A new study shows that sweaty hands can reduce the effectiveness of bacteria-fighting brass surfaces after just an hour of coming into contact with them. Brass is often used in hospitals and schools to mitigate the spread of infection.

Researchers at the University of Leicester have discovered that peoples’ sweat can produce sufficient corrosion to adversely affect its use to kill a range of microorganisms, including harmful diseases found in hospitals, which can easily be transferred by lack of hand hygiene.

“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," explains John Bond from the universities department of chemistry. "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."

The researcher points out that it has long been know that sweat corrodes brass, but that this study is the first to study the level of corrosion, in-depth.

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

The scientist said brass in public environments can be kept free from corrosion through regular and thorough cleaning. In the future, copper alloys may be manufactured with corrosion inhibitors in place, he said.