The development of rare earth element (REE) production in Canada could generate significant economic benefits, but also poses serious potential risks to the environment. Rare earth elements have been widely used in modern life and industries, and even are indispensable in some crucial advanced technologies (e.g. permanent magnets). Increasing demand and the context of current US-China trade tensions provide a commercial economic development opportunity for Canada, which has rich resources of REEs, to develop its own sector. However, environmental and health issues caused by REE production are challenges Canada has to face, given that significant environmental impacts have been reported elsewhere (e.g. China). Little literature is available on the potential environmental risks associated with the development of REE production in Canada. It is important to know what environmental issues, particularly those generated by REEs themselves, may happen in Canada in the future. Therefore, three major aspects are evaluated and summarized from multidisciplinary perspectives in this paper: 1) a general conceptual model of the transport of REEs as a group in the environment is established; 2) toxicity levels, biochemical mechanisms, and physiological effects of REEs on different organisms are reviewed, and case-studies from existing REE mining areas are briefly highlighted; and 3) considering specific environmental condition and risk factors, environmental risks Canada may face in future REE developments are identified and discussed. This review concludes with a macro-identification of potential environmental risks associated with the development of REE production in Canada considering both human and ecological health. We note that ingestion, inhalation and dermal exposure for workers and surrounding residents (including potentially indigenous communities), and sub-arctic/arctic climate conditions could increase the risks to human and ecological health in future REE production development in Canada. Finally, future research directions are proposed that could be applied to both Canadian and other geographical contexts.
Multi-Target Risk Assessment of Potentially Toxic Elements in Farmland Soil Based on the Environment-Ecological-Health Effect
