Human sweat is actually much dirtier and bacteria-filled than we initially thought. Scientists have found that sweaty hands can reduce the effect that brass objects have of fighting bacteria. Brass objects can be found in hospitals and schools and sweat can fight off its abilities just an hour after contact.
Brass objects have an antimicrobial effect on bacteria, and it even helps prevent the spread of disease. Human sweat produces corrosion that affects the copper's ability to kill microorganisms.