The Journal of Young Investigators: An Undergraduate, Peer-Reviewed Science Journal

06 November 2006 - Pooja Ghatalia
Science Journalist
The University of Texas at Dallas

Have you experienced the musty metallic odor when handling iron objects or rubbing away a drop of blood from a cut? Researchers at Virginia Polytechnic Institute & State University have now identified the chemical source of this odor.

Dietmar Glindemann and Andrea Dietrich exposed human skin to various forms of iron and used mass spectrometry to show that the resulting metallic odor is due largely to volatile 1-octen-3-one.

The organic compound 1-octen-3-one is formed as a result of an oxidation-reduction reaction between Fe2+ ions and the oils in human sweat. When iron objects come in contact with the skin, perspiration oxidizes the metal to Fe2+ ions, and the metal ions reduce and decompose the lipid peroxides in the skin oil. The product formed is a "bouquet" of organic carbonyl compounds. In blood, iron is already available as Fe2+ in heme molecules.

“The smell of iron on contact with skin is ironically a type of human body odor,” said Glindemann.

Test subjects who handled pieces of the metal or a solution containing Fe2+ ions immediately recognized the musty iron odor. In contrast, the testers who did not touch the metal didn't smell the odor.

"That we smell the metal itself is actually an illusion,” Glindemann added.

Besides solving an age-old mystery, the researchers believe that specific sets of organic carbonyl compounds could be used as "chemical fingerprints" for an individual's body odor, which could be used as a diagnostic test for certain diseases.
Other metals like copper and brass (a copper-zinc alloy) also give rise to metallic odors.

Written by Pooja Ghatalia

---