A Rule Worth Keeping?

Student guest post by Jay Watson

We've all been there at some point before: a hot summer day, your delicious ice cream cone or tasty treat, and that uneven sidewalk. After taking about ten steps away from the vendor, you mistakenly put your foot into a gigantic fault in the sidewalk and accidentally toss your tasty treat face-down into the pavement. For many of us, "what now?" is actually a deliberation of a bunch of different, yet seemingly important questions: Who is watching me? How hungry am I? How much did it cost? Does this thing look dirty? Can I salvage most of it? But perhaps what unites us all more than any of these ponderings is the underlying question that our clumsiness has begged numerous times before: "Is this thing safe to eat?"

The answer to this question (much like our own consideration as to whether or not we actually pick up that double fudge delight now complete with grit and germ topping) is that 'it depends.' Though all of us are probably familiar with the 5-second rule from elementary school days, in actuality, only a few have tested its validity with science. The first person to inquire about the topic was a senior high school student who was working through an internship at the University of Illinois in 2003 [3]. In her experiment, Jillian Clarke dropped gummi bears and fudge-striped cookies onto tiles of E. coli (with pre-established organism counts) to see how many microbes would be transferred in 5 seconds or less. The results of her experiments showed that organisms can be transferred within 5 seconds [5]. In addition, she dispersed surveys and found that significant proportions of people (70% of women and 56% of men) she sampled were guilty of pick-it-up behavior [1]. In order to further test this myth, researchers at Clemson University (using Salmonella as their organism and bread and bologna as their test food) used similar methods to test surfaces including tile, wood flooring, and nylon carpet. Among their findings, they discovered that the survival times for some of the organisms on each of the surfaces were several hours, even days [5]. Like Clarke, they also noted that organisms are definitely transferred to food items within five seconds, with actual counts increasing with an increasing duration of time (for instance, there was a notable ten-fold increase in bacteria between five seconds and one minute) [4].

Granted, minimal research has been done in this area, but with consideration of the outcomes of these few inquiries, and perhaps with a little bit of common sense, we might best leave anything that lands on something other than our tongue for the birds or for the trash. However, I believe that there's more to this matter than just how many germs or how fast they transfer. While many of us may have considered eating something off of the ground, it is less likely that we've considered eating it because it might be 'dirty.' Though it may sound like a ridiculous idea, perhaps there are more aspects to this issue than it would seem. While I'm certainly not promoting that we pick up garbage off the street and chow down, perhaps throwing out the 5-second rule wouldn't be in our best interest.

Why? Maybe we need a little more dirt; a little less antibacterial hand cream. According to Wikipedia, the hygiene hypothesis states that "the lack of early childhood exposures to infectious agents, symbiotic microorganisms, and parasites has increased our susceptibility to allergic diseases by modulating immune system development" [2]. Simply put, our immune systems may have gone awry because we've eliminated many of the challenges for it. This has several implications today: are we 'too' clean? Have we developed environments that disrupt our child's health? There are certainly others as well [6]. Many of these questions are definitely worth considering, but my point is that perhaps our immune systems need a little more in order to keep them in check. Now I would be the first to acknowledge that there are extenuating circumstances in all of this. After all, some floors (or any other germ-harboring surface for that matter) are dirtier than others; some materials are more absorbent and promote growth of organisms better, etc. Likewise, I'm not arguing that we should stop taking baths or eat our dinners off the floor. Common sense and a healthy lifestyle should by no means go by the wayside either. But next time, when you drop your lifesaver on the ground at work and run through that list of questions, you might consider whether or not "a little dirt don't hurt."

Works cited

[1] Clark, AS. 2006. Dry Floors Cleaner than Expected, but Existing Pathogens will Transfer. CBS News.

[2] Hygiene hypothesis. 2010. Wikipedia.

[3] Five-second rule. 2010. Wikipedia.

[4] Franko, M. Does the five second rule really work? 2010. HowStuffWorks, Inc.

[5] McGee, H. 2007. The Five-Second Rule Explored, or How Dirty is that Bologna? The New York Times.

[6] The Hygiene Hypothesis: Are Cleanlier lifestyles Causing More Allergies for Kids? 2007. Science Daily.

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Nice post - thanks. BTW - The Mythbuisters also did a segment about this.

Jay, I love this!

Back when I was an undergrad at a research-heavy university, we got used to having to pick pretty esoteric topics to explore, and as a result, nobody ready anybody else's stuff. You've managed to find something funny *and* serious, and to treat the subject with a respect that doesn't diminish its broad appeal.

If you ever decide to take it a step further, I would like to know if my kids are any safer because I only let them pick up dry things from dry surfaces within five seconds, and I insist they blow them off. Bologna? Never, no way, not under any circumstances. But an M&M? Fine with me, as long as it didn't land in a puddle.

This discussion reminds of a joke found among long-distance hikers, such as those attempting to hike the 2200-mile Appalachian Trail, AKA "thruhikers". People hiking just for the day are known as "day-hikers", and those hikers who do a portion of the trail are called "section-hikers".

Q:"How do you tell the difference between a day-hiker, a section-hiker and a thru-hiker?"

A: "Drop some M&M's on the trail--the day-hiker walks around them, the section-hiker picks them up and eats them, and the thruhiker gets down on hands and knees and looks for more."

I don't know the figures for day-hikers and section-hikers, but on average, about a third of thru-hikers have at least one episode of gastrointestinal illness on the trail...