Effect of rare earth elements (REE) supplementation to diets on the carry-over into different organs and tissues of fattening bulls

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.

A novel biocompatible Eu-based coordination polymers of cytarabine anticancer drug: Preparation, luminescence properties and in vitro anticancer activity studies

In this study, we use cytarabine anticancer drug to synthesize a new rare earth complex with Europium ion. The study work is an attempt to investigate luminescence and biological properties of the Eu-based coordination polymers of cytarabine (Eu-CP-Ara) anticancer drug which have been prepared by us. Eu-CP-Ara has luminescence properties with emission centering at about 619 nm excited with 394 nm. We study cytarabine and Eu-CP-Ara in vitro cytotoxicity. Cytotoxicity of Eu-CP-Ara against lung cancer cells (A549) could even be comparable to the inhibitory effect of cytarabine ligands, showing the advantage of antitumor activity. In addition, Eu-CP-Ara showed lower cytotoxicity to normal liver cells (L02). At the same, from the CLSM images, Eu-CP-Ara has successfully entered the A549 cell. Hence, Eu-CP-Ara can be used as a potential anticancer drug. Eu-CP-Ara may be an effective strategy for the tracking cytarabine against tumours and might impart better accurate treatment effect and therapeutic efficiency.

In Vitro Corrosion Performance of As-Extruded Mg–Gd–Dy–Zr Alloys for Potential Orthopedic Applications

In this study, different contents of rare earth elements with high solid solubility (Gd and Dy) were added into Mg and fabricated through homogenization and hot extrusion processes that enable few second phase formation to efficaciously inhibit the galvanic corrosion. The microstructure and phase characterization of the as-extruded Mg–Gd–Dy–Zr alloys were analyzed by scanning electron microscopy, electron backscattered diffraction, and X-ray diffraction. The in vitro biodegradation behavior of the as-extruded Mg–Gd–Dy–Zr alloys was investigated via the electrochemical measurement and immersion test. The results revealed that all the as-extruded alloys with different RE additions exerted fully recrystallized microstructures. The average grain size was appropriately 20 μm to 30 μm for all alloys and gradually increased by adding more RE. Only a few tiny second-phase particles less than 5 μm dispersed for all the samples and the volume fraction of particles increased slightly with the increase in RE content. The as-extruded Mg–Gd–Dy–Zr alloys with low RE content (GD0.6) allowed for a satisfactory corrosion resistance in Hank’s solution with a controlled corrosion rate less than 0.5 mm/year, which is considered as the tolerance limit for the corrosion rate of orthopedic implants. This study provides a cost-effective choice for promoting biodegradable magnesium alloys for potential orthopedic applications with low rare earth content in Mg alloys.

Geochemical signatures and natural background values of rare earth elements in soils of Brazilian Amazon

Rare earth elements (REEs) are generally defined as a homogenous group of elements with similar physical-chemical properties, encompassing Y and Sc and the lanthanides elements series. Natural REEs contents in soils depend on the parent material, the soil genesis processes and can be gradually added to the soil by anthropogenic activities. The REEs have been considered emerging pollutants in several countries, so the establishment of regulatory guidelines is necessary to avoid environmental contamination. In Brazil, REE soils data are restricted to some regions, and knowledge about them in the Amazon soils is scarce, although this biome covers more than 40% of the Brazilian territory. Thus, the objectives of this study were to determine the REE content in soils of two hydrographic basins (Solimões and Rio Negro) of the Amazon biome, establish their Quality Reference Values (QRV) and to investigate the existence of enrichment of REEs in urban soils. The ΣREE(Y + Sc) content of Solimões surface samples was 109.28 mg kg^-1 and the ΣREE(Y + Sc) content in the subsurface samples was 94.11 mg kg^-1. In soils of Rio Negro basin, the ΣREE(Y + Sc) was 43.95 15 mg kg^-1 surface samples and 38.40 mg kg^-1 in subsurface samples. The ΣREE(Y + Sc) in urban topsoils samples was 38.62 mg kg^-1. The REEs contents pattern in three studied areas are influenced in different amplitude by natural soil properties. The REEs content in urban topsoils were slightly higher than the Rio Negro pristine soils, but the ecological risk was low. QRVs recommend for Solimões soils ranged from 0.01 (Lu) to 145.6 mg kg^-1 (Ce) and for Rio Negro soils ranged from 0.05 (Lu) to 15.8 mg kg^-1 (Ce).

Safety of Lancer® (lanthanide citrate) as a zootechnical additive for weaned piglets

Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the additional data submitted on Lancer^® when used as a feed additive for weaned piglets. The FEEDAP Panel considered that uncertainty still remains on possible developmental neurotoxicity of Lancer^® since it was unable to identify a no observed adverse effect level (NOAEL) for this specific endpoint applying a read‐across strategy from the studies provided by the applicant. However, the FEEDAP Panel considered that the exposure to La and Ce from products of animals treated with Lancer^® at 250 mg/kg feed would not add a significant contribution to the background exposure of these elements. The FEEDAP Panel concluded that the use of Lancer^® in feed for weaned piglets (up to 120 days) according to the proposed conditions of use, does not represent a safety concern for the consumer and for the environment.

Differential Bioaccumulation of Trace Elements and Rare Earth Elements in the Muscle, Kidneys, and Liver of the Invasive Indo-Pacific Lionfish (Pterois spp.) from Cuba

The Indo-Pacific lionfish is a saltwater fish that inhabits the Red Sea waters and the Indian and Pacific oceans; it is an invasive species in the western Atlantic and was recently introduced into the local diet in the USA, Central and South America, and the Caribbean with the aim of controlling the invasion of this species. Due to its predatory nature, it tends to bioaccumulate metals and other contaminants via the marine food web and could thus constitute a suitable species for monitoring aquatic ecosystems. The presence and distribution of 23 trace elements and 16 rare earth elements (REEs) were investigated by inductively coupled plasma-mass spectrometry (ICP-MS) in the muscle, liver, and kidneys of lionfish from Cuba. Significant differences in metal concentrations were found in the different fish organs. The liver and kidneys registered the highest concentrations for most trace elements and for ΣREE, thus demonstrating that they are effective bioindicators of possible pollution on the environment in which fish live, and assuming great importance in the choice of early biomonitoring. Trace element concentrations in the muscle are instead of crucial interest for consumer safety. The limits set by EU regulations and Cuban guidelines for Cd and Pb in fish muscle were never exceeded, suggesting that lionfish from Cuba could therefore represent a good source of minerals and proteins for the local population. Graphical abstract.

Authentication of meat and dairy products using rare earth element labeling and detection by solution based and laser ablation ICP-MS

In order to meet the increasing customer demand for local food products, various methods for verification of food origin by means of region specific trace element fingerprinting have been developed. However, for products from conventional agriculture, without a close relationship to the local soil, other methods for food authentication are required. In an alternative approach, foodstuffs produced in a certain region, by a specific producer or under certain conditions can be safeguarded against imitation by chemical labeling. The objective of the present study was to develop a method for labeling lamb meat and goat milk by selective enrichment of terbium and thulium in the feed for the animals. Therefore, a distinctive rare earth element (REE) pattern is artificially introduced which can be determined in labeled food products. Detection of REE labels was carried out using inductively coupled plasma mass spectrometry (ICP-MS) after acid digestion. Alternatively, laser ablation ICP-MS (LA-ICP-MS) was applied, allowing direct analysis of bone samples and analysis of meat and milk samples after dry ashing and pressing pellets. After three weeks of administering 1000-fold terbium and thulium enriched feed to lambs, terbium and thulium enrichment was detected in all sample types except blood, following the trend bones > kidney > liver > heart > meat > kidney fat. Similarly, goat milk was successfully labeled after three weeks of feeding 500-fold terbium and thulium enriched feed. Hence, the present method allows discrimination of labeled from unlabeled animal products, while REE contents in all labeled products remained low enough to avoid any health risk for the consumer.

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.

Perspectives for rare earth elements as feed additive in livestock - A review

There is a need for newer feed additives due to legal prohibition on inclusion of growth promoting antibiotics in livestock diets in several countries due to antimicrobial resistance. In this context, rare earth elements (REE) have gained attention among animal nutritionists as potential growth promoters. Currently, several studies have reported better weight gain, milk production, egg laying capacity and feed conversion efficiency among different breeds of farm animals following supplementation with REE, with however largely inconsistent results. Furthermore, REE supplementation has also shown to improve ruminal fibrolytic and proteolytic activities as well as flavor of meat with negligible residues in edible tissue, however the mechanism behind this action is still unclear. According to existing research, due to their poor absorption and similarity with calcium REE might exert their action locally on gut microbial populations within the gastrointestinal tract (GIT). Moreover, REE have also shown anti-inflammatory, anti-oxidative as well as immune stimulating effects. The present review aims to broaden the knowledge about use of REE as feed additives for livestock and sum up efficacy of REE supplementation on performance and health of animals by comparing the findings. Till date, researches with REE have shown properties that make them a promising, new and safe alternative feed additive but further exploration is recommended to optimize effects and clarify discrepancy of various results before practical proposals can be drafted.

Feathers of Humboldt penguin are suitable bioindicators of Rare Earth Elements

Rare earth elements (REEs), also called lanthanides, are emerging contaminants worldwide, due to their unique physical and chemical characteristics that make them essential in a variety of industrial applications. However, there is still a gap in the knowledge of occurrence and accumulation of REEs in biota, and no investigations have yet been performed in penguin feathers, which have already been widely utilized as a non-invasive tool for the biomonitoring of trace elements. The concentrations of 16 REEs were investigated in a colony of Humboldt penguins (Spheniscus humboldti) housed at the Acquario di Cattolica (Italy). Multielement determination of REEs was performed by an Inductively Coupled Plasma-Mass Spectrometer after a microwave digestion of feathers. As this colony lives indoors in a controlled environment, it was the ideal choice for studying lanthanide occurrence in penguin feathers. Since there is a strict link between metal levels in feathers and the diet of penguins, their food (capelin) was also tested for REEs. Chondrite normalized values revealed the same pattern for REEs in feathers and fish, but REE concentrations were an order of magnitude higher in penguin feathers, demonstrating the suitability of this tissue as a bioindicator of REEs.

Rare earth elements in marine and terrestrial matrices of Northwestern Italy: Implications for food safety and human health

Rare earth elements (REEs) are central in several critical technologies; their use is constantly increasing as is their release into the environment. For this reason, it is important to investigate REE concentrations in different matrices to evaluate human exposure and environmental risk of these emerging contaminants. REEs were measured by ICP-MS in matrices of terrestrial (plant feed, fruit, honey, wildlife livers) and marine origin (seaweeds, zooplankton, bivalves, fish) collected from Northwestern Italy. Highest REE concentrations were measured at low trophic levels, both in terrestrial and marine environments, such as plants (ΣREE 1.8 mg kg^-1) and seaweed (ΣREE 12 mg kg^-1), the major source of exposure and transfer of REEs to food webs. REE concentrations were several orders of magnitude lower in fruit, honey, and livers from terrestrial wildlife, suggesting a negligible risk of exposure by these matrices. Marine biota, such as bivalves (ΣREE 0.16 mg kg^-1) and fish (ΣREE 0.21 mg kg^-1) may constitute a pathway for human or animal dietary exposure. The study confirmed that REEs have low potential for biomagnification, but instead are subject to trophic dilution. However, given the numerous sources of dietary introduction of REEs, they should be monitored for a possible harmful cumulative effect. Owing to the scarcity of data regarding REEs worldwide, our results contribute to assessment of the occurrence of these emerging contaminants.