I had always thought the “five-second rule” was a guy-thing that women disdained, until reading this:
A COUPLE of weeks ago I saw a new scientific paper from Clemson University that struck me as both pioneering and hilarious.
Accompanied by six graphs, two tables and equations whose terms include “bologna” and “carpet,” it’s a thorough microbiological study of the five-second rule: the idea that if you pick up a dropped piece of food before you can count to five, it’s O.K. to eat it.
I learned from the Clemson study that the true pioneer of five-second research was Jillian Clarke, a high-school intern at the University of Illinois in 2003.
Ms. Clarke conducted a survey and found that slightly more than half of the men and 70 percent of the women knew of the five-second rule, and many said they followed it.
On surfaces that had been contaminated eight hours earlier, slices of bologna and bread left for five seconds took up from 150 to 8,000 bacteria. Left for a full minute, slices collected about 10 times more than that from the tile and carpet, though a lower number from the wood.
What do these numbers tell us about the five-second rule? Quick retrieval does mean fewer bacteria, but it’s no guarantee of safety.
True, Jillian Clarke found that the number of bacteria on the floor at the University of Illinois was so low it couldn’t be measured, and the Clemson researchers resorted to extremely high contamination levels for their tests.
But even if a floor — or a countertop, or wrapper — carried only a thousandth the number of bacteria applied by the researchers, the piece of food would be likely to pick up several bacteria.
The infectious dose, the smallest number of bacteria that can actually cause illness, is as few as 10 for some salmonellas, fewer than 100 for the deadly strain of E. coli.
Of course we can never know for sure how many harmful microbes there are on any surface.
But we know enough now to formulate the five-second rule, version 2.0:
If you drop a piece of food, pick it up quickly, take five seconds to recall that just a few bacteria can make you sick, then take a few more to think about where you dropped it and whether or not it’s worth eating.