Large amounts of arsenic are becoming widely distributed in the backyards and landfills of the United States as a component of pressure-treated wood. Arsenic is commonly found in relatively low levels in most soils and in relatively high concentrations associated with copper, lead, and zinc ores and other minerals, especially pyrite. Nearly all of the world’s supply of arsenic is recovered as a byproduct of smelting concentrates derived from these ores. For most of this century, the United States was among the world's leading producers, but production ended because of the high cost required to reduce atmospheric emissions (which included arsenic) in order to meet environmental regulations. Nonetheless, the United States is the largest consumer of arsenic in the world and is now 100 percent dependent on imports to meet all of its industrial needs. Over the last 100 years, arsenic has had several major industrial uses as an essential component of animal feed (to promote growth), herbicides and pesticides, lead batteries, metal alloys, semiconductors, wood preservatives, as well as glass manufacturing. In 1998, 30,300 t (metric tons) of arsenic, contained mostly in compound form, was imported into the United States, mainly from the People’s Republic of China. Because of arsenic’s known adverse affects on human health, public concerns have stimulated debate over the safety of the large amounts of arsenic contained in some products, as well as their disposal. This report is a brief characterization of the historic and current flows of arsenic through the economy, with a focus on pressure-treated wood.