How Does Copper Kill Bacteria?

Copper is known to have many benefits; notable physical properties of copper are its ductility and toughness. Copper has a chemical makeup that makes it quite resistant to corrosion. From an aesthetic standpoint, copper is one of the more appealing metals with its lustrous brown-orange tint when freshly polished to its muted sea green appearance when oxidized. In addition to all of this, copper has one other extremely important benefit that differentiates it from other metals: it is superb at killing bacteria that come into contact with it. This unique benefit has not gone unnoticed, and as a result, copper has been used over the course of history in applications where microbial contamination is a concern.

The History of Copper as a Bacteria Killer

Although still not well understood as to why copper is such a good antimicrobial solid material, it has been known to have excellent bacteria-killing properties for millenia. Texts from ancient Egyptians have shown even they knew about copper’s antimicrobial properties. A noticeable rediscovery of this copper attribute can be found in mid-nineteenth century France. Cholera, a deadly bacterial disease, was running rampant through the country, but a small subset of people were spared completely; these people were copper workers and copper smelters. The invention of antibiotics and other sanitizers has since caused the popularity of copper as a disinfectant to decline because of cost reasons, but even today it is regarded as an effective killer of bacteria.

How Does Copper Kill Bacteria?

The exact reason why copper kills bacteria is not quite known at this time. In fact, some types of organisms require small amounts of copper in their composition in order to survive. However, in excess amounts, the same copper that encourages organism development actually destroys it.

Modern scientific research has potentially narrowed the cause down to several different reasons. One explanation for why copper kills bacteria is because it can cause lipids and proteins to oxidize. Another possibility is that copper bonds with other molecules on an organism and takes the place of other essential nutrients such as zinc. Copper in contact with bacteria can also form hydrogen peroxide, a commonly used antiseptic.

Scientific research continues to explore the exact cause of the antibacterial properties of copper. Many studies have been performed to show the effect of copper on a variety of different bacteria strains, with quite widely varied results depending on the bacteria strain being evaluated. Researchers have also been evaluating real world applications where copper could be used to prevent the spread of bacteria such as healthcare and the handling of hydrocarbons.

Although it is the copper element that kills the bacteria, a pure copper alloy does not need to be used. Bronze alloys, combinations of copper and tin such as C932 and C954, are also effective at killing bacteria. Brass alloys, combinations of copper and zinc such as C260 and C464, have a similar efficacy with regard to killing bacteria. As long as copper is present in large amounts, many types of copper alloys can have similar bacteria-killing effects to pure copper.

Common Antimicrobial Applications of Copper Alloys

While antibiotics and disinfectants are relied on heavily for bacteria management, some components are still made out of copper with the purpose of leveraging its antimicrobial properties. These include:

• High touch surfaces at certain medical facilities such as faucet handles, door knobs, and light switches where the spread of bacterial infection is a major concern.
• Laboratory equipment where the influence of bacteria may cause experiment results to be unintentionally altered.
• Other areas where the presence of bacteria is a major concern and the cost of copper does not prohibit its use.