Chapter 15 - Rare earth elements: Human exposure, risk factors, and health risks

Abstract

High-technology rare earth elements comprising of the 15 lanthanides (La–Lu), yttrium (Y), and scandium (Sc) are widely used in high-technology industrial and consumer products. Recently, REEs have been included amongst emerging contaminants, but earlier reviews on anthropogenic REEs were limited to sources, occurrence, and behaviour of REEs in the environment. The risk factors, exposure routes, and human health risks have attracted limited attention in earlier reviews. Here, evidence is examined to investigate the human health risks posed by REEs. First, the sources and occurrence of REEs in the environment are presented. The human exposure pathways to REEs in occupational and nonoccupational settings are discussed focusing on: (1) water and food ingestion, (2) inhaling air-borne REEs, and (3) dermal or skin intake. Human exposure and health risks in clinical settings during medical or therapeutic applications of REE-based devices such as Gd-based contrast agents in medical resonance imaging, and cancer therapeutic drugs are discussed. Risk factors promoting human exposure to REEs and high-risk groups are discussed. The evidence on human health risks associated with the various REEs is presented. A critique of the evidence shows lack of quantitative data directly tracing human health risks to REEs in the environment. In addition, it is currently unclear whether human exposure to typical concentrations detected in the environment poses human health risks. The available evidence is based on data from clinical settings where concentrations of REEs could be higher than their environmental ones. Hence, the understanding of human exposure and health risks of anthropogenic REEs in the environment warrants further research. Future directions and perspectives including several knowledge gaps are presented.