A REVIEW OF ENVIRONMENTAL AND HEALTH CONCERNS OF RARE EARTH ELEMENTS (REE): CAUTIONARY NOTES ON AN INCREASINGLY IMPORTANT GEOLOGIC RESOURCE

The use of rare earth elements is becoming increasingly common as green technologies develop, the most notable of which are wind turbines, cars, and electronics. Despite the benefits of these technologies, the excessive use of rare earth elements raises some environmental and health concerns. In comparison to other metals, the toxicity of rare earth elements is poorly understood. A review of the chemistry, uses and known environmental health risks are presented. Human exposure to rare earth elements can also occur during mining, transportation, accidents, consumer contact, and purposeful exposure such as during medical implants. A review of the literature indicates that there are toxic effects to organisms. In invertebrates, several rare earth elements have been found to have lethal qualities a high percentage of the time. In vegetation, evidence has been found supporting the idea that rare earth elements negatively affect germination. In vertebrates, they have been found to alter many bodily systems, such as renal, pulmonary, and mitochondrial functions, as well as blood coagulation. The limited but known effects on humans include impact on lung tissue. The routes of exposure for people include inhalation, ingestion, and direct uptake from skin. One aspect that has not been broadly considered is smoking, which may be a prevalent, but poorly recognized, method of exposure. In particular, cigarette lighters may be a previously unrecognized source of exposure, as each use emits particles that the smoker then inhales. Of particular concern is the difficulty the body has clearing itself of these elements, so habitual smokers may be at increased risk. Accumulation of rare earth elements in the body can produce free radicals as well as other reactive oxygen species, which can be extremely damaging to cellular processes and lead to serious diseases. Further toxicological studies are needed to better understand the effect rare earth elements have on human health. As rare earth elements continue to be an increasingly important geologic resource, detailed studies are required to prevent and mitigate large scale ecological and human health problems. A major focus should be on occupational safety in the mining and energy industries. Geological and mineralogical perspectives will be critical in future studies of toxicity.