Growing up, almost everyone has heard of the “5-second rule,” also known as the five “safe” seconds to pick your food up off of the floor while it’s still safe to eat.
Naturally, it’s too good to be true. No matter how fast you pick your fallen portion up off the floor, you’re picking up any given number of bacteria along with it.
Research by the Centers for Disease Control found that, “surface cross-contamination was the sixth most common contributing factor out of 32 in outbreaks of food-borne illnesses” (NY Times).
Donald Schaffner, a microbiologist and professor at Rutgers University said that, “the 5-second rule is a significant oversimplification of what actually happens when bacteria transfer from a surface to food… Bacteria can contaminate instantaneously” (Live Science).
Are different types of food more vulnerable?
Absolutely. Bacteria will cling to items with a high moisture rate. According to the Applied and Environmental Microbiology Journal, factors that influence the transfer of bacteria from surface to surface and have been shown to affect cross contamination rates are:
- The type of bacteria,
- The source and destination surfaces,
- Time postinoculation, and
- Moisture level
Put simply, bacteria will saturate items such as watermelon, other fruits or any “wet” foods more rapidly than they will attach to gummy candy, cookies or “dry” foods.
There is some truth to the 5-second rule, hence why it originated. Reduced contact time with any given surface corresponds with the amount of bacteria transferred. So the difference between 5 seconds and 5 minutes is significant when it comes to bacteria transfer. The longer the time in contact with the floor, the more “contaminated” the item is. There’s just no such thing as no bacteria transfer because the item was picked up in the first five seconds.
Does the type of surface matter?
According to the study at Rutgers University, “carpet had a very low rate of transmission of bacteria compared with tile and stainless steel; transfer rates from wood varied” (NY Times).
No matter the surface, bacteria will still be transferred.
So, to eat or not to eat before five-seconds? That one’s ultimately on you.
Montville, R., and D. W. Schaffner. “Inoculum Size Influences Bacterial Cross Contamination between Surfaces.” Applied and Environmental Microbiology 69.12 (2003): 7188–7193. PMC. Web. 23 Feb. 2017.
Mele, Christopher. “‘Five-Second Rule’ for Foods on Floor is Untrue, Study Finds.” The New York Times. Retrieved from https://www.nytimes.com/2016/09/20/science/five-second-rule.html?_r=0
Rettner, Rachael. “Still Good? 5-Second Rule a Myth, Study Finds.” Live Science. Retrieved from http://www.livescience.com/56158-5-second-rule-myth.html