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January 2018

Fact or fiction: 5 second rule [series]

Written by Nicole Horne
Cleanliness and Hygiene

We’ve all come across a situation whereby our favourite treat takes a giant leap toward the floor we watch in what feels like slow motion. Do you (a) pick up your morsel and dust it off before popping it into your mouth? Or (b) pick up the morsel and chuck it into the bin?

Of course this topic has been highly debated over time, and many say that by picking up food and eating it in five seconds since coming into contact with the floor is perfectly fine. Honestly speaking, just having to write the previous sentence made me feel rather disgusted. This so-called “rule” does not put my mind to ease, and frankly speaking as a hygiene ambassador, knowing what kinds of germs lurk about and the fact that some of them can live on surfaces for up to 48 hours, does not make it feel okay to me.

What does research say?

Unsurprisingly, a lot of research has been done on this topic. In fact, then high school learner - and now 2004 Nobel prize winner - Jillian Clarke, under supervision of Meredith Agle, doctoral candidate (now Scientist in new product development for Rich Foods in New York) at the University of Illinois, conducted a study on the 5 second rule.  

In this study conducted, Clarke swabbed floors all around the University - from the lab, hallways, dormitories to the cafeteria. Surprisingly few microorganisms were found! Agle said "I think the floors were so clean, from a microbiological point of view, because floors are dry, and most pathogens like salmonella, listeria, or E. coli can't survive without moisture."

They tested this by placing cookies and gummi bears on sterile tiles with measured quantities of E. coli. In this instance, the transfer of germs before 5 seconds was apparent since they were dealing with a large amount of cells.

Further research on the 5 second rule echoed the above facts. Professor A. Hilton from Ashton University says “Eating food that has spent a few moments on the floor can never be entirely risk-free.” He also says it unlikely that harmful bacteria will be picked up from a few seconds spent on an indoor floor. 

Furthermore, as per experiments done on the 5 second rule, the American Society for Microbiology’s journal of Applied and Environmental Microbiology reports that while it is a fact that food comes into contact with bacteria the moment it lands on the floor; the longer it stays on the floor the more the more bacteria-laden the food morsel will become. The same is also said by 

Contamination of food and the 5 second rule: what it comes down to

According to studies done as per the above discussed, the transfer of bacteria comes down to a few variables: the type of floor surface (pun intended!), the type of food, and the length of time it spends on the floor. Since these three variables all play a role in food contamination, researchers all agree that the moment the food hits the ground, it instantly becomes contaminated. 

  • Floor surface: If the floor is wet or damp, it is more likely to attract germs, as bacteria thrives in moisture. Smooth surfaces such as tiles are also more likely to attract bacteria compared to rougher surfaces such as carpets.
  • Type of food: As with floor surfaces, foods that contain high levels of moisture such as watermelon has a higher transfer risk compared to drier foods such a cookies or gummi bears as mentioned above.
  • Length of time: Most importantly, as mentioned earlier; the moment that food comes into contact with surfaces, it is contaminated. The longer it is left on the floor, the more bacteria will be transferred to the surface of the food morsel.

What to keep in mind when it comes to food and floor surfaces

Since we know that bacteria thrive in moisture rich areas it is important to ensure that spills are mopped up as they occur. 

In a previous blog, “How often do you need to clean the office fridge?“  we talked about foodborne illnesses and how food can become contaminated during any stage of the disease-causing lifecycle and cause food-poisoning. Even though in the majority of cases, this isn’t always harmful; my motto is to rather be safe than sorry i.e. bin the dropped morsel.

What also needs to be kept in mind is that cross contamination occurs through various areas - you might have decided to make a cuppa after visiting the bathroom, and those germs are transported from the soles of your shoes to the kitchen floor. Ensure surfaces are regularly disinfected - and the same goes for countertops and other surfaces. 

Besides what is walked into floor areas, is also the risk of ill employees that cough or sneeze onto surfaces, and the spread of other germs and viruses than can also be picked up along with your last slice of pizza.

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Recommended blog post : 7 most common office germs (and how you catch them)

Nicole Horne

Nicole Horne

Nicole is a Digital Marketing Executive at Rentokil Initial Hygiene in Johannesburg. A self-proclaimed germaphobe, her love for hygienic environments and curiosity of all things “beneath the surface” fuels her enthusiasm for writing about the impact of germs in the workplace. She is passionate about creating awareness and sharing her knowledge on the impact of good hygiene practices. Follow Nicole on Twitter and LinkedIn for updates on the the good, the bad and the germy.

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