The most recent studies show that the SARS-CoV-2 virus survives for days on plastic, glass or stainless steel surfaces, but disintegrates on copper surfaces in a few hours. This fact has not surprised materials experts, who have long known about the antimicrobial properties of this metal. Copper has demonstrated its antimicrobial power on numerous occasions. In 2015, experts proved its ability to destroy coronavirus 229E, a close relative to the one causing COVID-19 that led to common colds and pneumonia. While the virus survived up to five days in stainless steel and glass, copper had it killed in minutes.
This virus-killing power of copper was already known by our ancestors. There is prove of its use for the disinfection of wounds and water purification from more than 3000 years ago (it is mentioned, among other documents, in the Edwin Smith Papyrus). Egyptians, Phoenicians, Chinese, and other ancient civilizations knew these properties and made use of them to prevent diseases and infections.
Considering this, it comes as a bit of a surprise that stainless steel is so present in public spaces around the world and yet we do not find copper-impregnated surfaces so often, especially in frequently-touched surfaces in infrastructures such as hospitals and public transit systems.
Recent studies already show the effectiveness of using copper surfaces to reduce infections in health centers and hospitals. Michael G. Schmidt, Professor of Microbiology and Immunology from the Medical University of South Carolina, conducted a study for more than 3 years revealing a 58% infection reduction due to the use of copper surfaces compare to previously used surfaces made of plastic, wood or stainless steel.
Despite all the evidence, copper is not yet used in a standard way for this type of use in public and health spaces, partly due to funding limitations. Although its mechanical and durability properties are totally equivalent to those of stainless steel, copper is generally 25% more expensive, this difference being variable depending on the demand in global markets.
Another great advantage of copper is that its antimicrobial power does never wear off. Experts in this material have shown that its bactericidal activity on surfaces of more than 100 years old public spaces are still working, which is undoubtedly a strong argument in favour of its gradual introduction, especially in the planning of new infrastructures or renovation of longstanding ones.
But, where does the antimicrobial power of copper come from? Other transition metals such as gold and silver are antibacterial, but to a lesser extent. It is the electron configuration of copper, with a free electron in its outer orbital shell, that causes a high reactivity of this metal with any other element in touch with its surface. This property is also what makes copper an excellent electrical conductor, hence its extended use in electrical installations.
When a microbe lands on a copper surface, ions destroy the pathogen by preventing cell respiration, piercing the cell membrane or viral coating and creating free radicals that accelerate this destruction. And most importantly, these ions destroy DNA and RNA within the bacteria or virus, preventing subsequent drug-resistant mutations.
Although the use of copper as an antimicrobial is still very limited, the demand for this metal is constantly growing worldwide. In the last 25 years, this demand has doubled globally, which has a lot to do with its ability to be recycled without losing any of its properties. In the European Union alone, it is estimated that 41% of the copper demand is met through the recovery and recycling of manufacturing waste from the value chain and through products at the end of life.
In Spain, most of the copper national production comes from the Andalusian mines of the Iberian Pyrite Belt. They provide almost 100% of this production, mainly coming from Cobre las Cruces in Seville, one of the richest copper deposits in the world, Atalaya Riotinto Minera, with 197 million tons of mineral reserves and Minas Aguas Teñidas in Huelva.
There is evidence of very early human use of copper in several regions, not for nothing this metal designates the prehistoric period between the Neolithic and the Bronze Age. Given its superb properties and the challenges we are currently facing, it is quite certain to foresee an increased use of this metal in the near future.
Note: All images used in this post are Wikimedia Commons.