Virginia Tech scientists have shown that there are no metal molecules involved in metallic smell:
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.