Toxicological Evaluations of Rare Earth Elements and Their Health Impacts on Workers

The occurrence and distribution of yttrium and rare earth elements (REYs), along with major elements and heavy metal(loid)s (HMs) in coal fly ash (CFA) from five coal-fired power plants (CFPPs), were analyzed, and the REY-associated ecological and health risks were assessed. The individual REYs in CFA were abundant in the following order: Ce > La > Nd > Y > Pr > Gd > Sm > Dy > Er > Yb > Eu > Ho > Tb > Tm > Lu. The total REY content ranged from 135 to 362 mg/kg, averaging 302 mg/kg. The mean light-to-heavy REY ratio was 4.1, indicating prevalent light REY enrichment in CFA. Significantly positive correlations between the REYs suggested that they coexist and share similar origins in CFA. REYs were estimated to pose low to moderate ecological risks, with risk index (RI) values ranging from 66 to 245. The hazard index (HI) and target cancer risk (TCR) of REYs from CFA, estimated to be higher for children (HIc = 0.15, TCRc = 8.4 × 10⁻¹⁶) than for adults (HIa = 0.017, TCRa = 3.6 × 10⁻¹⁶), were well below the safety limits (HI = 1, TCR = 1.0 × 10⁻⁶). However, the danger to human health posed by HMs in the same CFA samples (HIc = 5.74, TCRc = 2.6 × 10⁻⁴, TCRa = 1.1 × 10⁻⁴) exceeded the safe thresholds (excl. HIa = 0.63). The mean RI and HI attributed to REYs in CFA were 14% and 2.6%, respectively, of the total risks that include HMs. Full article

(1) Objective: Rare earth neodymium oxide (Nd₂O₃) is refined and used extensively around the world, and the occupational and environmental safety of rare piles of the earth has attracted considerable attention. Nd₂O₃ enters the human body through the respiratory system, reaches various organs through blood circulation, and accumulates to produce toxic effects. At present, little is known about the reproductive toxicity of Nd₂O₃. Non-coding RNAs participate in a variety of physiological activities and are very important for spermatogenesis. However, it is unknown whether they are involved in Nd₂O₃-induced reproductive toxicity. Therefore, we conducted a pathological analysis, sperm quality testing, and RNA-seq on the testicular tissue of mice exposed to Nd₂O₃ to find the key genes and regulatory pathways of male reproductive damage and explore the early biomarkers and mechanisms of reproductive damage caused by Nd₂O₃. (2) Methods: After exposure of mice to Nd₂O₃, we carried out a pathological analysis and RNA-seq analysis for miRNAs/lncRNAs/circRNAs/mRNAs on the testicular tissue of mice, and the total RNAs were used to investigate miRNA/lncRNA/circRNA/mRNA expression profiles by strand-specific RNA sequencing at the transcriptome level to help uncover RNA-related mechanisms in Nd₂O₃-induced toxicity. (3) Results: Nd₂O₃ damaged testis and sperm morphology, significantly decreased the number of sperm, and deformed the sperm head and tail. RNA-seq analysis showed that the expression level of mRNA/miRNA/circRNA/lncRNA in the testicular tissue of mice exposed to Nd₂O₃ is abnormal. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis demonstrated that the functional enrichment of differentially expressed genes (DEGs) and their target genes was closely related to the related pathway of spermatogenesis. Furthermore, some miRNAs/lncRNAs/circRNAs that were greatly upregulated or inducibly expressed, implying their potential value as candidate markers for Nd₂O₃-induced reproductive toxicity, help us to further investigate the mechanisms of key genes, key signaling pathways, and inter-gene regulation for Nd₂O₃-induced reproductive toxicity. (4) Conclusions: This study provides the first database of a Nd₂O₃-induced transcriptome. This information is useful for the development of biomarkers of Nd₂O₃-induced reproductive injury and promotes understanding of the reproductive toxicity mechanism of Nd₂O₃. Full article

Rare earth elements (REEs) are a new type of material resource which have attracted significant attention in recent years. REEs have emerged as essential metals in modern-day technology due to their unique functions. The long-term, large-scale mining and utilization of rare earths has caused serious environmental pollution and constitutes a global health issue, which has raised concerns regarding the safety of human health. However, the toxicity profile of suspended particulate matter in REEs in the environment, which interacts with the human body, remains largely unknown. Studies have shown that REEs can enter the human body through a variety of pathways, leading to a variety of organ and system dysfunctions through changes in genetics, epigenetics, and signaling pathways. Through an extensive literature search and critical analysis, we provide a comprehensive overview of the available evidence, identify knowledge gaps, and make recommendations for future research directions. Full article