Although accounting for only a small share of American economy, the metalfinishing industry has had a profound impact on the natural environment. The industry supplies parts that are essential to products ranging from automobiles and household appliances to aircraft and military hardware. At the same time, metal finishing generates wastes from solvents, cleansers, and metal-ion-bearing aqueous solutions used for plating (such as hexavalent chromium, copper, gold, and cadmium). Acid from finishing cleaners is found in metalfinishing wastewater, and solvents from metal-finishing plants may also be emitted into the air or disposed of in solid form. Many hazardous waste sites that were once solid-waste landfills include contaminants from metal-finishing wastes. It is fair to say that metal finishing is an industry whose environmental impact may far exceed its economic significance.