Application of an electric current causes the anodes to dissolve and form copper cathodes on the starting sheets. Since this electrolytic process is capable of refining the metal to a high degree, the cathode copper usually exceeds 99.97 per cent purity. It is then cast into commercial shapes for industry to process into wire, rod, sheet and strip, tube, or for foundry applications. While the sulphur dioxide produced at copper-processing operations poses a hazard to the environment, technologies have been developed to meet stringent new environmental standards. With the development of new processes to capture and treat sulphur dioxide waste gases, copper producers have now also become major producers of sulphuric acid, a valuable industrial product.
Copper combines with proteins to form many enzymes critical for life.
One such important enzyme is superoxide dismutase which removes the superoxide radicals in the human body. Copper is also required to transport iron from absorption sites to the bone marrow where red blood cells are produced. Copper tube used for distribution of portable water supplies has beneficial bactericidal characteristics. It has been noted, for example, that the Legionnella pneumophila bacteria causing Legionnaire's disease and Pontiac fever were present in many hotel systems but not in those with copper water systems. The early uses of copper were related to its easy workability, softness, resistance to corrosion and its attractive colour and texture.