That Dropped Doughnut: How Soon, and How Often, Will It Come Back Up?

By Monica Hesse
Washington Post Staff Writer
Sunday, July 8, 2007

Last month, scientists at Clemson University in South Carolina determined that applying the five-second rule to dropped food will not actually prevent the food from gathering bacteria.

The nation's reaction to this: Duh.

The five-second rule. If you've never heard of it, ask any sixth-grader. "It means that if you drop something on the ground, you can still eat it if you pick it up in five seconds," says Kiara Hopkins, 11.

"God made dirt and dirt don't hurt," elaborates Christopher Evans, 13. "But after five seconds, it's nasty."

Imperative to the rule's effectiveness, Kiara and Christopher say, is yelling out, "FIVE-SECOND RULE!" as soon as an item has touched the ground. It is also acceptable for a friend to yell it on your behalf.

It would seem that the Clemson research would be the death of the five-second rule. But such thinking would be based on the notion that the five-second rule is like any other rule, bound by the rule-like constraints of practicality and public good. It is not. The beauty of the five-second rule is that it is utterly pliable and that it is not about food so much as it is about yearning and disgust and gastronomic history and evolutionary wiring and the implicit social contract we make when we break (and drop) bread with other human beings.

Following the rule requires understanding its intricacies. "I would never eat a pickle," says Anaiah Grissom, 9, "not even after one second." She also would not eat a hot dog, a burger or a piece of broccoli, because those get dirty really fast. A Chips Ahoy, according to Anaiah, can last up to 15 seconds, and Pop-Tarts, like, never get dirty.

Indoor floors are better than outdoors, but grass is better than carpet.

The tastier the treat, the longer it can be left on the floor. Cake tastes better than cookies, though, and gets germy before cookies. You can almost never use the five-second rule on cake. Parents will, however, employ it on any foodstuff with a high per-pound price. You pick that up and eat it! You know how much that cost?

If you spend your last dollar on something, the germs will give you a break and leave it alone for an extra 10 seconds, or until you can pick it back up.

Okay, Anaiah, but here's an important question. Pretend your friends aren't around. Pretend your mom's not going to read this. Is the five-second rule true? Does it really take five seconds for germs to grow?

"Nah. It's just what you say."


The purpose of the five-second rule is not to protect you from bacteria but from ridicule. It's shorthand for, "I know what I'm doing is gross, but citing this rule will allow me to eat this brownie and you to pretend there is justification for me eating this brownie." When invoked for someone else, it's an act of kindness: Go ahead. Eat it. I won't judge you. It's not just for children: In a 2003 survey conducted at the University of Illinois, 70 percent of women and 56 percent of men had knowledge of the rule.

"It's basically a way to make socially acceptable something we all kind of know is wrong," says Liz, a 30-something Washingtonian who also deems eating fuzzy M&M's out of pockets "totally okay." Liz would prefer her last name not be used for this article. When asked her profession, she whispers in embarrassment, "Public health generalist."

Liz should know better. We all should know better, really, considering that one in three Americans experiences a food-related illness each year. "We are all at risk," warns Paul Dawson, the author of the Clemson study, who has a Smokey Bear philosophy of preventing floor-eating. He cites the alarming rate at which salmonella can colonize on bread, bologna and unwrapped chewing gum. "There are a lot of high school kids working at fast-food restaurants," he says. "Do we really want them thinking the five-second rule is okay?"

Well, no.

But would that thinking necessarily be the end of humanity? Consider the results of another recent study, conducted at Connecticut College. Unlike Dawson's study, which measured how quickly bacteria could slather itself on food, the Connecticut research measured the likelihood of the slathering. Two biology majors spent a week dropping Skittles and apple slices in their cafeteria and concluded that it took an average of 30 to 60 seconds for bacteria to form on the food.

"That's not the point!" says Dawson. The average is irrelevant, he says. What matters is the fact that if food is dropped on a contaminated surface, it will gather bacteria faster than you can say "intestinal distress."

But that's not the point, either, is it? Eating off the floor is less about dirt and more about desire -- how much we are willing to deceive ourselves in the reckless pursuit of something forbidden. At the Monell Chemical Senses Center in Philadelphia, researchers induce cravings in study subjects by putting the human guinea pigs on a strict diet of nutritionally complete Boost. Within a mere 36 hours, the subjects begin begging for the foods they are not allowed to eat. A close proximity to forbidden fruits (and cookies) makes the cravings even stronger, as does the belief that the desired food is in limited supply. Dropping the last Oreo from the bag onto the ground creates a miasma of yearning:

1) We're not "allowed" to eat it;

2) But there's only one left;

3) And it's right there, taunting us.

We may scramble frantically under the couch, emerging minutes later with a dusty cookie and proclaiming "347-second rule!"

Wanting to believe that something is "still good!" is not, after all, restricted to things we eat. In life, the five-second rule translates into hanging on to rotten boyfriends long after we know the relationship has spoiled or suffering from the misguided notion that pregnancies can't occur if the contact is brief enough. Believing in the five-second rule requires an appreciation for risk, as well as an equal combination of naive optimism and self-loathing -- hoping for the best but willing to admit you deserve the worst, should the worst involve salmonella.

* * *

A brief history of floor-snacking:

Some folklorists have cited the five-second rule as an invention of Genghis Khan (who supposedly called it the 20-hour rule), but there's no proof. Medieval etiquette books make no prohibition against eating off the floor; in fact, it was standard practice to hoist a chicken leg up from the dirt. Julia Child also may be responsible, for her cheery rescue of haute cuisine from the kitchen linoleum. Not until the advent of modern germ theory in the late 19th century did eating off the floor become taboo.

But according to Thomas Shipley, a "food psychologist" at Temple University, the ability to assess food risk is biologically built into our makeup: "Disgust is basically an evolutionary health code," says Shipley. "We know we shouldn't eat gravel, for example, but the thought of it doesn't make us gag the way that [a] cockroach walking across our mashed potatoes does."

But why, instead of privately using our primate judgment to suss out which foods are gross, do we brandish the ones we want to eat for public support of their consumption.

"Eating has been a social activity for millennia," explains Shipley. "We've come to use each other's reactions to judge whether food is safe. If someone gags or makes a face, that tells you not to eat something."

And as for the rule's five-second precision? Brian Wansink, director of Cornell University's Food and Brand Lab, speculates that the time limit relates to human memory, how long we will recall that something dropped. "Much longer than five seconds and you start to forget the food was ever on your plate. It just looks like you're randomly eating off the floor," he says. Like we're dogs.

While it's one thing to rescue a recently fallen item, it's quite another to set up a five-course meal on the linoleum.

When we surveyed a group of eight nonprofit workers for their personal interpretations of the rule, most supported the theory behind Wansink's memory assessment. "I'll eat something off the floor as long as it's remained in my direct line of vision," says Sarah Schrag. "After that, it feels like it's been too long. Who knows what could have happened while I wasn't looking?"

But while the majority of Schrag's friends nod in agreement, Matthew Cole dissents. He has a more liberal definition of the five-second rule, solidified with a summer job he once held at a movie theater. "Sometimes when I'd be cleaning out a theater and I'd be really hungry," he says, "I'd eat a few Mike and Ikes off the floor."

A collective " ewwwww" rises from the lunch crew.

Cole shrugs. "What can I say? I never got sick."

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