The 5-Second Rule

The other day, JoJo chucked his binky in one of his typical fits of pique.  Normally, I follow the 5-second rule, scoop it off the floor and plop it back into his mouth (in order to terminate his fit of pique, of course).  This time, though, his aim was true:*

After I plucked it out, Rick suggested running it through the dishwasher, but I knew that I could never give that pacifier to my son without making myself queasy.  I threw it out, which meant that JoJo's fit of pique matured into a full-blown tantrum.


Afterwards, I wondered whether my husband's blase attitude about "eau de toilette," or my laissez-faire one about food and binkies hitting the floor, could be justified by any data.  My go-to source for health information, Yo Gabba Gabba, seems to contradict my practice:

Brobee picks up his Melba toast in a scant 3 seconds, but already it's swarming with tiny, ugly germs.  The little monster learns that germs can make him sick, but sadly, not that Melba toast makes for a terribly tasteless snack.


Since YGG didn't include any references in its credits, I did a literature search, and there was indeed a published study on the "5-second rule."  The microbiologists gleefully painted floor tiles, wood and carpet with Salmonella typhi, the agent of typhoid fever, and then dropped bologna and bread on these surfaces for 5, 30 and 60 seconds.  They then made some poor undergraduate eat the samples and observed him for signs of illness.  Kidding!  They probably couldn't get that experiment past an institutional review board.  No, they simply cultured the food afterwards, and found that there was almost no difference in the bacterial contamination rates among the 5-, 30- and 60-second groups.  They did find that the colony counts were 10 to 100 times lower on the food that fell on the carpet, so think twice before yelling at your kids for snacking on the expensive Oriental rug.


Of course, most households aren't teeming with typhoid fever.  So how dirty are your floors?  The vaguely sinister Journal of Hygiene published a study of microbial contamination in over 200 homes in Surrey, England.  Investigators cultured over 60 sites in the bathroom, kitchen and living room.**  Bacteria was found on most surfaces, though the majority of isolates were not pathogens.  However, E. coli, which can make you sick if ingested, was found in two-thirds of all households.  In general, dry surfaces were rarely contaminated: kitchen and bathroom floors grew E. coli only 3-5% of the time.  Toilet water, as you might expect, had E. coli 16% of the time, though at surprisingly low colony counts.  The worst area?  The kitchen sink, which grew E. coli 19% of the time, with much higher colony counts than toilet water.  Dishcloths and drainers were almost as bad.


So what do I make of this data?  I think you can safely say that the 5-second rule has been debunked.  Fortunately, it turns out that the average household floor isn't that dirty, which means that the rule can be extended to 60 seconds!  I usually throw JoJo's binkies into the kitchen sink to wash, but I've learned that reusing his toilet-tainted pacifier would have been less likely to make him sick.  

If only I could get past the ick factor.


*True story, but the photo is a re-enactment.  I thought about taking a photo when it really happened, but let's just say the bowl was, er, not clean. Like all the other moms I know, I bring my toddler into the bathroom with me so he's not left screaming outside the door.  Don't worry, I threw away the second binky too.
**The participants were recruited from "ladies' social clubs," so you could argue that maybe the ladies were scrubbing down the house before the arrival of the research team.  The scientists thought ahead and paid repeat, surprise visits and found no significant difference in their culture results.