Published on Nov 25, 2008 
 
 Paul Dawson 
 
 Food Scientist, Clemson University 
 
 
 
 The five-second-rule is a popular belief that if you drop food on the floor and pick it up within five seconds, it won't be too germ laden to eat. It's not true and we've proven it, it's well, bologna. My name is Paul Dawson. I'm a food scientist at the food science and human nutrition department at Clemson University. 
 
 
 
 My students and I have researched the five-second-rule and published the results in the Journal of Applied Microbiology. We did this as a creative inquiry project to learn how research is done. That is, research begins with a simple idea or a question, experiment is then set up to test this idea or question, data is collected, and finally a conclusion is drawn based on what the data showed us about that original question. In the case of the five-second-rule we found that bacteria was transferred from tabletops and floors to the food within five seconds, that is the five second rule is not an accurate guide when it comes to eating food that has fallen on the floor. 
 
 
 
 My students have done other creative inquiry projects. Weve researched what happens when someone double-dips. You have probably seen it happen; someone dips a chip, takes a bite, and then dips a chip again. We have also researched what happens when someone drinks milk out of the carton. 
 
 
 
 Both projects showed that these activities are bad ideas when it comes to healthy eating and food safety. The experiments are not silly but are not only designed to teach students about food science, which is food safety, tasteness and freshness, but also about how research is done and how it affects our daily lives, even if it's about dropping food on the floor. Most of all Clemson's creative inquiry program is about looking deeper in the world around us, learning how to question the facts and assumptions, whether it be in the arts or the sciences. ||||| The controversial “five-second rule” — the one that lets us eat dropped food if it’s quickly scooped off the floor — is a bunch of boloney, according to Clemson University food scientist Paul Dawson, who stirred up the long-debated issue in this month’s National Geographic. 
 
 Though previous research has shown we may have up to a minute to rescue certain types of spilled food before it becomes contaminated, Dawson and his students made a strong case for the “zero-second rule.” They found that salmonella and other bacteria can live up to four weeks on dry surfaces and be immediately transferred to food. 
 
 (Chicago Tribune illustration by Michael Miner) 
 
 The zero-tolerance standard, however, conflicts with the findings of two Connecticut College student researchers who sprinkled apple slices and Skittles candies in the college dining hall and snack bar for five, 10, 30 and 60-second intervals. The apple slices picked up bacteria after one minute; nearly five minutes elapsed before the Skittles attracted any. 
 
 Then there were the University of Maine undergraduates who concluded that using the five-second-rule could reduce food waste and possibly improve children’s immune systems. 
 
 Still, most researchers agree that the critical thing is not time, but location. It’s OK to brush off the bagel that fell from the stroller onto the sidewalk and give it to your screaming child, for example, because the pavement is cleaner than the kitchen floor in terms of the types of germs that cause illnesses, said Dr. Harley Rotbart, a professor of microbiology and pediatric infectious diseases at the University of Colorado School of Medicine. 
 
 “The kitchen floor, however, is probably a zero-second zone because the bacteria from uncooked meat and chicken juices are more hazardous than the ‘soil’ bacteria outside,” said Rotbart. The bathroom floor is another zero-second zone because “it’s a great potential source of bacteria and shorter-lived viruses that can cause gastrointestinal illness if ingested,” said Rotbart, the author of “Germ Proof Your Kids.” 
 
 Ultimately, however, most people assess their risk according to how badly they want what has slipped through their fingers and whether anyone else is looking. Women are more likely to eat food that has been on the floor than men, while cookies and candy are much more likely to be picked up and eaten than cauliflower or broccoli, research shows. 
 
 Unfortunately, despite the distress it causes, there’s just no rescuing ice cream. 
 
 Related content: 
 
 The five-second rule is alive and well at Illinois same-day surgery centers, according to Associated Press Medical Writer Carla K. Johnson. "Medical staff were observed picking up items that had fallen to the floor and behaving as if they weren't contaminated by germs, according to state inspection reports." Here's the full story, "Illinois clinics cited over infection control." ||||| Though conventional wisdom says you have three to five seconds before a dropped substance becomes infested with germs, two Connecticut College student researchers have found that we actually have 30 seconds to pick up moist foods and more than a minute to pick up dry foods before they're contaminated with bacteria. 
 
 Apparently we have more time than we thought when it comes to retrieving and eating food that has been dropped on the floor, a favorite topic among Julie's Health Club readers. 
 
 The students set out to challenge previous research on the topic by Jillian Clarke of Chicago High School for Agricultural Sciences, who tested the theory several years ago for a college internship by dropping food items directly onto e-coli contaminated tiles. 
 
 "That's not representative of what really happens," said Connecticut College's Molly Goettsche, a cell and molecular biology major. 
 
 Trying to simulate everyday life, Goettsche and Nicole Moin dropped apple slices and Skittles candies in the Connecticut College dining hall and snack bar for five, 10, 30 and 60-second intervals. They also tested them after allowing five minutes to elapse and then searched for any rogue bacteria. 
 
 The researchers found no bacteria were present on the foods that had remained on the floor for 5, 10 or 30 seconds. The apple slices did pick up bacteria after one minute, however and the Skittles showed a bacterial presence after remaining on the floor for 5 minutes.
– The 5-second rule may or may not protect your stomach from nasty germs (here's a no, here's a yes), but it probably depends more on location than duration, writes Julie Deardorff, who rounds up recent studies and talks to scientists for her Health Club column in the Chicago Tribune. Kitchen and bathroom floors, for instance, are nasty places where a 0-second rule is wise. The sidewalk, on the other hand, is safer because it's less likely to harbor the germs that cause illness. A kitchen floor "is probably a zero-second zone because the bacteria from uncooked meat and chicken juices are more hazardous than the ‘soil’ bacteria outside,” says one medical expert on the subject. Ditto for a bathroom floor because "it’s a great potential source of bacteria and shorter-lived viruses that can cause gastrointestinal illness if ingested.”