Does the 5 second rule really work?

We're on constant alert making sure the food we eat is safe: reading labels, monitoring food recalls, and avoiding restaurants with E. coli outbreaks. So why do we place so much faith in The 5 Second Rule?

Is it even scientifically sound? Food science professor Dr. Paul Dawson, who conducted the only 5 second rule study ever published, has weighed in. And like most things: it depends.

When the researchers dropped bread and bologna on the floor, it didn't matter how long they were in contact with the floor. They picked up bacteria. However, there were two factors that did matter in how contaminated the makings of the sandwich got.

First, how dirty the patch of floor was: the more bacteria on the floor, the more that was immediately transferred to the food. So it's not how long it's there, it's how infected the surface is.

And second, the type of surface. Looks like maybe you should install that shag carpet in your kitchen. Dawson writes "When carpet was inoculated with salmonella, less than 1% of the bacteria were transferred. But when the food was in contact with tile or wood, 48-70% of bacteria transferred."

So "The 5 Second Rule" is out. Maybe you think it's been replaced with "The Clean Carpet Rule." But why risk it?