We’ve all done it: dropped a piece of food on the floor and quickly scooped it up. Is it safe to eat? Folklore (but not science) has told us that if it’s been on the floor for less than five seconds, it’s okay to eat it.
A new study put that tradition to the test. It turns out that the type of floor, the type of food, and other factors impact the safety of this practice.
“Consuming food dropped on the floor still carries an infection risk as it very much depends on which bacteria are present on the floor at the time,” said Anthony Hilton, PhD, a professor of microbiology in the UK.
Dr. Hilton said the results of his study “will bring some light relief to those who have been employing the five-second rule for years, despite a general consensus that it is purely a myth.”
Dr. Hilton monitored the transfer of harmful bacteria from a variety of surfaces to toast, pasta, cookies, and a sticky sweet during contacts of three to 30 seconds. His team found that bacteria is least likely to transfer from carpeted surfaces and most likely to transfer from laminate or tiled surfaces to moist foods that make contact for more than five seconds.
“We have found evidence that transfer from indoor flooring surfaces is incredibly poor, with carpet actually posing the lowest risk of bacterial transfer onto dropped food,” Dr. Hilton said.