Copper is a micronutrient and is required for the normal functioning of plants, animals and most microorganisms.
It is incorporated into a variety of proteins which perform specific metabolic functions. Because it is an essential
metal, daily dietary requirements have been recommended by a number of agencies. The U.S. Department of
Agriculture and the National Academy of Sciences have recommended 0.9 mg/day as the adult dietary requirement
for copper. Some of the uses of copper are related to its ability to control the growth of organisms. This occurs
when copper is biologically available and at certain concentrations. As a result, copper is used in a range of biocidal
agents. For example, copper has been demonstrated to be an effective antibacterial*, antiplaque agent in mouthwashes
and toothpastes. Copper also continues to be widely used for the control of unwanted organisms in marine
applications, such as fish farming. Evidence in both fresh water and salt water indicates no hazardous effect to consumers
or the fish. Copper antifouling agents used on fish net pens have been considered a source of metal to the
sediments but there is little evidence that they provide a significant source of dissolved copper when there is adequate
water exchange for fish farming.