Mineral supply and demand data were used to track the flow of a material from its source through stages of production, processing, and fabrication into the consumption and postconsumption phases. In each stage prior to consumption, the quantity of material lost to the environment or recovered for reuse was determined. In the postconsumption stage, the quantity of material discarded was analyzed to determine how much was disposed to landfills, lost through incineration, or dispersed to the environment. Where the consumption stage involved releases to the environment, as in the use of fertilizer, this was noted also. The material flow studies also strived to determine the amount of recycling that was done in the preconsumption and postconsumption phases. Cumulative historical supply data were used to estimate the total inventory of the materials that have been put into service within the United States, and aggregated consumption data based on end use provided a basis for assessing the cumulative effect of those materials on the environment.