The burger patty that slides off the plate, the ice cream treat that plops on the picnic table, the hot dog that rolls off the grill – conventional wisdom has it that you have five seconds to pick it up before it is contaminated. Fact or folklore?
"A dropped item is immediately contaminated and can't really be sanitized," said Jorge Parada, MD, MPH, FACP, FIDSA, medical director of the Infection Prevention and Control Program at Loyola University Health System in Maywood, Ill. "When it comes to folklore, the 'five-second rule' should be replaced with 'When in doubt, throw it out.' "
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All items that come into contact with a surface pick up bacteria (and dirt!). How much bacteria and what kind of microbes it pick up depends on the type of object that is dropped and the surface it is dropped on, he said.
"If you rinse off a dropped hot dog, you will probably greatly reduce the amount of contamination, but there will still be some amount of unwanted and potentially nonbeneficial bacteria on that hot dog," said Parada, who admits to employing the five-second rule on occasion. "Maybe the dropped item only picks up 1,000 bacteria but typically the innoculum, or amount of bacteria that is needed for most people to actually get infected, is 10,000 bacteria. Well, then the odds are that no harm will occur. But what if you have a more sensitive system, or you pick up a bacteria with a lower infectious dose? Then you are rolling the dice with your health or that of your loved one."
And using your own mouth to "clean off" a dropped baby pacifier?
"That is double dipping – you are exposing yourself to bacteria and you are adding your own bacteria to what first contaminated the dropped item. No one is spared anything with this move," Parada said.
Parada said there are degrees of risk of contamination. "So a potato chip dropped for a second on a rather clean table will both have little time to be contaminated and is likely to only pick up a miniscule amount of microbes – definitely a low risk," he said. On the other hand, food that lands on a potentially more contaminated spot – such as the floor – and stays there for a minute is going to pick up more bacteria and pose a greater risk.
This article originally appeared in MedicalExpress, part of the renowned Science X network and previously part of the Phys Org family of medical research publications.
