Target Health Blog

Antimicrobial Properties of Copper (including COVID-19)

April 13, 2020

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History of Medicine
Source:

A copper disc (99.95% pure) made by continuous casting; etched to reveal crystallites
Photo credit: by Alchemist-hp (
pse-mendelejew.de) - Own work, CC BY-SA 3.0 de, https://commons.wikimedia.org

Copper and its alloys (brasses, bronzes, cupronickel, copper-nickel-zinc, and others) are natural antimicrobial materials. Ancient civilizations exploited the antimicrobial properties of copper long before the concept of microbes became understood in the nineteenth century. In addition to several copper medicinal preparations, it was also observed centuries ago that water contained in copper vessels or transported in copper conveyance systems was of better quality (i.e., no or little visible slime or biofouling formation) than water contained or transported in other materials. Molecular mechanisms responsible for the antibacterial action of copper have been a subject of intensive research. Scientists are also actively demonstrating the intrinsic efficacy of copper alloy “touch surfaces“ to destroy a wide range of microorganisms that threaten public health.

Ancient Egyptian technology may be our first line of defense from hospital infections. The first recorded medical use of copper is found in the Smith Papyrus, one of the oldest books known. The Papyrus is an Egyptian medical text, written between 2600 BCE and 2200 BCE, which records the use of copper to sterilize chest wounds and to sterilize drinking water. Other early reports of copper's medicinal uses are found in the Ebers Papyrus, written around 1500 BCE The Ebers Papyrus documents medicine practiced in ancient Egypt and in other cultures that flourished many centuries earlier. Copper compounds were recommended for headaches, “trembling of the limbs“ (perhaps referring to epilepsy or St. Vitus' Dance), burn wounds, itching and certain growths in the neck, some of which were probably boils. Forms of copper used for the treatment of disease ranged from metallic copper splinters and shavings to various naturally occurring copper salts and oxides. A “green pigment“ is spoken of which was probably the mineral, malachite, a form of copper carbonate. It could also have been chrysocolla, a copper silicate, or even copper chloride, which forms on copper exposed to seawater. In the first century CE, Dioscorides, in his book De Materia Medica, described a method of making another green pigment known as verdigris by exposing metallic copper to the vapors of boiling vinegar. In this process, blue-green copper acetate forms on the copper surface. Verdigris and blue vitriol (copper sulfate) were used, among other things, in remedies for eye ailments such as bloodshot eyes, inflamed or “bleary“ eyes, “fat in the eyes“ (trachoma?), and cataracts.

In the Hippocratic Collection (named for, although not entirely written by, the Greek physician Hippocrates, 460 to 380 BCE.), copper is recommended for the treatment of leg ulcers associated with varicose veins. To prevent infection of fresh wounds, the Greeks sprinkled a dry powder composed of copper oxide and copper sulfate on the wound. Another antiseptic wound treatment at the time was a boiled mixture of honey and red copper oxide. The Greeks had easy access to copper since the metal was readily available on the island of Kypros (Cyprus) from which the Latin name for copper, cuprum, is derived.

By the time the Roman physician Aulus Cornelius Celsus began practicing medicine, during the reign of Tiberius (14 to 37 CE), copper and its derivatives had been firmly established as an important drug in the medical practitioner's pharmacopoeia. In Celsus' series, De Medicina, books one through six list many purposes for which copper was used together with the preparation and the form of copper most effective for each ailment. For the treatment of venereal disease, for example, Celsus prescribed a remedy consisting of pepper, myrrh, saffron, cooked antimony sulfide, and copper oxide. These were first pounded together in dry wine and when dry, once again pounded together in raisin wine and heated until dry. For a non-healing chronic ulcer, treatment consisted of copper oxide and other ingredients including enough rose oil to give a soft consistency.

Pliny (23 to 79 CE) described a number of remedies involving copper. Black copper oxide was given with honey to remove intestinal worms. Diluted and injected as drops into nostrils, it cleared the head and, when taken with honey or honey water, it purged the stomach. It was given for “eye roughness,“ “eye pain and mistiness,“ and ulceration of the mouth. It was blown into the ears to relieve ear problems.

In the New World, the Aztecs also used copper for medical purposes. Don Francisco de Mendoza commissioned two learned Aztec Indian physicians to record the pharmacological treatments known by the Aztecs at the time of the Conquest. For the treatment of “Faucium Calor“ (literally, heat of the throat, or, sore throat) they prescribed gargling with a mixture of ingredients containing copper.

Copper was also employed in ancient India and Persia to treat lung diseases. The tenth century book, Liber Fundamentorum Pharmacologiae describes the use of copper compounds for medicinal purposes in ancient Persia. Powdered malachite was sprinkled on boils, copper acetate as well as and copper oxide were used for diseases of the eye and for the elimination of “yellow bile.“ Nomadic Mongolian tribes treated and healed ulcers of venereal origin with orally administered copper sulfate.

The first observation of copper's role in the immune system was published in 1867 when it was reported that, during the cholera epidemics in Paris of 1832, 1849 and 1852, copper workers were immune to the disease. More recently copper's role in the immune system has been supported by observations that individuals suffering from Menke's disease (an inherited disease in which there is defective copper absorption and metabolism) generally die of immune system-related phenomena and other infections. Further, animals deficient in copper have been shown to have increased susceptibility to bacterial pathogens such as Salmonella and Listeria. Evidence such as this has led researchers to suggest strongly that copper compounds not only cure disease but also aid in the prevention of disease.

In 1885, the French physician, Luton, reported on using copper acetate in his practice to treat arthritic patients. For external application he made a salve of hog's lard and 30% neutral copper acetate. For internal treatment, he used pills containing 10 mg. of copper acetate. In 1895, Kobert published his review of the pharmacological actions of copper compounds. Copper arsenate had been used to treat acute and chronic diarrhea as well as dysentery and cholera. A variety of inorganic copper preparations were found to be effective in treating chronic adenitis, eczema, impetigo, scorphulosis, tubercular infections, lupus, syphilis, anemias, chorea and facial neuralgia. An organic complex of copper developed by Bayer was shown to have curative powers in the treatment of tuberculosis. Copper treatment for tuberculosis continued until the 1940s, and various physicians reported on their success in using copper preparations in intravenous injections.

In 1852, physician Victor Burq visited a copper smelter in Paris's 3rd arrondissement, where they used heat and chemicals to extract the reddish-brown metal. It was a dirty and dangerous job. Burq found the facility to be “in poor condition,“ along with the housing and the hygiene of the smelters. Yet, the 200 employees who worked there had all been spared from cholera outbreaks that hit the city in 1832, 1849, and 1852. When Burq learned that 400 to 500 copper workers on the same street had also mysteriously dodged cholera, he concluded that something about their professions and copper, had made them immune to the highly infectious disease. He launched a detailed investigation into other people who worked with copper, in Paris and cities around the world. In the 1854 to 1855 cholera epidemic, Burq could not find any deaths of jewelers, goldsmiths, or boilermakers, all of whom worked with copper. In people in the army, he found that musicians who played 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 people - that's 3.7 people out of every 1,000. But of the 30,000 who worked in different copper industries, only 45 died - an average of around 0.5 per 1,000. After visiting 400 different businesses and factories in Paris, all of which used copper, and collecting reports from England, Sweden, and Russia on more than 200,000 people, Burq concluded to the French Academies of Science and Medicine in 1867 that “copper or its alloys, brass and bronze, applied literally to the skin in the cholera epidemic are effective means of prevention which should not be neglected.“

Today, we have insight into why a person handling copper day in and day out would have protection from a bacterial threat: Copper is antimicrobial. It kills bacteria and viruses, sometimes within minutes. Studies have shown that copper is able to destroy the microbes that most threaten our lives. It has been shown to kill a long list of microbes, including norovirus, MRSA, a staph bacteria that has become resistant to antibiotics, virulent strains of E. coli that cause food-borne illness, and coronaviruses, possibly including the novel strain currently causing the COVID-19 pandemic.

Using copper along with standard hygiene protocols has been shown to reduce bacteria in health care settings by 90%. A study from 1983 found that hospital doorknobs made of brass, which is part copper, barely had any E. coli growth on them, compared to stainless steel knobs which were “heavily colonized.“ This is significant because of how rampant healthcare-acquired infections are: In the U.S. alone, there are about 1.7 million infections and 99,000 deaths linked to HAIs per year, which cost between $35.7 and $45 billion annually, from the extra treatments people need when they get infected.

A study from 2015 found that a different coronavirus, human coronavirus 229E, which causes respiratory tract infections, could still infect a human lung cell after five days of being on materials like teflon, ceramic, glass, silicone rubber, and stainless steel. But on copper alloys, the coronavirus was rapidly inactivated.

In a new preprint on SARS-CoV2, the strain that causes COVID-19, researchers at the National Institutes of Health virology laboratory in Montana sprayed the virus onto seven different common materials. Results showed that it survived the longest up to three days on plastic and stainless steel, suggesting that surfaces in hospitals or steel poles on public transit could be places where people pick up the illness.

Sources: Wikipedia; Daily Kos; www.vice.com;www.copper.org

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