TRACE METALS AND MINERALS IN MATERIALS OF THE BUILT ENVIRONMENT: IMPLICATIONS FOR RECYCLING, DISPOSAL, AND ENVIRONMENTAL HEALTH

Many metal and mineral commodities are used in large volumes in the built environment, such as copper pipes and wiring, steel, cement, aggregate, and metals in electronics. Many are also present in lower levels as purposeful additives to other products, such as antimony in fire retardants, hexavalent chromium in pressure treated woods and pigments, rare earth elements in ceramics colorants, and clays in plastics. Some have been discovered as natural, intentional, or unintentional contaminants in other products. For example, amphibole asbestos was a natural accessory mineral discovered in vermiculite used in insulation and other building materials. There are also many recent examples of heavy metals such as lead discovered in manufactured foreign products sold in the United States.

The types, amounts, concentrations, and forms of metal and mineral commodities used have changed over time due to technology advances, safety concerns, substitution with cheaper or more durable materials, and recognition of potential environmental or health concerns. For example, some metal or mineral commodities that are now known to be toxic, such as lead in paint or asbestos in insulation, were used extensively in older buildings. In modern buildings, many potential toxicants are present in low enough concentrations to not pose a toxicity risk, are present in non-toxic forms, or are ensconced within materials that under normal conditions prevent problematic exposures to humans or other organisms. However, disasters such as floods, earthquakes, and fires can drastically alter the forms of and enhance the mobility of, toxicity of, and risk for exposures to potential toxicants from the built environment.

A new USGS project is summarizing existing data and collecting new information on trace metals and minerals in materials of the built environment. One goal is to understand their forms, concentrations, and environmental/ toxicological implications in materials that are recycled or sent to landfills when buildings are demolished. Another goal is to understand details of the built environment as a source of potential mineral or metal contaminants released by floods, fires, building collapses, and other disasters.