Impact Blog
Copper: More than just a conduit

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      By Suley SaleemESG Senior Research Analyst, Calvert Research and Management

      Washington - At Calvert, when we think copper, our minds turn to the metal's growing applications in electrifying our lives -- and by extension, its vital role in decarbonizing the world. We've identified copper, along with aluminum, as critical metals supportive of the broader energy transition largely due to its unique properties in conducting electricity and heat. However, copper has another unique quality that is gaining attention during the current COVID-19 pandemic -- the natural ability to neutralize the spread of pathogens.

      Copper has been used for its underappreciated health purposes as far back as ancient Egypt and Babylon, when soldiers placed copper fillings in wounds to reduce infections and speed healing. In ancient Greek and Aztec culture, healers used copper derivatives to treat skin infections. In the 1830s, studies in France showed that copper workers showed significant immunity against cholera outbreaks in 1832, 1849 and 1852, respectively. More relevantly, microbiologists at the University of Southampton discovered that copper can help prevent the spread of respiratory viruses linked to severe acute respiratory syndrome (SARS), as exposure to copper rendered the virus inactive within hours.

      Copper works in several different ways to shut down a cell's chemistry and physiology, but the primary route is the release of copper ions when microbes, transmitted via touching, sneezing, vomiting etc. land on the copper surface. These positively charged ions prevent cellular/capsid respiration, destabilize membrane integrity, and destroy the pathogen's DNA and RNA. The destruction of the pathogen's genetics prevent the microbe from developing a resistance to copper, which is critical against the backdrop of growing antimicrobial resistance that is estimated to claim 10 million lives and cost $100 trillion by 2050.1 In short, copper can be effective in mitigating the spread of many types of disease, from common infections to those that have no vaccine available, including those that mutate annually, such as coronaviruses and noroviruses.

      Studies have shown that with routine cleaning, the use of copper on frequently used surfaces in hospitals would yield a 90% reduction in the numbers of live bacteria present while studies across a small number of US hospitals showed a 58% decline in infection rates where copper was used instead of stainless steel.2

      So why don't more hospitals replace commonly touched surfaces with copper? Cost is a factor, as most hospitals see hand-gel dispensers as cheaper options vs. the up-to 50% higher cost of installing copper, despite knowing that these gels are less effective at killing microbes. However, studies by the University of York's Health Economics Consortium have shown that the payback for installing copper fittings in hospitals can occur in as little as two months when considering the reduced costs from shorter patient stays and treatments. Costs are comparable to installing stainless steel.3

      While stainless steel is perceived to be cleaner due to its brighter surface shine, its microscopic indentations and scratches from regular use actually create favorable environments for microbes to hide during routine cleaning procedures.

      These benefits of copper are in the early stages of gaining mainstream recognition by the health care community, as hospital systems in France are beginning to install copper fittings on flat surfaces and bed rails. However, there are applications beyond health care that would benefit from leveraging copper's antimicrobial properties. Transportation is one: Atlanta's Hartsfield-Jackson airport installed more than 50 water fountains made of "EPA-registered copper alloys" while Brazil's Congonhas Airport has installed copper handrails and counters, and Poland's newest city buses are the world's first to feature antimicrobial handrails. Elsewhere, the NHL's LA Kings installed copper surfaces at its training facilities to mitigate the spread of infections for athletes. In today's world, where large gatherings of people pose an increased risk in the spreading infectious pathogens, the opportunity set for copper is expansive with applications across entertainment venues, commercial and residential real estate, shopping malls and cruise ships, just to name a few.

      Bottom line: As we reexamine all facets of daily life including travel and mass gatherings during the current pandemic, copper surfacing presents a unique pathway to mitigating the spread of infectious pathogens by taking advantage of the metal's naturally occurring anti-microbial properties. Health care systems, municipalities and other private institutions are beginning to install copper more widely for these reasons.