Sources and Health Risks of Rare Earth Elements in Waters

Abstract

AbstractAnthropogenic rare earth elements widely used in high-technology applications are prevalent in the aquatic environment, thus constituting emerging contaminants. Yet reviews on the anthropogenic sources, behavior, and potential health risks of rare earth elements remain limited. The current chapter seeks to (1) highlight anthropogenic sources, behavior, and human intake pathways of rare earth elements, (2) discuss the human and ecological health and exposure risks of rare earth elements, (3) present a conceptual outline for assessing and mitigating health risks, and (4) identify the key thematic areas for further research.Anthropogenic hotspot sources of rare earth elements include wastes and wastewaters from medical facilities, rare earth elements mining and mineral processing, high-technology electrical and electronic industries, petroleum refineries, rare earth elements-enriched fertilizers and livestock feeds, and recycling plants for postconsumer electronic and electrical goods. The dissemination of rare earth elements from sources into the various environmental compartments is controlled by anthropogenic (industrial discharges) and hydrological processes. Human exposure occurs via occupational inhalation in rare earth elements-based industries, ingestion of contaminated food, and medical applications including magnetic resonace imaging. To date, evidence exists documenting rare earth elements in human body parts including the brain, hair, nails, milk, serum, and sperms. High concentrations of rare earth elements reduce plant growth and nutritional quality, impaired biochemical function in plants, and induce neurotoxicity, acute and chronic health effects, and genotoxicity in aquatic animals. The uptake, partitioning, and bioaccumulation of rare earth elements may also occur along the trophic levels in aquatic ecosystems. Human health risks include (1) severe damage to nephrological systems and nephrogenic systemic fibrosis induced by gadolinium-based contrast agents used in medical applications, (2) induced sterility and anti-testicular effects in males, (3) dysfunctional neurological disorder and reduced intelligent quotient, (3) fibrotic tissue injury, (4) pneumoconiosis, and (5) oxidative stress and cytotoxicity. In developing countries, the health risks of rare earth elements may be considerably high due to the following: (1) weak and poorly enforced environmental and public health regulations, (2) overreliance on untreated drinking water, and (3) lack of human health surveillance systems for early detection and treatment of human health effects. However, limited empirical data exist to establish the relationship between rare earth elements in the aquatic environments and their health effects. A conceptual outline for assessing and mitigating the health risks and thematic areas for further research were highlighted.KeywordsAnthropogenic sourcesEcological effectsEcotoxicologyEnvironmental reservoirsHuman health effectsHuman intake pathwaysLanthanides