What is it?
Copper has been known to mankind for thousands of years. Initially, copper was mainly used in jewellery and coinage, and also in plumbing, but today we know that it also has antimicrobial properties. “Copper and its alloys (brass, bronze, copper-nickel, copper-nickel-zinc and others) are natural antimicrobial materials. Ancient civilisations exploited the antimicrobial properties of copper long before the concept of microbes was understood in the 19th century. Copper’s antimicrobial effect is based on its ability to produce ionised copper ions that damage microbial cell membranes and proteins. This makes copper a powerful weapon in the fight against infections.
History
For thousands of years, long before people knew about germs or viruses, they have known about the disinfecting powers of copper. “Copper is truly a gift from Mother Nature, having been used by mankind for more than eight millennia,” says Michael G. Schmidt, professor of microbiology and immunology at the University of South Carolina School of Medicine, who studies copper in health care.
The first recorded use of copper as an infection-killing agent comes from Smith’s papyrus, the oldest known medical document in history. The information it contains is attributed to an Egyptian physician around 1700 BC, but is based on records dating as far back as 3200 BC. In hieroglyphics, the Egyptians named copper with the ankh symbol for eternal life.
The Chinese used copper coins as medicines to treat heart and stomach pains and bladder disorders as early as 1600 BC. The Phoenicians used to put shavings from their bronze swords into battle wounds to prevent infection. For thousands of years, women have known that their children did not get diarrhoea as often when they drank from copper pots, and they have passed this knowledge on to future generations. “You don’t need a medical degree to diagnose diarrhoea,” says Schmidt.
And the power of copper lasts. Keevil’s team inspected the old railings at New York’s Grand Central Terminal a few years ago. “Copper still works just as it did when it was installed more than 100 years ago,” he says. “This substance is durable and its antimicrobial effect is not lost.”
Why is copper antibacterial?
The antibacterial effect of copper is based on its chemical properties and its interaction with bacteria. Copper is a naturally antimicrobial metal that inhibits microbial growth and reproduction. When copper comes into contact with a microbial cell, copper ions penetrate the cell membrane and cause structural degradation of the cell. In addition, copper ions react with microbial proteins, which prevents them from functioning normally. These molecular effects make copper effective in preventing infections and fighting the spread of bacteria and viruses.
The mechanism of the antimicrobial effect of copper has been thoroughly studied in the laboratory. Several studies have shown that copper can kill many different strains of bacteria, such as Staphylococcus aureus and Escherichia coli, and viruses such as influenza virus and norovirus. Copper’s effectiveness in preventing infections has also been confirmed in clinical studies, which have found that copper surfaces have less bacterial and viral contamination than traditional surfaces.
Copper-related studies
Research on the antimicrobial effect of copper has been active in recent decades and the results are convincing. One study found that copper-coated door handles reduced the incidence of bacterial infections in hospital environments by up to 58% compared to traditional door handles. This shows that copper surfaces have a significant impact in fighting infection and improving patient safety.
Another study investigated the effect of copper on the spread of the influenza virus through contact surfaces. The results showed that the copper surfaces had a faster reduction in virus content and did not retain the virus as long as conventional surfaces. This study confirms the effectiveness of copper in fighting viruses and preventing the spread of infections.
Studies have also been carried out in Finland, for example by the Western Finland Deaconry: https://docplayer.fi/2738440-Antimikrobinen-kupari-terveytemme-ja-hyvinvointimme-suojana.html
Bacteria and copper surface
Copper’s antimicrobial properties are based on its ability to bind bacteria to its surface. Studies have shown that bacteria attached to copper surfaces are unable to continue their normal life cycle and die more quickly than on other surfaces. When a microbe lands on a copper surface, the copper releases ions, which are electrically charged particles. Copper ions burst through the outer membranes and destroy the entire cell, including the DNA or RNA inside. Because DNA and RNA are destroyed, the bacterium or virus cannot mutate and become resistant to copper or transfer genes (such as antibiotic resistance) to other microbes.
This prevents the spread of bacteria and reduces the risk of infection. In addition, copper can inhibit the ability of bacteria to form biofilms, which are protective mechanisms for bacteria and make them more difficult to eradicate.
Pia Voutilainen has a good article on surface materials: https://docplayer.fi/10997822-Antimikrobiset-pintamateriaalit-tulevaisuuttako-pia-voutilainen-turvallinen-sairaalaymparisto-31-10-2013.html
Victor Burq sighting in Paris
In 1852, the doctor Victor Burq visited Paris 3. in a copper smelter in the district, where the reddish-brown metal was extracted using heat and chemicals. The work was dirty and dangerous. Burq said the plant was in “poor condition”, as were the housing and hygiene of the smelters. Normally, their mortality rate was “pathetic”, he said.
Yet all 200 workers who worked there were spared the cholera outbreaks that struck the town in 1832, 1849 and 1852. When Burq learned that 400-500 copper workers on the same street had also mysteriously escaped cholera, he concluded that something about their profession – and copper – had made them immune to a highly contagious disease. He began a detailed study of other people working with copper in Paris and in cities around the world.
During the cholera epidemics of 1854 and 1855, Burq found no deaths among the jewellers, goldsmiths or potters who worked with copper. Among the people in the army, he found that musicians playing brass instruments (brass is partly copper) were also protected.
In the 1865 Paris epidemic, 6 176 people died of cholera out of a population of 1 677 000 – or 3.7 people for every 1 000. But of the 30 000 people working in the various copper industries, only 45 died – an average of about 0.5 per 1 000.
After visiting 400 different companies and factories in Paris, all of which used copper, and collecting reports from England, Sweden and Russia on more than 200,000 people, he concluded to the French Academy of Science and Medicine in 1867 that “copper or its alloys, brass and bronze, literally and heavily applied to the skin during a cholera epidemic, are effective preventive means which should not be neglected”.
Why is copper not everywhere?
Although copper’s antimicrobial effect has been known for years, it has not yet been widely used in different environments. One reason for this is the higher price of copper compared to other materials. In addition, installing and maintaining copper can be challenging, especially in large public spaces. And thieves… when copper is considered a precious metal, then they are valuable prey, as they can be sold to recycling companies for a good price.
Yle article on how thieves are destroying Alvar Aalto’s prestigious buildings: https://yle.fi/a/3-12426644
Summary
The power of copper in preventing infections is undeniable. Its antimicrobial properties can help reduce hospital-acquired infections and fight pathogens in different environments. Although copper is not yet widely used, its potential for preventing infections is huge. In the future, we hope to see more widespread use of copper in different spaces and more use of the antimicrobial properties of surfaces.
