The Five-Second Rule Could Actually Apply, But Mostly Outdoors

The Five-Second Rule Could Actually Apply, But Mostly Outdoors

You probably knew the old “five-second rule”—dropped food can be safely picked up within five seconds—wasn’t scientific. But scientists have analysed it anyway. One tip to walk away with? Food dropped outside is far safer than dropped in your kitchen.

Photo by alexlane.

Health blogger Julie Deardroff takes on the studies and science around the five-second rule, and comes to a pretty common sense conclusion: we’re all far more likely to apply an “It’s still good” attitude to food we’re craving over food we should probably eat for our health. But in asking around about the various studies with conflicting results, Deardroff digs up two bits of advice that probably mess with your perception of Dropped Food Science (DFS):

… Most researchers agree that the critical thing is not time, but location. It’s OK to brush off the bagel that fell from the stroller onto the sidewalk and give it to your screaming child, for example, because the pavement is cleaner than the kitchen floor in terms of the types of germs that cause illnesses, said Dr. Harley Rotbart, a professor of microbiology and pediatric infectious diseases at the University of Colorado School of Medicine.

“The kitchen floor, however, is probably a zero-second zone because the bacteria from uncooked meat and chicken juices are more hazardous than the ‘soil’ bacteria outside,” said Rotbart. The bathroom floor is another zero-second zone because “it’s a great potential source of bacteria and shorter-lived viruses that can cause gastrointestinal illness if ingested,” said Rotbart, the author of “Germ Proof Your Kids.”

That makes sense, but it also flies in the face of what many of us learned from our parents about “outside germs” or the like.

What’s your own personal dropped food rule?

Julie’s Health Club: Debunking the five-second dropped food rule [Julie’s Health Club via woot! the blog]


  • Channel 9 show What’s Good For You, did a “experiment” a couple of years ago. They tested the same 3 foods being left on the ground for 3 seconds, 30 seconds and 3 minutes, a left one as a control.

    The results were that the 3 second, 30 second and 3 minute, all showed the same amount of germ growth, so they concluded that there was no safe period.

    BUT they never showed the control – probably because it showed the same growth and disproved their theory.

  • Speaking as someone who is in no way an expert or even remotely well educated on the matter, I would think outdoors would be safer mostly due to conditions killing bacteria. Floors indoors will tend to be a lot more consistent in temperature and hover within a comfortable range. Outdoor surfaces are exposed to a far wider range of temperatures more frequently, and have the Positive Power of Sunlight™ to further sterilise.

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