Drugs and toxins: fact and fancy.

The scientific approach has reduced the burden of disease in society and removed much of the mystery, yet there is still much subjective illness and unease. Fear of poisoned water, bad food, and bad air may have been of evolutionary advantage to early humans, and these fears remain potent in today's sophisticated world. Perhaps the twenty-first century will see an understanding at the molecular and genetic level of the mechanisms underlying belief and its consequences.