If I Drop It, Can I Still Eat It?

Dropped Ice CreamWe thought we knew the answer.  Dropped food would not collect fresh germs if picked up within 5 seconds (or 30 seconds or a minute, depending upon whose expertise you believed).  The rationale behind these rules was that it took a certain period of time for the germs from the floor or ground to multiply on that delicious Lady Godiva chocolate that you dropped and still crave.  Now, new research tells us that those pesky pathogens move faster than we previously gave them credit for. To beat them, we’d have to pick it up in no seconds.


Where did this bad news come from?  The work of food scientist Paul Dawson of Clemson University was highlighted in National Geographic Magazine recently, and here’s what the magazine said: “His research discovered that salmonella and other bacteria can survive up to four weeks on dry surfaces and transfer to food immediately upon contact.” 


But wait. Don’t despair.  Your chocolate tidbit may be edible after all if you want to accept the research results of two Connecticut College students. They sprinkled apple slices and Skittles candies in the college dining hall and snack bar.  It took the apple slices more than a minute to pick up bacteria, and it took the Skittles almost 5 minutes. 


Another scientist says we’re asking the wrong question.  It’s the location not the time that’s most important to consider.  Dr. Harley Rotbart, professor of microbiology and pediatric infectious diseases at the University of Colorado School of Medicine, says that the pavement has fewer germs that cause illnesses than the kitchen floor does; the kitchen floor may have bacteria from uncooked meat or poultry, and these are more likely to cause illness than the bacteria in outdoor soil.  In this same vein, Rotbart points out  that the bathroom floor should be classified as another zero-second zone because “it’s a potential source of bacteria and shorter-lived viruses that can cause gastrointestinal illness if ingested.”  He ought to know.  He’s the author of Germ Proof Your Kids.


If you consider Snopes.com the greatest judge of the validity of  “contemporary folk wisdom,” you might be wondering what the site’s verdict is.  Snopes basically agrees with Professor Dawson and says bluntly, “There is no 5-second rule.”  The site explains, “Bacteria and viruses grab on by contact, and even brief encounters of the split-second kind can be more than enough for them to claim a new home address.” However, Snopes also suggests that how fast and how many bacteria get transferred from one surface to another might be affected by a) how wet the edible item is; and b) how dirty the floor is.  This reasoning may explain why different researchers have gotten different answers when testing the 5-second rule.   


This burning question of the validity of the 5-second rule is one that Shelf Life Advice has gotten all fired up about once before (http://shelflifeadvice.com/content/5-second-rule-true). The last expert we quoted weighed in on the side of the 30-second rule. 


Perhaps you’re savoring that piece of chocolate right now, unperturbed about the bacteria or viruses you may be consuming.  After all, they don’t contain calories.  Moreover, there are about 100 billion germs in your mouth already and some 100 trillion in your intestinal tract. So why worry about a few more? 


However, when faced with a really tough decision about a dropped edible, you may want to consult Andy Wright’s helpful (and humorous) flow chart.  Wright suggest that you consider these questions:  “Was it sticky?”  and “Did the cat lick it?”




Chicago Tribune  “5-second rule? Try zero”
July 15, 2010, p.3


National Geographic Magazine  “Science: The Zero-Second Rule” 7/1/10 


Snopes.com “Five Second Helpings”


SFWEEKLYblogs   “”You Dropped Food on the Floor. Do You Eat It?”


The Germ Freak’s Guide to Outwitting Colds and Flu by Allison Janse and Ph.D. Charles Gerba , 2009.


Germ Proof You Kids: the Complete Guide to Protecting (without Overprotecting) Your Family from Infections by Harley A. Rotbart, 2007.


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