Rutgers University study debunks the five-second rule

Research conducted by scientists at Rutgers University has debunked the popular “five-second rule,” which suggests that food dropped on the floor is safe to eat if picked up quickly. Laboratory studies measuring the transfer of the bacterium Enterobacter aerogenes found that contamination occurs almost instantaneously, within milliseconds of contact with a surface.

The study revealed that the primary factor influencing the speed and quantity of bacterial transfer is not the duration of contact, but rather the moisture content of the food. Wet or soft foods, such as watermelon, cream-filled desserts, or cooked pasta, absorb large amounts of microbes immediately. In contrast, dry foods like crackers or candy show a significantly lower rate of bacterial adhesion, though they are still not considered sterile.