Ever since Moses came down from Sinai with the stone tablet bearing the five-second rule, humankind has known that any food item dropped on the floor can still be placed in the mouth, provided it has been on the floor for less than one 12th of a minute.
Of course, there are still apostates who hold that floors are ritually unclean, and any timespan unsafe. Then there are those who are just happy to take their chances. But lately, scientists have been trying to get in on the act. And, much like Copernicus’s pesky observations about the rotation of the planets, their work is upending the ancient cosmology of buttered toast.
This week, Anthony Hilton, professor of applied microbiology at Aston University, will tell The Big Bang Fair in Birmingham that there may be variance between classes of object. That the likes of sandwiches, crisps, dry toast and biscuits can all be given a half-hour chillax on the floor, with no harm done. But sweets, cooked pasta and doughnuts still adhere to the five-second marker. He has also found that tiled surfaces are dirtier than carpets.
As astonishing as these findings are for the way humanity understands pasta spillage, the more amazing fact is that looking into the five-second rule has become something of a cottage industry in modern times.
In 2003, Jillian Clarke of the University of Illinois, established the power of the five-second rule to excite media attention when she showed that rough tiles would lead to the transfer of more bacteria to gummy bears dropped for five seconds than smooth ones. In 2006, Rutgers University concluded that the rule was a “significant oversimplification”. In 2007, Paul Dawson of Clemson University concluded in the Journal of Applied Microbiology that the dirtiness of the floor is much more important than how long the food lies there. Dawson also agreed that carpet beat tiles massively – with 1% contamination to 70%. In 2014, Aston University announced, to the sound of Nobel prizes thudding on its doorstep, that while contamination was generally instant, the load increased exponentially in the period from three to 30 seconds after landing.
All of which is fascinating if you’ve had a large sedative and three whiskies. But more broadly, it seems more like a canny symbiosis between researchers looking to get otherwise dry findings to a wider audience and headline-writers looking to sex-up otherwise dry findings.
The biggest story never told in five-second rule headlines is that it doesn’t matter either way. While cross-contamination remains a leading cause of food poisoning – the use of unwashed knives that have cut raw chicken for cutting vegetables, for instance – good food landing on a good-enough floor has seldom harmed anyone.
Hilton’s study covered typical floor types in bacteria, but found that dropped food picked up no more than 0.0004% of it.
Is the five-second rule dead, then? As the great monotheisms have already found, it takes more than a few dabs of science to kill off our deep desire to believe.
