What's the World's Worst Smell?

Dr. Pamela Dalton is a chatty, mild-mannered scientist—a sensory psychologist at the Monell Chemical Senses Center in Philadelphia—who just happens to have authored the world's worst smell. Her client: The U.S. Department of Defense, which wanted a world-class stink bomb, a violently potent, no-kill weapon all but guaranteed to make enemies drop their weapons and run away.

Here's how Dalton made her Frankensteinian creation, affectionately named "stench soup."

The Recipe:

Research shows that certain smells are hated in cultures the world over. Dalton surveyed the vilest odors from around the globe (fish oil factories, old toilet brushes, etc., ad nauseum—literally) and identified the key elements. Specifically, she focused on two kings of the stench world—rotting corpses and human waste—and recreated them in her lab. To these she added sulfur (that yummy rotting egg smell) and a sweet, fruity overtone. The exact recipe, of course, is a secret—we can't have Al-Qaeda running around cooking up batches of stench soup, after all—but suffice it to say that the final product smells something like a putrescent corpse lying on a mound of human excrement laced with rotten eggs and overripe fruit. Only worse.

How She Knows It's The Worst: Dalton tested her smell on volunteers. That's right—for the sake of science, people signed waivers saying that, yes, they were about to whiff something mind-blowingly, paint-peelingly hideous. Happily, all of the volunteers completed the study uninjured; Dalton says that it's very unusual for a smell, no matter how bad, to cause actual physical harm.

Why People Love Stench Soup: Once completed, stench soup got a lot of press—and a surprisingly enthusiastic responses. After reading about her creation, hundreds of people wrote and called Dalton to tell her about the God-awful smells that only she, as an expert, would appreciate.

Unsolicited "discoveries" shared with Dalton:
Burning cat poop (This person confided that, in the spirit of discovery, she had actually put her cat's poop on a lit barbeque.)
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Five pounds of raw shrimp left in a vacation home over the winter
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The fluid excreted by a dog's anal glands
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"My mother's basement"
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The socks and underwear of a guy named Gary. Wrote a friend of Gary: "All you would have to do is throw a pair of his socks in the Taliban caves in Afghanistan and I promise you they would come running out."

(For the record, last year Dalton told The Times of London that her favorite smell was diesel exhaust.)