How do Copper Pennies Kill Bacteria?

A. Copper has only copper in it, Faiza. Copper is one of the about 92 'elements' that cannot be subdivided into something else. Some metals like copper and silver and cadmium are unnatural environments for some life forms and will kill them.

I do know that copper is used to kill plant roots in old pipes and to kill algae blooms in ponds and lakes. But I don't know whether putting a single penny in your rose water will actually do anything; you'll have to try it. Good luck!

A. Copper salts are used by the wine growing industry to reduce the effects of fungus on the leaves and grapes. The mixture is called "Bordeaux Mix". I have not heard of copper being a bactericide, but it certainly does treat some fungal infections. As I understand it, the copper is toxic to the fungus and kills it off, like poisons such as strychnine or arsenic kill people and animals.

Take Ted's advice and do the experiment, but make sure you also use a control rose that doesn't get the copper treatment. Its Valentine's Day soon, so perhaps your favourite partner will buy you a bunch of roses to try out!

A. You might try looking at the copper nails or copper banding techniques used to stop trees growing for how the copper sulphate ⇦this on eBay or Amazon [affil links] plays a part.

A. Although this still doesn't answer your question about HOW copper exerts its bactericidal effects, I just remembered a book I once reviewed by a man named Estes (in Boston, I believe) who wrote a book about Ancient Egyptian Medicine.

In the book, he describes copper-based preparations that were prescribed to help heal wounds. If I remember correctly, copper was a fairly common ingredient in their medicines. On the other hand, so was animal dung!

My review appeared in an issue of Omni magazine in 1989 or 1990, if you want a better starting point than this post.

Good Luck!

A. I've never heard of using copper to kill bacteria, but silver is used quite commonly. There are many high-end antibacterials being made with tiny particles of silver. To top that, Band-Aid is making band-aids with woven silver instead of normal cloth band-aid material. It has something to do with silver interfering with the life-cycle of bacteria, preventing their reproduction. Note that it's actually solid elemental silver, not silver ions. Silver ions readily bind themselves to DNA molecules and other proteins and can actually poison humans. This is similar to the effect that copper salts (dissolved copper ions) have on fish, thus making them a good way to keep your pond blue and algae free, as well as a good way to poison fish.

A. Remember: Newer pennies are only 2.5 percent Copper!

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Hi, David. That number sounds approximately correct, although I didn't check it.

But if you aren't going to bite into a donut -- if you're just going to lick the icing to spite your sister -- won't it taste the same whether the donut below is devil's food or white cake?

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

A. E. coli O157:H7 has been associated with several large-scale food recalls by processors in the United States. This bacterium was found to be nonviable in a few hours when placed on copper surfaces, but survived for many days on stainless steel. The copper alloys tested included coppers, brasses, bronzes, copper-nickels and nickel silvers. The results confirm that the antibacterial effect is present in all the tested copper alloys, and increases with the copper content of the alloy. Furthermore, as expected, this action was faster at the higher temperature. The bacteria were found to be nonviable on almost all of the copper alloy surfaces in the range of one to six hours at 20° C. It took longer, with a minimum time of three hours, at 4° C. This anti-microbial attributes of copper alloys should be useful beyond food processing applications.

A. American Pennies made prior to 1983 have little copper in them.
Silver is a much more powerful killer of bacteria.

A. Thanks, Dave. Your second statement may be true, I don't know, but your first one must be a typo :-)

Coins before 1982 were 95+ percent copper according to the U.S. Mint website. It is pennies after 1982 that consist of a copper plated zinc core.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007

A. Do you remember the battery made with a potato, sticked with copper and zinc? .

This is an oxidation reaction, the zinc is destroyed creating energy. Same thing happens with galvanized iron (iron lines with zinc). Well, copper forms a electric bridge with bacteria killing it. But Silver has better effect. I suggest study the electrochemical series of metal to learn the levels of interaction between metals. Living organism as bacteria have metal in their structure, as Iron, Manganese.......

A. Recently, British pennies and similar coins have been made of steel plated with copper. I believe it is the same with American pennies, which adopted this process earlier. As the copper is on the surface, I don't think that would reduce the bactericidal effect at all.

It would be interesting to know if illnesses spread less quickly in countries where most or all coins contain copper (like the UK) compared to where they do not. Some countries are fond of aluminium and stainless steel coins, for example Italy before it adopted the euro.

A. I just did a college report about controlling hospital born infections. There was an article on wikipedia.org about Nosocomial Infections. Turns out that there are trials being conducted showing that rooms are being coated in antimicrobial copper at Memorial Sloan Kettering in New York to control and destroy microbes. It revealed that 99.9% of Gram negative bacteria and fungi were destroyed by copper compared to rooms without copper. Risk factors decreased 40% of people in these rooms getting infections before hospital discharge. It seems to be very potent, but I think it would take more copper than a penny to control the bacteria. Good luck with your project. I'd be curious to know if your hypothesis proved to have positive results.

A. Hi, William.

This is way out of the area of expertise of most readers on this site, certainly including me :-)

I think a discussion with your doctor or a poison control center may be helpful. Good luck..

Regards,

A. Copper is now approved with the EPA as an antimicrobial metal.

The problem is obviously cost when associating copper with manufactured goods.

Look for some new technology that will be readily available and expect consumer goods to have more antimicrobial surfaces in their products.

Here's a good link:

www.copper.org/antimicrobial/properties/multimedia/homepage.html

Super bugs will be a thing of the past with the new technologies being brought to the marketplace.

A. Hi, David. Very helpful posting -- thanks!

But your closing sentence sounds like a million statements of the sort in the course of history, and I think we're still hunting for the first one that proved true :-)

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
November 4, 2011

A. It exists Ted, at least to the extent that copper can be integrated as an antimicrobial surface in a cost effective way.

The applications are almost limitless.

David Dennis
- Burlington, Ontario Canada
November 7, 2011

A. Hi, David. I didn't say or mean to imply that the technology doesn't exist or won't be highly useful. My remark was philosophical, i.e., that technologies that propose to make pandemic scourges like superbugs "a thing of the past" rarely achieve it :-)

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
November 8, 2011

"Pandemic scourges"........love it Ted!

The technology is indeed new. I believe the technology is sound enough to help maintain sterile environments such as touch surfaces, operating rooms, public areas.

David Dennis
- Burlington, Ontario Canada
November 8, 2011

A. Canada has removed its copper pennies from circulation, effective February 4, 2013. Presumably, the United States will be following suit as well. Since copper is a natural antibacterial agent, is it not perfectly reasonable to expect that emergency hospital visits and health care expenses will rise dramatically as people become ill, even violently so from the removal of such natural antibacterial agents from the environment?