An Updated Review of Toxicity Effect of the Rare Earth Elements (REEs) on Aquatic Organisms

SIMPLE SUMMARY: Rare earth elements (REEs) have become important metals in modern-day technology. The process of discarding obsolete equipment containing REEs, use of REEs containing phosphate fertilizers, mining, and dispersion from indigenous rocks may increase the likelihood of REEs contamination in water bodies. Thus, the contamination may contribute to their release into surrounding ecosystems. This review paper aims to understand the bioavailability, accumulation, interaction, and toxicity criteria of REEs with aquatic organisms. The currently available literature is confined to reports of a few REEs. There exists substantial knowledge gaps persistence on the health effects. The REEs related to health effects also point to favorable and adverse effects after exposure. The studies have also demonstrated that REEs follow a hormetic concentration- related trend, making it stimulatory or protective at low dose levels and adverse at high dose concentrations. Based on limited information on REEs’ effects, we highlight the need for more detailed studies on REEs’ effects individually/collectively. The studies should also include detailed outcomes related to growth inhibition, embryotoxicity, cytogenetic effects, and organ-specific toxicity. We believe that aquatic biota is an efficient platform to study the effects of REEs and might yield beneficial human health information. ABSTRACT: Rare earth elements (REEs) or “technology metals” were coined by the U.S. Department of Energy, a group of seventeen elements found in the Earth’s crust. These chemical elements are vital and irreplaceable to the world of technology owing to their unique physical, chemical, and light-emitting properties, all of which are beneficial in modern healthcare, telecommunication, and defense. Rare earth elements are relatively abundant in Earth’s crust, with critical qualities to the device performance. The reuse and recycling of rare earth elements through different technologies can minimize impacts on the environment; however, there is insufficient data about their biological, bioaccumulation, and health effects. The increasing usage of rare earth elements has raised concern about environmental toxicity, which may further cause harmful effects on human health. The study aims to review the toxicity analysis of these rare earth elements concerning aquatic biota, considering it to be the sensitive indicator of the environment. Based on the limited reports of REE effects, the review highlights the need for more detailed studies on the hormetic effects of REEs. Aquatic biota is a cheap, robust, and efficient platform to study REEs’ toxicity, mobility of REEs, and biomagnification in water bodies. REEs’ diverse effects on aquatic life forms have been observed due to the lack of safety limits and extensive use in the various sectors. In accordance with the available data, we have put in efforts to compile all the relevant research results in this paper related to the topic “toxicity effect of REEs on aquatic life”.