Metal Smell comes from human sweat

(via Did You Know on Tumblr) Scientists at Virginia Tech have discovered where the smell of metal comes from -- which is weird, because I didn't know it was something that needed discovering.  It turns out, though, that when we handle metal, it reacts with our skin to accelerate the output of body odor, and that's what smells when we touch certain metals, like iron, copper or brass.

These metallic-smelling organic compounds emanate when sweat from human skin corrodes iron metal. This generates reactive ferrous ions that break down lipid peroxides in the skin to create odorous aldehydes and ketones.

'The smell of iron is only an illusion,' explained Dietmar Glindemann, a chemist at Virginia Tech and leader of the research team. 'What we really smell is a human body odor.'

Apart from being a very cool discovery, the information also has applications in medicine:

The team is now using their experience to develop iron-based diagnostic skin tests. People emit specific chemical fingerprints that can change when the body becomes distressed, such as when a person becomes sick. The volatiles that define these chemical fingerprints are often difficult to detect, but applying iron to the skin accelerates the decomposition of peroxides and improves the detection of volatiles.

'Since different sicknesses produce different amounts of peroxides, applying iron to the skin will produce different quantities of odorants,' explained Glindemann. 'Iron skin tests to detect diseases would be a great achievement.'