A breathalyser for disease

HIPPOCRATES, the father of medicine, was known to have used smell as an aid to his work. Generations of doctors followed suit. Syphilis, for instance, is thought to have a characteristic odour; the smell of rotting apples suggests diabetes. Today, things are more sophisticated. All sorts of volatile organic compounds (gases, known as VOCs, that are given off by living organisms) have been identified, in laboratories, as markers of specific diseases from breast cancer to cholera. A paper reported...