a rising tide of research clearly shows that breath analysis by artificial noses is very close to being a fast, noninvasive, and practical everyday diagnostic tool—as papers presented at the American Chemical Society National Meeting  (ACS, 8-12 Sept. in Indianapolis, Ind.) and the European Respiratory Society Annual Congress (ERS, 7-11 Sept. in Barcelona) underscore.

 

Odor has been a key diagnostic criterion as long as there have been people. Even today, parents and doctors know that there’s a “nose” in diagnosis. The breath of a child with strep smells metallic. Diabetics’ urine smells sweet, but their breath can smell of acetone and rotten apples. Infectious diseases like cholera, diphtheria, smallpox, pneumonia, tuberculosis, typhoid fever, and yellow fever all produce characteristic odors; so do many types of cancer. The sweat of a baby with phenylketonuria will smell like locker-room towels; other metabolic diseases produce scents redolent of sweaty feet, or maple syrup, or hops, or cabbage, or rotten eggs. Even a disorder like schizophrenia can be associated with a musty smell (a symptom noted in the 1870s and reconfirmed by gas chromatography-mass spectrometry (GC-MS) in the past decade).