We found that the REE content tends to decrease in dependence on the parent material in the following order: Carbonatite > basalt > orthogneiss > clay slate > loess > sandstone > Pleistocene and Holocene sediments > organic material. Also, we used data of earlier studies, summarized and newly evaluated those data aiming to quantify the factors influencing the total REE content in German soil profiles. The contents of REEs in soil profiles of different parent material showed significant relations with content of clay, carbonate, organic matter, aluminium, iron, and manganese. Geochemical fractionation results suggest that the bioavailability of REEs is relatively low while the residual fraction is relatively high in German soils. In soils, where water fluctuations are important, the redox potential is a key factor controlling the mobilization of REEs also via related changes of pH.