Human sweat can reduce bacteria defenses of door knobs and taps

June 18, 2014

Sweaty hands can reduce the effectiveness of bacteria-fighting brass objects in hospitals and schools after just an hour of coming into contact with them, according to scientists at the University of Leicester.

While copper found in everyday brass items such as door handles and water taps has an antimicrobial effect on bacteria and is widely used to prevent the spread of disease, Dr John Bond OBE from the University of Leicester's Department of Chemistry has discovered that peoples' sweat can, within an hour of contact with the brass, produce sufficient to adversely affect its use to kill a range of microorganisms, such as those which might be encountered in a hospital and which can be easily transferred by touch or by a lack of hand hygiene.

Dr Bond explained: "The antimicrobial effect of copper has been known for hundreds of years. It is thought to occur as a result of a charge exchange between copper and bacteria, which leads to a degradation of the bacteria DNA. We have discovered that the salt in sweat corrodes the metal, forming an oxide layer on its surface, which is the process of corrosion - and this corrosive layer is known to inhibit the effect of the copper.

We have shown that it is possible for sweat to produce an oxide layer on the metal within an hour of contact.

"While it is well known that sweat corrodes brass, this is the first study to quantitatively analyse the temporal corrosion of copper alloys such as brass in the first few hours after contact between fingerprint sweat concentrations of salt and the metal."

The research paper entitled 'Electrochemical behaviour of brass in chloride solution concentrations found in eccrine fingerprint sweat', published in the journal Applied Surface Science was co-authored by Elaine Lieu as part of a third year Interdisciplinary Science project investigating how easily and quickly sweat can corrode brass at the University of Leicester.

Dr Bond added: "Opportunities to improve hospital hygiene are being investigated by the University of Leicester from seemingly un-connected areas of research. This research is a different application of the study of fingerprint sweat corrosion of brass, applied to hygiene rather than to crime investigation.

"My short term advice is to keep the brass in public environments free from corrosion through regular and thorough cleaning. In the longer term, using copper alloys with corrosion inhibitors included in the alloy would be a good choice.

"While more research is needed in the study of and brass corrosion, anywhere that needs to prevent the spread of bacteria, such as public buildings, schools and hospitals should be looking at using alloy on everyday items to help in avoiding the spread of disease."

Explore further: Lead leaching and faucet corrosion in PVC home plumbing

Related Stories

Lead leaching and faucet corrosion in PVC home plumbing

June 2, 2008

Scientists in Virginia are reporting that home plumbing systems constructed with polyvinyl chloride (PVC) plastic pipes may be more susceptible to leaching of lead and copper into drinking water than other types of piping ...

Recommended for you

Findings illuminate animal evolution in protein function

July 27, 2015

Virginia Commonwealth University and University of Richmond researchers recently teamed up to explore the inner workings of cells and shed light on the 400–600 million years of evolution between humans and early animals ...

New polymer able to store energy at higher temperatures

July 30, 2015

(Phys.org)—A team of researchers at the Pennsylvania State University has created a new polymer that is able to store energy at higher temperatures than conventional polymers without breaking down. In their paper published ...

How to look for a few good catalysts

July 30, 2015

Two key physical phenomena take place at the surfaces of materials: catalysis and wetting. A catalyst enhances the rate of chemical reactions; wetting refers to how liquids spread across a surface.

Yarn from slaughterhouse waste

July 29, 2015

ETH researchers have developed a yarn from ordinary gelatine that has good qualities similar to those of merino wool fibers. Now they are working on making the yarn even more water resistant.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.