effects that include environmental degradation and diminished viability of the biosphere in general and human health in particular. As noted in earlier chapters, such health hazards include airborne dusts and gases, soluble chemical pollutants in both surface water and groundwater, and toxic substances in soils, crops, livestock, and manufactured products.

Modern societies are maintained by the extraction of energy, water, and other earth materials far beyond natural renewal rates, providing limits to future human use of such natural resources. As more intensive usage of earth commodities and energy takes place due to increasing global population, the attendant global demand for a better standard of living will result in an increase in the adverse impacts of resource-related health hazards unless steps are taken to address and ameliorate them (e.g., McMichael, 2002). The biological carrying capacity of the earth is finite— hence humanity eventually must reach a managed steady state with the available terrestrial resources and the life support system provided by the biosphere. Reflecting the intense desires of developing nations for an improved standard of living, our own security dictates the need for a much more equitable consumption of mineral commodities and distribution of wealth. However, to achieve mineral resource sustainability (NRC, 1996, 1999e) global research in science and technology must be increased in order to reach much more efficient levels in the development—and especially the conservation of—earth resources (WCED, 1987; Chesworth, 2002; Doran and Sims, 2002). An overridingly important part of this challenge will be to preserve an intact, healthy, functioning biosphere.

Mineral Exploration, Extraction, and Processing

The process of mining ore deposits and coal contains several steps that can potentially expose humans to toxic materials (e.g., Box 6.2). Although the steps can vary for different types of materials, they generally include some combination of extraction, processing and refining, use, and waste disposal. Although modern extraction technologies are much more efficient, and in many countries more highly regulated, than in the past, retrieval of materials from the earth for human use is one of the most serious sources for contamination of soils, water, and the biosphere (Selinus et al., 2005). In the case of metalliferous ores, the greatest environmental contamination generally comes from the mineral processing that occurs after extraction from the mine (e.g., CDC, 2005). This processing produces mine tailings, often consisting of very fine dust that can contain residual amounts of mineral ore and other harmful trace elements. Frequently left open to the environment, the tailings are subject to transport by both wind and water, resulting in contamination of surrounding soils, surface water, and groundwater.



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