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NSF News 06-164

The Smell of Money

Research suggests an absence of metallic chemicals in the strong metallic odors that result from people handling coins and other metals

Researchers have found that the molecules in "metallic" smells contain no metal.

Researchers have found that the molecules in "metallic" smells contain no metal.


November 20, 2006

This material is available primarily for archival purposes. Telephone numbers or other contact information may be out of date; please see current contact information at media contacts.

It's not hard to recall the pungent scent of a handful of pocket change. Similar smells emanate from a sweat-covered dumbbell or the water emerging from an old metal pipe. Yet no one has been able to identify the exact chemical cause of these familiar odors.

Now, researchers supported by a National Science Foundation (NSF) MUSES award and the UFZ Environmental Research Center in Germany have shown that these odor molecules come not from the penny or the pipes, but from metal-free chemicals erupting into the air when organic substances like sweat interact with the metallic objects.

The researchers--Andrea Dietrich, Dietmar Glindemann, Hans-Joachim Staerk and Peter Kuschk, all from Virginia Tech in Blacksburg--published their findings in the Oct. 20, 2006, Angewandte Chemie International Edition.

"We are the first to demonstrate that when humans describe the 'metallic' odor of iron metal, there are no iron atoms in the odors," said Dietrich. "The odors humans perceive as metallic are really a body odor produced by metals reacting with skin."

Because the makeup of byproduct molecules depends on which organic substances are reacting, the researchers believe the findings could help identify problem odors in potable water or aid doctors searching for disease markers in sweat or other body fluids.

The study, which focused mainly on the reactions of biological fluids with iron, also examined the scents emanating from iron in blood.

"We speculate that the 'blood scent' may result from skin reacting with ferrous iron because the same 'metallic' odor is produced if you rub blood on skin," said Dietrich.

One of the chemicals produced in the reaction is 1-octen-3-one, which has a mushroom-metallic smell and very low odor threshold, meaning that humans can smell it in extremely minute concentrations.

"This may have provided an evolutionary advantage that allowed early humans to track wounded comrades or prey," Dietrich added.

-NSF-

Media Contacts
Joshua A. Chamot, NSF, (703) 292-7730, email: jchamot@nsf.gov
Karen Gilbert, Virginia Tech, (540) 231-4787, email: karen.gilbert@vt.edu

Program Contacts
Matthew Realff, NSF, (703) 292-7081, email: mrealff@nsf.gov

Principal Investigators
Andrea M. Dietrich, Virginia Tech, (540) 231-5773, email: andread@vt.edu

The U.S. National Science Foundation propels the nation forward by advancing fundamental research in all fields of science and engineering. NSF supports research and people by providing facilities, instruments and funding to support their ingenuity and sustain the U.S. as a global leader in research and innovation. With a fiscal year 2021 budget of $8.5 billion, NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and institutions. Each year, NSF receives more than 40,000 competitive proposals and makes about 11,000 new awards. Those awards include support for cooperative research with industry, Arctic and Antarctic research and operations, and U.S. participation in international scientific efforts.

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