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Antibacterial Doorknobs

June 27, 2014

Sweat disables copper’s antibacterial properties, with implications for doorknobs and handles everywhere.



Bacteria, sweat, and copper.  I’m Bob Hirshon and this is Science Update.

Copper-containing metals like brass have antibacterial properties – a selling point for brass doorknobs, sink handles, and other fixtures in hospitals and schools.  But now, British scientists have found that handling those fixtures can actually disable their germ-killing powers.  According to University of Leicester forensic scientist John Bond, human sweat forms a corrosive layer on the metal surface.  That blocks an exchange of charged particles that would otherwise kill harmful bacteria.  And the fixtures that are handled the most would be most affected.

JOHN BOND (University of Leicester, England):

The more often it’s touched, you’re replenishing and indeed concentrating the active ingredient in sweat that corrodes the metal, which is just salt.

So even if an institution has germ-resistant copper fixtures, they still need to clean them and encouraging frequent hand-washing. I’m Bob Hirshon for AAAS, the Science Society.