IStock Photo 8874440 © DenGuy

In Germany circa 1812, a Dr. Justinus Kerner—a physician and poet—began to notice an unusual phenomenon. Dozens of villagers (76 by Kerner's count) in the town of Welzheim were coming down with a mysterious illness. Its first symptom was facial paralysis, especially difficulty blinking and swallowing. Then came gradual paralysis of the limbs, trunk, and at last, fatally, the respiratory system. The culprit appeared to be smoked sausages, eaten after they had spoiled.

Calling the disease "sausage poison" or "fatty poison," Dr. Kerner published the first scientific study on the subject in 1817. Eighty years later, Belgian scientist Emile van Ermengem finally isolated a bacterium that caused this disease from a piece of spoiled ham. By that time, the disease had already been given a name, derived from botulus, the Latin for "sausage": botulism.

Today, the botulinum toxin is widely known for two reasons. It is the most toxic substance known to mankind (millions of times deadlier than cyanide), and it is used in the most common cosmetic surgery: the Botox injection. In 2007 alone, 4.6 million Botox procedures were performed. Botox is so popular that even teenagers are getting it: the odds a teenager 13 - 19 will have Botox in a year are 1 in 2,671.

Botulinum toxin, a protein emitted by the bacterium Clostridium botulinum, is a marvel of toxicity. It is estimated to be lethal at doses as low as one nanogram per kilogram when injected. That's one billionth of a gram (0.000000001 g) per kilogram of bodyweight. However, the most common way by far to get botulism isn't injection but ingestion. Produced by the bacteria in airless environments like soil or unpreserved foods, the paralyzing toxin when ingested blocks the body's release of acetylcholine, the neurotransmitter that activates our muscles. Early symptoms of botulism are double vision, slurred speech, and difficulty vocalizing or swallowing, followed by facial paralysis and difficulty walking. Without treatment, botulism in adults leads to nearly certain death.

Fortunately, botulism is very rare in adults. The odds a person will be diagnosed with food-borne botulism in a year are 1 in 14,970,000, and the odds a person will die of it are even smaller: 1 in 66,950,000. Advances in food preservation, like refrigeration and pasteurization, prevent most adults from contracting botulism.

If you do contract botulism, what keeps you from dying? That comfort of comforts, an antidote (antitoxin, really). Several forms exist, and most local health departments carry them, not to mention the National Strategic Stockpile, which carries 200,000 doses in case of biological terrorism.

With the toxin’s virulence so well established, what could possess a human to actively pursue being injected with the end-all-be-all of poisons? Often, negative symptoms suggest positive applications. Consider antivenin and radiation therapy. Both derive from highly pernicious stuff—snake venom and radioactive elements—and yet are used for quite positive treatments. Thus with botulinum toxin.

In fact, the first person to suggest the positive use of the toxin was none other than Dr. Justinus Kerner. Early on he saw the value in such a powerful paralyzing agent, though it wasn’t until 1953 that Dr. Vernon Brooks discovered that injecting a tiny amount of botulinum toxin into a fluttering muscle temporarily relaxes it (i.e. paralyzes it). Then Alan Scott, a San Francisco ophthalmologist, tested small localized injections of the toxin on monkeys (in the 1960's) and humans (in the 1970's) and found that it "appears to be a safe and useful therapy for strabismus" (crossed eyes), an overactive-muscle disorder. By the end of the 1980's, the prescription drug company Allergan had purchased the right to sell Scott's ocular-botulinum therapy, absorbed his company, and given the drug a name: Botox.

Through the 1990's, medical researchers discovered countless new uses for such a powerful paralytic, treating everything from writer's cramp to excessive sweating to migraines to bladder spasms. But 1992 was the year of Botox's birth as a form of cosmetic surgery. That was the year ophthalmologist Jean Carruthers reported that her patients, injected with Botox for strabismus, ended up with noticeably fewer wrinkles around the eyes. The rest is history. Today, Botox injections are the most popular form of cosmetic surgery, having jumped from 1 million procedures a year in 2000 to 4.6 million by 2007. They are so popular that Botox injections have overtopped breast augmentations, even in teens: the odds a teenager 13 - 19 who undergoes a cosmetic procedure will have Botox are 1 in 20.38, while the odds a teenager 13 - 19 who undergoes a cosmetic procedure will have breast augmentation are 1 in 21.39.

To date, total Botox sales exceed $1 billion, outweighing the combined costs of nearly every major botulism-tainted-product recall: the Bon Vivant vichysoisse soup recall of 1971 (cost to the FDA: $150,000), Castleberry's Food Inc.'s 2007 chili sauce recall (cost to Castleberry: $35 million), etc. And so far its use in cosmetic surgery has caused no fatalities: between 1989 and 2003, Botox resulted in the deaths of 28 people, none due to cosmetic use.

So while chemically botulinum toxin is the most toxic substance on Earth, statistically it is nowhere near the deadliest. Case in point: in a year, you're roughly 200 times likelier to choke to death on food (the odds are 1 in 343,300) than to get a fatal case of botulism from it.