The Smell of Blood
November 19, 2006
An expert in Germany believes he has discovered why iron smells when it comes in contact with skin. He says the odor we can smell is not from the iron itself, but from a chemical reaction with our own skin oils.
This is the same reaction that occurs when blood touches our skin, as blood contains iron.
"The smell of iron upon contact with skin is, ironically, a type of human body odor," Dietmar Glindemann said. "It is an illusion that we are smelling the metal itself is."
Scent for survival
He believes this "blood scent" was useful to early humans in tracking down prey or other humans.
Glindemann has done some hunting himself, tracking down the responsible scent molecules, working in conjunction with a team of researchers from the Virginia Polytechnic Institute and State University in the United States, the University of Leipzig and the Leipzig Environmental Research Center in Germany.
In the scientific study, seven test subjects immediately recognized the musty, metallic odor when their hands came into contact with metallic iron or a solution containing iron ions with a two-fold positive charge.
Analysis of gas samples from the skin of the people involved in the test showed that a range of different organic compounds seemed to be characteristic of the metallic smell. The key component is called 1-octen-2-one, which smells fungal-metallic even when highly diluted.
Blood has same effect
And more intriguing is why iron apparently smells like blood. Rubbing blood over skin results in a similar metallic smell based on the same scent molecules, as blood also contains iron atoms.
"That humans can 'smell' iron can be interpreted as a sense for the smell of blood," Glindemann said. "Early humans were thus probably able to track down wounded prey or tribe members."
Based on this new knowledge, medical researchers should be able to further develop iron tests for skin, blood and tissues to identify specific "fingerprints" of volatile scent molecules as markers for individual body odor, oxidative stress and diseases.