Rare Earth Elements as Emerging Contaminants and Applications, Occurrence, Sources, and Environmental and Human Health Risks Caused by Them: A Review Study

Background and Objectives: Rare earth elements (REEs) are examples of emerging contaminants that have recently been increasingly spread to the environment through the extensive use in modern commodities, medical facilities, petroleum refining, mining, chemical fertilizers, electronic wastes and recycling plants. However, these elements are considered due to their potential human and ecological risks, but so far no comprehensive review have been conducted on the anthropogenic sources, environmental behavior, and public and ecological health risks of REEs. Therefore, the purpose of this study was identifying anthropogenic sources, transfer mechanisms, and environmental behavior of REEs, determining the human and ecological health risks posed by REEs and also identifying the gap between knowledge and future research directions. Materials and Methods: To achieve these goals, English studies conducted during 2004-2020 were used and considered by searching through databases. Results: Based on the results of these studies, ecotoxicological effects include reduced plant growth, function and nutritional quality, genotoxicity and neurotoxicity in animals, trophic bioaccumulation, acute and chronic toxicities in soil organisms. Human exposure to REEs via ingestion of contaminated water and food, inhalation, and direct intake during medical administration causes damage to nephrological systems, dysfunctional neurological disorder, fibrotic tissue injury, oxidative stress, pneumoconiosis, cytotoxicity, and male sterility. Conclusion: According to this study, future research on REEs especially in developing regions, given prevailing conditions predisposing humans to health risks is proposed to better understand environmental behaviors and their toxicity. Key words: Emerging contaminants, Rare earth elements, Resources, Transfer mechanisms, Ecotoxicological effects, Human health risks   Funding: This study did not have any funds. Conflict of interest: None declared. Ethical approval: None declared.   How to cite this article: Hedayatzadeh F, Ildoromi A, Hassanzadeh N, Bahramifar N. Rare Earth Elements as Emerging Contaminants and Applications, Occurrence, Sources, and Environmental and Human Health Risks Caused by Them: A Review Study. J Rafsanjan Univ Med Sci 2020; 19 (6): 619-48. [Farsi]