Antimicrobial Copper Is Effective in Everyday Life Situations
The antimicrobial activity of copper was known for thousands of years, at least since the ancient Egyptians, but the history of copper goes even further back in time. Copper, like gold, is found naturally in elemental form. Early humans knew well how to work with this ductal metal and produced tools, weapons, coins and jewelry as early as 10,000 years ago. By 4,000 to 5,000 years ago, the technology for mining and smelting copper-rich ores and casting molten copper was well developed in the Middle East. In fact, the latter part of the Stone Age is often referred to as the Copper Age, approximately 2,500 to 3,500 BCE.
The Egyptians introduced large scale copper production methods by about 1,200 BCE. Knowledge of these technologies spread rapidly throughout the Middle East, to Europe, to the Indus Valley and Pakistan, and eventually to China by 1,600 BCE. Oetzi, the Ice Man who lived about 3,300 years ago and discovered in 1991 in an Alpine glacier, carried a 99.7% pure copper axe.
The Copper Age was followed by the Bronze Age, which lasted from about 3,500 to 600 years ago, depending on the region of the world. This was the start of true metallurgical science. Humans experimented with mixing materials to improve the strength and other characteristics of the final product, referred to as an alloy. An alloy is a metallic substance composed of two or more elements, typically metals. Bronze is an alloy containing mostly copper plus about 12–12.5% tin, often with the addition of other metals. Bronze is less malleable than copper but has greater strength making it a superior choice for tools and weapons. Brass is another alloy of copper but with zinc (about 5-40%). A variety of other metals are usually added to improve characteristics like strength, corrosion resistance, and ease of casting.
Antimicrobial Copper - a Brief History
Civilizations exploited the antimicrobial properties of copper and copper alloys long before Louis Pasteur's discovery that bacteria were the causative agents of infectious disease. For the most part, ancient methods used copper salts and oxides to treat infection but metallic copper, copper splinters, and copper shavings were also used. Milestones in the use of antimicrobial copper for health and safety are listed below.
Egyptians used bronze surgical tools 6,000 years ago.
The Hindu tradition of Ayurvedic medicine dating back 3,000 years recommends collecting and storing household water supplies in copper vessels.
The Smith Papyrus, an Egyptian medical text from about 2,500 years ago, describes how to treat an infected chest wound and promote healing with copper salts and verdigris. green copper patina.
The Ebers Papyrus, dating to about 1,500 BCE, discusses treatments for eye ailments, burns, itchy skin, and infected wounds with copper compounds made from copper salts and copper splinters and shavings.
The Hippocratic Collection, partly written by Hippocrates around 460-380 BCE, recommends treating infected leg wounds, with a poultice made from copper salts and verdigris dissolved in wine.
Ancient Chinese law banned the use of paper money in public drinking houses. Only coins made from copper could be used based on empirical knowledge that disease transmission rates were lower.
Roman surgeon Galen (130-200 AD) used instruments made of bronze, an antimicrobial copper alloy.
French physician Victor Burq did an analysis of mortality and morbidity during two Paris cholera epidemics (1864 and 1865). He found only 16 deaths among about 30,000 workers in the copper industry while while there were 10 to 40 times that many in the general population.
Ayurvedic medicine tradition of collecting and storing household water supplies in copper vessels
Roman surgeon Galen's operating tools
Antimicrobial Copper - Still Working Today to Keep Us Safe
Members of the Copper Development Association's antimicrobial task force set about exploring a variety of situations in which the public is exposed to surfaces that are potentially contaminated with disease-causing organisms.
Coinage: When you handle coins, did you ever wonder if you could get an infection from touching them? The US mint produces coinage in which the exposed surface is a copper-rich alloy. Currently, pennies are made of zinc but have a thick pure copper plating. Previously, pennies were composed of an alloy of 95% copper 5% zinc. The so-called silver coinage - nickels, dimes, quarters and half dollars - are currently pure copper sandwiched between thick layers of a copper-rich alloy of about 75% copper with the remainder nickel. The dollar coin is made of "manganeses brass", which is over 88% copper. Thus, all of the coins' touch surfaces consist of copper-rich alloys that laboratory research has demonstrated have a high antimicrobial activity.
To test our hypothesis that US coins are antimicrobial, we obtained rolls of pennies from the bank that had been in circulation for years and determined the levels of bacterial contamination. Several hundred pennies were tested and found little to no evidence of bacterial contamination. Clearly, pennies are antimicrobial! While other denominations of US coins were not tested, based on the alloy composition of their surfaces, we expect that they too will be antimicrobial.
Public Spaces: When you used handrails in a train station, open the door to a hospital room using a push plate, or use a faucet in a public toilet, did you ever think "That must be covered with disease microbes!" Well, you were wise to be concerned. What if the level of contamination of that handrail, push plate, or faucet handle could be dramatically reduced? That would likely protect everyone who used the public space and thereby reduce the spread of infection.
We selected New York City's Grand Central Terminal to test if antimicrobial copper could make a difference. Grand Central Terminal is one of the world's ten most visited tourist attractions with 21.6 million visitors in 2018. Hundreds of thousands of train and subway commuters also use it on a daily basis. The station house was built in the early 20th century. Its interior is a magnificent example of Beaux-Arts design that makes abundant use of brass, an antimicrobial copper alloy. The photos below show the grand entry hall of Grand Central Station and the brass fixtures that abound throughout the public areas. The photo on the lower right shows brass fixtures and nearby wood controls that were sampled. In all cases, the same number of square inches of surface area were swabbed. The photo gives the startling results. The 60+ year old brass hardware retained antimicrobial activity!
The 60+ year old brass hardware retains antimicrobial activity!
Healthcare: Most individuals entering a healthcare facility are either sick, are the care giver or family member of someone who is sick, or are being tested for a potential problem. One should not be surprised that facilities like hospitals and nursing homes and outpatient centers are hot beds of infectious disease.
On the Clinical Trial page of this website, you can read the details of a 3-hospital clinical trial that demonstrated a 58% reduction in hospital acquired infections in medical Intensive Care Units equipped with antimicrobial copper surfaces. Below are some other examples of healthcare facilities that were studied.
Ronald McDonald House, Charleston, SC: Ronald McDonald Houses provide a temporary home for families to stay so that they can be close by their seriously ill hospitalized child. Nothing could be worse for a sick child than to be separated from the love and support of mom and dad and siblings. Often, families come from great distances to bring their child to a specialized hospital for treatment. These families are faced with the financial and personal crises. How can can children spend several weeks or months in the hospital separated from their rest family? At little to no cost, a Ronald McDonald House is a home away from home that keeps families together close to their hospitalized child.
Stethoscope, North Shore University Hospital, Manhasset, NY: An antimicrobial copper alloy version of a standard Littmann stethoscope was produced and distributed to doctors working in North Shore University Hospital by infectious disease specialist Dr. Bruce Hirsch, MD. After an extended period of use, copper and standard stethoscopes were collected and the levels of bacterial contamination on different areas compared. An image of the copper stethoscope is shown below. The presence of copper clearly decreases the bacterial load.
Schmidt et al. 2017. Antimicrobial copper alloys decreased bacteria on stethoscope surfaces. American Journal of Infection Control 45: 642-7.
A typical Ronald McDonald House
Interior hardware and furniture changed to antimicrobial copper alloy
Ronald McDonald House, Charleston, SC was selected for a demonstration make-over. At no cost to Ronald McDonald House Charities, antimicrobial copper was installed to replace a variety of items in the facility including handrails, table tops and chair arms, door and cabinet hardware, light switches, and more. A few examples are shown in the photo above. After 10 weeks of occupation, the components made from antimicrobial copper exhibited a 93% reduction in bacterial contamination!
Outpatient Phlebotomy Room, North Shore University Hospital, Manhasset, NY: Outpatients often need blood drawn in an outpatient facility or clinical testing site. Hundreds of people utilize these sites on a daily basis most for routine testing and monitoring but occasionally for serious diseases, like HIV. Whatever the reason, outpatient phlebotomy rooms, and the chair in particular, are as likely as other public spaces to be contaminated with microbes. Working with infectious disease specialist Dr. Bruce Hirsh, we tested the impact on phlebotomy chair contamination.
The photo (left) shows a typical phlebotomy chair with the antimicrobial copper components in place: the tray table on which the patient rests their arm during the blood draw procedure and a wide strip down the center of both arm rests. Swabs were taken from the tray table and both the alloy insert and the adjacent wood of the chair arms. These were compared to the same regions of all-wood chairs. The results are shown in the graphs below. Clearly, the antimicrobial copper caused a dramatic approximately 10-fold, about 90%, decrease in bacterial contamination. Amazingly, the copper arm insert had a "halo effect" producing a 77% decrease in bacterial contamination on the adjacent wood strip.
Rai et al. 2012 Evaluation of the Antimicrobial Properties of Copper Surfaces in an Outpatient Infectious Disease Practice. Infection Control and Hospital Epidemiology 33: 200-201.