The Five-Second Rule
I don’t know who came up with the five second rule, but I love them and it’s been one of the guiding principles of my life. It’s saved me countless skittles, pieces of sushi, and bits of burrito innards. During college I even expanded the rule to include items in the trash as long as they were on the top and in a container.
The rule seems logical to me. Bacteria can’t be that fast, and they must need at least, like, ten seconds to climb onto my tater tot after it hits the floor. So I’m a bit dismayed to report that some Debbie-downers decided to research the five second rule (1). They spread a certain type of bacteria on a bunch of different surfaces and then dropped watermelon, bread, butter bread, and gummy candy on the surfaces. They picked them back up after different amounts of time, ranging from 1 to 300 seconds. And they found that bacteria can contaminate instantaneously! Longer intervals resulted in even more contamination, carpet contaminated less than harder surfaces, and wetter foods were contaminated at higher levels.
Science and the quest for knowledge are mostly good, I guess. But some sacred truths are best left to ignorance.
1. Longer Contact Times Increase Cross-Contamination of Enterobacter aerogenes from Surfaces to Food. Miranda, RC, Schaffner DW. Appl Environ Microbiol. 2016 Oct 14;82(21):6490-6496.