In a latest study, published online in Applied and Environmental Microbiology in September 2016, researchers from Rutgers University dropped four foods (watermelon, plain bread, buttered bread, and hard gummy candy) onto four surfaces (stainless steel, ceramic tile, wood, and carpet) that were contaminated with bacteria and then allowed to dry. They allowed the foods to stay in contact with the surface for four periods—less than one second, five seconds, 30 seconds, and 300 seconds (5 minutes). Each scenario was tested 20 times. Watermelon became most contaminated at all time intervals, while the fewest bacteria transferred to the gummy candy. Once again, carpet had the lowest transfer rates. The study’s conclusion: “Although we show that longer contact times result in more transfer, we also show that other factors including the nature of the food and the surface are of equal or greater importance. Some transfer takes place ‘instantaneously’ at times less than one second, disproving the 'five-second rule.' “
The bottom line is to use common sense. Although our gastrointestinal system is pretty efficient at killing off germs, you can never tell when a telltale salmonella bug is wandering around on the floor. Better safe than sorry. Make it the no-second