When food falls, how safe is the five-second rule?

When a child’s cookie falls on the floor, a clock starts ticking in the minds of parents

(getty images)

It's been nine years since a high school intern at the University of Illinois dared question pop-culture convention and test the so-called "five-second rule'' - the one that says if food or utensils have been on the floor or ground for five seconds or less, they're probably safe from unseen ick.

That test found, however, that even after just a second or two, food on the floor can pick up thousands of potentially unfriendly germs.

Ever since, dozens of doctors and scientists have argued - on both sides - that the five-second rule is misguided. Some contend that parents should never give a child something to eat that's been on the floor. Others argue that 30 seconds or more should be the rule: dry food dropped on dry floors picks up far fewer germs than wet food and/or wet floors, they maintain, and generally takes longer to "attract'' germs.


While academics continue to duke it out, more than a few parents seem to have embraced the five-second rule. A recent San Diego State University survey asked 500 parents where they stood. Three hundred twenty-five, or 65 percent, said they practiced the five-second rule.

And in a lively recent exchange on, the amateur critics' site, more than 60 Boston-area people who identified themselves as parents of young children, aunts, uncles, nannies, or close friends of parents, debated the pros and cons of the five-second rule. With just three exceptions, they agreed it's OK to practice the five-second rule, with conditions.

Some of their kids aren't so sure, though.

"I know it's natural for parents to be concerned, but I tried to exercise common sense before,'' says Christine Christou, a marketing director in Boston with two young children.

"Before'' would be before Christou had her now-6-year-old son, who is a germaphobe.


"I still try to practice common sense with this germ issue,'' Christou says. "Avoid wet surfaces when it comes to food and the floor. But I don't go overboard with hand sanitizer or wipes. Common sense!''

As for her son, Christou says she doesn't know where or how his phobia started.

"A friend, a relative, another kid's parent. So far no one will 'fess up to putting this in his head,'' Christou says. "But you are bombarded with images in media, on TV, in film, that just show germs as being full of danger. And if you touch this or lick that who knows what could happen? And it does generate a paranoia in you that may or may not align with the facts.''

That paranoia peaked in the aftermath of the 2009 H1N1 flu scare. According to market analysts IBISWorld, hand sanitizer sales shot up by 200 percent in the United States, generating annual revenues of more than $190 million. The hand sanitizer market still continues to grow at a rate of more than 5 percent a year. Bottles of the stuff are everywhere - on teachers' desks, in dispensers outside restrooms, at malls, on key rings. Add to that the antibacterial wipes and soaps that fill store shelves, and it's no wonder that many young kids see germs as a dire threat.

"We're in therapy for this now,'' Christou says of her son, "because I don't want him to get worse, and I want him to enjoy his childhood and understand that germs are not all bad.''


Ashley Benner, 26, is one of the Yelp debaters who favors the five-second rule. But she says her three godchildren and their parents are definitely among those helping drive the hand sanitizer market.

Benner, a director at Brain Balance Achievement Centers for disabled children, and her husband are expecting their first child this summer. And they play very active roles in raising the godchildren.

"It's funny, we've spent the last seven years taking a really active role in their lives,'' Benner says. "They spend a lot of time at our house, overnight time, and we spend tons with them at their house. And I see the negative effects of them being clean all the time. If one of them breathes too heavy, it's Purell time! And yet they're sick a lot. My husband and I are not approaching this as though germs are the enemy. We're not doing it with our godchildren, and we won't do it with our child.''

Benner says that when her godchildren visit, if one of them drops food on the floor, she and her husband are quick to assure the child it's OK to pick the item up if it's dry and the floor is dry and apparently clean.

The children are so nervous about what "damaged'' food could do to them, they won't even eat a smushed sandwich because they worry about how it was smushed, Benner says.

"Look, if there's a dog hair stuck in it, or something like that, that's one thing,'' Benner says. "My godchildren's parents are so worried they could get sick. But we don't live in bubbles. The more we expose them in a controlled manner to germs, the better they can fight it off when they get older.''


Benner's attitude toward the five-second rule is the essence of an increasingly popular scientific theory called the "Hygiene Hypothesis,'' which says extremely clean environments may actually hinder the development of a mature and functioning immune system in very young children. Exposure to germs, the thinking goes, helps the body learn to defend itself properly.

Bill Hanage, a professor and microbiologist in Harvard University's School of Public Health, says he doesn't subscribe to any stringent theory when it comes to the five-second rule and other notions like it.

What parents should consider in that split second they are deciding whether to say "Pick it up'' or "Don't eat that!'' is that the average dry floor, especially hardwood and tile, does not harbor many bacteria, Hanage says.

"I simply encourage people to practice common sense, because there's an element of truth in [the five-second rule], but it's not something that can be boiled down to yes or no,'' says Hanage, father of a 2-year-old girl. "I would say if a floor is sticky and you drop food on it, probably a good idea not to eat it. Same goes for the food item: if it's sticky - peanut butter face down, for example - I wouldn't eat it or let my child eat it.''


James H. Burnett III can be reached at Follow him on Twitter @jamesburnett.